# Understand Dyno Data



## Snuffy

I recently purchased a Fantom dyno and am not clear on what it's actually telling me.

I've read through many of the threads dealing with motors and motor tuning and have Big Jims motor black book. 

I was hoping I could get some help understanding the information that is presented by not only my dyno but other models also.


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## DynoMoHum

Snuffy...

I'm not sure I can help you much... I have very limited experiance with Fantom dynos... 

I've got lots of experiance with the Robitronic Dyno, and a fair amount with the Competition Electronics dyno.

I'd love to understand the Fantom dyno better. Right now I'm quite confused by some of the numbers that people give from the Fantom. To me, they often seem to disagree significantly with both the CE TurboDyno and the Robitronic. I mean this in a very general way, because there is almost no way to directly compare the numbers from one dyno to another, perticularly when the dynos are differnt manufactures. In a general way I basicly always see the same thing when I compare dyno data on my Robi to the data I get from the CE TD. The numbers are a differnt, but the slope of the curves at least consistantly go in the same directions when you make changes to the motors being tested. 

If somone with a Fantom dyno could post some actual data that some of us non Fantom users could view, maybe we could get a better handle on what the differances are, and possibly figure out why they occur. If anyone does have Fantom data they'd like to share, I would be willing to put it up on one of my web pages... (basicly I have almost unlimited space, and bandwidth... at a low monthly fee that I pay out of my own pocket, it's a non comercial site, no banners or advertising) So... I'm offering a place to put it, all you'd have to do is get it to me... Hank is probably also willing to put up some data, but I can't speak for him...


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## Snuffy

I have some data. I try to save my pulls but don't allways. What are you looking for? The time based sheet? I don't really know what to send.

Also, I and possibly others would like to gain an understanding of what the CE and Robi numbers mean. They all spit out data, if you don't understand what the data means it's a useless tool. It was not my intention to limit this discussion to only the fantom dyno.


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## DynoMoHum

The single most common view I use is when showing the data in relation to AMP input. If the Fantom can display data in this format, I would like to see it for a few motors, with some explination of what type of springs and brushes are in the motor, etc...

What I was really thinking about is the actual data files that the Fantom surely must save. The Robitronic dyno saves two files, one is some sort of propritary data, and only the Robitronic dyno can read it (as far as I know). The Robi also saves a text file that can easly be read by almost any program such as Excel, Word, or any simple text editor. If the Fantom has some files simmilar to this, they could be posted somwere where others could download them, and then use some Fantom demo software to view them. (Assuming Fantom has demo software that allows people to view files).


As for dyno data in general... I feel peak numbers in general are not all that helpfull. At least not unless you have the surrounding data to put it all into perspective. Peak RPM in perticular is almost worthless, unless it has some indication of power/effciency that is being produced at that point. Even then, it's not of much value, except possibly to help choose gearing.

Somewhere Pat Collins (I think that's the name) has a pretty good general description of how to use a dyno. It's mainly focused on the Robitonic Dyno, but I beleive the principles he sites are pretty much universal. I'll see if I can find a refferance to it... it really is good reading.


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## Snuffy

Here's the data file from my Dyno. It's only readable by the Dyno software. It can be downloaded from http://www.deccosoftware.com/software/FactsII/Facts2-0199-CD.exe

Most of the motors should have comments assigned to them listing com size, brushes and springs but some of them don't.


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## DynoMoHum

There is a search facility here at Hobbytalk...

if you search for 'dyno data' there are quite a few topics simmilar to this one... one of them I starte contains the text that Pat Collins wrote that I spoke of earlier... it's about half way down on the following page...

http://www.hobbytalk.com/bbs1/showthread.php?s=&threadid=2424


I have never seen a whole lot of discussion about the Fantom. I think partly because Big Jim never really liked Fantom dynos, and I think some people may have felt intimidated and/or uncomfortable trying to discuss the Fantom here as a result. I for one really would like to understand the Fantom, because there are so many others that have them... At least I could have a reasonable chance of talking with Fantom users about motors if I understood their dyno data... So I'll take a look at the Fantom stuff you posted... 

rcavenger also just posted some stuff on the Monster Motor topic... so data is starting to apear now...


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## DynoMoHum

is there anyway to export data from the Fantom into a text file that Exel could read? 

I'm going to have to do some house cleaning on my lap top if I hope to install the decosoft program... it may be a while before I can acomplish this...


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## DynoMoHum

Ok... I downloaded and installed The Fantom Facts Machine software... I also downloaded and unziped a file called allData.abc, however when I attempt to open a file with the Facts Machine software, it doesn't see the file I unzipped...

WHat am I doing wrong?


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## DynoMoHum

Never mind... I think I figured it out...


So if I understand this correctly... all fantoms dyno data gets stored in this one file? Is there a way to create smaller files? like say you had 6 dyno runs that were all related and wanted to save them seperately so you could send them to someoene else to look at? 

Anyway... I'm starting to look at the data now... 

Thanks.


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## Snuffy

The windows version of the software doesn't allow that or I haven't found where it is in the program. I'm not sure about the dos version. I'll check on it.


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## DynoMoHum

Actually I think it is there... but it doesn't work in my demo mode...


The data sure does look a whole lot differnt then the data on the Robitronic dyno... I'm still trying to make heads or tails of it.


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## Guest

TMFU, 
You can save individual motors with the "File Transfer" button in the "Files" tab under "Individual Motor Test Maintenance & Viewer" button. It seems that the File Transfer saves the Files in the "Old" format. Then under "File" -> "File Converter", you can add the motor into the big list. With this info, you could export the motors you wanted to save separately, then rename your "allData.abc" to something else, and import the files you wanted into a new "allData.abc". That would allow you to send only the files you wanted to someone else. I know its a little convoluted, but it would work.


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## Guest

I compared all of Snuffy's motors to the Monster, and The monster does show to be better than any other motor that he has run, except for "RM". What does RM stand for? 

Now I'd really like to see the exact same motors run through a Robi and a Fantom. That would be interesting.

BTW, Snuffy, Thanks a Ton. I've been waiting a long time to view data from a Fantom.


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## DynoMoHum

Seperate issue/thing...

I've been trying to use the 'option' menu item 'post time based data to clipboard' so that I could transfer some of the data into excel... so far it keeps all I get is the same data over and over. That is, I can't seem to be able to get it to save the data I'm looking at to the clipboard, it just the only thing in the clipboard is for "2K2-08 1-1-02"... never seems to change... Is this because the demo version is cripled? or is it user error on my part? Which ever it is... can someone tell me how to do it, if it's possible from the demo version?

My ultimate goal is to view data in relation to amp draw... since that's what I'm most used to looking at...


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## DynoMoHum

Now I did something, and I no longer have anything in my clipboard... how do you get a perticular motor's data into the clipboard?


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## Snuffy

Mike, 
RM stands for Revenge of the Monster.


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## patcollins

Here it is, sorry I lost the spread sheet described at the bottom, I will work on making it again (computer virus hit me last year). 

The Robitronics dyno is a very nice piece of equipment and can be very useful to a knowledgeable user. The problem is that most people that I see using the Robitronics or any flywheel dyno for that matter just don’t know what to look for. Even the most experienced motor men can find themselves just staring blankly at a screen with tons of data not knowing what to do with it. Big Jim Greenemeyer prefers the Competition electronics dyno because it tells him the information he needs without the clutter of too much information. 

Many neophytes come on bulletin boards asking about the RPM of a motor, thinking this is what they need to know. Experienced racers try to tell them that is not really what to look for but they can relate to RPM the easiest. A semi-experienced racer knows it is power and not RPM that makes the car go, but many just look at the peak power produced which is only slightly better than asking what the RPM of a motor is. Most racers with the Robitronics dyno will tune their motor for the peak RPM, the maximum power, and the maximum torque numbers and total spin up time but do yourself a favor and don’t even look at these. They are next to useless believe it or not, more on this later. 

If you are new to the Robitronics dyno I recommend using the view data screen on the menu to look at your data. Its fairly hard to relate the graphs to actual performance, even for the most experienced motor tuner. 

I am going to limit the scope of this work to stock motors because they are what I have the most experience with. The most important thing about tuning a motor to perform on the track is actually knowing what you need the motor to do. Simply saying “I need a faster motor” can mean many different things. Often this statement doesn’t even have anything to do with RPM. By knowing what you need a motor to do you will have to approximate the amp draw of your motor in the situations that you feel that you need more power. If you constructed some type of speedometer you could work backwards and find the RPM range of the motor you also need more power, but I find that a good guesstimate will get the job done nicely. 

Here are my guesstimates for 6-cell stock touring car and offroad racing. If you feel that you need some more out of the corner punch try to increase the power at 25 amps. For more of a top end feel shoot for maximum power at 15 amps. For overall “goodness” of a motor look at the power at 20 amps. And also the average power between 15-25 amps is a good indicator of the motors performance on track. If you tune to these parameters and feel the motor is a little soft coming out of the corners bump them up a few amps and try again. I stress again the importance of tuning a motor for the range that you are going to run it. 

Now that I discussed what to look for when tuning a stock motor I am going to discuss the downfalls, shortcomings and quirks of the Robitronic dyno and its results. First lets discuss the peak power number and why it is not very important. Peak power is the power at one specific point in the power curve. When you are racing your motor is constantly changing RPM, even when going down a very long straight away. So you are probably lucky if you operate at one specific point 1/100th of the time it takes to make a lap. Secondly look at where peak power occurs, in stock motors running off 6 cells it is almost always at 35 amps give or take an amp. Just about the only time your stock motor draws this much current is when you peg the throttle coming off the line. In my experience in offroad and stock sedan a 20 amp average amp draw is fairly typical. 

Although I find the peak power number fairly useless, using it is not all that bad the next mistake is far worse. Tuning for the peak RPM is just about the worst mistake that a motor tuner can make. The flywheel dynos load is provided by the acceleration of the flywheel. When the flywheel has reached maximum RPM the load is very small because the acceleration is very small. The power required to keep a flywheel spinning at 30k RPM is only a few watts. However when a car reaches maximum speed there is rolling resistance between the tires and ground, wind resistance and mechanical resistance in the drive train holding the car back. One day I may design a flywheel dyno that also has some sort of braking resistance so it provides the best of both worlds. 

Spinup time can be somewhat useful in determining how quickly the motor can pass through its entire power band but it can also be quite misleading and I recommend that most people avoid using this number because its redundant if you use the power numbers to your fullest advantage. I say spin up time can be confusing because you can have two motors with virtually identical power bands where motor 1 takes 8.13 seconds total spin up time and motor 2 takes 5.84 seconds spin up time. (See the picture) You will notice that on motor 2 all of the extra time it took to spin up was at the very end of the power curve. Remember from before that it is impossible to get a motor in a car to operate in this range anyway, so this tells us that this extra spin up time reported by the dyno doesn’t mean a thing! You can check the elapsed time that it takes a motor to accelerate from a 30 amp draw to a 20 amp draw and use this number, but that is a fair amount of work and again it is redundant. 

To figure out how much total drag is on a car find out its speed and you can work backwards to get the RPM of the motor at this point. Then you can find out the wattage the motor puts out at this RPM and viola, that is the drag of your car at maximum speed. I have created a spreadsheet to calculate the rollout, the tire RPM and motor RPM using your car’s speed, tire diameter and gear ratio. (attached).


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## Snuffy

TMFU,

I think posting Time based data to the clipboard only works when you actually dyno a motor.


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## Dan the Man

I would really like to see this spreadsheet if you can find a copy. I was working on something similar... stymied for lack of data on drivetrain and rolling resistance. Drag is actually pretty easy, just pick Cd of 0.5 and area of 30 inches and it's pretty close.


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## Snuffy

TMFU, 
I stand corrected.

With the Save Time Based Data to the clipboard option checked, Open a motor test and go into the time based data. It is automaticly coppied to the clipboard. Just paste it into the program of choice.


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## DynoMoHum

Somehow I have 'un-selected' the save to clipboard option... and now I can't get it selected again... I even removed the program and instaled it again, and I can not get that menu item selected again...

Man... this really frustrates me... I got one set of data copied over and I can't get anymore... 

I have one question about the AMP curve... why is it not reasonably smooth? I would think that it should be smoother... On the Robi, the amp pull and all the other curves are much smoother. I can not think of a good reason for the amp input to have such pronounced changes. Does anyone know what causes this?


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## patcollins

TMFU

THe dyno not measuring fast enough would cause more pronounced steps in the curve, as well as a motor that arcs alot. I noticed on my Robi that if the motor isnt in the best of shape the curves were wiggly. 

Dan 

Here is an excel spreadsheet that I just made relating car speed to motor RPM, I threw a rollout and total gear ratio calculations in it for utility purposes too. Enjoy

PS had to zip it because this website dont allow xls files

Pat


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## patcollins

Dan some stuff I forgot

If you measure your cars topspeed you can then find the motors RPM using the spreadsheet. Now using your dyno (if its a Robitronics) you can find this RPM and the power associated with it and this power number will equal your losses. Its sort of the back door quick and dirty way of doing it but its much more accurate than guessing at some values.


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## Snuffy

TMFU,

What's your email address? I want to send you something that may help.


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## DynoMoHum

[email protected]

As for your dyno data... I sure wish I could view power, RPM, torque, and effciency all in relation to amp input... 

However I must say... if the Fantom is correct about your Monster, it sure does have some massive peak power...

I must say I am a bit skeptical... but that's my general nature I guess... I know my Monster doesn't show any kind of power like yours... at least not when I compare it to any other good motor I have... Your monster is has like 10% better peak power by the looks of it... I sure don't see that on my dyno... (neither one)


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## Snuffy

I have 3 monsters. The data I recorded was for the two lower motors.


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## Dan the Man

OK... Tire dia is usually more like 65mm, isn't it? ROAR rulebook says 63 min, Proline sells a 61.

Is that a typical rollout for a stock motor? Where would you gear a GM3?


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## patcollins

Oh I just stuffed numbers in it to make sure it worked, didnt pay any attention to what the numbers would be for.


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## DynoMoHum

The first thing I would do if I owned and Fantom and the Decosoft Fantom II software, is to demand that they add a view simmilar to this...











These are just the first two motors I compared like this... If the Fantom numbers are to be believed clearly there is a huge differance in where this power comes and at how efficently it's generated...


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## Guest

*Excel data to Clipboard*

TMFU, here is how to turn it back on...

I hope you like hacking...

Disclaimer: 
To anyone reading this: "If you don't feel that your computer skills are up to doing this, don't do it. You could really mess your computer up if you change or delete the wrong thing."

Press your Start button and go to "Run...". Type in "regedit". This will open the Registry Editor. Open the tree "HKEY_CURRENT_USER" -> "Software" -> "decCo SoftWare" -> "The Facts Machine II". If you click on the folder "The Facts Machine II", you will see a list of all the settings that are stored for the Application. Double click on the "Post Excel" and change its value to "1". It doesn't matter if that is 1 hex or 1 decimal (they are the same). 

Now my app copies all the time based data to the clipboard in Excel format.


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## DynoMoHum

Thanks for the tip Mike...

Let me comment a little about the graph I just posted. If you look at this, you can clearly see that bellow 26 amps(well it's not clear that 26 is the point... but trust me it is) but bellow that point the P2K2 motor shown hear is doing a much better job of putting out power then does the Monster(RM) shown. However above 26 amps, the Monster is kicking out the power at a much geater level. 

Based on this this data, the P2K2 motor would be a much better choice if you were racing in a Spec class or some other class where you were averaging less then 26 amps.

Conversly... if you were competing in a type of racing forced you to average greater then 26 amps to compete at a high level, then this Monster motor would be for you...

Now if you averaged exactly 26 amps during your race... it would be pretty much a matter of personal preferance as to wich motor you'd choose... The track would likely also dictate to you wether you'd gain most by having peak power(low RPM) or lite load power(high RPM). 

Either way... gearing becomes critical in getting the most out of the motor you'd choose.

Now... these are not my motors, and not my data... and quite frankly I have not seen the same kind of awesome peak power from my Monster... and/or my P2Ks and P2K2s do a much better job at producing peak power then this one does, if I tune them for it. That is... My own data doesn't back up this large skew in power output between these two types of motors.

I'm just trying to show how I would interpet Fantom data if I owned one... Your millage may vary...


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## DynoMoHum

Ok, here is Snuffy's Fantom data for two Revenge of the Monster motors, I've aranged it so that the data is all shown in relation to AMP input for both motors. I've used Excel to do this...

I'm pretty sure we are comparing apples to apples here since both motors have very simmilar RPM.

Based on this data, I personaly would be willing to say with out reservation that the motor labled here as RM-02 is by far the better motor of the two. If these were my motors and my dyno, I'd deffintlly go back to the drawing board on RM-03 and try to figure out just what is going on with it, and why it is so bad near it's peak RPM. Something really is causeing RM-03 to suffer badly bellow 32 amps. 

My guess is that both RM-2 and RM-3 would acclerate form 0 to 50% max RPM virtualy the same, but that RM-3 would lack all top end speed.

I have no clue at this point what would cause this type of behavior... perhaps a out of round commutator, or springs that were too soft??? I don't know.

I personaly have a very hard time seeing this obvious differance when I look at either of the two graphs that Fantom II software gives. I can kinda see the same thing on the Fantom's power graph if I look really closely and make my brain jump through hoops. But it gets kinda obscured by fact that the data in the Fantom graph is in relation to RPM. I basicly never use the RPM based graph on my Robitronic dyno for this reason.


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## DynoMoHum

Other interesting things about RM-02 and RM-03 from Snuffy's Fantom II...

If you look at the Peak numbers for these two motors these two motors, the are very simmilar. It's basicly impossible to see any significant differances in the peak numbers given for these two motors. This in my opion is a very good example of why PEAK numbers are worthless...

ALso... the Low Medium and High Power factors are quite simmilar, and I really don't understand these numbers and what they mean. Since I have not seen any documentation yet on how they come up with these numbers, I pretty much find them to be of dubious value. 

Input Power Factor, Output Power Factor, and Average Effciency... Does anyone know how they come up with these numbers or what they mean? At least with these numbers there are some significant differances between these two motors and that's a good sign.

One could assume that average effciency of 18% that is given for RM-03 is worse then the 25% figure given for RM-02 and with that assumption my assement of these two motors agrees with these two Fantom numbers.

What about Output Power Factor???? The Fantom is giving RM-03 a value of 102, and RM-02 a value of 93... Is lower better? or how can one interpet this???

Input Power Factor? I'm not sure I can even begin to guess how this number is used or caclulated.

Can anyone point me to documentation for these nubmers? Obviously IPF and OPF are used to calculate Average Efficency... but how do they come up with IPF and OPF? Do they just calculate the sum of all the input and output power nubmers collected during the dyno run or what?

How come the Low, Medium, and High Power factors don't seem to add up that way?

I'm confused by Fantom's numbers to say the least... Espeicaly when I view them as they relate to these two Monster motors that Snuffy has dynoed.


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## HOOPD1

The power factor numbers are calculated numbers that consider the input versus output at specific intervals.
I never look at the graphs as I think they are all worthless.
I have both software versions but I dont really like the windows stuff
The DOS version tells me everything I need to know,why make it complicated.
I find the user specified amp values to be the best way to sort out motors using the Fantom.


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## DynoMoHum

Is there somewhere to obtain the DOS software for the Fantom? I mean for download on the net? Or could someone send me a copy if that's ok?


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## HOOPD1

I can send you my copy as long as I get it back,send me your shipping address.


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## Snuffy

*More Data*

Here is some more data for those interested.

TMFU,

The graphs are very nice. I have one question. You said that you believe that RM02 is the better motor and I think I understand why but could you explain how you came to that conclusion?

Ultimately I'd like to be able to look at the data that my dyno spits out and be able to tell how the motor will perform on the track and what I may be able to do to tweak the motor to what I use it for. Right now I really have no clue as to what I should look at or what what I'm looking at means. The graphs do help. I'm going to try to make the graphs myself.

I found something in the software that's quite interesting today. If you graph more than one motor to compare in the software and right click in the graph area a window opens up displaying the peak values and the vlaues at the amp point you set in the options menu for each motor you are comparing. I think this will be very usfull when I understand just what everything means and how to use the info.


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## Snuffy

I almost forgot the motor data is an excel file.


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## DynoMoHum

Snuffy,

The reason I said that RM-02 was better then RM-03, is based on the fact that they both have nearly identical peak power, yet RM-02 maintains it's power out towards it's highes RPM output. RM-03 basicly falls off really badly as it's RPM reaches Maximum. The more I have looked at the RM-03, the more I feel it has some serious problems, I'm not sure exactly what is causing it to fall off (loos power) so badly as it aproachs max RPM.

I don't remember which one it is no, but it's either the Monster motor or the MOTOR TEST, but I bleive both of those are as good or better then RM-02, and One of them looks alot differnt then RM-02.


I'll try and describe better what I'm looking at and put it all in a web page... with the graph above and another graph or two.


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## DynoMoHum

Aside from all that....


I have observed something I find odd about the Fantom data that Snuffy has provided. If you look at the initial data for each of the motors, more offten then not, the motor with the highest inital RPM reading, also has the lowest initial Torque reading.... and of course the oposit is also true.. that is... more often then not the motor with the lowest initial RPM reading also has the highest initial torque reading..

That may seem to make some sense, if your thinking about the fact that High RPM motors ussualy do have low torque. However I don't beleive that really applys too the early RPM. 

Based on my basic knowlege of physics and torque, it would seem to me that a motor with high initial Torque would acclerate the flywheel much faster, and therefor achive higher RPM early on as the dyno does it's thing. Think of it like this... the torque is directly responsible for the accleration, so higher torque should mean higher RPM when checking the first reading. This would produce results that are pretty much just the oposit of what the Fantom seems to be showing in most of Snuffy's data.

I've looked at some of my Robitronic files, and the motors with high torque do indeed have higher RPM for the initial readings... this is what I would expect. It is also just the oposit of what appears in the Fantom data. I beleive this is very odd to say the least.

Further more... if your still thiniking I'm mistaken in my way of thinking... it seems that in Snuffys data, the motors with the highes maximum RPM also have very high Maximum Torque. This is really just the oposit of what I have seen in pretty much all of my motor testing...


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## Snuffy

TMFU,

I think your assesment of the Fantom dyno is right on target. I'm not sure if the software actually uses spool up time to caculate touque. Many times, I've seen it tell me motor A has more tourque than motor B, when motor B spools up faster. 

I'm beginning to think that that may be part of the reason I'm so confused about what it's telling me.


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## DynoMoHum

Well.... Total spool up time can be misleading, even if everything is being done correctly. Initial readings and final readings can change dramaticly over time, this is a direct result of how the power is distributed on a motor, and this will change significantly with normal tunning techniques such as spring changes, hood alignment, brushes, etc... 

However... if a motor constantly has higher torque then the one it's being compared to, then it had better reach any given RPM before the other motor... if it doesn't then in my opion something is wrong. When I say constantly, I mean from 0 to X RPM torque exceeds the other at every step along the way.

back to the idea that spoolup time is difficult at best to understand motor proformance... From my experiance Torque is rarely so straight forward that any given motor has the exact same shaped torque curve. One motor may start out with more torque then the other, and may very well finish with less toque. These same to motors may very well have the the same output power, but at any given moment the time to reach X RPM will be different... So it takes a person with a better mind then mine to figure it all out when you look at the numbers in realtion to time...

Looking at data in relation to RPM is much the same and I think it is also the same for the same types of reasons.... This is why I rarely look at spool up time or data in relation to RPM.


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## patcollins

Snuffy read my post again

The only way to get torque on a flywheel dyno is by using the change in RPM between two measurements and the amount of time that it took and you get the angular acceleration. Torque is then a product of the angular acceleration and inertia of the flywheel. Then once you have RPM cause it is measured directly, and torque you get power. 

Like I said in my original post spool up time can be misleading because the last 100 RPM can take over half of the spoolup time and on the track your motor will never be able to achieve this last 100 RPM anyway.

Oh and there were some questions of efficiency

efficiency is simply equal to power out divided by power in then multiplied by 100%

Power in = voltage*amps
Power out = angular velocity*angular torque


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## DynoMoHum

Pat, or anyone else for that matter... What is the actual formula for calculating torque from a flywheel?

At the following site...

http://www.land-and-sea.com/public/articles/kart_racer_dynamometer_article.htm

I found the following formula

Torque = JM * rpm per second / 9.551

where JM represents the Polar Moment of Inertia of our inertia dyno's flywheel.

Based on my knowlege of math, this is basicly a linere function . 

If my algerbra is correct, I could come up with the following formula to calculate 'JM' , when we know RPM per second and Torque.


JM = Torque * 9.551 / rpm per second

I used Delta RPM / .1 to come up with RPM per second from one Fantom data point to the next.

IF you use that formula and plug in the numbers that the Fantom has given for Snuffy's motors, the calculated value for 'JM' changes from one data point to the next. By my calculations sometimes the value I come up with changes by 10% or more from the average number. I think that it should remain constant... 

Can anyone confirm that these formulas are correct and/or double check what I have found with regard to the data that Snuffy's Fantom gave?


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## Snuffy

Doesn't the torque change depending on the RPM of a dc electric motor?
Wouldn't that change the value of JM from point to point? Or am I missing the point?


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## patcollins

JM is a physical property like weight and doesnt change unless your flywheel is falling apart while its being turned. 

Torque can be expressed in any number of units, mostly depending on what your JM is given in. It is easiest to use units of grams, meters...basic metric units without the prefixes. 

For angular acceleration you want to express it in units of radians per second. One revolution is equal to pi radians, where of course pi is 3.141592....... and for dimensional analysis radians per second is just expressed as 1/seconds. 

The equation for angular torque is expressed in most books by all greek letters so I will spell them out.

Tau=alpha*Iota
Tau is torque, alpha is angular acceleration, and Iota is inertia.

This is exactly equilivant to Newtons Law Force=mass * acceleration


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## DynoMoHum

Well.... near as I can tell the Fantom has some significant error in it. THe variation I speak of does not follow any easly seen pattern. I don't have any easy way to show you my data right now, or I'd post it. My best guess is that the erorr is somehow related to and error in sensing RPM and/or the time interval... Either that or the time intervals they post are not exact,... even so of the few dyno results I've looked at so far, some of the variation is in exsess of 15%. It really seems too large to be easily explainable.

To be fair... I currently have no ablity to check this same type of thing with my Robitronic data. This is because it is not easy to get the interval between data points. The data the Robi spits out is given every 100 RPM, and there is no time interval assoicated with it. It might be possible to kind see if the change in Torque is consistant with the power and RPM given... I don't know any easy way to figure it out. IF anyone else has ideas on how to check the Robi's data I'd give it a shot. Given that the Robi data is always so consistant , very smooth, and makes no sudden changes in direction I don't really expect any problems with it... but it would be good to double check it.


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## Snuffy

TMFU,

How are you making theese graphs? I've been trying to do it without much sucess. Could you post one of the Excel files that I can disect?


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## patcollins

TMFU time is recorded somewhere because there is a chart available that uses time as the X Axis. It doesnt necessarly need to be even time intervals, Im sure it is recorded in even time intervals somwhere and then the data is reduced and put into the format of points evey 100 RPM. 

The data needs to be taken much faster than it takes to complete one revolution at the highest RPM that the dyno will see for it to be accurate. If I were designing a dyno I would make sure that it sampled atleast 5 times in each of the flywheels quadrants (the sticker is 4 seperate sections) so lets say the fastest motor on the dyno would lay down 50,000 RPM that would be over 16,000 samples per second. So the information has to be "somewhere". 

I sold my RObi a while back because I just dont get to race enough to justify having a dyno but I have been thinking about buying a fantom or a CE just to play with and since they have good resale value I probably wouldnt loose anything.


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## DynoMoHum

Yeah, I'm sure internaly there is some record of the time interval. What I really meant is that the text file that the Robi produces dosen't include the time interval... so I can't use my formula too come up with 'JM' from the Robi data and verify any of the numbers the Robi is giving. I could get the numbers from the Robi by looking at some of the data screens the Robi is capable of, but this would be very tedious and prone to typos if I tried to do it on a big scale.

I've spent most of the weekend looking at this matter with the Fantom, I still haven't fully resolved it all, but at this point I have found no glaring errors as far as the Fantom is concerned.

I do think that fantom is doing some data smoothign or something however. Especialy with regards to the initial RPM and torque figures they give. I don't beleive these initial figures are accurate. When I calculate the initial torque with a constant 'JM' I always find the motor with the highest initial RPM also has the highsest initial torque. This is in stark contrast to what the Fantom reports for Torque at that point. However that should not be much of a problem in the grand scheem of things, but it is odd that Fantom seems to be fudging this data point.

The other large errors I appeared to be seeing, I think are related to realtively small errors in time and/or rpm measurmenet, and the largest errors occur at the highest RPMs, and at that point Torque is so low that the error becomes more or less insignificant. I'm still looking at this matter but it doesn't seem all that serious to me now.

I have also basicly come to the conclusion that the Fantom is not useing 'average RPM' to calculate power output. Either that or the figures they give are already averaged... I have yet to determin just how much of a issue this could be. The only thing I have to go by is the web page given previously that explains how dynos work. In that document it indicated that 'average RPM' should be used. I've only looked at this part of the puzle for a short time. At this point it does make some pretty serious diffreances in the reported power output, but it also seems rather consistant and at first glance it doesn't seem to make that much differance as long as you always caluclate it the same way.

I do see what appears to be a small bias toward higher RPM motors, but at this point the most I have seen is less then 1%. I have always figured that any dyno is going to easly have at least 1% error... so I'm not sure this is a big issue just yet. I'm still looking at it.

Does anyone know the actual figure that is used for 'JM' with the typical flywheel used on the fantom? Changing the 'JM' figure does effect the power curves rather significanty. I have yet to be able to reverse engineer this number with any degree of confidence. I have made an educated guess and started using a 'constant' number in my calculations. However I'd like to use the actual number if I could find it.


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## DynoMoHum

Back to looking at dyno output for the pupose of evaluating motors...

take a look at the following, it's a graph of two of Snuffy's best motors (in my opion). They are both monster motors. One is one he called RM-02 and the other is listed as MOTOR TEST.

I've used Mike Golden's "DynoViewer"(TM???) to display these two motors in relation to amp input.

Here's the graph...

http://www.wiltse.net/images/two_monsters.gif


I think the choice of these two motors is not a easy one to make. Motor one has peak power of 64 watts, and Motor 2 has a peak of 65 watts... advantage Motor 2... However Motor one only uses 29 amps to produce it's 64 watts, while Motor 2 uses 32 amps to produce it's 65 watt peak. Motor 1 puts out more power bellow 30 amps then Motor 2, and vica versa... I honestly do know know how to choose between these two motors. I think it's a very interesting study in motor choice especialy if your averaging 30 amps during your race. 

Anyone else have ideas on which of these motors is better? and why?


My guess is that Motor 1 had realitively light spring on it, realitive to Motor 2 that is... However it could be something else causing the lower RPM and higher effciency...


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## DynoMoHum

By the way... here is a graph made with Excel of the same two motors, in the same format (in relation to amp input). It took me a heck of a lot longer to make this graph then it did to use Mike's DynoViewer to view it...

http://www.wiltse.net/images/rm2_motor.gif

My graph is pretty nice, but Mike's dyno viewer is really slick.


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## Guest

Here is a link to the DynoViewer. 

I originally wrote it to compare gear ratios between 2 motors. The "Load From File" loads Robi .txt files, and the "Load From Clipboard" loads the Fantom's "Timed Based Data" from the clipboard. 

As it turns out this program works great for viewing Fantom data with relation to Amps.

This is Free software that I wrote. Anyone may use it as they like. Of course I will maitain the Copy Rights , but that doesn't mean much.


http://www.wiltse.net/zips/DynoViewer.zip


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## DynoMoHum

Mike's software really is pretty cool, espeicaly for viewing the Fantom stuff... His gearing change/viewer feature is something that the Robi doesn't have, so if your trying to figure out what happens if you gear things a certian way, his viewer does something that you can't do on the Robi or the Fantom as far as I can tell.

I'm still playing with his gear slider, in an effort to see just what the possiblitys might be in gearing a motor differntly to make better use of the power/effcinecy of a perticular motor. It's not always as cut and dry as one might think.


I put up Mike's viewer on my site just as a public service. The site Mike had been using didn't allow files bigger then 2M, and his package was just over that limit. He had to break it down into two or more items on the site he had been using, so I offered him a place to put it in one chunk... I certianly make no claims or warrantys to his stuff... (other then it seems to fill a need for some dyno users out there)


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## DynoMoHum

For what it's worth....

I was observing some of Big Jim's discussions on dynos recently. He appears to have clarified his comments about the Fantom giving High RPM motors favor over lower RPM motors. I don' t beleive I've ever seen him make the comments so clearly preiviously. Having read his recent comments, it seems it's likely the Power Factor numbers that he doesn't trust. 

At this point I would tend to agree. From what I have seen, the High, Medium, and Low power factor numbers seem odd at best. Mostly what I've observed about them is that there can be two differnt motors with clearly differnt power output when viewed in relation to amp input, yet the power factor numbers are nearly identical.

Does anyone have a clue as to how Fantom figures High, Medium, and Low power factors? My suspesion is that it's somehow relating power to RPM... If this is the case, then it would surely make a high RPM motor look best, that's just the nature of how things look in relation to RPM... Unless a motor is just pure junk...


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## DynoMoHum

I had an brief opertunity to do some testing on a Fantom dyno this weekend. Unfortunately I couldn't get the data directly on to my computer. I did write down some of the numbers that I thought might be most helpfull to me. 

I dynoed a EX-Street Spec motor that I know is a very good motor, and I also dynoed a Paradox handout motor that I know is a average at best stock motor. On the Fantom the EX-Spec motor did show up as being better then the Pardox, but only by 3% (based on peak power).

When I got home I dynoed the same two motors on my Robitronic dyno. On the Robi the Ex-StSpec motor shows 18% better peak power. This is with the 5 volt setting on the Robi.

I intend to run both these motors on the CE TurboDyno 45 tonight, to see what it says...


I find it extreemly stange that there is such a huge differance between the power output of these two motors when viewed on two different flywheel dynos. I could understand if one dyno was putting out slightly higher numbers but both motors showed the same level of increase... but when the differacne between the two motors goes from 3% on the Fanto to 18% on the Robi... makes me think that one of these dynos is not very accurate...

I did not do any on track testing with these motors to see what happend in that regard. That will have to be a future test. 

I can say that in the past I've always been able to back up my Robi data with on track proformance. I also have been able to see simmilar realitive proformance differances for motors when I dynoed them both on the Robi and the CE TD. So... that leads me to be more suspiscious of the Fantom then of the Robi... I will do more testing and keep you all informed of what I find.

I think I need a expert driver to run a EX-Spec motor and a Paradox... to get me some on track data...

Either way... I think something is very strange... I just don't know exactly what it is.


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## popsracer

*"DOG" Motors*

Hey guys;

I just curious what would cause one motor (everything being equal) to be a "DOG" and other to be a "ROCKET". I would think that the Armature would have more variables to cause this than the Can and Endbell to cause so much difference in performance between two identical motors.
Any thoughts on this (PLEASE don't tell me to do a search)

Thanks, Popracer


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## patcollins

pops I have found quite the opposite. The thing that matters most of course is the condition of the comutator and brushes but right after this is the proper alignment of the brushes in the endbell and that is what most people over look.


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## popsracer

*All the good stuff*

I have done ALL of the recommended tuning options to this motor and nothing seem to work. I have all of the tools needed to maintain and tune motors (except a Dyno) EVERYTHING is Aligned, broken in, seated and trued as per: Big Jim, Fantom & Trinity websites.

I suffered with this motor for several months of racing (P2K2) before trying another one in my car and what a difference. *Exact* same Motors tuned the *EXACT* same way in the *Exact* same car with the *Exact* same gearing.

That's why I am asking. Is there someway to tell in the package just by looking closly or is it just luck of the draw on motors.

Thanks, Popsracer


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## DynoMoHum

At some point all three play a role. Can, arm, and endbell. I honestly do not know which is more important. 

I do know this... I have one EPIC endbell that I can put on almost any EPIC arm/can combination and I often see 2 watts differance in the proformance vs. when I use a differnt endbell. 

I have tried to figure out just what makes this one endbell work so much better, but I can not figure it out. Once I realised this, I stoped trying to do extensive dyno testing of differnt model motors unless I could use the same endbell. I feel it's a unfair test if I use other endbells and then try and say... motor A is worse then motor B... 

I have also seen noticeable differances when exchanging only the can, or the arm in motors. I just don't have good data that I could say for sure how much your likely to see. I think if you have 5 motors and want ONE good motor you would systematicly take each component and test it aginst all the other components... find the best components and combine them to get one hot motor. This too could be problematic however... because at somepoint one can may work well with one arm, but not work well on another arm etc... I supose the same can be true for endbells...


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## DynoMoHum

IF you could trust the seller of the motor to provide accurate dyno results you could tell alot about a motor. However you often CAN NOT trust the dyno data given by some of the biggest names in RC motors. I'll try not to name any names... but company T used to use Robitronic dynos for their lables, now they use Fantom... I have NEVER seen a company T 'pro' motor with fully seated brushes.

I know for a fact that unless the brushes are fully seated, a dyno run means absolutely nothing. This is because the motor will run MUCH differntly once the brushes are fully seated.

Company T is not the only company I don't trust in this area... just an example of one...

If you find a small motor tunner, then you are much more likely to get a dyno lable you could trust... 

My general problem with even smaller motor tunners is this... What's the likely hood that I get a REALLY HOT motor from one of these guys? Arent't they very likely to keep the very best motors for themselves? and/or their sponsored drivers. I'm a natural born skeptic... so I like to tune my own motors, and I suspect I'm just as well off picking a motor randomly from a batch of un-touched motors directly from Japan.

Either way... never trust dyno data taken from a motor that is not fully broken in.


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## popsracer

*Exactly the answer I needed*

TMFU; (what does tmfu stand for?)

Thanks, Your response was what I was hoping someone would be able to provide. You just gave me another reason to buy a Dyno.
I had read somewhere awhile back that there was something to look for when selecting motors in the LHS's. But I wasn't into electric r/c then so I didn't save the information. 

Popsracer


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## DynoMoHum

TMFU stands for "The Man From Utopia"... my computer work station is named 'utopia'... and therefor I am from utopia... and a man... so...

I really should ask Hank to change my name. Too man people assume bad things about TMFU... One person was certian it has something to do with company 'T' and four letter words that are not very nice... It has nothing to do with RC or company T... It's a refferance to a obscure Frank Zappa album titled... 'The Man From Utopia'.


Even if you trust dyno lables... takes a fair amount of knowlege to interpet one... Most often all that is given are 'peak' numbers. Peak numbers are of minimal value by themselves... If I had to choose one single number that is most important I'd say EFFCIENCY. Many people would disagree with that... but my reasoning is this... Effciency is the only way to achive more POWER... if a motor is not effcient it will never use the input power effectively... Still... Effciency by itself is not all that usefull.


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## patcollins

If I was to pick a motor by using only one number it would be peak torque. 

I agree the best stocks that I have ever had were ones that were untouched. ESP sold me quite a few "tear down" motors without brushes springs etc. In the end they probably cost me a bit more but they were well worth it.


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## Guest

Greetings everyone,
I recently got a used robi dyno, and I would appreciate tips on what to look out for. 

I tried it on my race motor, a Tamiya "Super Modified 11T" (11x2 arm). Basically tested various timings. The odd thing about this motor is that the maximum power output reading as well as the RPMs stay more or less similar. Only when I up the timing, the efficiency goes down and the spool up time decreases. This happens till about 20 degrees. If I hit 24 degrees the spool up time goes down quite a bit. So I choose the timing with the best spool up time.

Whereas on my bashing 23x2, every time I up my timing the max effciency and max power actually goes up! But decided to hold back to run only 22 degrees.

I did not compare the other screens on my dyno because, frankly, the information is overloading me  

On the track though, the dyno seems to bear out. I get much better pick up (and I can gear up further) by picking the timing which gives me the best spool up time. Seems like the robi is a pretty good investment. 

Do appreciate you guys thoughts on this.

Thanks!

Regards,
Alvin


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## Rich Chang

*Re: All the good stuff*

A poorly aligned brush hood can drastically affect motor performance. And, with folks messing around with brush hoods, they have a higher risk of causing more harm than good.

Personally, I feel a lot of folks should not be messing with brush hood alignment. For the majority of Trinity based stock motors I have found them not to require as much brush hood alignment as Reedy based stock motors.

I've found on Epic based motors that just having the brush hoods in line with each other and centered to the comm that the motor works just fine in conjunction with the brushes properly broken in.

No need for anyone to tell me that having the brush hoods properly aligned gets max power out of the motor and that sometimes means they are not lined up with each other.

I am just saying that for the majority of club racers they do _not_ need to go through that lengthy process of messing with brush hoods.

I am a fairly experienced racer and an okay motor tuner (I tuned the motor that TQ'd stock touring car at the Cleveland Champs last year). I had a case where I adjusted the hoods on a motor where I thought the hoods were properly aligned. I threw the motor on the dyno and the power numbers were about 8 watts lower all around from where they should be and the over all motor stats just sucked. On a whim I used my rod and bar alignment tool in the motor, made everything parallel/in-line, threw the motor back on the CE dyno, and got 103 watts at 20 amps (7V fixed). 

Proper brush break-in is a lot more important. Too often I see folks just breaking in new brushes for 300 seconds. Sorry, the time for break-in depends on the type of brush (re: how hard the brush is). For the 767s I run, I have had to run the motor for over 1500 seconds at 3V before the brushes were completely broken in.

Anyways, Popsracer, if you aligned your brush hoods on the one doggy motor, I would start by aligning the brush hoods so they are in-line with each other and the bushings (hopefully you have a rod and bar type alignment tool), put new brushes in, break the brushes in, and see how the motor feels.

btw: not all motors can be geared the same -- even the same type of motor with the same brush/spring setup.

Anyways, those are just my opinions.

-Rich





popsracer said:


> *I have done ALL of the recommended tuning options to this motor and nothing seem to work. I have all of the tools needed to maintain and tune motors (except a Dyno) EVERYTHING is Aligned, broken in, seated and trued as per: Big Jim, Fantom & Trinity websites.
> 
> I suffered with this motor for several months of racing (P2K2) before trying another one in my car and what a difference. Exact same Motors tuned the EXACT same way in the Exact same car with the Exact same gearing.
> 
> That's why I am asking. Is there someway to tell in the package just by looking closly or is it just luck of the draw on motors.
> 
> Thanks, Popsracer *


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## DynoMoHum

For the most part I concur with Rich. My best motor/endbell is one that I never touched. It's one that came direct from Trinity with pretty good alignment, so I never fiddled with it. I have ruined as many bursh hoods as I have made better... I think I've gotten better at it after doing it 20 or 30 times... but still tweaking a brush hood can be a tricky thing. I have not really experiemented with in line with the arm shaft vs. wear marked down the center of the brush, but I have no reason to doubt Rich's experiance... I personaly know Rich... and what I know of him, gives me even less reason to doubt his experiances... (I also have no doubt that he's as good or better at tunning a motor then I am...)

I totaly agree with Rich's comments about gearing. Each motor is differnt, even between the same models. I've got data that I beleive proves conclusively that just changing springs on a motor can make the RPM change enough to warrant a gear change. This seems espeicaly true with todays high RPM motors like the GM3 and Revenge of the Monster.

All of this points me in the direction that a good dyno is a very usefull thing... but you must learn how to use it. You can acomplish the ultimate goal with on track testing, but in my opion that will be a VERY long procedure without some dyno data to help... depending on your driving and set up skills, you may never be able to relate motor proformance directly to on track proformance. Too many variables that can happan on the track... miss a turn by a inch or two, etc...

Back to hood alignment... one reason I have had doubts about using the wear mark down the center of a brush to determine ultimate hood alighment... What if the contour of the brush is not centered exactly when you start your hood alignment procedure? If the contour is not exactly centered on the bursh you start with, the wear mark would not be centered either. It would be VERY hard to verifiy if the contour of the brush is centered, without some really fancy equipment.


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## DynoMoHum

New findings on my quest to find out more about the Fantom dyno... 

I ran my Ex-Spec motor and the average Paradox motor on my CE TurboDyno last night. I never really quite found the Peak power output of the EX-Spec motor... I went as high as 40 amp load, and never found the motor to drop off in power. It had reached 106 watts at 40 amps, with voltage of 5 volts. The Paradox reached a peak power of 84 watts at 32 amps, 5 volts. So the differance in peak power on the CE is at least 26% in favor of the EX-Spec motor.

Review... The differance in peak power on the Fantom was about 3%... On the Robi the diff was 18%... both in favor of the Ex-Spec motor...

So... based on peak power alone all three of these dynos show the Ex-Spec motor with more power. That's a good sign... 

However I have serious concerns about the small margin of differance on the Fantom. I have stock motors that are at least 5% better then this Paradox. I have a very strong suspiscion that it would be very likely that a good stock motor may very well show up as being stronger then this Ex-Spec motor on this Fantom dyno. I am 100% certian that neither my Robi or my TurboDyno would ever find any stock motor that could exceed the power output of this Ex-Spec motor.

I beleive there is something wrong with the Fantom dyno... At the very least there is something very odd with it and the 'facts' it reports to it's users. If I get a chance I plan to investigate it further...


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## DynoMoHum

For anyone who is interested... I've made a web page with dyno data for this Pardox and Ex-Spec motor... It's got data I collected from a Fantom, my Robitronic, and my TurboDyno. I changed nothing at all on the motors between dyno runs... I have added commentary along with the data... I'd be happy to hear anyone's comments about what might be happening and why...

http://www.wiltse.net/facts.htm


If anyone knows how the High, Medium, and Low power factors are calculated on the Fantom I'd really like to hear about it... Based on this data... I can't make heads or tails of them.


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## popsracer

*Dog of a P2K2 Motor*

Rich Chang;

The P2K2 in question was a "Pro" version. I ran it one race and was not happy with the performance at all. I disassembled and inspected, decided to do all of the checks/maintenance that is normally done between race days.
The Hoods were aligned with a Stick through the hood only. I could not find the kind that goes through the bushings too, so i had to settle with the standard tool. The used Brushes look "Perfectly" aligned to the Com when examining wear marks. 
If I gear the motor for top speed at the end of the straight. There is NO punch in the corners. If I gear for punch, then top speed suffers.
What really told me that this motor is a DOG is when i replaced it with another P2k2 and applied the same tuning to it. The second motor is a rocket. Exact same type of motor, same tuning, gearing, everything. I suffered with this motor for several months of racing thinking that the problem lye elsewhere. NOW with just a motor change my car is competitive with the other cars in my class.

Thanks, Popsracer


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## Guest

I posted under the topic "Electric Motor Dyno help " how I understand the Fantom dyno calculates numbers. Post is too long to put here too.

When the "Fantom" was an "RSR" dyno many years ago, I sat down and calculated/reproduced the numbers for the dyno screen, so I'm pretty sure I did that right. The one number I was off a little on was the moment of inertia of the flywheel. It seems Fantom makes a correction to the flywheel inertia number for "earth torque," (i.e., the earth is also spinning) which I didn't have a value/calculation for.


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## DynoMoHum

I read your post on the other thread... I don't fully understand your comments about the power factors, but I kinda do... I started to assume they had something to do with RPM... but reading your discription it's not exactly directly related to that... Anyway... thanks for the comments your the first person that's commented about the Power Factors at all...

As for the Fantom's Torque numbers... at one point I was convinced that they some how calculate a 'realtive' torque... that is it sort of seems that they give each motor 100 (or 98) as the maximum torque which occurs at start up, and then torque reaches 0 at max RPM... This may be exactly what they are doing, I don't know for sure... I do know there torque numbers seem a little odd.

This is the first time I've heard of 'earth torque'...


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## Dan the Man

I think what the Fantom gets that others do not is the motor's own moment of inertia. I can see how a more lightly built ROM would look better than a P2K or whatever, even though the power curves at a more steady state would be equivalent (as we've seen). I'm not sure how well this will translate to car performance. A motor with a light arm and a small pinion might have less inertia but it has to get to a higher RPM to make power.


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## DynoMoHum

I am going back to the idea that the Fantom is comming up with Torque numbers that represent 'realtive' torque. Realitive to Maximum for that perticular motor.

At this point I went back to Snuffy's Fantom data... I looked at MOTOR TEST (a new Monster), and a motor listed as FRP2K-01. I've taken the data from the clipboard and pasted it to Mike Golden's DynoViewer... For both of these motors, torque starts out at more or less 95 and goes sperate ways from there... 

I bascily NEVER see this behavior with Robitronic Data... Especialy when you have two motors with such differnt max RPM. 

I am about 96% convinced that the Fantom is comming up with something that I would term 'realtive' torque. If this is true... then it would likely go a long way to explaining the behavior I was seeing with my Ex-Spec motor and my Paradox when I recently tested them on a Fantom.


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## patcollins

RWB the Correllieous (I think i mispelled it) force from the earth rotating is so small that it would be negligible. Anyways if it wasnt it would matter if your dyno was pointed north-south or east-west. And since we are taking a relative measurement anyway why would they include this? Nobody is racing out in space on a stationary platform.


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## Guest

Pat:

The explanation of the earth torque correction is directly from Dave C. himself, who wrote the program.


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## DynoMoHum

Latest findings on the Fantom 'Facts'...

I've figured out why the Fantom torque numbers seem to be inconsistant when trying to reverse engineer the value for 'JM' talked about earlier.
It seems that Fantom is using the acceleration numbers from the next time period to calculate torque for the present time period. That is...

If you look at the numbers for .1 second, the torque values for that interval are derived from the increase in RPM listed for the .2 second interval... the same is true for each time interval afterwords... 

As reported earlier Fantom also uses the current value of RPM in their 'power' calculation. From what I have read average RPM for the time interval should be used.

If you go through and caculate numbers for Torque and Power using the the average RPM and actual accelertation for the present interval, you tend to get higher output power numbers, and the effciecy numbers also increase as one might expect. The numbers start to resemble those that can often be seen on a Robitronic or TurboDyno.
(that is effciency starts to go up to at least 60% at it's peak for a good stock motor)

I have no idea why Fantom is doing what they are doing. Near as I can tell what they are doing is wrong. Based on Snuffy's Fantom data the error is not all that great when you compare it as it relates to potential differance between the most favored motor vs. the most handicaped one. Perhaps 1% at most on all of the stock motors Snuffy had given data for. It seems that this does favor higher RPM motors... I haven't figured out exacly what the worst case senerios would be, but I do know that any motor that has a sharply declining Torque slope will be handicaped by Fantom's methods. On the contrast a motor with a torque slope that doesn't decline as rapidly will tend to show slightly improved power numbers over much of that motor's power curve. As I say... I have no idea why Fantom would do this. I don't know if it's just a plain old mistake, or if they for some reason feel this is the right thing to do and have reasons for it...

I do know that the Competition Electronics TurboDyno that actualy measures Torque and can use fixed 5 volts for testing, does not agree with Fantom's methods and/or 'facts'. Personaly I would tend to beleive the TurboDyno's results more willingly, simply because there is very little that could be wrong with their method of determining power output and/or effciency. So... based on what I have seen, I can't help but think that Fantom is doing something wrong.

Now, I still haven't fully been able to explain what I'm seeing when I dynoed my EX-Spec motor and compared it to a average Paradox motor. At this point I can't prove with math that Fantom's 'Facts' would be off enought to cause the very small margin of differance seen on these two motors. I still don't have ALL the numbers from my Fantom test of these two motors, so I have been unable to do an extensive analysis of the dyno runs... I really do feel that it is very odd that the margin of differance on the Fantom is only 3% on these two motors, yet on the Robi and TurboDyno it is at least 18%... I really want to find out why.


Meanwhile... The way Fantom is doing things seems to discurage certian motor tuning techniques... It makes me wonder if people who use Fantom 'Facts' machines are tuning motors in ways that make them look better on a Fantom, but actualy are not living up to their true potential. This would seem to be especialy likely whith high torque motors like the P2K and even on other motors like the EX-Spec with it's realtively low timming... Things that ussualy make a high torque/low RPM motor run better, may show up as being a bad thing on a Fantom... This may account for one reason some companys seem to think their newest High RPM motors are somehow better then their older lower RPM motors... At best... I don't trust Fantom's Facts machine as much as I do either the Robitronic or the CE TurboDyno and I'm getting closer to figuring out exacly why...

I'll soon post my Excel spreadsheet that has some of the calculations and such that has lead me to the point I'm at now.


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## patcollins

RWB either they are feeding you a major load of BS or they have no idea what they are doing.


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## DynoMoHum

More and more I'm thinking maybe both are true when it comes to the Fantom Facts machine...

From what I've seen, I think the problems could be corrected fairly easily however... unless I find something further to question...


ALso...

RWB... I've tried to use your info on the Power Factor numbers to figure out how they are calculated. You may very well be on the right track, but at this point I've not come up with what I consider to be the actual method used to calculate high, medium, and low power factors that Fantom gives. I must say... these power factor numbers seem to be almost worthless, and quite possibly very misleading... I really wonder why they were included at all in the dyno output of the Fantom.


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## TeamGoodwrench

I have a question guys -- it seems that in scanning through this thread, there is a lot of negative comments about the Fantom dyno.

Yet, at our track, and at the recent ROAR Region 5 Oval championships, the Fantom was the ONLY dyno you saw there. NO others -- no Robotronic, no CS.

These guys are factory drivers and could have whatever they wanted. So why are they all -- 100% of them -- using Fantom dynos ???

Thanks for clearing this up


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## Guest

Pat:

I've sometimes wondered if there were some fish stories to some of that...

TMFU:

The low/mid/hi power numbers were somewhat useful when stock motors were "slower" (i.e., spin-up times of 3+ seconds??). One track we ran at years ago was a 100+ ft drag race with 180 degree turns at either end. You almost came to a complete stop before turning. In that case, you tried to get the low and mid range power numbers up (more or less just some guidance). Another track was so smooth and fast you just tickled the throttle to set the chassis (if you lifted at all). People were always looking to maximize the hi power range numer for that track. In these cases, the power range numbers were easier to understand that trying to figure out spinup times or portions of spinup times (which the program doesn't calculate). If you look at these as guidance numbers, rather than absolute numbers, they do ok. Perhaps these numbers are now outdated if most people today have a better understanding of power bands and how to tune within/to a given power range.

There's something else you can do with Fantom that you can't (at least I haven't figured out how to) do with the CE. If you look at the tail of the RPM vs time (??, it's been a while since I've done this, but I think that's the right screen) curve, it should be smooth. If it has bumps, its's a good indication that there is brush bounce, need higher pressure springs or smoother comm. So again, this is great for 5 volts, and if they do convert to 7 volts, this could also be a useful indicator for 6 cell.


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## Rich Chang

I'm not an oval racer but I'm pretty sure Oval racers primarily care about RPMs? 

From what I have found (like what Glenn said) RPM motors look much better on the Fantom dyno. Torque motors look better on the CE dyno. That is my experience (and it was tested many times this past weekend at the US Indoor Champs at Cleveland).

So, the Fantom dyno seems much better for Oval racing than a CE dyno would be.

However, as long as you know how to use the data and gear accordingly, one can win with either dyno.

-Rich


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## PizzaDude

Teamgoodwrench,

From what I understand at this time is that the problem is that Dyno and Pat just can't see the logic in the Facts numbers. (BTW I don't either).

That's the reason why they are discussing this.
They are testing and trying to figure this out.
Someone who's just bashing, wouldn't go through that much trouble.

But Teamgoodwrench, maybe you can shed some light on this item.
Can you explain these numbers?

Or maybe you know someone who could respond to this thread and shed some light on matters.
Participate in the discussion!


Regards,
Pizza


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## TeamGoodwrench

Thanks for the posts!

I just got a Fantom, so I'm a newbie with it I'm afraid.

From what I've seen at the track, the guys are looking at the power number primarily and the RPMs second.

After that they are using the DOS version of the software to get the required rollout using the track record as the target lap number.

I haven't seen them using the Windoze version of the software at all.


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## DynoMoHum

From my perspective I'm just simply trying to understand the Fantom Dyno and the numbers it gives. I have heard negitive things about it for a long time, but I'm trying to figure it out for myself and trying to report the facts about what I find. I find that if you look on the surface it's numbers are just not very beleviable... Especialy it's effciency numbers, they are WAY lower then what I've seen with other dynos. This alone just doesn't make sense...

I have looked at Snuffy's Fantom data quite extensively and I see what I beleive are obvious flaws in the data and/or how the data is represented. At this point I would clasify the flaws as being somewhat minor... however I also have concerns that the flawed data could quite easly mislead you into thinking that tunning for HIGH RPM is the best thing to do. I don't see this with the Robitronic or the TurboDyno.

As for oval racers, and their use of the Fantom and/or high RPM motors... well maybe they go hand in hand... If the Fantom tells you that high RPM motors are better then Low RPM motors, then the likely conclusion would be that Fantom users would prefer high RPM motors. However the fastest oval racers in my area only play around with the Fantom... They also use the CE and it's my belief that they put more trust itn the Turbodyno then that do the Fantom. My sample is very small... and maybe strictly a regional thing...

I personaly beleive that ANY of the current EPIC motors are fully capable of putting out huge peak power numbers these days... THis includes the P2K and Paradox motors... Most people buy the newest motors, simply because they are the newest thing and people like to try them... I also still know fast guys who use Paradox motors at times...

One of the most interesting things I've heard recently about the Fantom is that the local fast Oval guys are not at all impressed with the gearing features of the Fantom... for years I have heard nothing but praise of the Fantom gearing thing... So I found this really odd that the local guys don't think much of it.

Anyway... I really am trying to give the Fantom a fair evaluation... I'm not trying to purposely slam it or give it negitive comments without cause. I'm just reporting what I've found. At this point I personaly wouldn't buy one if I needed a new dyno. However if it was the only dyno I had available, I beleive I could make sense of it's data one way or another. I do beleive that it's current software is flawed and could could likely be made much better with a few realtively minor changes.

I'm going to ask Mike Golden if he will modify his DynoViewer to calculate Torque, Power, and effciency they way I beleive they should be calculated... Perhaps he will make it so that you can see Fantom's numbers or the numbers I feel are more accurate... If Mike will do this, then I would likely use his softare to view Fantom data if I ever had to use one as my only source of dyno data...


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## Rich Chang

Just for fun, here is the CE dyno sheet for the 1/12th motor I ran this past weekend at the US Indoor Champs.

This motor ran like a charm (I was 2 seconds ahead of TQ in the 4th round with less than 2 minutes to go before I got hit by a back marker and a crappy solder joint I made gave way and the battery pack came apart). 

*This motor looked like crap on the Fantom dyno.* On the Fantom dyno it barely had 51 watts peak power.

-Rich


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## DynoMoHum

If anyone want's to see the Excel spreadsheet I've been playing with to figure out what Fantom is doing, they can get it here...

www.wiltse.net/zips/facts_III.zip

Sorry but there's not really and comments in it... but if you looke closely you can see the formulas I'm using and can see some graphs that represent Fantom's data compared to my data... On the graphs I currently have I've used 'relitive' numbers for the Fantom numbers... What I mean is I've made the Fantom's peak power numbers for Snuffy's best motor equal the peak power numbers I caclulate for the same motor. All other "rel" numbers are realtive to this motor... You will see that some of the lower RPM motors get a boost from my calculations, and the location of the peak power changes... It's my beleif that my numbers are more accurate.

I didn't include Fantom's torque numbers on the graphs... mainly because they basicly mirror my numbers, except for the fact that they are off by .1 seconds on each occurance...


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## TeamGoodwrench

Which version of the Fantom software are you guys saying is "flawed" ?? The DOS version or the current Windoze version ??

Or both ??

Thanks


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## DynoMoHum

I am working with the Facts II data... At this point I have no way to get the data from the DOS softare... however based on the fact that the DOS software also gives very simmilar power and effciency numbers, I would conclude that it too has the same flaw in it.

I'm not sure anyone else here is going as far as to say they see flaws in the Fantom data... Some are pretty much backing this up with there comments, but I have data that seems to indicate there are indeed flaws in the data and/or the way it's reported. 

Over the years there have been many people make very vague claims that the Fantom is flawed... Not many people have given data that directly supports there opions however. My analysis of the Fantom is about as extensive as I've ever seen in this regard.


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## TeamGoodwrench

So... I'll raise the question again. If it is indeed "flawed", then why, for example, did ALL (100%) of the ROAR Region 5 Oval Championship drivers last month (factory sponsored and all) rely on the Fantom dyno exclusively ??

I'm confused.


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## DynoMoHum

From what I have seen with Snuffy's data the flaw I see only changes the peak power by a 1 or 2 percent. When I compared Snuffy's highest RPM motor(and best overall motor) to his lowest RPM motor, the flaw is responsible for like 1% or very close to that in favor of the high RPM motor. This is a very small amount...

However it is significant in my opion... because the way it shows up... If you have a naturaly torquey motor, and you use the Fantom to tune it, it's going to tell you to tune it in a way that is not likely to put out the most power for that motor. 

Peak power is KING in Oval racing... Many new motors are fully capable of putting out large amounts of peak power... If you go to a race with handout motors, the flaw may not even show up... since the nature of all the motors used is going to be simmilar, quite possibly may become a non-issue... especialy to a knowegable racer...

And the simple fact that these top level drivers likely use on track results more then their dyno... 

Why do they use the Fantom? I don't know... you'll have to ask them... however in my opion they'd get better data from a CE TurboDyno or a Robitronic Dyno...


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## patcollins

It could be that they dont know any better and it really doesnt mater that much anyway (maybe we dont need dynos to go fast hmmmm). 

I base nothing on what "everyone is doing. I just bought some batteries from a national caliber racer...this guy is in the A all the time at oval races. The packs looked like a 10 year old built them. They are great cells but if you put them together like he did you loose any advantage that you get from the great cells. (You know who....if your reading this I didnt mean to offend you, the batteries themselves are great.)

The fact is most racers don't understand how these things work and basically put faith in a "magic box"


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## DynoMoHum

You know what I find really quite funny (or maybe quite sad) is that one of the biggest motor makers in the world has switched to the Fantom dyno... I don't think they do much factory Oval racing however, so they are not likely the sponsers of the racers Team Goodwrench has observed.

Now as I say, the error in the Fantom data is quite small... however for me when I tune motors I'm extreemly excited if can find a 1% increase in power... so when there's potentialy a 1% error in the data under certian condtions I find this totaly unacceptable for myself... I guess I'm just too much of a perfectionist...


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## TeamGoodwrench

Which motor maker are you referring to ?


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## DynoMoHum

I beleive they spell it TRINITY...

They used to use Robitronic to make lables for their 'Pro' motors. A few months ago they switched to the Fantom.

I asked why they switched on their techtalk forum... I beleive part of the answer was... 'the dyno test takes less time'.

I have to wonder how much of their motor design is based on the Fantom numbers... They seem to be leading the parade of high RPM stock motors.


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## HOOPD1

A dyno doesnt make you fast it is just a reference point,I had a Turbo dyno for a long time and I now have a Fantom.Neither one is perfect.I never even considered a Robitronics mainly because I worried about service and no one I know has one.
Mainly I look at specific amp draw on the Fantom but the oval gear calc is a useful thing if you figure out how to relate it to a paticular track and your driving style.
Find a motor combo thats fast on the track and use it for a reference point for stock motors thats about all there is to it. 


Teamgoodwrench,If I were you and I had all those guys to race with that were at the Region 5 race I would ask them about the Fantom,
Shwambeck,or Danny D,or almost anybody else that races at Trackside can tell you more than you will ever learn on this thread.
Cant wait for the nats in april,great track.


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## PizzaDude

Hoopd,

I think everybody on this thread is pretty open minded.

So would you be willing to talk to those guys and let them inform us on the ins-and-outs af the Fantom.

As for Teamgoodwrench,
If all your other club-mates use this dyno you probably did the right thing in buyinmg this one.
They should be able to help you out guite good.


Regards,
Pizza


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## Rich Chang

You definitely get a lot more data (at least from the DOS version) from the Fantom than you get from the CE dyno.

-Rich


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## TeamGoodwrench

Hey -- just getting ready to fire up my Fantom for the first time. I don't have a manual with it -- there are 2 sets of red and black wires on the right side of it. Do the both go to the battery/power supply or ???? One set is shorter and heavier guage wire than the other set. Both sets have alligator clips on them.

Thanks !


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## HOOPD1

The longer leads hook to the pwr supply,the other two connect to the motor.Make SURE you dont hook up the pwr supply leads backwards or you wont get a chance to use it.


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## Snuffy

TeamGoodWrench

The longer pair goes to your power supply. the shorter pair powers the motor being tested.

There is actually 2 windows versions of the Facts machine software.
The other Windows version is the production version. 
I think that's even more inacurate than Facts II. It only purpose is to produce a label for the motor. It's test cycle is settable between 3, 5, and 7 seconds. It also has a setting to adjust the test voltage between 5 and 7 volts. But the dyno has to be modified to use it. 
And it ALLWAYS ALLWAYS shows higher numbers for a motor.


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## PizzaDude

Teamgoodwrench,

Let us know how you did with your first dyno-run!
Good luck.


Best regards,
Pizza


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## DynoMoHum

Last night I was trying to figure out just how much this flaw I see with the Fantom could effect the way I would typicaly tune a motor. At this point I'm inclined to think that it would not have much effect on the way I tune a stock motor. 

Based on my current thinking, the flaw is most significant when you are attempting to compare two motors with drasticly differnt Torque and/or RPM curves. Such as when trying to compare a P2K to a Revenge of the Monster motor. The effects of this flaw are directly related to the slope of the acceleration curve... the steeper the curve the bigger handicap placed on the motor. In my experiance a steeply sloped acceleration curve pretty much directly assoicated with higher peak torque(initial torque on these motors).

I don't have the data for my Ex-Spec motor, but I beleive a motor like this is likely to be handicaped a great deal by this flaw. Because it has a very steep slope, due to it's high torque and low RPM. I really woulld like to view the data of my test of the Ex-Spec and one of my Paradox motors, I think it would tell me alot.

So... my advice right now for Fantom users would be to be carefull when comparing motors with drasticly diffent Torque/RPM curves... My best guess is that when compareing two of todays's stock motors, such as the P2K to a Revenge of the Monster motor, the P2K is likely to be handicaped by 1 or possibly 2% at peak power. I can't say for sure and I really don't know much about how much the flaw will effect power at other points... 

Your best bet would be to only compare simmilar model motors to one another...

I do beleive that changing the timming of a motor will also cause this flaw to have greater effect then anythiing like spring tension... I'm not sure how differnt brush compounds would effect the slope of the accleration curve. I just don't have much experiance with the effects of differnt brush compounds as it relates to torque and RPM.

Oh... actualy the thing to watch out for is when you are attempting to compare two motors with drasticly differnt spin up time... this flaw seems directly related to spin up time since spin up time is directly related to accleration and/or torque... the shorter the spin up, the more negitive effect... The longer the spin up, the less likely the flaw will effect the data... this is in very general terms because the slope of the acceleration curve can change at differnt points in the dyno run depending on motors being tested.

If you should ever play with timmed brushes, this would also likely have cause this flaw to rear it's ugly head... Changing the width of the brush contact surface will also likely awaken this flaw to one degree or another. Also as with all dyno testing, if the brushes are not fully broken in, your results could be really strange and unpredictable, this is mostly due to the fact that the actual contact area of the brush and comm will not be consistant untill after full break in.


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## DynoMoHum

Snuffy,

I'm currious about this other version of the software... From what I can see, one of the effects of this flaw is to cause lower overall output power on all motors I've looked at. It just simply effects high torque motors to a greater degree.

If the output power numbers are higher on this other version of software, it's possible that they may have corrected the problem... but then the higher numbers you speak of could be due to something entirely differnt.


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## TeamGoodwrench

Yep -- Once I looked at it for a minute I figured it out.

Thanks !


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## Guest

Dynomohum-I took a look at your Fantom Data graph. Seems like a dramatic difference between your calculations and the Fantoms. I had a couple of questions. Did you calculate your Power and Efficiency numbers based on the spin up times? What numbers did you use for the Rotational Inertia of the flywheel and for the armature.

Another wrinkle in comparing different brands of dynos is that the Robitronic Dyno uses an armature inertia (the default 4.20)that is an average for mod motors. If you run stock motors on it, it will tend to read a little high. If you want more accurate stock motor data use 3.12 for the armature inertia (moment of inertia). (The value for a stock motor with proper units and powers of ten is 3.12 x 10^-6 kg-m^2 This is calculated for a stock arm which weighs about 47 grams and has a 2.304 cm diameter)


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## DynoMoHum

Yes there is a dramtic change in output power when you calculate things the way I think they should be done. However if you look at it in realtive terms, the error is fairly small (about 1% near as I can tell). Realtive to best case senero to worst case, and adjust for the new power differances. At least this is true for all 18 of the motors in Snuffy's Fantom II data. I always felt Fantom's power and effciency numbers seemed really low, my calculations bring them up closer to what I would expect... My power and efficnecy expectations are based on my experiance with both the TurboDyno and the Robtroinc dyno.

For the moment of Intertia I reverse engineered Fantoms Torque figures. I question the figure I came up with, not in it's accuracy based on Fantom's data... but I question if it shouldn't be a little higher. I beleive this based on power and efficency numbers that the TurboDyno gives for 5 volt tests. Even my new re-calculated power numbers are lower then the TurboDyno typicaly gives. This is a very minor issue however... as long as your looking at the data realative to other corrected data.

.0432 is what I came up with for the moment of intertia for the Aluminium flywheel Snuffy was using for his dyno runs.

I vaguely remember someone once saying that no two fantom flywheels are exactly alike... I don't know if that is really true or not, but it certianly would effect the true moment of intertia for any given Fantom dyno.

I'm using Fantoms figures for RPM and time interval, as given from the Facts II 'time based motor data'. I think torque should be calculated using delta RPM that uses 'present_RPM - previous_RPM', rather then 'next_RPM - present_RPM' like Fantom seems to be doing. Past, present, and next reffering to time intervals that are associated with the data as given by the Fantom...

Fantom also apprears to be useing present RPM rather then 'average RPM from previous to present' to calculate Power, using their apparently flawed torque figures. This issue of average vs. present RPM seems to have little or no effect on the output power numbers when viewed in realitive terms. I use Average RPM for my calculations. I based this on info leared from the following web site.

http://www.land-and-sea.com/dynamometer/kart-dynamometer-article.htm


It's good to see John come and particapate in this discussion... I welcome any and all reviews of my findings... Especialy from someone like John who has shown himself to be very objective and skillfull in anything I've ever seen him evaluate...


Oh... I did get Mike Golden to modify his DynoViewer to allow the option of calculating Fantom data my way...  I think Mike would be comfortable in making this public... if so I will make it available soon.


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## DynoMoHum

Near as I can tell, the moment of intertia figures used does little more then cause ALL the power figures to go up or down in a uniform fashion. This also seems to be true for the armature's moment of intertia, although it's value plays an even smaller role... most likey because it is so much smaller.

So... if you change these values it might effect the peak power, but it also effect power at 10, 15, 20, or whatever. So in realtive terms it doesn't seem to matter much what you use.

I'm not trying to compare dyno numbers one for one... I don't think that can be done. There are just too many variables involved, such as test voltage... I do beleive that the Fantom should give nubmers that are a little closer to those that other dynos give. I bleive that test voltage seen at the motors is the single biggest factor in making it impossible to compare dyno number one for one on any electric motor dyno I've seen. The Robitronic varys it's voltage based on load and user settings... The Fantom uses constant voltage and it doesn't change with load... This causes torque, spinup, RPM, effciency all to be so much differnt then the Robitronic dyno that I don't think you could ever compare the two one for one. 

(The same basic problem comes into play with the TurboDyno, but since it's not a flywheel dyno there's even more variables...)


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## DynoMoHum

The following web page attempts to show and explain the differances I see when comparing my calulations to Fantom's calculations... The graph is all the way at the end of the page...

http://www.wiltse.net/facts_iii.htm

There is a link to that page from my other page that addresses the oddity when I tested my Ex-Spec motor and a Paradox and attempted to compare them both useing a Fantom dyno... that page is located here...

http://www.wiltse.net/facts.htm


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## popsracer

*Thanks to all.*

Guys;

I am truly greatful for all of this discussion on Dyno's. This has allowed me to make the informed decision of purchasing a Robitronics Dyno. I feel based on most everyones opinion that it will provide me with the most useful data out of all the Dyno's.

Again, Thank you, Popsracer


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## TeamGoodwrench

Well, I'm going to stick with my Fantom. It's the only one that is being used at our track. No one uses the CS or Robotronic and there is only 1 CE.

It would be too hard to compare my motors with all the other guys if we weren't all using a Fantom.


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## DynoMoHum

I'm the only one in my area that has a Robitronic dyno. I don't mind it... If I want to compare my motor to others, I'll ask them to let me dyno it on my dyno... or I'll dyno my motor on their dyno...


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## Guest

Dynomohum-I have a set of Fantom Dyno Runs. I reverse engineered the Flywheel inertia like you did and came up with 4.10x10^-5 kg-m^2. This is similar to the moment of the Robitronic Dyno flywheel. I took a different approach to calculating Power than you did to avoid the following dilemma.

"I'm using Fantoms figures for RPM and time interval, as given from the Facts II 'time based motor data'. I think torque should be calculated using delta RPM that uses 'present_RPM - previous_RPM', rather then 'next_RPM - present_RPM' like Fantom seems to be doing. Past, present, and next reffering to time intervals that are associated with the data as given by the Fantom..."

Instead I made a graph of Angular Velocity vs time based on the RPM data in the data file of a stock motor. I fitted a fifth order polynomial to this data so that I would have an equation to predict the instantaneous angular velocity at any point in time. The derivative of this equation would give the instantanious angular acceleration at any point in time. Torque can be calculated from Torque = Rotational inertia * angular velocity. The Power in Watts can then be calculated as Power = Torque * angular acceleration. The graph of my calculated power and Fantoms are very similar. Be glad to share the spreadsheet with anyone. E-mail me at [email protected]

And of course the RPM data that we are using is calculated from more basic measurements that have the same dilemma, where to center your average. If I had a set of the more basic time measurements at each rotation of the flywheel, I coud bypass the dilemma completely.

Have not tinkered with the efficiency yet.


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## popsracer

*Visiting other planets*

DynoMoHum & John S;

You guys are WAY too smart for me. Have you ever considered working on flying saucers? :wave: 
REALLY, I am very impressed with your methods of Dyno comparisons. Why don't you use your calculations to write a better program for the Fantom Dyno. 

Popsracer


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## Snuffy

I agree with popsracer! My brain hurts just reading your results. It would probably explode if I tried to figure all this out for myself.:lol: 

I also believe that the main problem with the Fantom dyno is the software. I'm just don't know enough about programming to write my own program. I have, however, created a schematic diagram of the electronic circuitry inside the dyno itself. I just don't have the equipment to extract the prom data.


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## Guest

I guess I should state my main point another way. I don't see a problem with the Fantom Dyno Software. Seems to calculate power and efficiency OK.


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## JPHRacer

*Nitro Dyno*

I was wondering if anyone knows what fantom has up their sleeve for their new nitro Dyno? I am either going to make my own inertia dyno or get the fantom one if it looks good.

My other question is how do you figure out angular velocity? Would Time Base * Angular Velocity = Torque work for a nitro motor if I had the time base for a set acceleration? Or would it be better for a nitro motor to use Torque = Polar Moment * rpm per second / 9.551?  I hope I don't come off sounding like a idot, I'm only a Senoir in HS. Thanks. :wave:


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## Guest

TMFU:

A couple of ideas to throw out to you.

1. I don't remember how I got the raw (number of revolutions, time) that the Fantom calculates everything from. If we get a snow day tomorrow, I'll see if I can get you some raw data from the DOS version. I think these values are better to work from: I seem to remember the RPM's are calculated with a centered difference formula, the acceleration from a centered difference also. Both would be second order accurate. There is probably enough round-off error in the rpm numbers you wrote down to give a couple percent error in a calculated peak power, but the Fantom calculation wouldn't have that. (Just a guess/recollection at this point, it's 10+ years since I tried to sort all this out myself.

2. Another thing to "screw with ya" (ha, ha). Run the CE dyno going from low amp draw to high. Let the motor/magenets rest overnight, then do the same test, but go from high to low. The curves will not be the same. It seems whatever we do for dyno comparison, the "history" of the test plays a role in our stuff. To make comparisons, you have to have the same "test history", not just the same loads.


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## DynoMoHum

Pops and Snuffy... John has lost me... I'll leave the space ship building to others... Now I might be willing to take it for a test drive and give my opion of it when it's done... but I'm no engineer... I did manage to figure out that John was saying he didn't think that Fantom is/was doing anything wrong.

John, If you don't think there is anything wrong with the Fantom's Torque, power, and effciency numbers, then can you offer some explinations for a few things that I see as very odd? 

For starters... Why is the power output and efficiency reported by Fantom so low? Low when compared to the TurboDyno and/or the Robitronic dyno. On a TurboDyno at 5 volts, a average stock motor can easily achive 85 watts of peak power, and also has no trouble at all achiving over 60% peak effciency. While from what I've seen on a Fantom a really good stock motor will be hard pressed to achive 70 watts, and often they put out 65 watts or less. On the Fantom I have rarely seen or heard of a motor that will achive more then about 50% peak effciency. This all seems very odd to me.


Secondly how can it be possible that a Ex-Spec motor that will put out over 105 watts peak at 5 volts, yet only barely is able to show up as 54 watts on a Fantom dyno???? Not to mention this Spec motor is greater then 19% better then a perticular Paradox on a Robi, and more then 24% better on a TurboDyno, yet the differance between these same two motors on a Fantom only shows as being 3%...


How can this be? Surely there must be something wrong with the Fantom... either that or the TurboDyno and the Robi are both wrong. 

Quite frankly I don't really see how the TurboDyno could be wrong... It measures torque and I can verify it's numbers are quite accurate. If I had to put all my faith in one single dyno it would have to be the TurboDyno for giving accurate numbers. 

For more details on this second odditiy, check out this page...

http://www.wiltse.net/facts.htm


I will send you a message requesting your data... At this point I really don't understand how your caluclating things... I would love to hear any thoughts on the odditys I've spoke of earlier in this post...


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## pancartom

Dyno, in a few words, who cares what the exact numbers are that each dyno spits out. the key here is repeatability, and user friendliness. i started out with a turbo dyno, but after a year decided to switch to a fantom.... and continue to use the same dyno 8 years later. the key here is, it works for me. i don't care if i win the "biggest number" dyno war. what matters to me, is being able to tune my motors so i can go out and be competitive. that's it. as a side note, in the real world, i dyno test and tune race car engines for a living. the really saavy race car teams don't care a lick what numbers my real dyno spits out at the beginning of the day. the only thing they are interested in is the net improvement at the end of the day! 'nuff said.


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## DynoMoHum

RWB... I'm likely only to have my TurboDyno for a few more days... I will have to make sure I run a backwords and forwards test before I sell it. I have noticed that if I run a test what has steps of say 20 22 25 28 and 30 amps, then run another test with steps of 28 30 32 35 40 and 45 amps... the power numbers will not be exactly the same for the 28 and 30 amps steps of both dyno runs. However they are ussualy within a couple percent... I've not given this a whole lot of thought however.

My local Fantom owner (ther's only one guy I know that has one), says he regularly sees that the second dyno pull on his Fantom will show better numbers then the first pull... 

My personal observation of consitancy on the Robitronic is that most motors will repeat the data easly within 1%. Ocasionaly you get a motor that will not repeat very well, but I suspect this is due to motor problems rather then dyno problems. I've got one motor that recorded a peak of 128 watts at 7 volts when I first got it... I've used it so much that the comm is down to about .271" and I still get dyno runs from this motor that are very close to the orginial run I made over a year ago. THis motor has always been my favorite stock motor. (P2K)

I do understand that the ideal torque/RPM measurments would be more or less instantainious and/or that you calculate torque and power all based on a very narrow window of time... if you don't use a very narrow window, then you lead to problems such as I've been seeing... I also realise that the numbers Fantom is reporting may not be the most precise numbers it has available, that is it's likely to have more accurate numbers used internaly... (at least I sure hope they do)... Either way... I still feel there is something very odd going on with the results typicaly seen on a Fantom dyno. I really would like to figure out what it is... at this point for me, it's just nagging at me and I just can't seem to let go of it. 

If anyone knows of a way to get the actual voltage seen at the motor during the Fantom dyno runs that could be helpfull... It could be that it's not actualy keeping 5 volts constantly at the test motor. Even a small amount of voltage variation could explain alot...


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## DynoMoHum

Pancar... I'm not trying to win any biggest dyno number award, or anything close to that. I'm trying to understand dyno and motors to the best of my ablity. 

As stated in my previous post, I get excelent repeatablity with my Robitronic dyno... I do agree with you that repeatablity is key to having a usefull dyno.

Why am I still interested in the Fantom and the numbers it gives that I feel are very odd? Well it's basicly just curriosity, and the possiblity that my efforts may help or be of interest to others.

The single biggest thing that nags at me now about the Fantom is... Why can it not see a large differance between the output of a 21 turn EX-Spec motor and a 27 turn 24 degree stock motor? Why does this nag at me? Well... If a dyno is unable to show a significant differance between two obviously differnt motors like this, what is going on? It just can't be good as near as I can tell.


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## TeamGoodwrench

Well I'm no MIT physicist... but the Fantom is an accelerometer while the Turbo Dyno is more of a load generator. To me it seems they are 2 completely different beasts.


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## DynoMoHum

Yes... but power is power, torque is torque... it sure seems to me that a good dyno could measure and/or calculate these in a way that would come very close to what another good dyno would read.

In the case of this Ex-Spec motor the differance in power output reported is about almost 100% greater on the TurboDyno then it is on the Fantom. I'd like to see a MIT physist explain why.


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## Duley

DynoMoHum said:


> *is there anyway to export data from the Fantom into a text file that Exel could read? *


You can export it directly to Excel. When you save a motor it will as you if you want to save it as an ASCI II file. Answer yes. Open Excel and import the file to a spreadsheet.


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## tfrahm

Well... I'm not an MIT Physicist, but I did get 3 years of pre-engineering before settling down and getting a BS in Physics from a smaller college in the midwest... I confess that my Physics is too rusty for some of the detailed science involved in certain dynos, but I do recall one principle of Physics that probably plays a big roll in this discussion. Werner Heisenberg is the scientist who first put forth what we know as the "uncertainty principle" -- this, in simple terms says that when we measure something we either introduce a measure of error in the measurment or actually alter the thing we are trying to measure. For the Fantom dyno, for example, measurements are taken as RPM readings from a spinning disk by passing light through holes in the disk -- but those holes have a width, and the disk is constantly changing speed, so that even an average of the time it takes the hole to pass includes some error. 

You can apply similar logic to almost every dyno out there and find minor flaws in one or another of the measures -- for example, a TD45 can produce flawed torque readings of the wires to the slave motor are allowed to bind on the sides of the hole where they pass down into the box (it's RPM measurements are also subject to an error similar to the Fantom's)...

None of this changes the central point: *Know YOUR dyno, "baseline" your motors, note the way the dyno numbers compare (or DON'T compare) to on-track performance, and then GO RACE...* I know guys who do well with a Tekin dyno, and I raced for 6-7 years using a home built dyno similar to the Buds unit. Do I do better now with my TD45? -- Sure! But I did "OK" before, because I knew what my dyno was "telling" me. You can't compare dynos -- heck, even Big Jim constantly reminds people to not even compare one TD45 to another!

For me, the issue is "Joe Racer" -- the person without a dyno, who trusts those labels on the motors in the hobby shop. That person is in a world of hurt -- totally at the mercy of Lady Luck, since those labels mean almost nothing. Like the person who started another current thread who was confused by Trinity's old and new labels, and thought that the much higher numbers from the Robi dyno (7v) meant a much better motor than the ones with lower numbers from the Fantom dyno (5v)... 

I think we may need to start a new thread on "Reading Dyno Labels in the Hobby Shop" or something. Joe Racer wants to know what motor to buy off the shelf and doesn't care about the science -- us hard core types don't buy off the shelf and we care a great deal about the science. Two completely different discussions...? agree? disagree?

Along the "scientific" path, I have a question as a TD45 owner to other TD45 owners: By definition, doesn't the TD45 "favor" motors with more efficiency? Their lower amp draw at a given load seems to produce higher torque and power readings, since the dyno must load that motor more heavily to make it draw a specific amp value. Thus, with the TD45, the tendency is actually to "tune" for efficiency (whether we realize it or not). For 4-cell stock oval, I'm finding that this tends to encourage use of lighter springs (to make the dyno "happy"), but on the track, I seem to end up going up one level of firmness to get the performance I want... *Am I correct in my assumptions? Why does the dyno disagree with the track? Is this unique to 4-cell stock oval, or does this apply to other racing classes?*

I'm not saying the TD45 is wrong, just that my experience has raised this question... I guess I should note that I've been using 20 amp numbers and based on another discussion it looks like 4-cell stock oval motors actually average closer to 25-27 amps -- is this my problem?

Thanks in advance and keep that info flowing!


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## TeamGoodwrench

Here's one data point for consideration -- it comes directly from Dave at Decco software...

"The Robi only looks at the flywheel speed twice per revolution where the Fantom looks at it 4 times per revolution so the resolution is lower by 50% on the Robitronics. "


So... going back to tfrahm's post above, there IS a measurement difference between the Robitronics and the Fantom.


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## Rich Chang

I definitely agree.

I've found that motors that pull a lot of amps typically have a lot of RPM and low efficiency. And, on the TD45 they don't look that great (like, 100 watts and below at 20A/7V) but look awesome on the Fantom Dyno.

All my motors that pull low amps and have a high effiency all show much better power numbers on the TD45 yet look horrible on the Fantom.

-Rich



tfrahm said:


> *Along the "scientific" path, I have a question as a TD45 owner to other TD45 owners: By definition, doesn't the TD45 "favor" motors with more efficiency? Their lower amp draw at a given load seems to produce higher torque and power readings, since the dyno must load that motor more heavily to make it draw a specific amp value. Thus, with the TD45, the tendency is actually to "tune" for efficiency (whether we realize it or not). For 4-cell stock oval, I'm finding that this tends to encourage use of lighter springs (to make the dyno "happy"), but on the track, I seem to end up going up one level of firmness to get the performance I want... *


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## Guest

TMFU:

It's been a while since I've seen a Robi dyno. How similar is the Robi flywheel to the Fantom flywheel. I was just thinking that, just as is the case for the CE where the loading (up or down) changes the readings due to heating of the winds, knocking off some of the magnetic flux at the magnet tips, etc, does the choice of flywheel and how it "stretches" rmps vs. time influence the values measured? And how much is this influence?


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## patcollins

The Robi flywheel has 4 different sections, that means that it trips the sensor 4 times per revolution. Where they get twice I dont know. Again this tells me more and more that they either dont know what they are talking about, or just trying to sell their own product. 

Pat


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## Rich Chang

I was at a race in Toledo last year where the guy that writes the Fantom software was there. He went up to Josh Cyrul (I was pitting right behind Josh) and basically told Josh that he and the Trinity folks have no clue how to properly tune and build a motor.

Whether his claim is true or not, I don't know. But, the way he did it and said it sure didn't make any friends.


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## TeamGoodwrench

So why has Trinity now switched to the Fantom dyno for all of their motors ???

hmmmm ???


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## Rich Chang

Robi - expensive and couldn't handle motors lower than a certain wind (until recently). I think it was a 10 turn limit? Still made, so it is an option.

Fantom - cheaper than the Robi plus can handle very low wind motors. Still made, so it is an option.

CE dyno - no longer made so not an option.


So, there are basically two options. The Robi or the Fantom. And, since the Fantom can handle pretty much any wind motor it would appear the Fantom would be the dyno to choose.


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## TeamGoodwrench

Well with the gobs of money that Trinity has, I'm sure if the wanted to they could use the Robi for Stock motors and the Fantom for Mods... if cost was the real issue.


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## tfrahm

Yep! Even without using a different dyno, the "track dyno" tells me similar things. It's not that the TD45 is telling me "bad" things, it's just that you have to understand how it works -- since it is normally used with fixed amp steps, a motor that pulls more amps will automatically produce lower power readings at 20 Amps for example.

(NOTE: My TD45 is "conservative" with it's numbers, so don't compare 'yours' to 'mine' -- my best reading ever at 7v was only 98 watts at 20A/7.00v, with most of my 'good' motors being in the low to mid 90's...)

I've found that my 97 watt motors (lower no-load amp draw, etc.) feel "soft" on the track and don't have the punch that these power readings would imply -- yet I have had very good on-track results with motors that "only" produce 90-92 watts (higher no-load amp draw). In fact, my 91-93 watt motors almost always out perform my 97-98 watt motors on the track. Clearly there is a point where this breaks down -- if I try a motor that shows in the mid 80's on power, it is usually a slug on the track, so this theory only goes so far. 

This implies that for *MY TD45*, the "sweet spot" is probably around 91-93 watts, as this shows a motor that has 'power', but also has a bit lower efficiency, but has a good "balance" of performance. (This is why I talk about knowing YOUR dyno and what it is "telling" you.) When tuning motors, I'll initially tune for max power (shoot for that 97-98 reading), as that indicates an efficient, well built motor, then I'll go up on the spring tension a step, knowing that the power readings will fall into the low to mid 90's, but the extra punch (and reduced brush bounce) from the stronger springs will pay off on the track. It took me a while to figure this out, but the final payoff has been more than worth it!



Rich Chang said:


> *I've found that motors that pull a lot of amps typically have a lot of RPM and low efficiency. And, on the TD45 they don't look that great (like, 100 watts and below at 20A/7V) but look awesome on the Fantom Dyno.
> 
> All my motors that pull low amps and have a high effiency all show much better power numbers on the TD45 yet look horrible on the Fantom.
> 
> -Rich *


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## Rich Chang

Yeah, a buddy of mine who works in the dyno department for Tennecco Automotive said I might want to start using the TD45 in *torque* steps and not *amp* steps.

What do you think?

I'll have to mess around with that soon. Maybe over Xmas.


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## tfrahm

Rich Chang said:


> *CE dyno - no longer made so not an option.
> *


Well... Actually not "quite" true... If Trinity went to the folks at CE and said they wanted to buy 10-20 TD45's -- I'd BET that they could work out a price that would "encourage" CE to build the dyno's they wanted!


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## Rich Chang

I wish they would. 

I was told they couldn't get certain parts. But, that could mean they couldn't get certain parts for cheap anymore.


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## tfrahm

It sure might be worth a try... I know that I've seen torque readings from 7.0 down to 5.5 at 20 amps, yet motors all over that range "work" on the track, with good "punch", but with gearing that varies widely from one extreme to the other... Using *torque* steps (assuming you had an idea of what the "target" torque was for you tuning), you could measure/tune all your motors at (for example) 6.5 for optimum performance...?

It would be interesting to see how motors you KNOW are good, but which don't put up the big power numbers at 20 amps would look at some specific torque value...

Let us know if you get a chance to test...



Rich Chang said:


> *Yeah, a buddy of mine who works in the dyno department for Tennecco Automotive said I might want to start using the TD45 in torque steps and not amp steps.
> 
> What do you think?
> 
> I'll have to mess around with that soon. Maybe over Xmas.  *


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## Guest

On a CE dyno if you run your high amp test first it will alway be higher than if you run it last. There is considerable heating of the test motor when it is run for 4 seconds at each step. If you run the high amp step last the motor has been heated by 5 four second cycles previous to the high amp step.

One difference between the CE equipment and others is that it uses a separate small set of lead wires to sense voltage at the motor terminals. This is probably a better way of keeping the test voltage where its supposed to be. I am curious also what voltage the Fantom actually delivers to the motor terminal. There is considerable voltage drop over the lead wires at high amperages.

If I had two dynos and one was always reading low it would be hard to tell which dyno is more correct without a research grade instrument. It don't think these differences are that important. It is helpful if different machines of the same brand would read the same. All that I can attest to is the Fantom calculations seem to be OK. If you calculate power using the large .1 seconds steps of the ASCII file without some calculus you are bound to incurr some error that the fantom software does not have to deal with as it uses finer steps.


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## Snuffy

DynoMoHum

I know for a fact that the actual voltage at the motor is NOT 5v. I've measured it during a run. At the beginning of a pull it dips and ramps up. Very similar to what an actual battery pack. The voltage control circuit does get feedback from the motor to adjust the voltage as needed. The highest I've seen the voltage at the motor is 4.85 or so.

I've also talked to Al at wizard, the guy that builds theese things.
His calibration procedure involves putting a load in place of the motor and making sure he gets 5A at 5V with the load. He has a special program for this.


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## Guest

Rich:

I'd ask your friend why he think's that so. I can "understand" amps since that is related to the power source (the battery pack) and that you can to tune the power band to make use of that power.

If you test in torque increments, it's just like testing in rpm increments. A torquey motor would show one part of the power band, an rpmy motor would show another part of the power band, but how would you compare the two if the power bands don't overlap.

It's not torque, but the power and then choice of gearing to make use of that power. So I'm not sure what your friend is getting at "for electric motors." Now internal combustion engines, I could understand measuring based on torque steps.


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## Snuffy

Damn!!! guys.

I started this thread because I wanted to learn how to use my fantom dyno to tune motors, Not to start a "which dyno is better" war.

I think some of you are taking DynoMoHum's work and observation a little out of context. I really don't think he's trying to slam the fantom or any other dyno. He's just trying to understand it, as am I.

All dyno's have advantages and disadvantages.


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## DynoMoHum

The Robitronic Dyno also has small wires that attach more or less directly at the motor, these wires are used for measuring voltage. This is just like the CE TurboDyno. I did not pay that much to the wires on the Fantom, next time I use it I will pay more attention.

Along those same lines, I have played around with adding short peices of wire between the Robitronic motor leads and the test motor. I don't remember the exact numbers right now, but there was something like 1 watt drop in power for every inch of 12 gauge wire added. I don't think this alone would account for the realtively low power readings of the Fantom. In the tests I did with the EX-Spec motor and the Paradox motor, they both had the same hook up, so it really should be a non issue if we look at the numbers in relation to one anther. Either way the small voltage sensing wires are a good thing if your attempting to get accurate power and effiency numbers. This could easily account for some of Fantom's low power numbers if they don't use this type of thing to measure voltage.

As for the CE and efficency stuff that Tfram is talking about... I have to re-read that and see if I can grasp it a bit better... I am however quite convinced that 20 amp numbers are only a small part of the picture in todays racing... especialy in Oval racing. If I was using a TurboDyno I'd look at 28 amp numbers as much or more then 20 amp numbers. Anything bellow 20 is pretty much not usefull... I see Big Jim basicly says that the 15 amp setting is just to get the motor warmed up/moving... I'd actualy be more inclinded to use 15 20 25 30 35 and 40... (or maybe 38)... Sometimes it's hard to get a CE TD to force a stock motor to pull 40 amps... I think many stock motors should peak between 35 and 40 amps, and I do beleive that peak power is very important these days.

I know for sure that I am quite easly averaging at least 25 amps in my stock oval racing, and higher in 19 turn. My batteries are starting to become a limiting factor from what I can tell.

12th scale road course is differnt... 20 amp numbers are probably still pretty important. However I also think 25 and 28 amp numbers would be a good indicator of acceleration in 12th scale...


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## Snuffy

I'll have to look at my schematic of the dyno but I don't believe there is any actual "measuring" of the voltage to the motor at all.


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## Rich Chang

Hi,

Yeah, I asked him to post on here. This stuff is pretty much over my head (but I have definitely enjoyed and learned some stuff reading it all) so I would have no idea how to explain any of this. I just use the dyno to give me an idea as to what the motor is producing and work from there in conjunction with track performance. I'm definitely not getting the full potential out of the dyno readings. 

-Rich




RWB said:


> *Rich:
> 
> I'd ask your friend why he think's that so. I can "understand" amps since that is related to the power source (the battery pack) and that you can to tune the power band to make use of that power.
> 
> If you test in torque increments, it's just like testing in rpm increments. A torquey motor would show one part of the power band, an rpmy motor would show another part of the power band, but how would you compare the two if the power bands don't overlap.
> 
> It's not torque, but the power and then choice of gearing to make use of that power. So I'm not sure what your friend is getting at "for electric motors." Now internal combustion engines, I could understand measuring based on torque steps. *


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## DynoMoHum

Man Snuffy... your now giving us some info that could probably does explain alot... If the voltage is droping significantly bellow 5 volts during the test then the output numbers are deffintly going to be low. Just how low will depend alot on what the actual voltage is... If the effciency numbers don't take into acount the lower input voltage then tye too will be low...

Power = Voltage * Current... at 35 amps 1/10th of a volt is 3.5 watts. at 29% effcinecy that is 1 watt of output loss. It's critical that voltage is maintained to at least a 10th of a volt in my opion. Voltage drop is fine if it is consistant, repeatable, and you take it into account when you calculate effciency... but if you don't take into account the voltage drop your going to have all kinds of issues come up.

Generaly speaking the higher the load(amp load) the harder it is for a power source to keep up it's voltage. Higher the load, the more critical the voltage level is to maintain consistant and accurate numbers on a dyno.



One last thing Snuffy... I don't think too many folks here misunderstand my comments here... maybe one or two that have commented... but I beleive this discussion here has be very productive and quite helpfull to me. I think most others see it that way as well.


I do beleive it's very important that a dyno user understands his/her dyno very well... If you don't understand your dyno, you'r likely to misinterpet it's data... and we wouldn't want that.


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## Fred B

Typically, motors become more powerful and less efficient as the brushes break in more. There's a point where this stops being true but that's what happens in general.

The problem is that it takes less torque to make a high amp draw motor (the brushes are full and overlap more) run at say 20 amps than a motor with more narrow brushes. Just because the motor makes more power at a given current doesn't mean that it doesn't make good power.

Looking at our motors by current draw doesn't make much sense with the new batteries because we don't dump. Have you ever heard anyone bragging about how much power their big block Ford makes at 20 gallons per hour of fuel? Nope... In the end the only way to compare 2 motors head to head is by using either RPM (like the auto industry) or by torque. At a given torque, the motor with the higher RPM makes more power regardless of the current that it takes to get there.

Amp draw is still very important because it can have an affect on efficiency. An inefficient motor will not perform at the end of the race because it's going to get hotter. More efficiency=cooler motor.

You can estimate the torque settings required with a little work on the track using your rollout and split times. Or just use settings in the area that you normally look for (around the 20-25 amp range).


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## Fred B

BTW: I've seen over 40 amps in 12th and about 25 continuous.


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## Snuffy

DynoMoHum,

I agree that this discussion has ben very helpful and extreemly informative. It just seemed like some posts, the last few days, were a little on the argumentitive side. It's not a complaint, just an observation.

Knowledge is power. I for one have enjoyed participating in this thread emencely and have learned quite a bit.

I also want to personally thank you and everyone else for all the effort put into this thread and the sharing of your findings and knowledge.


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## DynoMoHum

FYI

By accident this morning I left the voltage sensing leads disconnected on my Robitronic Dyno as I was testing a 19 turn Chameleon motor. This dyno run was at the 5 volt setting. Peak power was 77.4 watts, after I hooked up the voltage sensing leads, I ran the same motor again and it peaked at 89 watts. That is about 13% loss in power essentialy due to the voltage drop of the power leads that go from the dyno to the motor. On the Robi these are about 18 or 20 inches long.

Next topic...

I beleive much of what Fred is saying is true. With todays batterys, run time is kind of a non issue. However pack voltage is also important, and at some level, reducing battery consumption by having a more effcient motor will keep your battery voltage up at higher levels during the time you are running. How much of a factor this is would depend on how much voltage your packs are loosing while you keep discharging them. So... effciency can't be completely ignored, but it is much less important then it used to be. Almost to the point of being a non issue. Unless of course your running spec batterys... then it is just as important as it was 10 years ago...


Mainly what I mean is this... if you have a motor that puts out 60 watts peak, and the peak occurs at 30 amps, yet you have another motor also with 60 watts peak, but it achives this peak at 26 amps, then the second motor would be the better choice in my opion. 

If the peak power isn't exactly the same, it gets a bit more complex... but you should see my point.


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## patcollins

I believe Trinity said on their site they switched over because supportability of the Robi was a bit of a problem. 

Trinity rarely does something because its a better way to do it, they do stuff because they can sell more of something, make a buck etc etc. 

It is also faster to mount the motor in the fantom that it is the robi for a place that churns out 1000's of motors saving 10 seconds each would save time which would save money....


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## Mayhem

*Fantom question*

Here is one for all the fantom Guru's.... I own and understand the Fantom dyno quite well but was debating one number with another owner. The number in question is "efficiency amps" shown as EAMPS and relates to the power and efficiency numbers at a particular point in the run. This is separate and not to be confused with overall, max, or average efficiency. While comparing two motors numbers on the screen and "E" or "p" is pushed this number is shown. Any takers? Thanks in advance.


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## Guest

Could be the amperage at which peak efficiency occurs. At 7 volts on the CE dyno, stock motors have peak efficiency around 16 amperes. What numbers are returned?


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## Mayhem

Dont think so, there is a separate screen for that, I'll pull up a run and check to see if its the same though.....returns seem to be in the 14 - 18 range though for 19 turns. best i can figure is that it attempts to tell how many amps in relation to overall amps are being wasted maybe as heat???Thanks for the input.


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## patcollins

There really isnt such a thing as wasting current, you waste power not current. 

This might seem kind of simple but is it efficiency multiplied by amp draw at a certian point?


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## DynoMoHum

Wow... this topic is starting to get about four differnt discussion threads going at the same time, all related to one another... it is getting harder and harder to respond to them...

I went back and read Tfram's comments about the TurboDyno and if it was inherently causeing a bias toward effciency in motors. I still don't understand his logic that brought him to the question, but I think I understand the basic question he's asking... It seems to apply directly to what Fred and Rich were saying... (probably no cooincdence since they were replying to his post)... Basicly I don't think the TD itself causes the bias towards effciecny, I think it's the way we interpet the data.

I think it boils down to how you look at the numbers. I started to look at some of my data in relation to Torque, at first glance it seemed to make sense to me... then I looked at a motors that have drasticly differnt max RPM... then it get's really confusing for me. Since we have fixed gearing in our RC cars, you have to compensate for the gear selection if you view by either RPM or by Torque.

At this point I still like to look at data in relation to Amp input... However I'm looking at graphs that show the data from min to max amp input, and it's easy to see where the motors peak at and in my head I am able to force the power curves to shift to the right or left simulating what would happen if I geared the motor differntly... The Robitronic actualy has a screen that even solves this mental gear shifting issue pretty well.

On the Robitronic dyno they have a option that lets you view the data in relation to percentage of maximum RPM. This view is really quite interesting, and from what I can see it pretty much eliminates alot of the issues with viewing 

I think I'll have to write up a litttle discription of what I'm talking about including some graphs that illustrate it...


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## Fred B

DynoMoHum,

In reading through your last post I'm noticing that you're fucusing alot on peak numbers. Be very careful about looking at only peak numbers because the overall powerband is very important. Just as an example, back in the "turbo era" in F1, BMW made some of the most powerful engines in history. The problem was that the powerband was very narrow and they needed alot of differant gear ratios to make the car perform (5-6 speed gearboxes). On the flip side would be the trusty old American V8's used in drag racing. By design the V8's have a huge powerband and are more suited to using less gear ratios (3-4 speeds back in the day). In RC we only have one ratio to work with and need a wide powerband. The entire curve needs to be considered.

When looking at graphs based on RPM, it is very easy to see how far you have to shift your gear ratio in order to hit the same area of the powerband of two differant motors. Each motor will have it's own sweet spot and needs to be geared accordinglly.

One thing for us to remember is that when all is said and done, it's a combination of torque and RPM (POWER) that sends our cars around the track. How much current that is used is just a product of efficiency; it needs to be considered and improved but is not what moves the car.


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## Guest

If you control the input power like the turbo dyno does, and power increases, then efficiency also increases. I still just look at the power number for stock motors.

A reason to use ampdraw (rather than torque) as a basis to compare motors is that we have a handle on amp draw. We can easily measure the average ampdraw in a race and tune our motors to maximize power near this amp range. If you plot your power curves vs ampdraw it is a lot easier to see differences in motors. 

I believe that in many fullzize car races,long distance LMP or Lemans cars (where fuel is limited), Nascar where an extra pit stop will cost you the race, that engine makers may indeed be looking at how much power is produced for a given fuel consumption.


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## Duley

John Stranahan said:


> *
> 
> A reason to use ampdraw (rather than torque) as a basis to compare motors is that we have a handle on amp draw. We can easily measure the average ampdraw in a race and tune our motors to maximize power near this amp range. If you plot your power curves vs ampdraw it is a lot easier to see differences in motors.
> 
> *


You got it John!!!!!! If your best motor is drawing 30 amps average for 4 minutes, tune the rest to draw the same amps.


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## DynoMoHum

I NEVER used to pay ANY attention to peak numbers... However I recently have decided that it may be the single biggest factor in electric RC racing. Not the only factor howerver... width of the power curve would be one of the next items I would consider along with the location of the peak in relation to amp draw(bringing effciency back into the picture).

I have what I beleive are very sound reasons for my new approach. At the heart of my new approach is that a stock motor of today, typicaly achives peak power between 30 and 40 amps when operating around 7.2 volts. Average is around 35 amps for the motors I've dynoed on my Robitronic (we could debate the accuracy of this till the cows come home... but anyway that's what I'm going by for now). So... with a 3300 pack, you could average up to about 39.6 amps during a five minute race and then dump... In 4 minute racing, you could average 49.5 amps and dump... My point is that with todays batterys you could aproach 40 amps average during a race and still make time.

At around 4.8 volts a stock motor typicaly peaks between 25 and 30 amps.... and this makes my new theroy even more appealing...


You can never get more power from a electric RC motor then it puts out at it's peak. If you pull 40 amps from the motor and it peaks at 29 amps, your wasting power by operating in a extreemly ineffcienct area of the motor's operating range. Idealy if you could constantly operate the motor at exactly the peak location you would make most use of the motors power. However with having to slow down and speed up at various points in the track this is impossible... Still... at it's most simple form my theroy says never gear a motor so that it averages more amp consumption then then the motor draws when it's achiving peak power...

If you follow this logic peak power is the most important number on a motor. The next two most important charactoristics would be the width of the power curve around it's peak, and the effciency of the motor around it's peak. 

Furthermore... if you follow my theroy then it becomes very interesting to ponder the idea that we should be gearing our cars to produce as much power as possible, and this would seem to occur where the motor achives peak power. 


Trying to take the theroy a step further I am forced to question if we really should make every attempt to avoid exceeding a amp load, that would exceed the current consumption at the motor's peak power point... Obviously you can not do this ALL the time... if you slow too much you will have to operate in that area where effciency is really bad and you have not achived peak power yet... (So driving becomes a huge issue in achiving the second part of my therortical goal)...


Anyway... do you see what I'm talking about?

By the way... for those of you have not followed my other threads on current consumption... I'm am 99% convinced that in todays racing, amp draws of 25 to 30 amps are happening every day by many of the top level drivers. This is what first got me thinking much more about peak power...

Clearly width of the power band is very important, as is effcinecy... but only if you've got power first.


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## Fred B

Average ampdraw only works in oval racing (sometimes not even then).

I know that in sedan we're seeing amp draws between 20 and 50+ amps several times a lap. It's important to have good torque out of the corners and good horsepower on the straights.

If using amp draw seems to make sense then use it. I'm just saying that sometimes it will be misleading and it's not the best way to compare motors with the turbodyno's because the amp draw is related to efficiency. If you test by torque, a motor with more RPM makes more power regardless of how efficient it is.

Yes, efficiency is important in some forms of racing. And it used to be in stock RC racing. Now, we see sedans coming off the track with 100 seconds of runtime left so there isn't an issue with ampdraw. Also, with the new cells, the voltage doesn't drop much at the higher currents. Tuning to amp draw is like all the Nascar engine builders that are living in the stoneage taking notes down in "the book" instead of using computers. Yes, it works for them but it could be better.


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## DynoMoHum

One of the reasons I've started to break away from the average amp draw as the basis of all my tuning and choosing needs... If you always tune based on previous amp draw use, then your pretty much eliminating the possibity that you could actualy go faster if you tried something else... like maybe you could go faster if you had a motor with higher peak power, and geared up just enough to start using it... 


For now I'm sticking to the idea that you should avoid gearing in a way that forced you to operate in a condtion that leads to averge amp draw that exceeds the amount of current used by the motor when it achives peak power. This is not to say I don't beleive that you will never operate above that point... but it does mean that I beleive that if you operate at average amp rates higher then the location of the peak, your probably over geared... or your not keeping your speed up enough in the corners and need to work on setup and/or driving skill...


Of course this is all just a starting point... and you still have to use lap times for your ultimate dyno.


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## Guest

A motor that makes more power will show more power on the dyno sheet. No need to even look at RPM until you are ready to adjust the gearing.

Fred-I see that you have a handle on the amp draw as well. A stock truck on an indoor clay track will pull 75 amps coming out of the corners. I would tune the motor for this truck to have more power higher in the amp range than a touring car that draws fewer amps coming out of the corner due to the higher corner speeds. I don't see you quoting how much torque the motors put out coming out of the corners. The reason for that is the only way to know would be to use the ampdraw that we know the motor is pulling and then use dyno data to find out what torque it puts out. Torque increases linearly with ampdraw. Not much difference between using one or the other. No need to use insults.

When you tune near the average ampdraw you should bias your power higher than this value because when the car is accelerating it pulls more than the average. The average just gives a starting point.


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## DynoMoHum

Ok... ok... lets all just calm down... I know that discussing dynos is alot like discussing religion or politics, but I think were doing pretty good here. I don't see anyone insulting anyone else myself...

Now if your refering to Fred's comments about the NASCAR guy useing a notepad insted of a computer... I wasn't aware that any of us here are NASCAR engine builder.... so it shouldn't be insulting to anyone...

I could say that anyone useing a CE TurboDyno is alot like a NASCAR engine builder using a notepad insted of a computer... and that might be insulting to some... But hey... that's actualy a reasonable analagy... One of the main reasons I don't use a TurboDyno is there is no interface to the computer on them... 


But seriously... I don' think anyone has been insulting here... lets keep it that way.


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## Fred B

I don't mean to be insulting. Like I said, if using amp draw works for you or anyone else, then use it.

I would figure torque based on logged RPM, voltage, and motor temperature. You could do the same with amp draw and temp for a given motor, that's not the point that I'm trying to make. My point is that it makes more senst to compare multiple motors based on a fixed torque rather than current draw.

Once you find out how the car is performing on the track it makes more sense to compare motors based on that torque rather than current draw. If the motor has more rpm at a given torque it will go faster on the track. If you compare two motors based on Current and power, it becomes harder to make that assumption because two motors rarely make the same torque or RPM at a given amp draw even though the overall power might be the same.


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## HOOPD1

Fred B,thats something I always did when I had a turbo dyno(test motors by torque settings}But as you said you must first know what works on the track.Back when I had a Turbo six cell oval was still going strong and I used 4,6,8,10,12 for settings on the dyno,on short tracks I tuned for more rpm at 10 and 12 and for large outdoor tracks more in the 4to8 range.Always worked for me,and it was easier to relate track performance to the dyno.
With the Fantom I mostly look at specific amp loads simply because I dont think any flywheel dyno gives an accurate torque measurment.
On a CE dyno if you have one motor that makes 16,500 rpm at a 10 torque setting on one motor and 17,500 on another motor the latter will be faster as long as the amp draw isnt considerably higher.
This is just my opinion that I base on what I have seen and done,your mileage may vary:wave:


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## Guest

Sorry, but I don't "get" the torque steps. I see a huge fault in it. What if one motor puts out considerably less Torque and considerably more RPM than another motor? 

What I'm getting at is that we always gear different motors differently, and some are even geared 8 pinion teeth different. If these two motors produce the exact same power curves, then they will perform exactly the same on the track (this is independant of amp draw, which may vary). Now if we looked at these two motors with torque steps, then one will look MUCH better than the other.


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## Guest

Mike,

Huh, 4:51PM ? How come you aren't writing code?

Jep


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## Guest

Jeff,

Um, 4:53... Still at work?


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## PizzaDude

Tom, Pat, John and Dyno,

I've got one for you!

John mentioned about a truck pulling 75A when accalerating out of a corner.
How did you measure this, John?

Now one for the group.
I'm thinking about using some kind of data logger to see what kind of amp numbers are really used per track/motor combo, etc...
Suppose it says; average Amps are about 39.
What would I be able to do with that number, if (what I understand from all of you) all dyno's are differently.

I mean this info would still be meaningless/useless.
Because if I would tune my motor using a Robi, instead of f.i. a Fantom or so I would be tuning it differently.

Guys is this right?
What is your point of view on this one.


BTW love to see so many enthousiasts making there points, and supporting those by very interesting theories.
Keep it up you all.


Regards,
Pizza


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## HOOPD1

One will look much better than the other......yes and it will perform much better also as long as the amp draw is within reason.


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## Fred B

When you compare motors using torque, the torque values are the same. If motor A makes more RPM than motor B at the same torque then it will be faster on the track at that torque given the same gear.

If you need to change the gearing you'll have to figure out what the new torque is just the same as you would have to figure out what the new amp draw was. A motor with a completely different powerband will typically draw a different current. If you're tuning mod motors this is more of a problem. Also, figuring the torque is much easier on an oval than on a roadcourse because on an oval you have less turns/current spikes.

The biggest advantage of tuning by torque is when you're tuning a single motor with the same gear. If the RPM goes up at a given torque it's faster. If you tune by current the power might go up on the dyno but if there is a change in efficiency, you might not see the same result on the track.


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## Fred B

I've been using a datalogger to take my measurements on the track. I try to sample at about every foot on the fastest part of the track.

Track data is only useful if your dyno can run at the same voltage you see on the track. Some dyno's can and some can't but in general all of the dyno's on the market do a fairly good job of showing improvement over a baseline.


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## PizzaDude

Fred,

what kind of data logger do you use?

Pizza


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## Fred B

I've spent too much time looking around to let everyone know what I'm using...There's alot out there from cheap ONSET units to more expensive systems like the Valitec system. The one I'm using is similar to the Valitec system without digital channels. Look around you'll need about 10Hz sample and enough memory for an entire run. The smallest I found was from Siliconsoft but it's too slow. Whatever you get, you'll have to strip it out of it's case to get the weight down.

There's a few ways to get the current, most use a current shunt. I found a neat little module that slips over the power wire.

For the oval types, the ONSET "HOBO" is probably good enough to get some average and peak data for a run but it's too slow for roadcourse stuff.

FB


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## Mayhem

I believe the new keyence zero extreme performs some of these functions i've heard?


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## DynoMoHum

If you guys would like to take the time to look at a series of web pages I've made that show pretty much all of the ways you can view dyno data... There are four pages total, with a couple images on each page with some questions and comments. It's really not very long winded like I can be... but I think it would be interesting to have some discussion on these methods of viewing motor data...

Start here

http://www.wiltse.net/torque.htm

follow the links at the bottom of each page, and come back and discuss these if you like....

Personaly I can't make heads or tails of data in relation to time, RPM, or torque... Amp input and Percent of max RPM make perfect sense to me however... All these images show the same two motors by the way...


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## Guest

*Maximum Amp Draw of a Stock Truck.*

I used to race on a high grip indoor clay track. We used to set the slipper quite tight due to the good traction. You could hear it slip on the slow corners. I just hooked up an analog amp meter in series with the motor. With the truck stalled and full throttle applied the meter read 75 amps max and then 58 amps continuous while the slipper slipped. In separate test on two speed controls I reduced the amp limiter in steps until I noticed a slight reduction in punch out of the corners. At about 65 A there was a noticeable reduction. Fast laps on this track were achieved if I optimized the motor at 40 A on the CE dyno. Really simple. Took fairly stiff springs. In the touring car I optimize it to give the best average power from 15-30 amps. A bit lighter springs are required. You optimize the range that gives you the best track performance.


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## PizzaDude

Anyone,
Ever tried using the Victor Hi-IQ data logger?

Fred B
Do you have a link for such a unit?

Regards,
Pizza


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## Snuffy

Victor engeneering is out of bussines. Stormer hobbies still has units available in their closeout section.


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## Fred B

Try a search engine...the sites should come up if you use the company names. There's alot out there so do some digging.


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## Guest

Ok Dyno, I'll reply to your web pages...

I'm going to comment on your last graph. You said that both motors will perform the same on the track if geared to make the following graph.










I believe that Motor 1 will out perform Motor 2 any day at the track. Here's why...
After we apply gear ratios to motors and installing them in our cars, all power numbers can be thrown out and we only need to look at the Torque that is being produced at the rear wheels of our cars. Torque is the acceleration of our car, because the weight of our cars is constant. The formula is F=MA or Force = Mass times Acceleration, but I really should put it A=F/M or Acceleration = Force over Mass. Force here is the Torque of our motors.

Now with that being said, Motor 1 has more Torque in the initial RPM range. In a drag race, Motor 1 will always beat Motor 2, as long as they are geared the same as in the above graph. This is because Motor 1 will always put out more Torque at a given wheel RPM than Motor 2. If we change gear ratios, it changes everything.

The reason we compare 2 motors by looking at power numbers, is because we don't know what the gear ratio will be yet, so the power numbers take that into consideration by using both RPM and Torque. When we apply a gear ratio, we can make the motor have a Ton of Torque, by gearing it really low, or we can have a motor with a Ton of Speed (wheel RPM) by gearing the motor really tall. Now what every racer wants is both of these, great acceleration and great top speed. Both are trade offs and the motor with the most Power will have both, because it can be geared taller than another motor and still have the same acceleration.


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## DynoMoHum

Mike, I think one or both of us misunderstand each other... and/or this graph... This graph is in relation to percentage of maximum RPM for each motor. If you select the gears correctly Motor 2 will have to have a lower gear (higher ratio?) then Motor 1. Based on info that I beleive you and others told me previously, it's my beleif that with optimal gearing for each of these, the torque and RPM at the wheels will be identical for both of these motors when you choose the correct gear... I'll put the same data into your dyno viewer and adjust for something like 20 amps, and I think you'll see what I'm saying is true. Either that or I'll find out that I'm wrong...


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## popsracer

*Correct me if I'm wrong*

Dyno Guru's;

Correct me if I'm wrong on this. Motor #1 produces more torque throughout it's power-band than M2. Motor #2 has less overall torque but a considerable higher max rpm.
Therefore; 
M1: gear lower numerically to take advantage of its superior torque characteristics and make up for its lack of rpm over M2.
M2: gear higher numerically to provide more acceleration while the higher rpm will provide an equal top speed to M1.

Question;
With any motor, how critical is having the exact gear ratio. Say an EXPERT motor tuner KNOWS his car needs a 7.00 final drive for motor XYZ. BUT can only get within +/- 2% because of Gear availability or chassis limitations.

Thanks, Popsracer


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## DynoMoHum

Well... I learned something I think... But my intial idea is still valid... I just didn't understand how the efficiency differnance of these two motors would change the picture... It turns out that if you make your gear selection based on 20 amps, you will in effect over gear Motor 1... or undergear motor 2... However if you use RPM at 35 amps (peak power, equal effciency) you get the desired effect...










I'll add this to my book of tricks... and my web page... In my opion this reinforces my idea that peak power is King, and I also beleive it pretty much backs up Fred's idea that effciency is not all that important... but you have to twist your mind like mine to see this... 


I'm confused about image attachments to posts... they seem to go away eventualy... that's why I've been avoiding them lately. As well as to spare people who don't want to view them.


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## DynoMoHum

Pops... in my opion gear selection is absolutely crititcal... too high and you get a mushy feel, two low and get great acceleration but poor top end.

In terms of actual gear ratios and how far off you can be... I don't have that answer. I'm still working on figureing out how to gear correctly. I mean I know how to do it on the track, but it's trial and error for me now, I want to figure it out much better using dyno data and/or comparison to notes I have from another motor that I also have dyno data for...


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## popsracer

*Finally a reply from Fantom*

To all;

I finally received a reply from Fantom on having a Facts Dyno converted to 7 volts.
$50 + shipping and you must use the special software they designed for Trinity (which they don't use). The software is downloadable from DecCosoft.

Popsracer.

BTW; I have ordered a Robitronics.


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## tfrahm

*Golden's DynoViewer*

Any chance of a version that would allow entering CE Turbo Dyno data?


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## popsracer

*M1 & M2 comments*

DynoMoHum;

Were my assertions of M1 & M2 correct, or am I way off base.

I probably be asking LOTS more questions once my Robi Arrives.

Thanks, Popsracer
R-C Tech Forum


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## Rich Chang

*Re: Correct me if I'm wrong*

If when you are saying that by gearing lower you mean use a lower pinion, then I am pretty sure it is the opposite (at least I do it the opposite).  

If a motor has more torque then I would use a larger pinion since it has enough 'rip' but not enough top end (RPM). If a motor has less torque, then I would use a smaller pinion since it has more RPM but less 'rip.'

-Rich




popsracer said:


> *Dyno Guru's;
> 
> Correct me if I'm wrong on this. Motor #1 produces more torque throughout it's power-band than M2. Motor #2 has less overall torque but a considerable higher max rpm.
> Therefore;
> M1: gear lower numerically to take advantage of its superior torque characteristics and make up for its lack of rpm over M2.
> M2: gear higher numerically to provide more acceleration while the higher rpm will provide an equal top speed to M1.
> 
> Question;
> With any motor, how critical is having the exact gear ratio. Say an EXPERT motor tuner KNOWS his car needs a 7.00 final drive for motor XYZ. BUT can only get within +/- 2% because of Gear availability or chassis limitations.
> 
> Thanks, Popsracer *


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## DynoMoHum

Opps... Mike... gear selection based on some specific power number (not amp input) is what I want from a viewer like yours... This would make the effciency issue a non-issue... (I think)

I'm quite certian that if you took these two motors and geared them based on their RPM at some perticular output power number you would get a graph just as the one I have shown above when I used 35 amps as the gearing point.


By the way... Motor 2 in this data is owned by Hobbytalk's own Jake from, Mt Pleasant, Michigan... that's a motor I dynoed for him at a race a couple weeks ago... Motor 1 is one of my motors... I choose them specficly because they were so equal in terms of over all power output, yet the RPM and Torque are SOOOOOO much differnt. This RPM/Torque differnace is what makes them so confusing when you start looking at data in relation to RPM or Torque.

I still maintain with firm commitment that both of these motors are witin about 1% of each other with the exception of Effciency... that is once you gear them properly. 

I have also just a hour or so ago figured out why looking at at electric motor data in relation to amp input can be misleading... (back to Tfram's comments of a day or so ago)... In my humble opion if you have not found the peak of the power curve, you haven't got the whole picture yet... More on this later...


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## Guest

If you look at the view of Dynomohum's two motors as power vs ampdraw a couple of things are apparent. Motor 1 has more torque and less RPM. It is going to have to be geared taller than motor two (more pinion teeth). When geared correctly the power from 60 amp to 25 amps is very similar, so the two motors will accelerate a touring car on a high grip track about the same. At an amp draw of less than 25 amps motor one has the edge. It has more power. It is going to be faster on the straight where the motor does not pull as many amps due to high motor speed.

Gearing-in a touring car on indoor asphalt a .05 difference in the cars overall ratio is easily felt on the track. Keep tinkering with the gearing. Often a single tooth change on 64 pitch gears is way too much. Have a selection of spurs and pinions so that you can split the gears finely. Work out the ratios on a calculator for the different spurs that are available.

Power vs Amp Draw


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## DynoMoHum

Gearing gets so confusing, espeicaly when some people talk about high gear, they really mean lower ratio, etc....

I find it much less confusing to speak in terms of pinion size... When I say lower gear, I mean smaller pinion size. Higher gear, refers to larger pion.. 

Motor 2 needs a lower gear, becuse it has more RPM and less torque. Motor 1 has more torqu and less RPM so it needs a higher gear...

If I'm not mistaken... when I say lower gear, I really mean a higher gear ratio... Just like a 4.11 rear end is a lower gear then a 3.83... so now if your not confused... then you follow me.


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## popsracer

*Ok got it right*

DynoMoHum;

OK, I got it right then. I meant Numericly higher/lower 7.00 vs 6.80 FDR. 7.00 would be HIGHER ratio numerically but a but a LOWER ratio in relative terms to the 6.80 ratio.
That's why I like to use Final drive ratios when comparing one car to another.If someone says he's got a 87~27 spur and pinion. That doesn't really tell me much unless I'm running the Exact same car. BUT Final ratio can be applied no matter what brand of vehicle you are driving.
I don't believe a rollout calculation is nesessary for touring cars as most all rubber TC tires assemblies are VERY close to the same O.D. with few exceptions.

Popsracer


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## popsracer

*Gearing understood*

DynoMoHum;

I used to Drag/Street race my 1968 Plymouth RoadRunner back in the late 70's and 80's, so I understand how gearing works. Yes it can be confusing when two people are not on the same page when disscussing gear ratios.

Popsracer


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## DynoMoHum

Actually pops, I think a large number of racers go by 'roll out'... that is how many inches does the car move with one revolution of the motor. This really is the best way to do it. Tire size plays a significant role in the final gearing.

THis goes back to what you orginaly asked about... lets say your missing a pinion size and you can't get the perfect gear as a result... well you could use differnt size tires... 

Also many racers use the largest spurgears and finner teeth gears, this allows a higher resolution of final roll out... but then your motor needs to be able to slide in and out far enough to work with the bigger spur gear, etc...

But like I say I'm still somewhat of a gearing novice...


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## Fred B

Judging by the chart you provided, Motor 2 will be faster given the same gear ratio as long as you never see a load over peak power on the track. At least that would be the case provided the less efficient motor doesn't heat up and lose power. Motor 2 will also consume more power in order to go faster.

Motor 2 looks a little sick judging by the graph because of how abruptly it falls off. I'd see if it was in need of a turn or if the brushes needed more breakin.

Looks like it's another one of those trade off deals. Motor 1 is good under a heavy load and motor 2 is better under a lighter load.


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## DynoMoHum

I can see were all starting to go in differnt directions here... John was refering to my graph in relation to amp input, and I'm not sure what graph Fred is refering too...

I really think my graph made with Mike Golden's dyno viewer tells the real story. This graph takes into account gearing, and the graph pretty much tells us what will be seen at the wheels of the car when you gear these two motors based on the RPM location of Peak power. However for some reason I can't see the dotted lines in this graph, so I can't tell you for sure which lines are which... I can tell you that the amount of power, torque, and RPM differance when geared this way is not significant. If you do the math as Mike did to make the graphs, this is clear.

Now if Mike could tell us actual spur, pion, and tire sizes needed to get this gearing acomplished we'd be all set.


All other graphs I have shown can easly be misinturpeted one way or another...


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## popsracer

*Rollout calculation*

DynoMoHum;

I believe that mostly it's Oval Racers that use the rollout calculation. That 1/10 % in gearing can really make a difference in the cars ability to maximize a motors power and rpm, that could be .05 mph difference over the others cars on the track.
On the club level in T/C that I race in. I have yet to see anyone take tire diameter into account. With Foams in T/C class, it's all about compensating for uneven tire wear.

Popsracer


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## popsracer

*Wouldn't it be Great*

If Mike Golden or someone could provide a utility to aid in gearing selection based on what you selected as the criteria power/rpm/etc.
It would sure be useful to us guys that don't have 10 yrs experience racing with electric motors.

Popsracer


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## DynoMoHum

Mike is going to have to start charging for his program if it gets much more usefull... 

Racers of all types that I know use roll out... 

I can tell you this right now pops... motors, gears, and such are a very minor part of racing for a average driver it's almost not funny. What I mean is that most of us racers driving and other car setup issues are a much bigger issue.

Even for myself, this stuff is not going to do much for my on track proformance. My driving just really isn't good enough for it to matter that much. I personaly love playing with motors and dynos, and that's the main reason I do it. It also helps me understand fully that my driving is a problem... 

I know Fred and Rich personaly, we often race at the same places, and I know these guys are good enough that getting the most out of a motor can actually help them a significant amount. I know other racers that couldn't tell the differance between a GREAT motor and average motor under any conditions. I am somewhere in between. 

Fred, Rich, and nearly any good driver will tell you that the secret to speed is to keep it in the corners... If you slow down too much you'll never keep up with the really fast guys... I'm learning that this is also a huge factor in how high you can gear a motor... I could probably gear either Fred or Rich's cars about 2 teeth higher then I could gear my own car... they can keep the speed up in the corners and I can't... so their cars never get so low in the RPM range that they really work hard like mine would at the same gearing... 

So... keep all that in mind when you start trying to apply dyno data to on track proformance.


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## DynoMoHum

Mike is going to have to start charging for his program if it gets much more usefull... 

Racers of all types that I know use roll out... 

I can tell you this right now pops... motors, gears, and such are a very minor part of racing for a average driver it's almost not funny. What I mean is that for most of us racers driving and other car setup issues are a much bigger issue then motor tuning.

Even for myself, this stuff is not going to do much for my on track proformance. My driving just really isn't good enough for it to matter that much. I personaly love playing with motors and dynos, and that's the main reason I do it. It also helps me understand fully that my driving is a problem... 

I know Fred and Rich personaly, we often race at the same places, and I know these guys are good enough that getting the most out of a motor can actually help them a significant amount. I know other racers that couldn't tell the differance between a GREAT motor and average motor under any conditions. I am somewhere in between. 

Fred, Rich, and nearly any good driver will tell you that the secret to speed is to keep it in the corners... If you slow down too much you'll never keep up with the really fast guys... I'm learning that this is also a huge factor in how high you can gear a motor... I could probably gear either Fred or Rich's cars about 2 teeth higher then I could gear my own car... they can keep the speed up in the corners and I can't... so their cars never get so low in the RPM range that they really work hard like mine would at the same gearing... This is as true in oval racing as it is in roadcourse...

So... keep all that in mind when you start trying to apply dyno data to on track proformance.


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## Fred B

I'll try to explain what I'm talking about and add a disclaimer.

In comparing the data (Disclaimer: assuming that the gear is optimized for motor 2)given the same gear ratio, motor 2 will be faster on the track. It will pull max power in the turns and taper down from that in the straights. Even though it uses more power in the process it will be faster until it heats up, then it will probably take the MVP style power dump.

Motor 1 will be undergeared and never really use it's entire powerband. If geared up it will perform similar to motor 2. Perhaps marginally better near peak power and marginally worse at high speeds (low current draw).

I would actually choose to run motor 1 because it has a wider powerband and is more efficient. Motor 2 will probably heat up and fall off at the end.

If you read this before the edit, all I can say is noodle fingers...


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## DynoMoHum

I see what your saying now... Your talking about if you optimized the gearing for motor two in your car, and then simply put in motor 1 and didn't change anything else... 

Under those condtions I beleive a realatively bad driver like me, might actualy go faster with Motor 1... Because I would be going slower in the corners and because it was undergeared it would acclerate better for me as I came out of the corners slower....


We are deffintely getting closer to the same page on this... I'm not sure I agree with your final assement of how each motor would proform if they both had their own gear that was optimized for each motor... however it does seem that we pretty much agree that what ever differances there are, they are reasonably small..

I also am not sure how you figure motor 2 is more effcinent. Maybe when it's pulling more then 35 amps, but certianly not when it's pulling less then 35... Perhaps ther is a typo? or are we seeing something totaly differnt here?


I just thought of a Yoggi Berra(sp?) type saying for RC racerss... (actualy maybe for all racers...)

The faster you go, the faster you can go...

that is... the more spead you carry in the corners, the higher gear you can pull in your car, and this leads to faster entry into the next corner... I think the only point where this falls apart is on a really big track where you might get to the point where wind and rolling resistance prevents you from going any faster.


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## tfrahm

DynoMoHum said:


> * The faster you go, the faster you can go...
> 
> that is... the more spead you carry in the corners, the higher gear you can pull in your car, and this leads to faster entry into the next corner...*


You just hit the nail right on the head! I've raced 1/12 scale 4-cell onroad, 4 and 6 cell oval, offroad truck, buggy, and 4wd, touring, etc. and one thing always holds true -- among the better drivers, corner speed becomes the thing that separates the TQ from the rest. 

Example: I don't get to race oval as much as I used to, but I still enjoy it. I can build good horsepower, and I can gear it "just right", and the big dogs still eat me up. I'll pull them on the straight (but only because "my" gearing is lower than theirs so I can get punch out of the turns after bogging down), but I don't carry the speed in the corner (I have to set my chassis up "tighter" than they do due to being a bit "rusty"). So my HP and my straight line speed doesn't help me -- they lap me at under two minutes into a race... Using identical motors, they can always gear one tooth taller than I can -- that corner speed of theirs just compounds and multiplies by virtue of their ability to pull that extra gear...


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## popsracer

*The Total Experience*

Guys;

I am definetly not a Pro caliber driver, but I am a respectable club level driver that most always finishes in the top 3 spots for the "A" Mains. I do believe that with most of us having less than perfect laps. That any little extra bit can only help you overcome lost time from the occasional bobbles. I can't remember how many times that I have errored or been hit and sent to last place and then been able to make it back in the top 3. WHY, because every bit you do to improve your TOTAL package of Car, Driver and equipment, can only help to make you faster in the long run. It's ALL a Delicate balance of Man and Machine, no matter what your skill level is.

Popsracer


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## DynoMoHum

That's good pops... I could not remember what level of driver you had said you were... You are likely to learn alot from the dyno...

Hey, I took the Robi text file and put both M1 and M2 in a Excel spreadsheet... made it calculate wheel speed and torque at the wheels after gearing is applied... If I gear M2 with a 21 tooth pinion and a 81 tooth spur, and use a 24 tooth pinon and 81 Spur on M1, the torque and RPM is so close to identical that it almost amazed myself...

Sometime this weekend I'll put up the spreadsheet , graph, and data on a web page.

I'm telling you these two motors put out exactly the same power, torque and RPM once gearing is applied correctly for both. The only thing significantly differnt between the two is that M1 has a bunch more effciency from 50% to 100% RPM... In my opion the effciency advantage alone is the only thing left to sway the choice of which of these two motors to choose.


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## Snuffy

Ok. Now my brain really hurts.:lol: 
It's this that makes me understand the statment "Ignorance is bliss"


I have learned a lot about motors, dynos, and what dynos tell you about motors. The only thing I'm not too clear on is how to apply this knowledge to get me around the track faster. 

Of course using the dyno to tune/find my best motor will get me around the track faster. I don't think I understand how to use the dyno to pick a gear ratio. I not even sure I can pick the right motor. From all this discussion it sounds like the right motor doesn't nessasarily have to be the motor with the highest peak power.
It sounds like the best motor for the track is the one that has the peak power in the right place. How do I determin where that place is?
And What can I do to move the peak power to where I need it to be?


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## Mayhem

Good stuff dynomohum. Its nice to see people who are able to use the latest technology, and better yet understand it to yield lower lap times. I saw the rejection of your wonderful data you were so thoughtful to provide over on that "moronothon" motor site recently 
Those guys who are stuck using technology from the eighties are still making horsepower from the eighties anyway! Personally I appreciate your work here as should any one who wants to learn.


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## DynoMoHum

well thanks for the support... however I really would appreatiate it if we could keep insults to anyone down to something that aproaches silence... I have learned ALOT from just about EVERYONE on this board. I also would like to say that I am not thoough figuring this out... Two months ago I didn't beleive any of what I'm currently thinking about how to effectively judge one motor vs. another. I was totaly convinced that veiwing data in relation to amp input was the best way to go. I still can look at data that way and make alot of sense out of it. So I'm not willing to say viewing data in relation to amp input is completly wrong, however I'm getting close to that point...  

I know for sure if it had not been for this discussion right here I would never have started to ponder the path that I'm on now. Tfram, Rich, Fred, John, Snuffy, popsracer, Mike, and everyone else that has been contributing to this has been a HUGE help to me. 

What Tfram was asking earlier about how viewing motor data in relation to amp draw and how it can bias you towards thinking the most effcienct motor is always the best motor is what I'm trying to ponder mostly right now. Especialy as it relates to how a person could use a TurboDyno more effectively...

I think there's going to have to be some math involved. At this point I just don't see any other way around it. Basicly the issue I'm thinking is needed is to know exactly what RPM a motor achives at some minimum power figure. Then you view all torque and RPM (and in effect Power) by looking at this with gearing involved. Torque get's multiplied by the gear ratio, RPM gets devided... The only way it seems to work is if you pick the correct gearing point... and I think this MUST be done using POWER as the common element for the point you use.

Robitonic's data in relation to %RPM sort of does this... but they use some minimum value for torque as the point for max RPM. This is flawed however... but it does usualy get pretty close. They also don't modify the torque and RPM figures so they are corrected for gearing, so it still kind of confuses the issues.

For all who still are thinking I'm crazy... Well I would have thought the same thing a few months ago... and I'm sitting here awake at 6Am on a Saturday moring trying to figure out a way to convince myself and others that I'm at least on the right path...

maybe I am crazy... when I can't sleep because dyno data is bouncing around in my head, and it's all just a toy car... that is saying something...


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## PizzaDude

I have to agree.
This thread really does what's suppose to do.
People with different opinions giving there point of view.
And being open minded to listen what the other has to say.

We do not have to agree about everything, just as long as respect each others opinions.
A healthy discussion is what's happening her.
I too have learned quite a bit from all of you, but maybe not figuring out everything as specific as you guys do.

Regards,
Pizza.


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## Mayhem

One thing that i think needs to be said is not to overthink all this data. It still really comes down to one thing: The motor with the best balance of power and efficiency usually runs best on the track. After 10 years of racing before i got a dyno, I learned all this stuff based on feel on the track. Now i am able to confirm my gut feelings with the dyno. The combination of the two is hard to beat, when your dyno confirms your gut feeling for what gear or motor to run you know you are really on the right track.


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## Fred B

DynoMoHum,

You read it before the edit...I was writing a report and posting at the same time so everything was running together. Motor 1 is more efficient.

The motors will be the same speed at peak power as long as you compensate for gearing. They make the same power. When you gear motor 1 to hit it's maximum load slightly above peak power it will probably be slightly faster out of the corners and about the same at the end of the straight.


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## DynoMoHum

OK, here is the view that I belive tells the story pretty effectively. My opion is that geared as shown in this graph, there isn't a racer in the world that would be able to tell the differance between these two motors on the track. At least not for the first minute or so. Eventualy M2 will drain the battery of more power then M1 does, and the batteries will have less voltage due to the way bateries behaive. Motor 2 will also eventualy get warmer then M1 will, and M2's effciency and power output will delcine more as a result... so in the end you would stay faster for a longer period of time with M1.










If you'd like to look at the data for these motors and play around with the gearing and see what happens, you could download the Excel file I used to make this last graph... It's really kind of interesting... as you can see what changing one tooth will do... or changing the Spur gear, etc...

www.wiltse.net/zips/M1vM2.zip


I think this whole study in these two motors and the various ways of viewing the same data point out some down falls of nearly every commonly used way to display dyno data... I'm thinking a graph like this last one is the best way to veiw things... Mike Golden's DynoViewer creates a very simmilar graph... however there seems to be a bug/feature that makes it impossible to see differance between the dotted lines and the solid lines...


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## DynoMoHum

Snuffy... I'll have to get back to you on your last comment/question... The basic answwer is Peak power and effciency are both critical... Large peak power with poor effciency will not work well... neither will high effciency and low peak power.

Mayhem basicly said this... in his last post... however I beleive you can figure this out with a good dyno and some knowlege of how to best interpet the data. It's my mission to figure out the best way to do this. I am very confident I can do it with a Robitronic Dyno...

Today I've been trying to figure out the best way to go about it with a TurboDyno. I think the best way would be to plug the numbers in a spreadsheet and figure it out based on gearing... However I've been looking at my Robi data and trying to imagine what I would do with a TurboDyno and only 6 steps to work with....

I think in 90% of all cases the following method would work reasonably well... for 6 cell racing... use the following steps at 7 volts constant... 10, 15, 20, 25, 30, and 35. Find the motor that has the highest power at 30 amps. Most likely this motor will also have the higest power numbers at 35 as well... Peak power should come somewhere very close to 35 amps... but it may not be super critical if you don't find the exact location... The next part of the process will be to evaluate the effciency of the motor, do this by examining the rest of the numbers... If you find a motor that has awesome power at 30 amps and also has good power at 20 amps, then you have a good motor... I couldn't tell you exact numbers to look for however... You'll have to figure that out on your own... I would say that 100 watts at 20 amps is still a good number to shoot for, however if your 30 and/or 30 amp numbers are not also excelent then motor will not be as good as it can be...

For 4 cell the process would be simmilar, but I think peak power is probably between 25 and 30 amps at 5 volts, so 35 amp will likely be lower then the 30 amp number on nearly any stock motor...


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## Guest

Dynomohum- Only rub here is the ratios selected have to actually work in the car. A slight difference in the ratio selected produces distictly different curves on your spreadsheet. When you multiply the ratios in your spreadsheet by the car ratio (which you might add) you get quite a spread in gears. One is very low for a stock motor one is quite high. More than say going from a green machine to a P2K in my experience, but then maybe not in your experience. Looks like an interesting approach.


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## DynoMoHum

I'm a pan car guy mostly... so this is the exact ratio the car would see from motor to wheel in a pan car...

If I was interested in a car with a gear box, I would take into account the final drive ratio including the gearbox... once you did this, you could acomplish the same thing. 

Tire size and roll out ultimately need to be considerd as well... The spread sheet as it stands now, is just a starting point. However in my humble opion, it proves that these two motors could be geared to make them have virtualy identical RPM and Torque at the wheels when geared apropreately.

Yes the curves change significantly when the gears get changed.... Just as in real life...  I don't beleive there is any mistake in what I did, unless you are looking at it from the perspective of a guy with a gearbox in his car... You are correct that this would be a nice feature to add... as would rollout.

Any one got a typical gear box drive ratio that I could start with? I'm not up on my gear box car info...

For what it's worth M1 is a P2K and M2 is a GM3... neither of these motors is what I would call excelent. That is, I have other motors that are better, and I have seen a few other motors that some of my competitors have that are MUCH better (when tested on my dyno). I'd call these motors average... and I personaly would never use a motor that didn't proform at least as good as either one of these does. I also beleive this is quite typical of the differances I often see between a typical GM3 and a typical P2K, and this is exactly why I don't perticularly care for the GM3 motors. I don't really mean that as a slam on GM3s, but this really is very typical of what I see with both of these types of motors.


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## PizzaDude

Dyno,

I've been looking at your motor comparison sheet in Excell.
I like it !

How can I use it myself?
Import my own motordata into it, and fiddling around with gearing?

BTW did you use the robi gear calculation at first to check its recomendation?
Or does it differ from your own findings?

Thanks,
Pizza


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## DynoMoHum

Mike Golden's DynoViewer basicly does the same thing as my spreadsheet, it just doesn't give you actual torque and RPM at the wheels the way my spreadsheet does. With Mike's DynoViewer you can load data direct from Robitronic text files, or past Fantom Facts II data in from the clipboard. 

My spreadsheet is pretty easy too add other Robitronic data in, but it would be harder to try and make Fantom data work... 

Robitronic's gear utility has what I consider to be a flaw... it uses some minimum torque amount as the common point for calculating gearing. This doesn't work all that well... In my opion POWER must be used as the common element... So, no I didn' t use Robitronic's gearing utility for this. Mostly I just played with it, till I got the torque curve to match up...

I've played with about 5 of my best looking older dyno runs, trying to test the theory that Peak Power is the single biggest facotor in determining how well a motor will work for a short duration. It seems to hold up very well. Effciency is the next most important factor as far as I can tell. I don't have a fool proof plan for determinging just how much efficiency is enough and/or best... My basic thinking is that if your loosing more then a couple percent of peak power by tweaking things to get more effciency, your basicly playing a loosing game.

Based on my early exploration, I think the concept of a wide or narrow power band is a myth... that is of all the motors I've put in my spreadsheet, they all show the same basic power curve when you gear appropreately... I'll try and demonstrate this soon with graphs and such.

Right now I want to try the same basic idea with some TurboDyno data... Since I sold my TD this weekend, all I can do is find some old data to play with... I really want to see if this what I'm seeing only applys to Robitronic data or if the principle will hold up with other data.... For the time being I'm not going to monkey with Fantom data much, because quite frankly I still don't trust it... On the other hand I have Snuffy's data already in a spread sheet and it wouldn't be hard to play with.


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## DynoMoHum

I've started to anyalize some TurboDyno data I had for the Monster and a P2K... the same two motors that Mike Golden did a anyalisis of usig my Robitronic data for the same motors... 

Anyway... I can get the slope of the Torque curves to line up in a very simmilar way to what I see when I use the Robitrnoinc data... I have to use drasticly differnt gear ratios then I expected to do it... and even then the RPM range from start to finish is differnt with the two ... Given the the fact that the TD is a breaking type dyno, and the Robi is a flywheel, this may account for it all...

Basicly I'm still tring to figure it out.

I'm currious now about the Fantom and if I can get data from it to show up simmilar to what I see with the Robitronic data...


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## DynoMoHum

FYI...

For those of you that may have at one time or another doubted the voltage curve that the Robitronic dyno uses when it tests motors... I was just trying to evaluate the differance between a ESC that I felt was causeing me proformance problems, and a new Keyence Zero V. I jamed the dirve train on my car, with a 19T chameleon moto in it, measured the voltage across the motor and the battery while I gave the ESC full throttle... on the old ESC I had just 1.4 volts across the motor, and 3.97 volts at the battery. WHen I put the new Keyence ESC in the car, I did the same procedure... I got 2.25 volts across the motor, and 3.0 volts at the battery... THis is all with a 4 cell GP 3300 pack, about 50% charged. Reading 5.1 volts at rest.

So what does this mean? Well first off, it means my old ESC was a big burden on my proformance and I should really see a differance on the track the next time I go racing... 

I went back and looked at a recent dyno run of this chameleon when tested on the Robi at the 5 volts setting.... at 69 amp (startup current) the Robi was putting 2.3 volts to the motor... Based on my observation during my ESC evaluation, I'd say the Robitronic dyno is doing something pretty reasonable with the way it does it's voltage curve thing... 

Makes you wonder how valid a dyno test at a constant voltage is likely to be...


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## Guest

Here are my thoughts on Efficiency...

With an electric motor, we put Electrical Power into it and get Mechanical Power out of it. When tuning one of these motors, we would like it to convert all of the Power we put into it to Mechanical Power. This would be 100% efficient and impossible.

Now let me back to the point. When we tune a motor, what we are really doing is maximizing the efficiency of the motor at a specific Power Input. We can tune a motor at higher Power inputs or Lower Power inputs. Any motor that puts out more Output Power at the same Input Power is always more Efficient, as per the definition of Efficiency. 

So we can tune a motor to be the most efficient at the Power Input that we feel we use the most while our car is on the track, or we can tune a motor to be more efficient at its peak. Either way we are still making the motor more Efficient somewhere with respect to a specific Power Input.

Efficiency is King in the motor tuning world, but the real question is, *Where do we want the motor more efficient?*


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## DynoMoHum

I totaly agree with your comments Mike. Now the question becomes, how best do we use a dyno to simulate as close as possible the condtions the motors will see on the track... Or at least get as close as possible. Also, how can we view this data in a way that doesn't mislead or confuse us?

I also beleive there could be a lengthy debate about what/where the effciency is best placed. For instance... should we average 20 amps, 25, or even 30 amps or higher to make most use of the power source and motors that we use??? 

Using Robitronic Dyno data, I beleive I can show with very little doubt that with todays batterys peak power is likely to be much more important then power at any other location. Essentialy my present thinking is that if you had a motor that put out 132 watts at 28 amps and just 90 watts at 20 amps on a TurboDyno, it would be a much better motor then a motor that put out 100 watts at 20 amps, and 129 watts at 28 amps. I don't have enough TurboDyno data to make a good study of this, however I beleive I have plenty of Robitronic data that I can make my point with. My next project is to illustrate this idea as best I can. I suspect that I will be able to convince at least a few people that this is likely to be true.

This is a complete flip flop for me... so I'm still trying to convince myself of this as well... That's the primary reason I'm persuing this. It turns out that in my past motor tuning, it just happend that 95% of the time when I tuned my motors I got better peak power along with better power at lower amp loads... so my past dyno data was pretty much always backed up by my on track proformance and doesn't really conflict with my current thinking.


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## DynoMoHum

Ok, ok... I have something that I beleive every racer with a dyno should see. In my humble opion this study of two motors I'm about to show you, proves what Tfram brought up a few days ago... Does viewing data in relation to amp input inherently cause a bias towards effciency? It's not the dyno that is causing the bias howerver... it's the way we see the data...

I call this one... the great paradox... ( I wonder just how Trinity did come to name there older motors Paradox...)

http://www.wiltse.net/paradoxical.htm

I really do encurage you to look at this and try and understand it... I beleive this is a key to understanding dyno data in away that I've never before seen quite so well defined... I also beleive it shows just how important peak power really is... Please feel free to discuss this. If I'm not mistaken this will stand conventional dyno viewing procedures on it's ear...

By the way... if you want to play with the spreadsheet with these two motors in it you can get it here...

http://www.wiltse.net/zips/paradoxical.zip

I think I changed the gearing on M8 before I ziped that excel document. You need both motors geared to 30 tooth pinions to get the graphs to show as I have them in the web page.


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## Mayhem

I,ve always tuned for peak efficiency at peak power. Assuming gearing is correct this would be nirvana and one would think the motor is optimised. This is easy to do but at the sacrifice a decent power rating. In my experience it is better to let the peak efficiency number slide a bit to gain a few extra watts. I tune for the highest power number, within reason, then try to maximize efficiency without letting max power degrade too much. Gearing that is really on the money will make up for a lot of sins of a motor that is a little in-efficient. After a while you come up with certain parameters you need for a good running motor confirmed by track testing. I like the Fantom for the fact that you can really fine tune the gearing calculator to be very accurate. Mine is usually accurate to within 1 or 2 rollout points for any given motor.


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## Guest

Side Note.

Paradox was named because it was the first rebuildable stock motor.


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## Snuffy

DynoMoHum

If I'm understanding you right, your saying it's better to compare motors on the basis of RPM and not Amp draw, right??


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## Guest

dynomohum-I see that you noticed that maybe the gear ratio spread to make two motors look just alike at the rear wheel might be too wide also. You can probably make the rear wheel torque of any stock motor look similar by picking a suitable ratio. They definitely behave differently on the track, though. How about picking two motors that you have optimized the gear ratios on the track, using lap times, and using their ratio data in your spreadsheet. Then I think you might get a more realistic comparison that might lead to a better way to compare motors. Maybe you have done this and I did not see it.


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## PizzaDude

Dyno,

Jon's suggestion is a challenge.
Can't wait to see the outcome on that one 

CU
Pizza


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## DynoMoHum

Perhaps I was a bit too dramtic in my statment about how much value I see in this new way to view dyno data... and I didn't give enough information about the value I see in it. I'll try to better describe why I think that the best way to view dyno data is to apply some gearing and then compare the numbers... 

So Snuffy, that answers your question... no I don't see viewing data in relation to RPM as being valid unless you apply gearing before you view it. At that point you could view in relation to RPM or torque equaly well I think. Adding the gearing is the key.

I told an untruth previously... to get the graphs I show on the web page I used gearing with a 30 tooth pionon and a 100 tooth spur gear. Previously i had mistakenly said I had a 81 tooth spur gear. The graphs actualy change a little when you use 81...

Yes, John, I beleive your idea is a good one. Take the two motors on the track, choose gearing based on lap times and then plug them in to this type of viewing senerio. It should tell alot. Unfortunately I don't own M7, and the guy who does, may not even know which of his motors it was/is. It was a year ago when I tested that motor for him.

My best motor is M8, a P2K. If/when I find another motor that has the charactoristics of M7, I will race it, and probably never look back on my days when my best motor was M8...

If you take my spread sheet and go up 2 teeth on Motor 8, you will see that the amp consumption of both motors gets to be more or less identical. At that point motor 7 has much better low end power, both motors then have nearly identical output at mid range, and M8 has higher power at high RPM. This makes it look pretty much like you'd expect from looking at the data in relation to Amp input.

If you choose 31 tooth for M8 it will be beaten in output power at all but the highest RPM range.

Choosing 30 tooth for both motors in my opion makes M7 have about 3% higher power throughout the intire RPM range. (actualy 30 toot for M7 30.5 tooth for M8 gives the most uniform torque/power advantage to M8. IF you gear this way, it's my opion that M7 will proforma better then M8 on all areas of the track. Current consumption will go up by aproximately 2.5 amps... So if you were like me, and your best motor was M8, and then you found M7, geared at 30/100 for each motor, your average current consumption would go up, but so would your on track proformance. Say if you were operating at a average current of 23... you would then be operating at about 25.5, however you would have better power on the track...

So... I really like this new way of viewing my dyno data. Only time will tell if the Robitronic dyno numbers are accurate enough to hold up to actual on track testing... I personaly feel I have a much better handle on motor proformance issues. I also feel I have a much better understanding of how gearing will effect the on track feel of a motor... If my Robi data is reasonably accurate, I feel confident that I could use this new dyno viewing method for chosing a proper gear for the new motor as long as I have a baseline gearing for a motor I already own.

If you down load the spreadsheet and start playing with the gearing I think you'll like it too...

Snuffy, I'll start playing with your Fantom dyno data in this mannor to see what it looks like when I do... I'll report back soon. I can tell you right now that your MOTOR TEST motor is likely to show up as the best motor.... (I think that was the name of the one I liked best)


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## DynoMoHum

Mike Golden,

I'm currious about what my spreadsheet is doing differntly then your DynoViewer... If I compare my Excel graph with gearing applied to your dyno viewer with some ratio changes, I can get some simmilar results, but the are not exactly the same. Apparently you and I are doing something slightly differnt then one another...

My procedure was to recaluclate torque and RPM based on gear ratios... I multiply the Torque by the final drive ratio, and I divide the RPM by the final drive ratio. I do this for each data point, and then graph all the data in relation to the newly calcluated wheel RPM. 

One of the biggest differances I see with my method vs. yours is the amp numbers...

It seems that one of us is doing somethign wrong... either that or we are doing something that is not quite the same and can not be directly compared... I'm not sure which.


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## TeamGoodwrench

My head hurts reading these 

How about this question for us mere mortals...

Using the Fantom FACTS software, I can get the required rollout to achieve a given number of laps. If I enter the TQ laps and time, and then get the required rollout, how do I know that the motor will actually "pull" that gear ??

In other words, when I dyno the motor and then go to the gearing screen, if the required rollout to make a TQ run is 2 or 3 teeth higher on the pinion than I've ever run on the motor, I would obviously be suspicious as to whether the motor can actually "pull" it and not be glowing red after the run.

Are there some indicators that you guys look at in this respect to determine whether the motor can handle the required gear ??

Thanks!


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## DynoMoHum

I am no expert at the Fantom or about the topic your asking about Goodwrench. However I have thought about a very simmilar thing in a differnt way. It's my beleif that there is no simple answer to your question. I belive it is highly dependent on car setup and driving driving ablity. It goes back to the idea I had that says... 'the faster you go, the faster you CAN go'...

To make it less complex lets talk about oval racing. The faster you can drive through the corner the faster you will be going when you come out of the corner. The faster you come off the corner the less force you will need to accelerate to a very high speed at the end of the straightaway. It all snowballs... This means the TQ guy's motor does not have to operate in such a broad range of RPM. It's my beleif that this allows him to gear much higher then you could if you can't get through the corner as fast as the TQ guy. He can gear for the most productive spot on his top level motor... you have to operate over a wider range, and it's virtualy impossible to get the same kind of power and effciency from your motor even if it is a top level motor.

Of course if your driving and setup are as good or better then the TQ guy... then you should be able to do what your asking about.

Does that make sense? and can you now understand why what your asking about is almost impossible to do? Or am I completely crazy?


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## TeamGoodwrench

OK... what does "can gear for the most productive spot on his top level motor" mean ??

Where exactly is the "most productive spot" ???


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## DynoMoHum

I'm still trying to figure that one out Goodwrench...

I'm thinking that at it's most basic level, it's geared in such a way that you you rarely operate at a RPM that is lower then the location of Peak power, yet you also do operate at Peak power a significant amount of time. 

In oval my best guess is that you should be geared so you are operating at peak power in the corners. Then you'd accelrate up to the area where peak effciency occurs... My current thinking is that this is in the right ball park anyway. 

Like I say... I'm still trying to figure out the answer to your question Goodwrench.


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## Guest

I agree that the faster driver can gear a little higher. About .1 higher on the overall ratio at ReflexRC in a touring car. Not a couple of pinion teeth unless it is a stock motor with a different style of armature say a P2K2 vs a P2K. You are not going to gear a stock motor up to draw 2.5 more average amperes unless it was really undergeared to start with. It will fade badly. The way a stock motor handles heat is an important consideration with on track performance. This is hard to simulate on the flywheel dyno's. The CE dyno does a better job of this due to the long test, but then there is more wear and tear on the motor as a result.

I think the only way to know if a motor will pull a gear is to stick it in the car and look at the lap time sheet. If the motor fades you will feel it toward the end of the race and see lower lap times as a result toward the end.


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## TeamGoodwrench

John -- that's exactly what I was getting at. Gearing it up to the point where it generates heat and fades badly. 

I'd like to find a way to look at some data on the dyno run and be able to identify that the motor just won't be able to do a TQ run. 

Thanks


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## DynoMoHum

So John, What kind of average amp consumption are you currently operating at in your racing? I haven't heard from too many TC guys on this topic. 

Oval guys are telling me they operate between about 25 and 30 amps average during 4 minute races. The fast guys I race with rarely if ever fade much at the end...


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## Guest

I am at about 19 ampere average in the touring car. If I gear up .05 I loose considerable punch out of the corners,The car feels soft and unresponsive. I seems to be a very narrow range of gears on the touring car that will work well on the track. In the summer motor temperatures are about 180 F. Any higher and the motor fades or feels sluggish.


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## DynoMoHum

Interesting... 20 amps * 300 seconds is 6000 amp seconds... divide this by 240 seconds and you get 25 amps. 25 amps kind of the low end of what I hear fast Oval guys average. It seems that for oval... the smaler the track, the lower the amp average. (this seems counter intuitive to me... but thats what I'm hearing).

What size track is this that your running on John?


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## DynoMoHum

Also intersting is this... those last two motors I have shown data for have peak power at about 36 amps, and peak effciency at about 19 amps.

Actualy M7 hits peak power at 36.8 amps, and peak effciency is at 20.0 amps. M8 has peak power at 34.8 and peak efficency at 17.4 amps... Both peaks occur about 2 amps differnt on these motors.

Until I see differntly my theory on thes two motors is that you could go faster with M8, but you'd wind up averaging something close to 2 amps more doing it.


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## Guest

The track is medium sized indoor asphalt. Maybe about 120 x40 feet. Can't pull 25 amps average. The stock motor will be on fire. A touring car will pull much higher amperage coming out of corners than an oval car. This concentrates heat on the comm itself. That is the weak link. If you smell the motor after a run and smell burning Bakelite plastic then you are geared a little high. The shorting of motor 2% of time increases comm temperatures. The motor will also have less cooling than an oval car due to lower motor speeds.

Small comm mod motors can generally be geared to dump the pack on our track without feeling sluggish. They are more efficient and don't have the shorting to deal with. They run about 180 F at a 35 amp average on our track.


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## DynoMoHum

I'm not sure what you mean by 'shorting' of the motor. I don't beleive I've ever heard that term...

Well the other big factor is the time... Oval is typicaly 4 mintues, TC 5 minutes...

Even so, I was thinking some of my local TC fast guys were telling me they average up torward 25 amps... in 6 cell stock racing.


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## tfrahm

*Touring 6-cell Stock* -- Racing this summer on a concrete parking lot, large track with about a 285' racing line, TC3 with Optional AE motor clamp for more cooling AND small clip on heat sink as well(clip on heat sink stored in ice in cooler until right before race to maximize cooling, well tuned P2K's with a rollout around 1.15-1.24"... Motor temps ranged from 185-230 degrees F. (weather and air temp played a part here). Amp draw averaged around 25 amps, but this was REALLY pushing it (you could actually blister fingers on the motor after a 5 minute race). This is clearly as hard as you can push a motor and not kill it -- at this load, the comm would begin to discolor slightly, developing an orange color to it. Car was fast, made every A-main I attended all summer, and won my fair share, so this is about the limit I was willing to push the motor...

*"Shorting" the motor* -- Modern stock motors with laydown brushes have a "situation" that actually shorts out the comm. Fully seated brushes have too much overlap, and every comm segment will physically touch BOTH brushes (thus it creates a "short") twice per revolution (once at the "top", once at the "bottom"). So 6 times per revolution, for a brief moment, the comm is shorted and carrying high amp loads (HEAT)... My "solution" is to shave just under 1/32" from the trailing edge of each brush. This is a minimal change to the brush surface, and eliminates the short. I seem to gain torque and lose a marginal amount of RPM, but the motor is more efficient and runs cooler... (Trinity's P94 ads used to have good images of the laydown brush shorting situation...)

http://www.teamtrinity.com/motors/images/brush/brush3.gif

Note the yellow segment is touching both brushes -- the copper segment creates a dead short from one brush to the other....


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## DynoMoHum

Cool... thanks for the Info Tfram... I had never heard of this shorting issue... Learn something new every day... Somedays I learn more then one thing...  Looks like the idea of triming the trailing edge could be just the ticket...

Another interesting tidbit about M7 and M8... at 21.6 amp load both motors put out exactly the same power (and by deffinition effciency). M7 produces greater power at higher loads then this, and M8 puts out more power at loads lower then this.


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## DynoMoHum

25 amps for 5 minutes would be very simmilar to 31 amps for 4 minutes... between 20 and 25 seems likely the range for TC and 25 and 30 for Oval... this is based largely on what others have told me, and somewhat on what I've seen with my own oval racing. This is for stock racing, with other motors like 19 Turn Spec or other mod motors they will work at higher amp loads because of their effciency curves.

Oval racers can get away with larger rollout as well because they don't slow down as much and punch at very low speed is not much of a factor.

Then if you go to 4 cell... it's a whole new game... 4 cell stock motors peak at a much lower point... more like 26 to 30 amps for peak power.
(Based on Robitronic data) Since the overall power is lower they can likely operate at higher at peak power though out a race without much trouble.

Just random thoughts about all this...


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## Guest

To directly look at the heat a motor will produce, all we have to do is look at the unused power. 

Example:
M7 is 60% Efficient at 36.5 Amps, it is putting out 133 Watts while taking in 221 Watts, which leads to a 221-133 = 88 Watts of Heat.

M8 is 60% Efficient at 34.7 Amps, it is putting out 128 Watts while taking in 210 Watts, which leads to a 210-128 = 82 Watts of Heat.

The two samples I used above were the peak power of each motor. You can see that M7 will get hotter running at its peak than M8 will, even though they have the same Efficiency.



Also, you may find two motors that have the following characteristics:

M1 is 65% Efficient at 35 Amps, and putting out 137 Watts while taking in 210 Watts, which leads to a 210-137 = 73 Watts of Heat.

M2 is 63% Efficient at 33 Amps, and putting out 125 Watts while taking in 198 Watts, which leads to a 198-125 = 73 Watts of Heat.

These two motor, which I made up, would have a 2 Amp difference in battery consumption, but they would both run at the same temp.


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## tfrahm

*"Average" amp draw...*

I agree with your analysis of why some forms of stock racing can "get away" with pulling more amps than others...

With my TC3 for example, I run an LRP SR speed control (with the "chips" to control amp draw)... Even though the "average" was 25 amps, I did some testing and I can tell you for a FACT that I could feel the difference between a 50 A chip, a 65 A. chip, and running with NO chip (unlimited amp draw)... I normally ran with a 65 A. chip because it still allowed good punch with some reduction in motor temp. 

But all this means that, at times, I WAS pulling that full 65 amps on the track! So the 25 amp average is misleading, because you have to be able to handle and dissipate the HEAT that 65 amp load generates! The average helps you tune the motor, but it only gets you in the ballpark...

On the other hand, a well setup oval chassis might have a motor that averages 30 amps (which would sound excessive if a 25 amp average nearly cooks a TC motor), but that motor may spend the whole race in the range of 25-35 amps, so it never has the monster heat and power demands of the TC at 65 amps...


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## Guest

My motors are about 20 degrees hotter on the top magnet than the bottom which is subjected to some airflow. I measure the bottom. Some things that happen when you run a stock motor too hot. The magnets get loose after a couple of weeks. The epoxy is weakened by the heat. I have a suspicion that this is why Trinity secures the magnet with springs and epoxy in the GM3's. Keeps the magnets in place. People seem to burn up this motor a lot from overgearing. The other thing is that the bakelite will burn off the inside of the comm segments. This creates a gap and increases the comm temperature. Both events result in a mysteriosly slow motor. You can get away with some overgearing when the motor is new, with a fresh large comm. After a couple of cuts then you probably have to change gearing a bit.


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## Fred B

Heat is definately more of an issue now than it was with the older batteries. Some of the top drivers at Cleveland were running cooling fans in TC. They do work and when you're 2.5oz under weight it's doable.


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## DynoMoHum

Great stuff guys... all this stuff is important if you want to lean how to go faster... I really do beleive that more then ever we are operating on the ragged edge of what these stock motors are capable of... I honestly will be amazed if any truely break through developments are made in stock motors themselves... maybe liquid cooling might help...  would that be legal?


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## DynoMoHum

I have to confess... I don't have any idea what kind of motor M7 is... After investigating why my graphs didn't match Mike's DynoViewer graphs... I discoverd that I was compareing two differnt motors with my spreadsheet then I was with Mike's DynoViewer... I wasn't aware that I had two differnt dyno runs that looked as good as M7 does... Compareing M7 to the run I thought it was, leaves me thinking theres a good chance that M7 is indeed a Paradox, simply because the two files are so much alike in terms of RPM and Torque.. However I can not say for sure what kind of motor M7 is... there were no notes assoicated with this motor. I the only clue is that I named this file US001 which means nothing to me... 

Well it's a good motor what ever it is...

Oh, and it also points out that Mike's DynoViewer is one slick peice of work... If you've got a the Fantom Facts II or a Robitronic dyno I suggest you get his viewer and play around with it... 

For you TurboDyno guys... you'll have to ask Mike nicely if he'll try and work on accpeting TurboDyno data with his viewer...


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## DynoMoHum

Snuffy,

RM-02 11-09-02 is your best looking motor. I has the best power of all your motors, and it's effciency isn't bad either... 

The 'MOTOR TEST' motor has some awsome effciency, but it doesn't put out as much power as RM-02...


THe RPM is so close on those to motors, you don't even have to shift gears to see the differance... 

Use Golden's dyno viewer to view these two motors I think you'll see why I like RM-02... Look at the RPM graph... Previously I had thought MOTOR TEST was better because of it's effciency... it still may be a better motor, but these two are likely the best two of the ones I have data for.... all of the Monster motors looked pretty good though... one has REALLY poor effciency though... I don't know why... it looks really strange compared to the others.


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## DynoMoHum

I take it back... I can not defend the choice of RM02 over MOTOR TEST.... the effciency differance is just too great, and the power advantge of RM-02 too small. If you look closely there are some places that RM-02 uses 10 amps more power to produce 1 or 2 watts of power... 

I do think the study of these two motors is a very interesting situation... If you compare the amp veiw to RPM view with Golden's dynoviewer it is pretty amazing how much differnt things look...

Based on the data, I have to go back to saying MOTOR TEST is the best motor Snuffy has given us data for.


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## popsracer

*Robitronic questions*

To the Dyno Guru's;

I have my brand new Robitronic Dyno sitting in front of me and would like to ask a question. MUST I solder the power leads on every-time that I want to check a Motor or would it be acceptable to put a Deans plug on the end of the lead. I use a short Deans pigtail on all my motors and it sure would be nice to have a plug in connection too. BTW I am ONLY testing/racing stock motors.

Thanks, Popsracer


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## Mayhem

I cant think of any reason why not. It cetainly wont hurt anything. try the same motor both ways and see if there is a performance gain/loss. There might be a slight difference but who cares if you do them all the same way every time, its all relative. The connectors might actually be more consistant over the long run...


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## 300M

Mike:
For referance heat is measured in BTU's British Thermal Units. You multiply watts by 3.41 to get BTU's In the example with M8 & M7 yeilds 300 BTU's for M8 and 280 BTU's for M7. Dealng with heat disapation there is not much differance between these two and I would consider the differance irrelavant. However as you pointed out, this is waste heat and needs to be dealt with! If you could expose the motor to the airstream you could make a considerable differance in the losses. You could drop temps by ~30%.
When I run my TC and crank the numbers I get an average of 24.8 amp draw also. This seem to be a good indication of what the avarage value is for TC

Pops: I have done both. My Turbo and Fantom both had aligator clips that I used, I was lazy. I just switched to soldering on the Turbo and the numbers went up. But mayhem hit the nail on the head. Do it the same way every time and it will not matter.


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## DynoMoHum

I hate variables... I solder the leads directly to the motor every time when I use my Robitronic dyno. It's really not that hard and I beleive the results will be much more consistant as a result. I litteraly am looking differances as small as 1 watt when I do motor tunning or selection. Small differances in resistance will make noticeable changes in dyno numbers. Why take a chance that your dyno run is flawed because of a bad connection?

I've done tests, I don't remember the exact numbers right now, but if you add about 8 inchs of 12 gauge wire (two 4 inch peices) you will notice the differance in power... I beleive it was in the neighborhood of 3 or 4 watts peak on a stock motor. Now if you do this consistantly with the same lenghth wires and the deans connectors are always in good shape, your results may remain consistant and the variations small enough that it doesn't matter.... 

If you could move the voltage sensing leads to the motor, then adding wire or reducing wire would have very little effect... 

Anyway... it's not that hard to solder the leads to the motor... so I do it all the time. Just keep the solider iron warm and handy.


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## DynoMoHum

We need to develop some formulas that allow us to evaluate motors taking into account effciency and output power as two seperate things. Hopefully not get too complex, but at least take into account heat and loss of battery voltage do to current drain on the batterys... Maybe it has to be reasonably complex but I beleive some aproximations could be used in many areas... 


A seperate but somewhat realated issue that I've been thinking about for some time now...

How much of a motor's effciency and/or power output is due to RPM and/or Mechanical issues as oposed to Voltage and Current?

For example... a stock motor generaly produces peak power at about 50% of it's maximum RPM. If you apply less then full voltage to the motor when it's rotating at this same point, is the effciency the same? or is effciency more a product of votage and current?

I beleive that realtive RPM is the key element here, but I don't know for sure. Realtive to max RPM... When I view data for the same motor at 7.5v vs. 5 volts the power curve looks like it relates directly to percentage of max RPM... The effciency curve appears to follow this as wellf. This would tend to make gearin independent of Voltage and current... which would be a good thing to know...


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## Guest

I'd say to just run the plugs, because that's how you'll race it. If a motor runs like crap on the dyno and you find that its a bad plug, then you'll be able to see and fix the problem. But if you just solder, you'd never see the problem.

I also like Dyno's idea of connecting the voltage sensing wires to the motor. I think a set of alligator clips on those would work great.


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## DynoMoHum

I haven't done any math on this, and I have no idea of what engineering principles are involved, however I question if adding wire and moving the voltage sensing leads would somehow cause the Dyno to opearate beyond it's capablilitys and potentialy cause some problems.... For this reason alone I would advise caution in tryng this sort of thing... I in no way would take any responsiblity for what might happen... 

I don't think it should be a problem... I just don't know for sure. All the more reason I'd just stick to soldering directly to the motor... It really isn't that hard...

Mostly I'm just paranoid and like to control any variables as much as possible.


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## popsracer

*Controling the Variables*

DynoMoHum;

Don't you think that SOLDERING could be a variable. 
BTW: I found the problem with the Data read. Was the software.

Thanks, Popsracer.


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## DynoMoHum

Sure soldering can be a variable... however the leads on the Robi are about the same thickness as motor connectors, so the heat distribution is very even on both ends, and it is realtively easy to get a good solder joint on these connections... So any decent solder job should be very consistant...

If you can't solder this connection quite easly, you need the practice anyway... they really are about as easy a soldering as anything I know of in RC... I'm serious about this... if your having trouble soldering these, then it would be good for you to learn better technique or get a better iron or something... they are very easy to solder with the right equipment and technique. It's very rare that I have a problem... ussualy it's a very dirty dyno connector or motor connector...


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## popsracer

*Soldering the connections*

DynoMoHum;

Soldering quality is not a problem for me. Been doing it since I was about 10 yrs old. (seriously) I have a Hakko 927 station. The TOTAL length of wire and DEANS connector is 2" and the same on all of my Motors +/- 1/8".
I was concerned with the wear and tear on the leads and MOSTLY with having enough space on my PC Desk for all of this stuff. I do all of my R/C mechanics out in the garage but the PC is a desktop inside the house.

Thanks again.


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## DynoMoHum

Ok... if your keeping within 1/8th of an inch on the lenght of wire... no problem... I wouldn't bother with moving the voltage sensing leads I don't think... I'd do a couple dyno runs on a motor with direct solderd connection and get a benchmark... next I would put the connector and wire on the motor... then compare... keep this for future referance in case you want to try and compare data to someone else...

You may be able to bump up the voltage just a tick on the settings to compensate for the wire length... like maybe .1 volts or something... It just might equal out...


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## Snuffy

I don't own a Robi dyno so I don't really know if this is actually true. This is just my opinion based on my knowledge of electronic principals and what I've picked up on this and other forums.


If your going to use connectors I'd recomend NOT moving the voltage sense wires. Reason being, I believe the sense wires give feedback to the dyno and adjust the voltage to the proper level. If you using connectors with the sense wires directly attached to the motor you will not see the influence of the connector in the data because the dyno will compensate for any losses it produces. You won't be able to detect a bad connector.


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## TeamGoodwrench

I've got a question about how everyone is using all of the dyno data we get.

Here's an example to work from:

Assuming I dyno my motor (GM3 or Monster) on my Fantom and get all that data...

1) I'm running 4-cell oval on a 200 ft run line track.
2) The TQ every week is about 45 laps in 4:02
3) My rear tires are 2.28"

What numbers do you guys look at from the dyno run and what calculations do you use to figure a rollout given what the TQ run usually is ?

This should be of interest to everyone I think.

Thanks!


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## Mayhem

I take a known good motor that runs well and dyno it and save the data. Once you get a the fastest run possible you are happy with,a djust the track length until it tells you to run exactly the rollout that you ran. Save the parameters and that is your bench mark gearing run UNTIL you make a faster run, then repeat the process for a new benchmark. Eventually it will tell you exactly the rollout to run for any motor on THAT particular track. This is the short version, there is a much greater amount to know but this will get you started in the right direction. Keep doing this process until the dyno can predict the gearing better than you can. Good luck though the process never stops as you keep getting faster as the dyno helps you more and more. Then you can start on the efficiency and powerband tuning... a whole nuther book.


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## TeamGoodwrench

So pure trial and error until you get lucky enough to hit a gear that one of the motors likes and you get that TQ run ???


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## Mayhem

Basically yes. Some use others stats to fine tune thier dyno. Your fastest run is the best info available until you go faster.I like that better than hypothetical data. Mine spit out the exact rollout good enough for TQ today so track length will stay the same until I go faster. the shorter you can get the track length to while still matching your rollout on a good run tells you your line is good also.The fantom is an awesome tool when used properly. CHeckout the rollout program feature for doing timed practice runs where you can display the laps of up to 3 cars also. Better than a stopwatch.


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## DynoMoHum

I've never used the Fantom gearing thingy... so I really can't comment on that. However I'm inclined to beleive you can not reverse engineer rollout by using the length of the track and TQ's lap times. Last week my main reasoning is/was that it is dependent on driving ablity and cars setup. This week I have new data and expeiance that is leading me in another direction. It all revolves around this question...

Is all RPM created equal?


My new experiance tells me it's not. This weekend I raced with a half a dozen guys that are like REALLY fast in oval racing. We were all running 4 cell 19 turn motors. Some where using the handwound adjustable timming ARCOR motors. Others were not. I had an opertunity to dyno two Chameleon motors I had, and about 4 of my competitor's motors. The ARCOR motors appear to be down on power when compared to a Chameleon, the consensus is that this is due to the laydown brushes on the Chameleon motors. However, even though the ARCOR motors seem to be down on power, they were very competitive. Virtualy no differance that I could see in the overall outcome of the race. 

The two motors I had were both Chameleons, on the dyno the peak power numbers were just about identical, like easly within 2%. However one has a interesting RPM curve when compared to the other. The one with the interesting RPM curve was hands down the best motor on the track for me. So much so, I was amazed and somewhat confused.

I am begining to think that there is more to RPM then can be seen at first glance. I'm still trying to sort it all out, however I beleive I'm on to something. Perhaps others have known about it for quite sometime, but it's all new to me.

When I see a guy on the track make a motor that appears to be 5% down on power go just as fast if not faster then another guy, it makes me start asking myself lots of questions about how and why... 

Film at eleven...  (graphs and numbers to come, but not sure how soon)

The basic observation involves RPM that has a slope that is not linear. That is the RPM tends to increase more rapidly as it aproachs max RPM. 

This same idea futher proves the point that Tfram made a week or so ago... looking at data in relation to AMP input causes bias toward Efficiency. My idea about looking at dyno data corrected for gearing helps defend my newest observations and experiances as well.


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## tfrahm

(copied from my post in the "Monster" thread, where the same question was asked.)

Goodwrench...

First, I don't own a Fantom, but I "borrow" one when I'm racing oval (there are always several in the pits)...

I assume you always use the built in oval calc routine...

If the "big dogs" are running 45/4:02, I know from experience that I'm 1-2 laps off their pace. (Background: I don't run oval very often any more, and I know my car is "tight" compared to theirs, but that's a necessary compromise due to a lack of track time, etc. -- this combines to keep me "off-pace"...) So I would take the gearing for a 44 lap run (being optimistic, but what the heck)... The other way I do it is to just use the numbers they have setup (45 laps in this case), and then drop one tooth on the pinion, since I know I can't carry the speed in the turns that they do, so I need more punch out of the turns (although it sacrifices raw speed, it's necessary)...

Is this the sort of thing you were looking for?


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## Mayhem

Dynohum. Absolutely not. You actually touched on the next topic i was about to mention. That is the reason 2 motors with identical numbers on the Fantom, say P2K and a GM3 need to be geared 3 teeth differently to run the same lap/race time.
You must create a separate set of data/parameters in your fantom for each type of motor as track names, say, P2K, GM3,MVP THEN after you spin a motor the first thing you do is save the run under that "track name/data set using the tab key. Then retrieve your run and the correct gearing will appear for that type of motor.Using this technique, the fantom will give totally different rollouts for 2 different style motors that have identical power and RPM numbers. Hope i made myself clear LMK if you need more clarification. Each motor brand/type has its own unique characteristics that no dyno can measure such as flux/leakeage magnet stregth and ability to stay cool.


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## DynoMoHum

I've seen this kind of behavior on two of the same type of motors, in this case both are 19 Turn Chameleon motors. I beleive I can illustrate the point very well with graphs, right now I'm having a hard time getting the main graph I want to use to come out right...


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## DynoMoHum

Ok, I think I've got my graphing problems mostly sorted out...

First take a look at this graph. Notice the curved shape to the RPM curve of the higher RPM motor here. I beleive this is very significant and may be very telling about what makes this a better motor then the other. The the peak power of the lower RPM motor is not very far off from that of the higher RPM motor and the effciency is much greater on the lower RPM motor... However on the track the Higher RPM motor was much faster. I even had a guy who was previously sponserd by Woods racing doing the on track driving for me in the on track testing phase. (as well as my own driving)











I'm still working on the rest of the story, with more graphs and data. Further details can be found at the following page.

http://www.wiltse.net/rpm_equality.htm


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## BigBob_01

Hey Guys,

I have been reading this thread the past couple of days to catch up with what was going on before posting any replies (so I don't sound like a moron!). The reason I started reading in the first place is because I am convinced that I need to purchase a dyno if I want to continue to improve my abilities. Plus, I am kind of a gear nut and like to tinker with things. Hey, if I could afford it, I'd race real cars! But for now, I race 4 cell (stock and 19T) and 6 cell (stock) on a flat indoor carpet oval with 10L30's.

Everyone I know that has a dyno has the Fantom, and my LHS swears by them. In fact, his sponsored driver took 4th at Cleveland I believe in stock 1/12th and did well also in the other classes he entered. Not bad for a local guy at a national race! And that is what they tune with. So naturally, I was set on getting a Fantom as well. That being said, I was quite surprised at some of the negative things that I was reading on Big Jim's forum and here on this thread regarding problems with the Fantom dyno. So I started thinking I needed to stay away from Fantom and try and find a Robi or CE TD45, or maybe something else if it even exists. But now that I have read all of the posts, I think I am coming full circle back to getting the Fantom...for a couple of reasons:

1..It appears that the dyno info is all relative and that as long as I learn how the Fantom dyno is working and what it is telling me, I can use it effectively. And while there may be some quirks with the Fantom, all of the available dynos have there own pros and cons.

2..I know others with the same dyno (including my LHS, which is a great guy!) so I have a network of people that can help me use it correctly and give me advice when I need it. Not to mention all of the nice people here on these threads that are so open with their knowledge and opinions.

So, before I go and blow almost $500, does anyone have any strong opinions why I should rethink my plan?

By the way, thanks so much for all of the GREAT information. It has been truly helpful and is very appreciated...GOOD WORK GUYS!


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## DynoMoHum

If I haven't already convinced you that the Robitronic dyno is the best dyno available... then do what you want... Personaly, you'd have to pull my Robi from my cold dead fingers before I'll give it up...


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## TeamGoodwrench

Get the Fantom.


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## BigBob_01

WOW!...you guys are good...I never expected such a quick response!

Dyno...I can tell you really like your Robi. And I also read where BJ thinks the Robi is the best flywheel dyno. So believe me when I say that I seriously considered it. I respect your opinion very much based on your apparent knowledge and all of the work you have done with the calculations and all. In fact, your work is what has pretty much convinced me that I will be "ok" with the Fantom. I am sticking with stock and 19T and will not be messing around with any of the more radical mod motors. If I ever get into that (which I doubt) maybe then I'll see the need to get something else. All of that, along with the price and availability of the Robi when compared to the Fantom just points me in that direction. Plus like I said, I have a network of help just a phone call or short drive away. But thanks again for your honest opinion and all of the good work you have been doing!

Goodwrench...Thanks for the advice!


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## TeamGoodwrench

All of the guys at my track have Fantoms -- there must be 15 of them.

It's a great help to be able to walk over to any of them and talk about numbers, results, etc.


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## 300M

You want to start a gernade war, just ask BJ what he thinks of the fantom. Me TurboDyno. Had a fantom and sold it!


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## TeamGoodwrench

I'm not saying the Fantom is better than the others.

It's just that at my track it's the ONLY dyno in use. Nobody uses any of the others.

I'd feel kind of lost if I was the only one with a Robi or CE -- nobody to help me there.

The Robi and CE are great dynos I'm sure -- maybe better than the Fantom. But nobody at my track has one and I really like being able to talk with those guys and compare stuff.


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## 300M

Well said! Dyno is a tool only, track data is the best. I dyno all my motors at home as I have to climb stairs with all my stuff


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## DynoMoHum

There's no doubt about it that having someone local to help you is a plus... on the other hand... if somoene local has one... why not just use their's??? 

I never minded going with a dyno that no one else in my area has. It forced me to look at things my own way. Lean for myself what works and what doesn't seem to work. If you've really read most of my posts, I think you'll see that I've changed my ideas about what a good motor looks like on a dyno. I beleive I'm going in a better direction now. My previous work has helped me alot, and I wouldn't be were I'm at today if I had not gone through the process of learnign that I have. One of the things I like the most about the Robi is that I can veiw the data in many differnt ways... This could be my downfall too if I'm not carefull. I'm still having fun however, and if I want to use a Fantom I know a guy that's got one... I also know a guy with a TurboDyno, but I'm still the only Robitronic guy in my area...

I still have reservations about the Fantom... I have a nagging feeling that it's doing something odd. I can't place my finger on it however. Clearly there are many people that use and enjoy their Fantom dynos and go very fast on the track.


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## 300M

Dyno: That is also why I have a TD. Everyone at the track has the fantom. They feel the dyno is gospel. I did a lot of trial and error until I hit a setup that works for me. Like Dyno has said what works for you may not work for others.


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## BigBob_01

Dyno,

Respectfully, there are a few reasons why I can't just use someone else's...

1. I rarely get enough time in one solid block to spend time running to my friend's house. I only get a couple hours at a time here and there. If I am driving 20 to 25 minutes each way, I have wasted half of my time. So convenience is an issue

2. Learning on my own IS a reason I don't want to use theirs. In other words, what I see happening (because it has happened) is that I don't get to tinker with my stuff. I keep hearing..."just put this spring on" or "use this brush...those are junk", "do this", "do that" when I go to their house. I don't get to just try stuff to see if it works. And then study and think about the results. I am just constantly trying to get done and get out of there.

The other benefit for me buying a fantom is that when I race at my LHS track, he will let me (and others) check my motors on his dyno if I need to. So if I am familiar with the workings and operation of the fantom, I can get more out of it without lugging mine to the track.


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## DynoMoHum

I was basicly just joking about using other peoples dynos insted of buying one... 

I deffinetly understand the value of having one's own dyno. 

I also understand that your needs for a dyno might be differnt then mine, and ultimately the choice is yours to make. It seems you've looked at all sides of the issue and are going into it with your eyes wide open... all of this is a good thing.

Becarefull when you go from one Dyno to another... the numbers will not likely be exactly the same. This is true of all dynos, even dynos of the same brand and model...


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## BigBob_01

Dyno,

I did read that among these posts that even the same brand dynos could be calibrated differently and give different results. But thanks for the reminder. And thanks again for all of the info!


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## Snuffy

I have a fantom. I'm not very happy with it. I sent it in for repair last April. I bought it last December. Right now it's not operational. I had to fix a problem in the RPM circuit and in the process broke of the legs of the output transistors. The manufacturer has been discontinued the part. They're hard to find. Fortunately Al at Wizard is willing to sell me 4 of his.

I'm VERY seriously considering the CS dyno. One of our local guys has one. I really like the fact that it's a small standalone unit that can be used with or without a PC. I've heard they're making some changes to the unit right now so I'm waiting for the new version.

As a fantom owner. I would not recomend a fantom dyno. I will be selling mine when I replace it with something.


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## DynoMoHum

Very interesting Snuffy... 


I have even bigger reservations about the CS dyno then I do the Fantom... but I have to admit I've never used the CS dyno. My concern about the CS dyno is repeatablity... I just don't see how the numbers would be repeatable, unless you used some sort of external power supply other then a battery pack... 

Unless of course they are adding some sort of feedback loop that controls the voltage somehow... 

As I say I have never used the CS... only read about it's operation and such... I am skeptical to say the least... 

I know the Robi is expensive... but I'm the type of guy that says... I can buy the best now, or buy it later... Or something like that... Basicly I hate to buy one thing, and then decide later I should have just bought the more expensive thing to start with...

Back to this RPM thing.... I am becoming more and more convinced that there is more to RPM then gearing alone can change... It appears that the general shape of RPM is not linear with all motors. I'm not sure that's the best way to describe it... but there is more to RPM then I had originaly been lead to beleive by my own observations and by people who claim to know all there is to know about motors and dynos.


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## Snuffy

DynoMoHum,

Dyno choices are very limited right now. If you want a "real" dyno there are only 4 options; CE, Fantom, Robi and CS. The thing I like best about the CS is it's small footprint. If I'd known about the CS before I bought the fantom I probably would have bought that in the first place.

I've also heard about a powersource specificly created for the CS dyno. I don't know if it actually exists or not yet. 

Right now I'm gathering information about it. Thru you and this forum I believe I know everything I need to know about the other dyno's in order to make an intelligent decision.


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## DynoMoHum

Have you actualy seen the Robitronic dyno? From what I can see, the footprint of the CS and the Robi are basicly identical... with the exception being that the Robi has the motor platform as a seperate unit (and it's detachable when not in use). I really like this... I have found that I can pick the motor stand up, replace springs and put it back down and proform another test... The other advangage of Robi's vs CS... the motor is held horizontaly, not verticaly... What was the last RC race car you had wher the motor mounted vertialy???

Actually if the CS didn't have the issue with potiential repeatablity problems I probably woudn't have any complaints about it... 

You should talk with Tom (TheBoss) before you actualy purchase a CS dyno... he has used one and didn't like it much at all from what I could tell. I think Tom recently purchased a new Robitronic... after owning(or at least using extensively) all of the dynos named here...


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## Guest

My motors are usually vertical several times during my race.


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## Guest

*RPM vs Current graphs*

Dynomohum-This is meant just as information to add to the pot. If you test a motor at constant voltage some patterns are made more clear.

If you plot the RPM vs Current graph which Dynomohum has displayed above, but do the test at constant voltage on a CE dyno, then the graph is an exceedingly straight line. RPM decreases with amp draw in a straight line fasion. If you dyno two different stock motors, then, the RPM vs amp draw graphs will be straight lines, but have different slopes. If you apply gearing (which ammounts to a correction to the slope), it is not surprising that you can get the graphs at the rear wheels to come out the same on paper.

If you do the tests on the Robitronic the RPM line is no longer straight. There is a voltage ramp thrown in. Essentially you have a straight line(RPM vs Amp draw) times a straight line (the voltage ramp). The result is a curve (a quadratic), but the curves of two different motors will have a similar shape. I expect that if you apply the exact gearing you can always make these two curves coincide at the rear wheel on paper.


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## Guest

*Next Generation Dyno*

It seems that our current dyno's do a good job of comparing the same type of motors, say 2 P2Ks. But have some difficulty comparing different types, say a GM3 vs a P2k. It might not be a matter of not having the right data analysis technique, but rather the fact that the dyno does not take two important on track properties into account, motor inertia which limits acceleration, and motor heating which limits acceleration.

So the next generation dyno might be like the CE dyno in that torque is measured directly, A hydraulic brake if neccesary for reproducibility, the Voltage Ramp of a Robitronic to better simulate a battery pack plus a speed control built in. Several track profiles to choose from obtained from telemetry data of amp draw and RPM in the car obtained by the builder. The test would last five minutes to test heat effects. The speed control would allow measuring power at part throttle. The motor would accelerate and decelerate like it does on the track when you select a profile. Output would be elapsed time. Well they have it in Formula 1 anyway. And then as soon as someone builds it motors will become brushless and it will be obsolete.


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## patcollins

When you think about the price of a dyno compared to other test equipment it really is quite cheap. I have an O-Scope at work that cost over $100k, a good multimeter is about $200, etc etc. It actually brings up the question with me how good can they make a dyno for this price. I investigated making my own and it would have been well over $1500 for a flywheel dyno (the cheaper of the two to make).


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## DynoMoHum

Well... it seems to me that any dyno worth it's weight had better give us something that we can use to help predict what type of motor will go faster on the track. Wether it's a P2K, a Monster, a EX-Spec, or even a Putnam Pro 19 turn motor. To some degree I beleive that any of the current dynos (CE, Fantom, Robi, and even the CS) can do this. I do beleive that some of these have more potential then others at doing this. 

I may not have yet found the perfect way to view dyno data, but I beleive I am much closer then I was a month ago. 

One thing I am 99% sure of... viewing data in relation to amp input is only a very small part of the picture. I also beleive that viewing data this way can be misleading... and in some cases it seems to be down right deceitful.

It seems that it's one of those things that if you focus in on any one thing, you miss the big picture. I'm trying to step back and view things with a broader perspective in mind now. I beleive that adjusting for gearing helps me achive this. Unfortuantely none of the dynos I have used do this directly, forcing me to use other methods of viewing the data. 

Mike Golden has been refining his DynoViewer, and it's looking better all the time. He's even added a way to enter CE TurboDyno data now. So currently it can accept Fantom, Robitronic, and TurboDyno data. He's also added the ability to display up to 4 motors at one time. Unfortunately my laptop doesn't display colors very well or something, and I'm having some minor problems as a result... So for now I prefer to use my own Excel spreadsheet... but Mikes DynoViewer really is quite cool.


By the way... The HS19 motor in my last test is a Putnam Pro motor... It's a Chameleon 2 motor that Mike Valentine sent me to do some testing with. I've since sent the motor back to Mike, so I can not do any further testing on it... I do have a fair amount of data that I collected during the time I had it... I'd really like to publicly thank Mike for sending me this motor for testing, it's been an eye opening experiance for me...

Thanks Mike...


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## TeamGoodwrench

Where is the Dynoviewer located for download ???


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## Guest

Dynomohum has been putting it on his web site for me. I'm just finishing up the latest version. I should be up today. There is a link to the older one somewhere in this thread...


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## DynoMoHum

A older version is located here...

http://www.wiltse.net/zips/DynoViewer.zip


I'm not sure if Mike is ready to release the newest version yet... If so, you'll have to replace the .exe file that is ziped into the download above... Eventualy I'm sure it'll all get ziped into the location given above.

THe older version does Fantom and Robitronic data... and does two motors at once...

Now that Mike has posted too... I'll post something when the new version is ready to go... for now... the older version is quite usefull so it's not a waste of time to download what's there now...


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## Snuffy

Mike,

I'm not sure if your aware of this or not. I bring it up because you working on revising the program. The old version doesn't display fantom data with the torque measured in Newton/MM in a way that's usefull. It seems to make the y axix so broad in numbers the rest of the graph lines are bunched up on the bottom.

Just an FYI.


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## DynoMoHum

Oh... Mike has even corrected some of the color problems I was having... 

The new DynoViewer is now avaiable as a complete package at... 

http://www.wiltse.net/zips/DynoViewer.zip

If you downloaded it in the last minute or so... you've already got it... The new viewer does Loads Fantom II data from the clipboard, it also alows the 'wiltse' fudge factor for Fantom data from the clipboard... it also does Robitronic data from Robitronic text files... and it allows you to enter Competition Electronics TurboDyno data in via a data entry facility... 

Here's a screen shot of the newest DynoViewer showing two of my competitor's ARCOR motors. THe data came from my Robitronic dyno.

http://www.wiltse.net/images/newviewer.gif

I'd post this as a image, but I'm not sure how many of those I should do... this image is like 50K...

In the image the two motors are geared like 1 tooth differnt... I'm pretty confident that these two motors would run nearly identical on the track geared like this...


Mike has done a exclent job on this program... I am highly impressed with his work...


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## TeamGoodwrench

What is the "gear motor" section on the right side ?


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## DynoMoHum

Oh... Mike also made AMPS as a secondary Y axis... this does something quite interesting... (at least it does on Robitronic data) You can see the almost one for one relationship of Current(AMPS) and Torque... I thought this was really cool.

I haven't looked at any Fantom Data yet with the newest version of the DynoViewer...


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## DynoMoHum

If Mike doesn't answer before I do...

The gearing section does a couple things....

There is a slider bar that allows you to apply diffent ratios to two differnt motors, it then redisplays the graphs with the new gearing. This only works for two motors. You select two of the four motors using the radio buttons under 'Referance Motor' and 'Gear Motor'. 

The "Apply Gears" button uses the amp number to the right of it as a point to calculate gearing from... That is... if you use 20 amps, and then click on "apply gears" it chooses a ratio based on the RPM of each motor at 20 amps...

I personaly use the slider bar mostly... and ocasionaly play with the "apply gears" tool to see what it says...

Is that clear as mud?


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## DynoMoHum

Here's a screen shot of two of Snuffy's best Monster motors... a 1/2 tooth pinion change would achive this... 

Notice the huge differnace in current between these two motors... yet the power output is basicly identical...

http://www.wiltse.net/images/snuffymonsters.gif


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## TeamGoodwrench

Forgive me .. I'm trying to catch up.

Where/How are you seeing 1/2 tooth pinion ?


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## MIKE VALENTINE

DynoMoHum no problem any time. i haven't been keeping up with the thread for awhile, it's just to much, i'll stick with track testing
:roll: i'll send some brushes out to you tomorrow so you can try them in your own motors. good luck mike


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## TeamGoodwrench

Another question -- those motors look like they have peak power at 55 amps -- yet from what I've seen in this thread, it's doubtful that in 4 cell oval you would actually pull 55 amps.

right ?


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## DynoMoHum

Goodwrench... I may be wrong on this... I haven't exactly figured it out yet... I said 1/2 tooth... because when I used the gearing slider to get the torque curves to match up pretty evenly from one end to the other... the ratio the DynoViewer gave is 1.02:1.00 ... 

It is/was my assumption that if I took my pinion on the referance motor and multiplied it by 2% I would get the 1.02:1.00 ratio used in the graph of Snuffy's monster motors. This would seem to be exactly correct if you had a 100 tooth spur gear... With other size spur gears the calculation gets more complex I think... but not that bad... 



OK... here is Mike's Putnam 19 Turn Spec motor compared to Keith Ractnor's (sp??) 19 Turn ARCOR motor... Keith was the guy who helped me test drive my car with Mike's motor vs my own motor... I think Keith won the race I was in this past Sunday... Keith used to be sponsored by Woods Racing.... Motor 1 is the Putnam motor, and Motor 2 is a Kisbey 19 Turn ARCOR motor. Geared as I have them in this graph, I beleive the tops speed would be very simmilar with these two motors... Again in this graph the gearing less then 1/2 tooth differnt...


http://www.wiltse.net/images/arcor_vs_putnam.gif


With a good driver and good setup, this Putnam motor should have been significantly faster then the Motor Keith ran... in my humble opion... Keith was just lucky I'm not a good driver and my car setup is not as good as his...


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## Guest

I'll try to explain what the Gear Numbers mean.

If it says 1.02:1, and you usually gear the base motor or "Reference Motor" at say 5.2 overall ratio.(I just made that number up.) Then you would gear the new motor or "Gear Motor" at 5.2 * 1.02 = 5.304. Now that could be anywhere from 1/2 a tooth to 3 teeth.

Basically I'm just showing the ratio's between the two motors. I don't see a need to gear both motor to a ratio. I just leave the Reference Motor at a 1:1 ratio and change the Gear Motor's ratio up and down accordingly. It works out really simple that way, plus you can compare it to 3 other motors at the same time, if you want.

I should add a gear calculator along with the other gearing stuff...


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## DynoMoHum

Might I suggest that if you provide a gear calculator... you also provide a roll out computation... Currently I have to jump through hoops to calculate rollout and it's not really that difficult to do...

Of course with rollout your just a step away from computing a therortical MPH speed...


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## TeamGoodwrench

How do you get the motor data from the Windows Fantom FACTS II software into the program ?


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## DynoMoHum

One of the features of Fantom Facts II is the ablity to save the 'time based data' to the clipboard. You have to have the full working version of the software... or you get basicly one chance to use this feature when you first download the trial version.

To actualy do it... you have to have the 'Option' menu item "Post Time Based Data to Clipboard" selected... once that is selected, every time you go view the time based data, it saves a copy of it to the clipboard. 

Once it's in the clipboard, you go to Golden's DynoViewer and select "past Fantom data" from the apropreate 'Motor' menu... 


For each motor, you go back and forth between the Facts II software and Golden's DynoViewer... saving and pasting as you go... 

I hope that explains it enough...


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## Guest

Dynomohum- Do me a favor if you are willing. Apply this viewer or your own dyno viewer spreadsheet to a typical P2K file (not that one best of all motors) and a P2K2 file if you have one and use 1.065 as the gearing multiplier for the P2K2. Or send me a couple of motor files. The reason that I suggest this is that I determined this gearing as the optimum on the tight technical track at ReflexRC in my Losi XXXS. Actual gears were 7.09 for the P2K and 7.55 for the P2K2. Car ratio is 1.83. Now the motor which works best for me with traction compound seems to be the P2K. The motor that works best without traction compound is the P2K2. The GM3 is not even in the game either way. If you gear a GM3 to be competive on this track you tend to burn it up quickly.


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## DynoMoHum

I'll see what I can dig up... I know at one time I had a P2K and a P2K2 that put out nearly identical peak power... It may take a while to find them...

One thing I will warn however is that based on other tests I've done, sping tension can make a big differances in RPM on anything with more RPM then a P2K... so the two motors I find may not be very typical at all... Maybe I can find a couple differnt senrios...


By the way... Mike has added a few features since this morning...  He he... it's really turning into quite a nice program... I beleive I'm going to be using it alot for trying to figure out a starting point for gearing once I have one motor that I know works reasonably well...


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## TeamGoodwrench

super.

Might also be good to put a Help > About on the menu with the version number so that we can tell what version we have vs. what is the most current.

Thanks!


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## Guest

Dynomohum- Thanks. If someone else has a couple of P2K2 motor files from the Robitronic Dyno, I would appreciate them as well. I have several P2K files and GM3 files already.


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## DynoMoHum

It didn't take as long as I though it might...

These 2 motors are so simmilar in power it's scary...

before any gearing...

http://www.wiltse.net/images/before_gears.gif

1.08:1.00 gearing...

http://www.wiltse.net/images/after_gears.gif

And as John requested 1.08:1.00 gearing...

http://www.wiltse.net/images/johns_gears.gif


Motor 1 is the P2K2, and Motor 2 is the P2K...

In this case, I'd say RPM is created equal. Most of the time this is what I see between two differnt EPIC motors with differnt RPM... but apprently things aren't always this close...


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## DynoMoHum

When I get a chance I'll put together a small collection of various Robitronic data files for people to play with. There are a couple included in the DynoViewer zip file I think...

I pluged some TurboDyno data in yesterday... the problem with it is that it's such small range of data it's hard to get a good idea of what's really going on. I was to some extent to get the torque curves to line up when some gearing was applied... but I didn't play with it too much.


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## Guest

Someone mentioned earlier that the torque numbers are different from one dyno to another(which I knew). Does anyone know the conversion from one to another? I would like to convert all torques read to the Robi form. Or the other way around, I don't care, just so they are the same measurement.


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## DynoMoHum

Personaly I would prefer that you don't change them... at least not as the only way to view them... perhaps offer a conversion feature but not change them outright and have no way back...

I plan to use your viewer hand in hand with my Robitronic software, and I'd like to be able to look at the data on the Robitronic software then bounce over to your software... if the torque was in some other units it would get all confusing...


Actually the Fantom offers two torque units... "grams per centimeter" and "newton millimeters"... presumably the differance between a 'newton meter' and a 'newton milimeter' is a few decimil points...

I beleive Robitronic's torque are in newton meters.


The more I think about it... ablity to switch between these three as well as 'inch ounces' or 'foot pounds' would be a cool feature... 

Heck we might even be able to get Big Jim to use a flywheel dyno if he could view the data in english units of measure... 

Oh... for the record... you can try to compare dyno data between all three of the dynos that Golden's viewer supports... but you'll quickly find they just don't compare very well... However you can see some simmilaritys between them... especialy between the Fantom and the Robitronic dynos... the curves are somewhat simmilar...


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## Guest

Mike:

To convert Fantom (DOS version) to Turbo Dyno torque numbers, (kgf*cm)*13.887 = (in*ozf)


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## Guest

Mike here are some conversions

1 oz-in = 7.07 N-mm = .0722kgf-cm
1 N-mm = .141 oz-in = .0102 kgf-cm
1-kgf-cm = 13.9 oz-in = 98.0 N-mm

Torque units of some common dynos

Competition Electronics Turbo dyno- ounce-inch
Fantom- kilogram-force-cm (at least the older ones)
Robitronic- newton-millimeter


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## Guest

Here is the latest version. You need to have it already installed on your computer. This is just the .exe. You will need to replace the DynoViewer.exe on your computer with this one. Your DynoViewer.exe should be in folder "C:\Program Files\DynoViewer\". 

Also, I include sample data with the installer. It can be found at "C:\Program Files\DynoViewer\Sample Data\".


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## Guest

I added the About under Help, so that file is Officially Version 1.2.0. 


With this newer version, you can do the following:
1. Click on a Point on a Curve, and it displays its value and hilights the curve.
2. Click anywhere and drag in a lower right direction will Zoom In.
3. Click anywhere and drag in a upper left direction will Zoom Out.
4. Right Click and drag will move the graph around.
5. New options for viewing each individual Curve. You can turn off Torque for example.
6. New Help Menu has About, which shows current Version.
7. New File Menu that allows Exit.


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## PizzaDude

Mike,

Did you also put in the gearing option, as Dyno did in his spreadsheet.

BTW I allready downloaded an earlier version from you.
But there are some things not entirely clear to me.
I'm a bit short of time right now, so I'll be posting some straight q's later.
Any help would be appreciated.

CU
Pizza


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## PizzaDude

Mike,

I did have a quick peak.
Man this looks great.

But I do not quite understand how to use yoer amps and gearing options?
I mean, I race TC and use other gearing than is mentioned here...
Could you, or one of the others here please explain this.
Thanks.


Pizza


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## Guest

Lets set up a senerio.

Say Motor 1 is a motor you know how to gear. Lets say it is geared 72 spur 25 pinion with a tranny of 2.5 (TC3). That is a gear of 7.2. Now you have just dynoed a new motor (Motor 2). Now you want to gear the 2 motors so that their 20 amp RPM numbers overlap. You simply type in 20 amps in the "Amps" box, make sure Motor 1 is the "Reference Motor" and Motor 2 is the "Gear Motor". Then Hit the "Apply Gears" button. 
You will see the Graph for Motor 2 Change. Lets say it now says the ratio is "1.08:1". Just take your Motor 1's Ratio and Multiply it by 1.08. This would be 7.2 * 1.08 = 7.776. 7.776 would be your new final drive ratio. 

Rollout would work the same way too.


Does that help?


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## Rich Chang

Can someone post the entire DynoViewer package or at maybe tell me which page in this thread has it? I'm not feeling too eager to go through every page on here looking for it. 

Thanks!
-rich


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## TeamGoodwrench

Mike -- WOW!!!!!!!

This is really eye-opening to look at.

I thought my Monster was a better motor than my GM3 because my Monster showed 64 power on my Fantom and the GM3 only showed 60.

BUT -- looking at the data this way shows that the GM3 puts out WAY more power from 0 to 28 amps.

Now the question becomes what is the correct amp factor to use for the gearing section. What is correct for motor comparison if you are running 4-cell oval on a large track where you are basically full throttle all the way around ?? 

Thanks!


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## Mayhem

for 4 cell oval with no lift i would look at the power # at the point of peak efficiency....the point at which are up to speed and not accelerating any more. That is where your motor spends the majotity of its tim eon the oval...FWIW


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## PizzaDude

Thanks Mike,

I'm going to fiddle around with your advice.
It makes sense.
I'll let you know if Ireally get it, or wants some additional support.


Pizza


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## Snuffy

Rich,

DynoMoHum posted a package a page or two back. It's close by.


Mike,

Thank you for all the work you put into this wonderfull program and making it freely available to all of us.


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## 300M

MIke Thanks for the program. I will try to add some turbodyno data in there and see what I can do.


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## Rich Chang

Snuffy - awesome. Got it. Thanks!


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## DynoMoHum

Be carefull with the "apply gears" at some specific amp feature... I think sometimes it does exactly what you would want a gearing thing to do... sometimes it doesn't...

This feature was one of the orginal functions of Mike's dyno viewer, I think it came about from some comments I had made along time ago (weeks). 

If you "apply gears" while your looking at the RPM based graph, and the slope of the torque curves for the two motors are not very simmilar, it's my beleif that you don't really have a very good gear selection... This sometimes happens when using this feature... I don't currently have any explination of when and how this occurs... not enough experiance yet...

What I do, is try to get the torque curves to match up as close as possible. If the shape of the torque curve is simmilar, then you can do this quite well, and based on my limited experiance with this and on track proformance it seems to be quite accurate... at least with Robitronic data...

I deffintely think this tool allows you to visualise exacly what differnt gearing will do... Lower pinon (higher ratio) will give you more torque at low RPM but your tops speed will suffer... gearing in the other direction will do just the oposit...


If someone could post some graphs of TurboDyno Data, that would be cool...


I just thought of something for future versions... If it's not to difficult, perhaps Mike could make a way to save TurboDyno data... so you wouldn't have to repeatedly type it in... and could recall it for future refrence....


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## TeamGoodwrench

I looked at a Monster as motor #1 and a GM3 as #2.

The Monster peaked at about 21000 RPM and the GM3 at 19000.

When I did the "apply gear" at 20 amps, the ratio factor was 1.28.

However, you would not want to multiply the gear ratio used for the Monster by 1.28 because this would give a HIGHER numeric ratio -- what you need for motor #2 (GM3) is a LOWER numeric ratio because it turns LESS RPM than motor #1 (Monster).

Right ??


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## DynoMoHum

Try using swaping around which motor is the "reference motor" and which one is the "gear motor".... Either that or muliply by the inverse... 0.72...

However... that sounds like way too much of a gear change for 10% differnce in RPM... but I'd have to see the data and/or graph to say for sure... Is there anyway you can send me the data for these two motors? or your whole data file if you like... send to [email protected] tell me which to motors your refering too...


By the way... I've started playing with some TurboDyno data... I can tell you that having the Torque in inch ounces really makes it diffucult to veiew... The way Mike has things set up currently it works better if the torque figures are in units that resemble the same ammount as power... otherwise the data looks very tiny... 

You can get around this by zooming in on the Torque, or only displaying Torque, etc... but conversion would be cool...


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## TeamGoodwrench

I'll post it and then post a link to it here tonight if I get a minute. The GM3 had a lot more torque and power than the Monster at amp loads of 0 to 20 amps. I know you said earlier that motors with different torque curves could be a problem.

Thanks.


----------



## DynoMoHum

On my dyno I find most stock motors have very simmilar torque curves... at least in terms of their basic shape... The actual amount of torque can be compensated for with gearing in most motors. It's only the ocasional odd motor that has some odd shape that presents a problem... 

Currently I'm trying to figure out exacly what causes the variation in the shape of the curves... It may be brushes but I'm not sure just yet.


----------



## DynoMoHum

I've been playing with some TurboDyno Data... I don't think gearing based on RPM at some specific AMP input point will work very well... 

The best way to do it is to view only 'torque' on the RPM graph that the DynoViewer provides, then move the slider back and forth till you get the torque to line up... I beleive that is where your gearing will be best. Depending on the effciency of the motor, this may use more or less current... Once you get the torque lined up, you can turn on the other data types to see the other stuff...


NEWS FLASH.... 

Golden's DynoViewer has been improved once again... It now has a gear calculator complete with rollout, and the ablity to save and recall TurboDyno data...

get DynoViewer Version 1.3 here...

http://www.wiltse.net/zips/DynoViewer.zip

and you can also get some TurboDyno data to view here...

http://www.wiltse.net/zips/turbodynodata.zip


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## TeamGoodwrench

What if the torque curves aren't parallel ? I mean -- rather than being able to line up, the curves cross each other at only one point -- where do you move them to intersect ?


----------



## TeamGoodwrench

Is there a bug in the gear calculator ?

I entered:

Transmission: 1.0
Spur: 116
Pinion: 36
Tire Diameter: 2.28

It calculated:

Final ratio: 3.22
Final rollout: 23.08 ???????

My math says the rollout should be: 2.22 

right ??


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## DynoMoHum

If they aren't parallel... then that theorticly is the differance in power you'll see on the track... That is if the low RPM side has more torque then it'll accelerate faster in slow corners. If the high RPM side has more torque then it'll be faster at the end of the straightaway... 

With the TurboDyno data it's very hard to see the big picture because you don't have data for the big picture... only a small window to try and see into the motors proformance...

With the fantom and Robi data, you should be able to see the bigger picture... Now I'm not saying that the TurboDyno is not as good... but it does limit the amount of data you have to look at...


If peak power of the two motors you are viewing is drasticly differnt then the torque will not be parallel... there are also an ocasional few motors that have torque curves that just have differnt shapes, regardless of the peak power... (like the Putnam 19 turn I showed earlier compared to my 19 turn....)

Differnt types of motors such as a 19 turn vs. a 27 turn will also have very great differances in the slope of the torque curve... your guess is as good as mine as to how to try and deal with those...


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## DynoMoHum

Yes, I bleleive your right Goodwrench... seems to be a bad calculation... I've emailed Mike... he'll likely have it fixed promptly... I'll let you know when the corrected version is ready...


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## Guest

TeamGoodwrench, 

May I see your math in long hand. You may very well be correct, but its really hard for me to tell what I did wrong if I cannot see how you came to your answer.

After reading that is comes of as sounding defensive, but I'm not trying to be. I'm just asking how to do it right.


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## TeamGoodwrench

Here is my math:

Spur: 116
Pinion: 36
Tire diameter: 2.28"

Final ratio = 116/36 = 3.2222

Final rollout: (2.28 * PI) / 3.2222 = 2.22


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## DynoMoHum

I know when I put the numbers into the Robitronic gear calulator they come out like Goodwrench's do...

Robi lists the calculation as...

TyreSize x PI / ratio

(complete with funny europian spelling of tire)


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## TeamGoodwrench

I left out the tranny reduction -- for our pancars its 1-1.

But for sedans and buggies, I'm not sure where it goes in the formula.


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## Guest

Fixed bug...

I had Tyre * Ratio, not Tyre / Ratio.

New Version is 1.3.1


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## DynoMoHum

Goodwrench...

With fantom data, you should be able to get most torque curves pretty close to paralell with most any motor of the same type... the ones with more power will be higher torque uniformly across the entire RPM range... this is if you follow my method... If you use the "apply gears" button, then you will often get a torque curve that intersects at one point and is higher or lower on either end... My personal opion is that is not the correct gearing... at least not if the slopes are greatly differnt with the same type of motor...


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## Rich Chang

Great program! I think there is a minor calculation error for the suggested gearing formula?

The reason why is I used two motors and one had a lot less RPM but a lot more torque than another motor. The higher RPM motor (my base motor) is geared at 31. However, the program told me to gear the higher torque (less RPM) motor down to a 28 pinion. In reality it should be geared up to 34.

I think the factor should be divided and not multiplied?

-Rich


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## Rich Chang

Here is the motor data I used:

Motor 1 - GM3

RPM Torque Watt Eff Amps
24006 4.2 74 71 14.9
22643 5.6 93 74 17.8
21761 6.5 105 75 20.0
20906 7.4 115 74 21.9
19943 8.5 126 72 24.9
18846 9.5 133 68 27.8

Geared 31/100

--------

Motor 2 - blue end bell

RPM Torque Watt Eff Amps
21895 4.8 79 75 14.9
20506 6.4 97 77 17.8
19587 7.3 106 75 20.0
18336 8.3 113 73 22.0
17604 9.4 123 70 24.9
16569 10.6 130 66 27.8

-Rich


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## TeamGoodwrench

I had exactly the same thing happen with a Monster as Motor #1 and a GM3 as motor #2. The GM3 turned less RPM and it still told me to go down in pinion size for the GM3.


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## PizzaDude

Mike,

Keep up the good (and might I say very guick) help for all us racers.

Thanks....

Pizzadude


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## PizzaDude

Mike is the tire dia in inches or can I also use mm's...
Or maybe you could make this an option in your next release?!

Thanks for the gearing calculator!

Pizza


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## Guest

I have a question about gearing for p2k and green3,,I always hear that the p2k needs 2-3 teeth higher pinion than the green3, however my Fantom program is telling me to run the same pinion gear, maybe 1 tooth more, depending on track size(105, 110, 115, and 118) for the green3. Spur is the same size for both. These motors have a few runs on them, grn3 power is 61.95, 19560 @ 3.1, torque is 93, p2k is 59.40, 18059 @ 2.7, .911 torque...Where am I going wrong with this deal??? I have never seen this gearing difference show up in the program, seems to be the other way..


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## Guest

PizzaDude, 

It doesn't matter. If you put in mm, you'll get mm out. If you put in inches, you'll get inches out. The only thing that varies is weather your talking about diameters, radii or circumferences. But I already allow for that.


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## PizzaDude

Thanks Mike,

I see that now...

Pizza


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## DynoMoHum

Yes, I think Mike has a boo boo in it... It seems he's either named the "referance motor" as the "gear motor" or the other way around.... the gearing info is basicly just the oposit of what it should be... unless I and others are just confused... I hate to say it, but I think it's a mistake... 

This really is a great program... If I'm not mistaken when I pluged other data Rich had given us previously for his Cleavland Paradox motor and a Monster motor he gave us data for on the other thread... it would require like 6 or 7 teeth differance in gearing... The data for these two motors was included in the dynodata.zip file I gave earlier.... If this is accurate, it's way differnt then what I beleive Trinity has been telling us... Don't they say something like 3 teeth differnt??? perhaps they are saying 3 teeth differnt then a GM3... that maybe I could beleive... I haven't really compared a GM3 to a Monster yet... hmmm I do have dat for Mike's GM3 and his Monster... 

I know I feel much more confident that I could take a motor out of my car and place anohter one in it and have what I beleive should be gearing that is very close to what it should be... assuming the first motor was geared well... If the dyno data is accurate, and my method of selecting simmilar gearing is correct, I beleive I should be able to finnaly swap a motor out and not have to do a whole bunch more fiddling with gears and on track testing... but only time will tell if this holds up well or not... I am exteemly hopefull that it will.


Well I went and looked at the data for Mike's Father's GM3 compared to Mike's Monster (the strongest of three dyno runs he gave) and it said about 4.5 teeth differnt for gearing...

I beleive there is not doubt if you only used 3 teeth differnt like Trinity says, the Monster would either be faster on the track, or burn up... one of the two... however I don't think that would be the ideal differance in gearing...


One thing I eventualy would like to discuss with TurboDyno guys... what is it that seems to make the lengtht of the 'torque' curve (and other curves too) of a higher RPM motor longer then the curve of the lower RPM motors? (I'm talking about after you show the data with differnt gearing) Is this just some odditity in the way things work when using a Dyno such as the Turbodyno? or is this somehow indicating that more RPM is better??? 

I beleive it's a oddity of the way the dyno is doing it's job... I don't beleive it indicates anythign about the proformance of the motor... I think you just have to imagine that the proformance for the lower RPM motor will continue on in the same general path as it's taking... baiscly that it's a matter of perspective and understanding that your looking through a window so to speak at this bigger thing... I think since the torque at the dyno is lower for the high RPM motor, the data is spread out further with relation to RPM... That's my theory anyway...


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## Fred B

I hate to be the bearer of bad news...The rollout is a bit off.


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## DynoMoHum

Oh... for the record... if there had been a program like Mike's available and a interface between the TurboDyno and a computer so that the data would transfer automaticly.... I may not have sold my TurboDyno...

If someone was extreemly ambitious, I bet a IR interface to the TurboDyno could be made... But I'm in no way shape or form suggesting that anyone such as Mike do this... However that would be one extreemly cool thing for TurboDyno users...


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## Rich Chang

Hi Glenn - I don't know if you want to use the Monster Stock numbers I gave a while back for comparison.  I don't think I fully broke in that motor and the brush setup I put on it doesn't seem to work very well. I am going to mess with it a bit today and use a different brush setup and see what happens.


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## DynoMoHum

Did you get the updated .exe file Fred? we thought we had the rollout calculation fixed yesterday afternoon...

The package isn't updated yet... and it looks like there is at least one other bug that needs fixing so the package won't likely get updated till the others have been fixed...

I have to apologize to Mike... I've been acting as his chief beata tester... and obviously I haven't done my job very well... my only defense is my work is as good as my pay...


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## Rich Chang

Fred, version 1.3.1 has the corrected roll-out.


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## Fred B

missed the post...


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## Guest

Well...

I have to say that my work is as good as my pay too.  

I'll have the new bugs fixed soon.


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## Rich Chang

I'll disagree with you, Mike. So far your work is priceless (in a great way) compared to your pay. 

This program is something I've been looking for for a long time. I'm sure if you wanted donations you'd get it. I, for one, would donate.


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## Guest

Ok, here it is, Version 1.3.2

I flipped the way it calculates and applies ratio's to the motors.

It now tells you to gear a RPM motor lower than a Torque motor.


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## Guest

If anybody wants to donate money...

I do take Paypal. All proceeds will go to new motor purchaces. All you need to do is use my email, [email protected]


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## TeamGoodwrench

Super Mike!

Hey ... back to a post I made a couple days ago.. what do you think the amp number should be in the "apply gears" section for 4-cell stock oval ?? 

Does anyone have that info ? 

Thanks


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## Guest

Also, I'd like to hear suggestions. You can post them or email them. Or call, or snail mail, or tell me or what ever. (The last sentence is me being sarcastic to myself)


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## Guest

TeamGoodwrench, 

If you look at what Dynomohum said a few posts back, there might be a better way. Basically, if you make the torque curves look parallel when the graph is in RPM view. There are a few caveats to this, but he talked all about it above.


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## TeamGoodwrench

OK.. I'll try that. I thought he was saying to make them overlap -- which mine never do. Making the PARALLEL makes sense.

Thanks!


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## Fred B

Now that my internet connection is working again...

The gear motor rollout has the ratio applied backwards. As the calculator gears down, the rollout gears up.

Thanks for all the work!


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## Guest

TemGoodWrench:

To choose what amp draw to do the "gearing," you should have an estimate for the average amp draw of your motor during a race. Do do this, you need to have cycled your batteries at some point. For example, let's say your batteries were cycled at 30 amps and discharged in 280 sec. You then race. After the race, discharge the pack at the same 30 amp setting to 0.9 volts/cell. Let's assume this comes out to 60 sec. (The key to this being "easy" is to cycle and dump at the same amp draw.) Your average amp draw would then be 30*(280-60)/280 = 24 amps. Now comes a little be of "art." If you're running oval and never lift, this is probably a pretty good average amp draw. However, if you are lifting in the corners, or running road course where you lift, then the actual amp draw is probably slightly higher, maybe 26 amps or so. This will get you close for an inital guess that can have the gear ratio refined on the track.


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## TeamGoodwrench

RWB -- Thanks!


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## DynoMoHum

Goodwrench.... If I could get your data I could pretty easly show you what I think is the best way to do it... without the data it's very hard for me to explain my ideas... I could use snuffy's data to show you some examples, but I think it would be much easier and clearer if I just showed you with your own data.


Fred... are you still using the older version? or the most recent version? (I haven't even tried Mike's newest version yet... I just got back home from a Dr visit...)


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## TeamGoodwrench

DynoMoHum -- I'll get you the data over the weekend. Thanks for the offer !!!

I use a Fantom -- what is the best way for me to get you the data ?


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## DynoMoHum

I beleive the average amp draw idea is slightly flawed. I don't think that it's totaly baseless or meaningless, but I do beleive the differnt motors can operate at differnt amp rates and be more or less effective depending on lots of factors. Primarly efficiency... but anyway...


My basic idea where Golden's dyno viewer comes into play has nothing to do with amp draw, or such... it has to do with on track testing to find the correct gearing for a motor. Then taking that motor's dyno data and comparing it to another motor's dyno data... then you use something like the gearing slider on the DynoViewer to choose gearing that will most closely resemble the torque output of the motor that you know works well... Depending on effciency and other factors you may be able to gear the motor up or down a little from this point to go even faster... 

In the end one motor might work best at a average of 25 amps, and another might work best at a average of 27 amps... it depends on the effciency of the motors... Obviously the more current you use, the more likely heat buildup will become a issue... However + or - 2 or 3 amps may make you go faster or slower... but still Torque at the wheels is what really makes you go fast on the track. 

This is kinda of a new concept... not really new, but differnt then many of us had previously been considering...

Average amp draw is a good thing to know... but it is only part of the picture... because of effciency mostly amp input is somewhat of a meanigless item by itself. 

I'm still refining my ideas on all of this... so bear with me... 

Fred B has on track data that shows 45 amps or so is not unheard of in roadcourse racing... and in fact may be hit once a lap or more...

For oval racing, it's differnt... Diffent for 4 cells then it is for 6, differnt for short courses vs. Long... differnt for Stock then it is for 19 turn, etc... For 4 cell I beleive about 30 to 20 amps is the most important area... but depending on which dyno you use... 30 amps on the dyno might not be at all what your motor sees in the car... the dyno is just a rough estimate in many cases... No dyno gives you exactly the same condtions as will the motor will see on the track and in your car...

For example... if you put a 30 amp load on a 4 cell pack, the voltage will not be 5 volts... and the current at 3.2 volts is much diffent then the current at 5 volts.... So current numbers on a dyno are not one for one with current numbers in the car....


----------



## DynoMoHum

Goodwrench... I beleive that the Fantom Facts II dyno keeps all the motor data in one file... I forget the name of the file right now, perhaps someone else will give us the name... I'll check it out eventualy and get back with you... 

Theoreticly you can either email me the file, or post it somewhere on the internet and tell me where to get it... 

If you send me the file with all the motors, tell me a couple in perticular that you are interested in, then I could start looking at those first... I think once I show you my idea, you'll be able to duplicate the same basic tehnicque quite easily...

Snuffy gave us all his dyno data way back when... (a few weeks ago... I bleive the name of the file is somewehre in a previous post to this topic... I'll go look)


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## DynoMoHum

The file is alldata.abc (I think) it's probably best if you zip it first... but then you could attach it to a post here if you like...


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## TeamGoodwrench

OK.. will do.

Thanks!


----------



## DynoMoHum

The DynoViewer instaler with the latest version of Golden's DynoViewer is available at the usual location...

http://www.wiltse.net/zips/DynoViewer.zip

I haven't personaly tried this new version yet... but based on what I've heard it should have all previously discovered bugs corrected...


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## Snuffy

DynoMoHum is right. The Fantom filename is Alldata.abc.

You can also export individual motor files to the dos format. I'm just not sure how to do it offhand.

Another way is to export it to excel.


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## DynoMoHum

I think I'd prefer just to look at the alldata file...


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## Snuffy

Sorry DynoMoHum, I didn't mean to imply that I was speaking for you.

I was just giving the options for exporting fantom data.


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## DynoMoHum

That's alright... I just don't know how to deal with the other stuff... besides if he gives me/us the alldata file I can look at all his motor data and maybe offer some suggestions as to which motor I think is best... Basicly the more data the better...


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## Snuffy

Works for me.


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## popsracer

*Motor power band*

DynoGuru's;

From what I have been reading in recent weeks. I gather that most of you are Oval racers only. With that said, now my questions.
For TC racing, what should I be looking at in the Robi Dyno data when comparing motors. Also would you consider a 1 watt increase in power after some tuning, significant?

Thank you, popsracer


----------



## DynoMoHum

For the most part a motor that works well on a Oval will also work well on a roadcourse, at least in my opion it will.

Depending on what voltage you are testing at, one watt can be more or less significant. I beleive it if you have consistnatly 1 watt more with one motor then another, then it's most deffintely significant. 1 watt of peak power on a 7.5 volt test is less then 1%. One watt of peak power on a 5 volt test is almost 2%, hence the reason I say voltage matters in this. It's all realitive.

My current thinking is that viewing data in relation to AMP input is decieving. I think this is just as true in TC as it is in oval. Data in relation to amp input is more about effciency then it is anything else. Efffciency is important, but not the only thing that's important. 

I currently beleive that peak power is more significant then most other numbers. If you use Golden's DnyoViewer looking at the RPM graph, then adjust the gearing to compensate for differnt motor speeds it becomes pretty clear that a motor that has more peak power, also has more power at all other RPM once gearing is applied. It may take more current to produce this power, but it does have more power thougout the full RPM range in just about every case I have seen to date.

To me this tells us that a motor with more peak power will be faster on the track for short periods of time (like on minute or so) then a motor with less peak power. After the first minute lots of other factors come into play as a direct byproduct of effciency, or lack of effciency. Currently I see no way to easliy predict the effects of poor effciency over time. I mean you can make some assumptions that a more effcienct motor will stay fast for a longer period of time, because it wont heat up as much as a motor with very poor effciency... You can also assume that you battery packs will get drained quicker with a motor that has poor effciency, but this is not likely to be much of a factor in modern racing, not when we've got 3300 mAh packs. So... in my opion at this time... peak power is King, followed closely by the Queen who's name is effciency. 

RPM is mostly for choosing gears... although I have seen in rare instances where this is not 100% true.

To find the right ballance between power and effciency, I beleive that on track testing is the only way to do it at this time.

If your running with low capacity batterys such as the 1200s and 1300s of days of old, then effciency is much more important then it is today. Spec batterys tend to fall into this class. However I know very few (None) people who use spec batterys in TC, or most other highgly competitive forms of roadcourse racing, or even off road racing.


By the way... if anyone can prove to me that peak power isn't pretty much 100% indicative of general output power across the intire RPM range of a motor, I'd like them to show me how they are doing it...

Sorry I can't give you exact numbers that will tell you if a motor is great or not...

On my Robitronic 60% peak effciency is about the minimum I would play with... even that is pretty low in my opion... Typicaly I see in the neighborhood of 65 to 75 on a good stock motor. 134 Peak power is the best I've seen... 128 is the best any of my own motors have done...(this is at 7.5 volts... 62 watts is my personal best at 5 volts)


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## popsracer

*Motor intricacies*

DynoMoHum;

Your the man as always. I was refering to a Monster stock that I am favoring in my TC right now. When I first got back into electric TC racing my car was so much slower than everyone elses. I was running a P2K2 at the time. Did all the normal tuning things but nothing ever seemed to make a difference. Bought a Monster stock and swapped it out with the P2K2 and WOW. Now with my Dyno I see about 120w on the P2K2 and The Monster 123.6w after some minor tuning. But I have an OLD Reedy Rage Stock that is showing 122.8 on the Dyno with more Torque and less RPM (this figures). The Reedy was always so slow in my other car no matter how I geared it. This leads me to believe that a Motor with a Higher RPM and similar Power outputs will perform better on the track because of a wider power band. Providing you are geared to take advantage of that.

I gotta do some more tuning to shoot for that 125w mark. When I get some time I'm going to try different endbells and cans together to see if there is any improvement by using one over another.


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## TeamGoodwrench

DynoMoHum --

Here is my file from the Facts II.

There are several Monster motors and a few GM3s in it.

The motor named "MHP PRO" was really strong last night -- TQ and 2nd in the A-Main. Had really good power in the corners.

The motor named "JIMS BEST GM3" was a very strong GM3 in my friend's car -- both were strong.

The motor named "Team1 GM3" is the one that I am interested in comparing to the "MHP PRO" motor in terms of gearing difference.

Thanks


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## DynoMoHum

I'm still looking closer at the high RPM thing... for the most part I don't really think high RPM by itself is of any great bennifit... however I don't have enough on track experiance to say this definitively. Theoreticly I see no real advantage to high RPM... 


Anyway... POWER is what I know for sure helps...

Goodwrench... I've got your file now, and Golden's most recent viewer... I'll look at your motor data soon.


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## DynoMoHum

Still looking at your motor data... I came back to get the info about what motors you were running and which one you specificly wanted to compare...

However the motor in MOTOR TEST is your strongest motor in my opion, and it has better effciency then MHP Pro. MHP pro and MHP 1 are nearly identical... I'd choose the one with more effciency just because it is more effcienct...

If you geared up MOTOR TEST one tooth above what you ran with MHP Pro, it would be even faster down the stratights and have nearly the same power in the corners. If you left the gearing the same, it would be stronger in the corners and nearly identical top speed... However the efficency is significantly better on MOTOR TEST, so it should work very well pretty well either way...

I'm going to try and make a web page to illustrate my points... 

I'll go back and look closer at the ones you specificly mentioned...


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## TeamGoodwrench

I think "MOTOR TEST" was actually the dyno run on "MHP PRO" after the TQ qualifying run.

I pulled it out of the car, sprayed it out without removing the brushes and threw it on the dyno. Then I put it back in the car and it was really good in the A-main. I used the same gearing.


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## DynoMoHum

That's good... I knew they were very close to the same thing... You must have things setup quite well.. when they come off the track as good or better then they went on, that is a very good thing.

I had Ranked MHP 001 second best, I felt it was slightly better then MHP Pro, but not buy much. If I'm not mistaken gearing should be very simmilar on both of these...

I felt Jim's best GM3 was the fourth best looking dyno run... just slightly better then MHP 003... I'd have to look close, but gearing would not bee more then 1/2 to 1 tooth off of the MHPs... 

Team 1 GM3 looks pretty bad compared to your best motors, and even compared to Jim's Best GM3... I'll get bak with you on the gearing... but really don't think you'll ever get it to go as fast as the MHP PRO... not unless you do some work on it...

This all assumes the Fantom is giving accurate data for all motors... I can't vouch for it... but I'm not going to tell you it's wrong... only you can decided if it's giving you informatin you can relate directly to the track... I suspect it does give you data that for the most part translates directly to on track proformance... However, if you rank these motors in terms of Peak power... a list of motors ranked by Max RPM is almost one for one with the peak power list... with the exception of MHP benchmark... that motor does somethign odd right at the end of the dyno run... it jumps about 500 RPM at the last moment... MOTOR TEST also gives slightly lower RPM then MHP Pro, even though MOTOR TEST has slightly higher Peak power...

In contrast I quite often see motors on my Robitronic with significantly lower RPM, yet have equal or better peak power then another motor. So I'm quite confident that this isn't directly related to a Flywheel type of thing... However it may have something to do with the fact that the Fantom tests at constant voltage, and the Robitronic doesn't... I still can't figure out why there are several realatively unexplainable differances in the Fantom and Robitronic data.

It could be that you just never dynoed a low RPM motor that proformed really well... I havne't used the Fantom enough to know if it does happen as often as it will on a Robitronic...


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## Mayhem

I can understand how the in-experienced Fantom operator might get the impression that higher RPM motors always produce the most power. Most of the time, but not always, the higher RPM motor IS actually making more power with some exceptions. Before Dyno's we used to apply a fixed voltage to the motor and listen to the pitch it produced, which was actually RPM. 9 times out of 10 we were right.Secondly, if you take a real close look at the Fantom time base, peak RPM is not actually peak RPM of the motor at all, just peak RPM over a specific alloted length of time. To prove this, just watch the peak RPM number displayed on your screen while the motor is spinning, then watch the max RPM recorded in the time base. The Fantom stops recording max RPM at a certain point, the point of zero amp draw if my memory seves me right, therefore only recording useable RPM, a very nice feature in my book.The experienced Fantom owner knows motors can easily be tuned with very high power and low RPM, where track conditiond require, like touring car.The myth that the Fantom dyno always produces higher power numbers for higher RPM motors is just that: a myth, and just exposes the operators lack of experience with this Dyno. Please don't anyone take this the wrong way, but you DO have to have a certain minimum amount of knowlwedge to get the most from this or any dyno. After 6 years and thousands of motors I still learn some little trick every week to help tell me which motors will perform best on the track.


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## Shiloh

In my experience (which is all road course racing; no oval racing), I would definitely say that peak power is totally meaningless. In fact, peak power seems to have absolutely no bearing what so ever with on track performance. What I look at is each AMP step from 20 to 28. I tune so all the steps look good and so peak effeciency lands close to 23 amps, since my average AMP draw during a race is usually close to 23 AMPs.

I've done enough stock motors with my Robi to know what numbers I want to see at each AMP step. For example, any stocker with at least 90 watts at 20 AMPs and 110 watts at 28 AMPs is going to run strong. My best motors are around 96 watts at 20 AMPs and 120 watts at 28 AMPs. Keep in mind these numbers only apply to my dyno, since you cannot compare dyno results from one to another. For example, one friend's Robi shows totally different numbers when dynoing the same stock motors. Anyway, the key is to dyno a lot of motors using your dyno and the track to get an idea what numbers are good or bad.

If you just tuned for peak power, there is a chance that some motors with good peak power will also have a great powerband from 20-28 AMPs. However, you will not know for sure by only looking at the peak numbers. In fact, some of my best peak power numbers came from motors that stunk on the track. Those motors stunk on the track because their numbers between 20 and 28 AMPs were poor, even though the peak power number was very high.


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## DynoMoHum

First off... The web page I promised Goodwrench... I compare 5 of the motors he provided data for. First I compare his best dyno run 'MOTOR TEST' to what he has named 'Team 1 GM3'. Next I compare his friend's motor 'Jims Best GM3' to 'MOTOR TEST'. 

Then mostly as a illustration of how gearing for two simmilarly powered motors that have RPM that would warrent at least a one tooth gear change... In this case I used 'Jims Fresh GM3' to 'MPH 003'. 

The web page is located at...

http://www.wiltse.net/gwrench.htm


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## DynoMoHum

Next...

I fully admit I don't have enough experiance with the Fantom to know if it does ever show good low RPM motors to be as good as good high RPM motors... The only data I've really examined closely is Snuffy's and Goodwrench's. From what I have seen of these two data sets, I rarely see a motor with good Power that also has low RPM. There are a few specific cases in their data that i can find this type of behavior in their data. My data set is far to small to say anything conclusive on this matter.

I still would like to see data for a really good EX-Spec motor comapared to a really good 'Stock' motor... my perosnal experiance with testing this two differnt types of motors on a Fantom leaves me scrtching my head.


As for Peak power having no value at all... a month ago, I would have agreed whole heartedly... but I am changing my tune. I'm not saying it's the only thing to tune for... but I'm saying it's much more important then I had previously given credit to. 

I've not tototaly given up on looking at data in relation to amps... but I no longer look at it as my sole means of evaluating a motor... 


Shiloh... Do you have some data I could look at of a motor or two that shows one with exclent numbers from 20 to 28 amps, but doesn't also have exclent peak power? Also, do you have some data that shows exclent peak power but really crappy power between 20 and 28 amps?

I have some data that shows the second point, so I know it happens... I'm not saying it doesnt... however I'd like to see some of your data and examin it in the way I currently am... I suspect your method and my newest method come to the same conclusions about what makes a good motor.

Actually... I've got some data that shows pretty much how peak power alone doesn't make a good motor... however peak power with excelent effciency will show ALOT about what makes a good motor.

Back to Popsracers question... I didn't include this in my last response about what I think makes a good TC motor, as compared to a good Oval motor...

Oval races are shorter, effciency is less important then TC. TC races last one minute longer and effciency is more important as a result. TC racers can likely not average more then about 27 amps in a race without a meltdown... 6 cell Oval guys can likely average 30 without problems. To me, this basicly means that TC motors need slightly better effciency to be good throught the entire race. 

Also... after reviewing some Robi data for 6 cell... I think a motor should have a peak effciency of at least 67% to be good for TC. Previously I had said 60% is as low as I'd play with... I'm thining now that 60% on a Robi is way too low for any decent motor I've seen on my dyno.


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## DynoMoHum

Here is a work in progress... attempting to illustrate a few things... mainly the fact that Peak power without effciency is not good... at least not if you can find a motor that has both...

It also illustrates how veiewing data with relation to amp input is also somewhat limiting, especialy if you should zoom in and only look at power between 20 and 30 amps...

In the end, the idea of viewing things with a big picture in mind is best I think... That is never over look one thing while focusing on another.

... Ok ok... so looking at amp input data makes the effciency thing really obvious... but how are you to make a gearing choice based on that info??


Anyway... the work in progress is here.

http://www.wiltse.net/king_and_queen.htm


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## Shiloh

Glenn:

I am not sure I have a good data file that shows excellent peak numbers and poor 20-28 AMP numbers. I used to have several, but they were on my old Win98 laptop, which I reformatted and gave to my wife. All of my more recent dyno data has been collected onto a new WinXP workstation, and I do not think there are any good examples in that collection of dyno results. One brush combo that consistently causes great peak numbers and pathetic track performance is the Trinity 4391 combo. That combo usually provides 10-15 watts more at peak power, but loses about 10 watts at each AMP step. If I can find a pack of those, I will try to build a good example motor and then gather dyno data from it.

I am not sure what you mean by good effeciency. I look at effeciency at each AMP step, because peak effeceiency will not always be in the AMP draw range where I race. For example, a motor with 73% effeciency at 12 AMPs will not be any good to me. I need good effeciency at or near my average AMP draw. I want to see 70% eff at 23 AMPs, because fast TC guys at our track will usually average about that much AMP draw.

Keep in mind that effeciency is simply the percent of input power that is converted to kinetic power. The rest of the input is converted to heat. IMHO, effeciency has no bearing on runtime, since I run 3000 and 3300 cells. With an average AMP draw of 23 AMPs, I have no worry about dumping during a 5 minute race. Effeciency is only a concern to me because a lack of effeciency will lead to a surplus of heat and hot motors run slow. A motor with only 60% effeciency will get hot during the race and the magnets will feel weaker, and the performance will fall off. A motor with 70% effeciency will feel consistent throughout the race, because there is less heat building up in the motor.

In my experience, if you have good numbers at 20 AMPs and 28 AMPs, and your effeciency is good at 23 AMPs, then your motor will be strong on the track. This rule of thumb seems to work regardless of what the peak numbers are. But keep in mind that I run touring car on a road course, and your method of interpretting the dyno results may be better for oval than my method. I've never raced oval, so I cannot say how my awesome TC motors would fare in oval racing.

Shiloh


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## DynoMoHum

I was just telling Mike in private email... If I had to use a TurboDyno I would look first at power at 28 amps (Actually I'd probably change it to 30 or 35 amps), then I'd look at power at 20 amps. The power at 28 amps would basicly tell you how strong the motor was, and the power at 20 amps would tell you how effcient the motor was...

On a Dyno with constant voltage, the output power is essentialy the same thing as effciency, when viewing data in relation to AMP input.

Now I know that Shiloh is talking about his Robitronic data... however I beleive the same basic technique could be used... However I see no real need to limit one's self to this... after all with the Robi we can view the data any way we choose... 

Personaly I've never seen a stock motor have peak effciency located any higher then about 26 amps.and often effcincy peak around 20 amps... From what I have seen, when peak effciency occurs at above 20 amps, the actual peak is lower then it would be if it peaked at a lower amp location. 

Again from what I have observed... If you have a motor that has peak effciency of 75% at 20 amps, it's likely to be even more effciency at 25 amps then another motor that has peak effciency at 25 amps...

Notice the peak effcicincy curves of the these two motors... this low effcincy on Motor 1, is very typical of what I see when I find a motor that has peak effciency that occurs above 20 amps. 

http://www.wiltse.net/images/ppa.gif

Anyway... sure effciency is important... just how important and how much is nessasary is still open for debate. Basicly... in my opion... if the motor doesn't fall off before the end of the run, then it's effcient enough... If it falls off, or goes up in smoke then it wasn't effcienct enough... Or you need some ice on it before the start of the race...


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## Mayhem

Dyno....Actually there is no other form of racing more runtime dependent than oval. With 4 cells we have been forced to run 7 turn flat wires to duplicate 6 cell times, avarage amp draw has actually increased so we are back to square 1. There is still a very fine line between dumping in 4 min race with big 3300's at the top levels of oval racing anywhere right now! A setup even a little off can dump a pack in 3:45. I just race for fun with my sedan, and admittedly nowhere near the top levels but so far dumping isnt a problem in mod sedan for me. I'm not sure if the cleveland guys were dumping or not in mod sedan. Also very track dependant though. In my opinion Peak wattage is THE most important factor in a motor, at least you will be fast for most of the run, maybe finishing a little slow, but still allowing a pretty decent run. Without peak watts youll never get up to speed. Power AND efficiency is what we are all after. I tune to get my peak power where i want it in the powerband, then try to gain efficiency throughout losing a minimum of power at those points. The GP3300's make life a lot easier in the efficiency dept though..now throw motor power/efficiency drops into the equation and it really gets fun.


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## Snuffy

I have a question about Mike's Dynoviewer.

What is being done to the fantom data when you use the paste fantom data and correct option?


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## DynoMoHum

I should have qualified my statments by saying they are intended to apply to 'stock' racing only. I'll include 19 Turn spec as well, but I have veritualy no experiance in modified racing. 19 turn spec motors are much more powerfull and effcienct at high amp draw, and will not dump a 3000 pack no matter how you drive. 4 cell and 6 cell are also two totaly differnt ball games, and only some of the basic priciples I've been advocating apply to both. (actualy most do apply to both 4 cell and 6 cell, but there are addtional factors I havne't really spoke of too much that relate to each of these individualy)

Now that you mention it... Effiency in 6 cell oval may very well be as important if not possibly more important, then it is in Sedan... I really have very little experiance in either of these clases.

One thing I am sure of... power is very important. in all forms... you only need as much effciency as is needed to finish the race without proformance decline. Power is what makes you go fast, efficeincy is how much power gets to the tranmission/wheels compared to how much your putting into the motor

Snuffy, 

The paste and correct Fantom from clipboard, does the DynoMoHum fudge factor to the Fantom data. Basicly it re-calculates Torque by using the RPM given by Fantom for the current interval. Fantom seems to be using the RPM change for the next interval to calculate torque. We went round and round about this a few weeks ago. In the end John Stranahan did some calculus on the Fantom data, and he says fantom is not doing anything wrong.... However my fudge factor makes the data look alot more like what you'd get if you had a Robitroinc Dyno... not exactly the same, but power and the efficeincy numbers come up alot and are far more beleivable to me in the 'corrected' form.

It doesn't really seem to change much in terms of which motors are good, and which are not, unless you would try to compare one that doesn't do the correction, to one that does... So if you start to play around with that feature, make sure you don't start compareing the corrected version to the non corrected data...


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## DynoMoHum

I got me some Putnam green and blue shunt brushes... some time off work, and dyno ready to go... I even got some track time lined up for this weekend... This should be a good holiday...

Maybe I should have got some red shunt burshes to go with the Christmas theem...


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## Snuffy

I'd be happy with some time off work right now. If I had a functional dyno that would be even better.:lol:


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## DynoMoHum

Well I tried the Putnam brushes this weekend... They worked well, but didn't proform magic or anything like that... I had tried some of the new Trinity 4503 brushes the week before, and they also worked very well. 

I didn't have any other 19 turn motors to compare my results to... and being my driving and car setup is not as good as it should be... I didn't win any races with either of the brushes I tried in the past couple weeks... 

On the Dyno the 4503s and the Putnams profromed quite simmilarly... Same with on the track... but I had no way to do any side by side comparisons.or anythign close to that. I do know that my motors came off the track dynoing as good or better then when they went on the track with both sets of brushes. 


Speaking of dynos.... I finnaly got my Paradox and EX-Spec data off of my friends's Fantom dyno... All I can say is... Either my friends dyno has a problem... or all Fantoms do... I am trying to figure out a way to determin which... I only know of one other person local with a Fantom, and he never brings his to the track... So my options are limited in how I can persue this.

What I have observed is this... On the Fantom dyno I used, there almost seemed like a current lmiter of about 50 amps or so... That is, with both the Paradox and the EX-Spec motors they both pulled very close max current. When I test these two motors on the Robi, or the Trubo dyno, the EX-Spec will pull 25% or more then the Paradox. Not so on this Fantom...

Looking back at Goodwrench's data... I see his Monsters were pulling around 70 amps at start up. So, I know that at least some Fantoms are capable of pulling more then 50 amps... 

Anyway... I'm kinda stuck right now in trying to figure out what's going on with this Fantom I have accesss too ocasionaly... About all I know is that this Fantom is using a lawn tractor battery as a power source... I don't know if it is somehow limiting the current or what. When I've used my Robitronic with a lawn tractor battery, I've not seen this happen, so I don't think it's directly related to the type of battery...

Any ideas on how to persue this? My next step was going to get some 19 turn data off my friend's Dyno and see if a 19 turn motor pulls more then 50 amps....


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## pancartom

there's a problem with your friends dyno/power source. i regularly run 7 and 8 turn motors on my fantom and they all pull well over 100 amps at startup. i'm using a car battery for power with a small 10 amp charger attached to it. fyi, my monster stocks pull 55-60 amps at the start....


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## Snuffy

I agree with pancartom, there's something wrong with his battery. 
A quick check is to try using your battery with his dyno.


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## Mayhem

I see a lot of people using alligator clips and 14 Guage wire to connect to thier battery, not the hot setup to pass 100 amp through. The length of the wire is also critical, even 1 inch difference off spec produces different numbers.
Also check the setup menu. There is a setting to limit current used for the "speed control" choice, which attempts to simulate your speed controller if you are using the current limiter on your speedo. The numbers you are seeing could be the dyno current limiter set to 50 amps......this is the DOS version. Pull up a screen summary of 2 compared motors and hit "s"


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## Tempest2000

there is a setting on fantom dyno software to turn off the current limiter...


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## DynoMoHum

I've sent a message to the owner of this dyno, telling him about this... I won't get a chance to see him or this dyno for a couple weeks from now. So I won't be able to do much more myself with it for the time being.

I know the Robitronic has the ablity to limit the current as well... This type of feature may have some use, but I haven't made any attempts to use it myself. However recently I did notice that the Street Spec batteries may very be incapable of putting out much more then about 50 amps anyway...
I'm still investigating this phenomina...

Either way... next time I get a chance I'm going to look closer at the output of this Fantom... THe first thing I intend to do is to dyno a 19 turn, and see how much current it pulls at startup... I figure that surely a 19 turn will pull more then 50 amps.


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## Mayhem

almost double...


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## Snuffy

I didn't even know there was a way to limit current on the fantom. 
I know there's a amp setting to use for comparing two motors at but, I don't think that has anything to do with what is supplied to the motor being tested.


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## pancartom

exactly....


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## DynoMoHum

I'm confused now...

Almost double I assume is a refferacne to a 19 turn motor pulling almost double the amount of current as compared to a stock motor? 

Or is almost double a referance to hos much power a motor would put out if it was really geting 5 volts as compared to about 3 volts at say 40 amps.???

I'm also confused about the current limter feature of the Fantom... Does it really limit the current? or does it just effect the way the data is viewed?


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## PizzaDude

Dyno,

did you receive my email?

Pizza


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## DynoMoHum

Yes I did get your email... I haven't had a chance to look at the data yet. I still haven't even taken a shower yet this morning... and then... well... with any luck I'll take a look later today...

Did you buy a Robitronic? I thought you had a Fantom or something like that... or is this data from a friends Robi? (just currious)


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## Mayhem

Dyno- almost double as in ampdraw compared to a stock motor.My stockers draw 60+ amps, my 19T's around 100amps, you do the math.
Not sure on the current limiter question, but what does it really matter, if its on, it will affect your readings accordingly. I was trying to answer someones question on why he was seeing the results he was seeing...


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## Snuffy

Damn! it got awfully quiet in here.


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## DynoMoHum

Well... after this weekend I may have some more Fantom data to work with... I'm pretty confident I'm going to have access to two differnt Fantoms this weekend...

Also I'm going to be playing around with my Monster...

Another thing I'm working on is my revision to Snuffy's hood alignment ideas... I think it's going to work out well... my preliminary testing was very encuraging. I really would love to have a better more consistant way to align hoods... I think Snuffy's helped me come up with something good.


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## Guest

*Spikes in Robitronic Data*

I just wondered if some of you guys with Robitronic Dynos have made some progress in eliminating spikes in the data and if so how did you do it?


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## DynoMoHum

In a word... NO.

In multiple words... I don't buy the argument that this is somehow related to bushings... It happens on Chemeleon 2, 19 turn motors with bearings as well...

I've tried increasing the mass of the motor stand by holding on very tightly with my hands when I make dyno runs, and this seems to have no effect at all on the spikes...

Basicly I just live with it...


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## tfrahm

DynoMoHum said:


> *Another thing I'm working on is my revision to Snuffy's hood alignment ideas... I think it's going to work out well... my preliminary testing was very encuraging. I really would love to have a better more consistant way to align hoods... I think Snuffy's helped me come up with something good. *


Hmmm... I've gone back through this whole thread... ??? Where are "*Snuffy's hood alignment ideas*" ???

By the way -- I have a P2K that has me puzzled right now... Looks good on the TD45 (very high torque, rather low RPM's, but solid power), but it heats up QUICK! One or two dyno pulls get it hotter than I like, and in my offroad truck, it runs STRONG! for 3 minutes, then starts to fall off and it finishes the last minute at about 3/4 speed... This thing is a killer for those first 3 minutes (geared properly of course)... Brushes are aligned, comm's been trued (and shows no signs of excess wear), bushings feel "free" enough... *Possible cause(?)*: When I center an arm, I normally have left them a bit "sloppy" because that was "safe". On this motor, I got to thinking that "sloppy" shimming of the arm could lead to problems (Big Jim always said the arm moved toward the can under power and toward the endbell under braking) -- so I shimmed this one with much less "play" in the arm. It is "free" on the workbench, but *is it possible that thermal expansion under load causes it to get "tight" at that 3 minute mark?* Any ideas are welcome... (I really want to get this motor sorted out -- it was so strong for the first 3 minutes that I still managed to win the A-main, but only by 0.5 seconds, because second place was really charging hard as I was falling off...)

FWIW: (sort of a change in subject) I ran an Integy V10R with my own "tuneup" in my XXX buggy and won the A-main. My V10 is high RPM, sort of low on torque, but the power is HIGH. Again, I had to gear it right, but this thing impressed me!


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## Shiloh

tfrahm: It sounds like the P2k has low effeciency, and is simply getting too got during the run. Tune it to get the effeciency up at the amp draw you average. I'm not sure what all you have tried with it so far. Here are some things to look at:

1) Is there too much side to side play in the bushings? In other words, are the bushing worn out, and allowing the shaft to move around. If yes, then the brushes are bouncing, and that is causing some sparks. The sparks cause input energy to be wasted as heat instead of converted into kinetic.
2) Is the comm surface rough? A worn comm will cause from friction when the brushes glide over it. Recutting the comm may be the solution.
3) Spring tension may be wrong. Too little and the brushes bounce. Too much and they become brakes. Either way, effeciency tanks. Try using a pair of red springs as a baseline setup with a P2k.
4) Try putting a vertical slot in the positive brush. That will usually increase effeciency.
5) Clean the motor really well.
6) Oil the bushings with Tribo.
7) Recheck hood alignment.


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## DynoMoHum

So what are the Dyno numbers? 

Snuffy has never posted his alignment idea... he sent a email to me, asking me what I thought about a idea he has. I am somewhat hesitatant to say exactly what his idea is... only because it is his idea, and I wouldn't want to make it public without his consent... I am actualy farily sure he wouldn't mind, I mean it's not like he's trying to keep it a secret.

Oh, what the heck... 

Basicly Snuffy sent me a drawing of a hood alignment bar he had dimensions for, it's alot like many typical alignment bars, such as the Racer's Edge centerline alingment tool. Dimensions of the bar are basicly very simmilar, the height and width being basicly the same as a brush. The lenght of the bar would be the lenght of two brushes, plus the diameter of a commutator. Essentialy when you put it in the hoods, and stick the shaft through the bushings and the alignment bar, the ends would wind up eaxctly where the end of the brushes would be in a working motor. The idea was then to align the hoods with this bar in place... bushing the hoods in such a way that they would be posistioned exacly like would be needed to do proper hood alignment using the 'wear mark' method... Only you don't really use the wear mark... you use the tool to make sure it's physicaly centered...

If I missed anything I'm sure Snuffy can and will correct it... 

My idea was that I didn't think it mattered too much if the ends of the tool were at the exact same location as the ends of the brushes... that you could just use a longer tool, and the differance would be insignificant, as long as both hoods were aligned the same (realtively speaking)

I modified my Racer's edge bar, just a tiny bit and started working with Snuffy's idea... I got a peice of 1/8" music wire, sanded it down to .124", so it woudl fit very snugly through the motor bushings... I enlarged the holes on my Racer's Edge bar to .125", and set out to align some hoods...

My procedure is this... loosen the spring post, and the other screw that holds down the brush hoods... (losen both sides) Put the bar through both hoods, then put the modified music wire though the bushings, and the hole in the alignment bar. Next push the bar, and the hoods in the advanced posistion, hold it there and tighten down the brush hoods. I don't stop there... I take my L shaped needle nose pliers, and tweak each hood a litttle more, I use a clock wise twisting motion to do this final tweak of te hoods. This cocks the hood slightly, however the bar is still in place, so it's virtualy impossible to bend too far... At this point your hoods should be REALLY close to perfect... take the music wire, and the alignment bar out of the motor, and then test fit a brush in each hood. If it's a little too tight, use the alingment bar to open up the hood a little. Not too much, because you don't want alot of slop in there... 

When I did this myself, I put a new set of 766s in the motor I did, ran it for a few seconds, and checked the wear marks... They were about as close to centered as I've ever seen, I don't think I could get them any closer with any other method. Dyno results were darn good on this motor as well. I beleive I coudl repeat this methold consistantly without any trouble. After I get more confidence in the methold, I beleive I could stop checking the wear marks, and basicly just start to assume I've got the alignment good enough. I've only done two motors this way so far, but both turned out very well.

The main reasons I like this type of aproach is, that it that it should be very easy too do for just about anyone. I also beleive it will be very consistant, and that I can actualy save time by doing it this way, and not have to worry about doing more harm then good. Based on limited testing of this method, I beleive it will work quite well. Also... if it really does work out as well as I think it will, I can stop buying all these new brushes, with the sole intent of using them strictly for hood alignment procedures...

I beleive the wear mark method requires too much skill, and can be somewhat inconsistant, mostly do to lack of skill and patiience. I also beleive there has to be a way, some way that is realtively fool proof. I thnk my modified version of Snuffy's idea is a good one.

I have a few ideas that may make this slightly better, but I'm not very confident in them at this time, so I won't elaberate on them.


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## tfrahm

Shiloh said:


> *tfrahm: It sounds like the P2k has low effeciency, and is simply getting too got during the run. Tune it to get the effeciency up at the amp draw you average. I'm not sure what all you have tried with it so far.*


Thanks for the ideas. Most have been covered in my tuning... New motor, comm was cut right before going racing (after initial breakin), Springs are Red+(7.75 FS)/Green-(7.5 FS) (yes, the green does seem a bit "firm"), I use TRIBO on the bushings, motor is smoooooth on a 4cell test pack and on the dyno, hoods are aligned (Big Jim style), Brushes are 4499's (full face, with a 1/32" off the trailing edge).

Efficiency is good (on my TD45, at 7.00 volts the best I've ever gotten was a Paradox that put out 20,733 RPM, with 6.4 torque for 98 watts at 20 amps, with 70% eff.) -- this motor puts out 94 watts at 67% efficiency. (17,873 RPM with 7.1 torque)... *Please note that my TD45 seems to be "conservative" and produces lower power numbers than most others, but trust me, my best motor RIPS and the motor I'm talking about here really hauls with the right gearing -- I just have to keep it cool for 5 minutes...*

I'll consider going slightly softer on the springs (at least get a more typical Green on the - side). I'll also be re cutting the comm as a part of normal maintenance... I also want to recheck the bushings to make sure they are as free as I think they are... 

*NOTE: I recently got a P2K2 with bushings so "tight" that I may have to go back to some sort of break in sauce to get it freed up -- it dyno's strong on the first pull, then heats up and falls off -- very much like the symptons of this P2K, but I'd swear the P2K bushings are OK...?*


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## DynoMoHum

What are you getting for 28 amp numbers? what is your best?

Your occurance sound quite strange... 

How much curent does this motor draw at say 3 volts with no load? is it more then with other P2Ks you have?

I know you said your hood alignment is fine... however one thing I've seen is that if hood alignment is off, it does make efficency go down... and amp draw go up... Have you tried useing a differnt endbell? one that you've used before, and have not had problems with?

I'm not sure I have any answers for you, I'm just thinking out loud about things I'd check or look at.


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## calvin

Dyno

I had an idea very similar to the one you posted above (I posted it on BJ’s forum but he never responded) – Ref below which includes a sketch of my idea

http://rccars.com/forums/showthread.php?threadid=2&perpage=15&pagenumber=2

After thinking about it some more I let the idea drop. The problem that I envisioned was that if the hoods were cocked too much, you wouldn’t be able to remove the tool after you got them aligned without messing up the alignment.


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## tfrahm

Dyno...

The best I've seen at 28 amps and 7.00 volts is 126 watts, with 120-122 watts being more typical for GOOD motors. This "hot" motor puts out 117-119 watts at 28 amps.

During brush break in (on a 5v power supply with a small fan on the shaft) the motor drew a peak of 9.7 amps -- most of my good motors will draw between 8-10 amps under the same conditions...

(the good thing for me is that everyone else seems as puzzled as I am... somehow that is oddly reassuring...)


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## PizzaDude

Tom,

you cut 1/32 of the trailing edge.
So actually you're running timed brushes right?!

That's also something which could seriously contribute to your problem with your motor.

Why don't you horizontally cut these brushes or slightly narrow them, (in combo with lighter springs f.i.)

Good luck.

Pizza


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## DynoMoHum

No offense Tfram... but based on your numbers... I can't help but wonder why your thinking the motor should run very well on the track... From what your saying, it seems that every number you've got with this motor is a bit lower then your good motors... 

I guess what your trying to figure out is how to make it better... did you check the capacitors??? I personaly have never experianced this, but I keep hearing people tell me about how the caps can cause strange motor problems...

The only other thing I can think of is... some arms just plain don't work very well. Not sure if it's because of the windings, or if the comm slots are cut strange, or what.... but maybe it's just a bad armature. One of my common procedures is to swap arms and such in a known good can. This can be time consuming if the comms aren't exactly the same size on two differnt motors, but if you really want to sort out some funky problems, swaping peices one at a time is the only way to go.


Calvin... One of the first suggestions to Snuffy, was to modify the alignment bar exacly like your idea... Soon after that I decided that it probably wasn't even nessarary and may cause more harm then good. I think you are correct in your thinkng that you may not get the tool out once you've aligned the brushes that way...

One of my thoughts on a mod that might help a tiny bit... a too that is a couple thousandths of an inch more narrow then a real brush. This would possibly allow even slightly advanced brush alignment... although I also beleive it would tend to cause the hoods to get pinched too much if you use pliers like I do...

I plan to take some photos, and make some drawings of my methods... I think that it can work pretty well... and I also think I could put together some step by step procedures that would make it pretty easy for most anyone to do this pretty well.

For what it's worth... I think that it should be possible to have slightly advanced timing with some creative hood alignment. I also think that if both hoods aren't concentric with one another, it doesn't matter if one side is perfect... if they both aren't perfect you've got problems. You'd be better having both sides slighly retarded then having one side dead on, and the other off a bit.

And I think the same goes for cut burshes... I think if you don't get your 'timed' brushes trimed pretty closely on both sides, your going to have problems related to mis-matched timing. This could be Tfram's problem... I don't know for sure, it's hard to say what's going on with his motor.


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## tfrahm

DynoMoHum said:


> *No offense Tfram... but based on your numbers... I can't help but wonder why your thinking the motor should run very well on the track... From what your saying, it seems that every number you've got with this motor is a bit lower then your good motors...
> ...
> And I think the same goes for cut burshes... I think if you don't get your 'timed' brushes trimed pretty closely on both sides, your going to have problems related to mis-matched timing. This could be Tfram's problem... I don't know for sure, it's hard to say what's going on with his motor. *


No offense taken. Keep in mind the numbers for this motor are close to my "good" motors (it actually starts out stronger, but by the second pull it has heated up enough to fade a bit). For local "club" racing, I don't use my "best" or the better "good" motors -- I save the cream of the crop for bigger races...

I also have learned over the years that it is the motors like this that can teach me new tricks as I try to figure out why it acts "funny". After all, even "as is" it won the A-main! I figure that if I can "cure" it, I will probably pick up a new trick...

As to the "bad capacitors" thing -- I have worked on a hundred or so new style EPICS (I tune motors for a lot of people locally), and I have seen 3 that absolutely nothing would "fix" until I took the caps out and installed external ones. Big Jim always said that maybe I just installed the brush hoods with a better alignment after taking them off (and he might be right), but the difference on them was like night and day (from total pig to race motor -- as much as 15 watts improvement)!

As to the "timed cut" (someday I'll start a furball thread on that issue, since my Physics and Engineering background tells me the timing doesn't change, it's the DURATION the pole is energized that changes)... Anyway -- I have built a rig to do a precise, repeatable shaving of the trailing edge of the brush (cutting both sides with my rig produces a perfect "Big Jim" 0.14" MVP brush). So both brushes are the same, and both hoods showed identical wear patterns when originally tuned.

The cut I use is designed to be the optimum to eliminate a flaw in the design of laydown brush motors. A full face laydown brush produces a DEAD SHORT 6 times per rotation, as a comm segment momentarily overlaps the trailing edge of one brush and the leading edge of the other. The cut I use is the minimum to just barely eliminate that short. My experience has been that this improves efficiency (by eliminating the wasted energy from the short), keeps virtually all the RPM's of a full face brush, and brings torque up noticably (as you'd expect on a TD45 -- less amp draw and greater efficiency always shows as more torque at a given amp load)...

On the subject of hood alignment -- your alignment bar mod shows a lot of promise. As you point out, the WORST thing is mis-matched hoods. Better to have consistent, repeatable alignment results that mismatched hoods...

Anyway -- I'm enjoying this thread a ton! Always nice to discuss and debate without flames and bashing...


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## Snuffy

tfrahm said:


> *As to the "timed cut" (someday I'll start a furball thread on that issue, since my Physics and Engineering background tells me the timing doesn't change, it's the DURATION the pole is energized that changes)... Anyway -- I have built a rig to do a precise, repeatable shaving of the trailing edge of the brush (cutting both sides with my rig produces a perfect "Big Jim" 0.14" MVP brush). So both brushes are the same, and both hoods showed identical wear patterns when originally tuned.
> 
> *


Tfram,

Think about this some more. 
Trimming the trailing edge of the brush changes both the timing and duration. You can visualize it by drawing a straight line through the center of the contact area of the brushes. The difference won't be a lot but the centerline of the contact area will shift slightly in relation of the magnets.


On second thought, I see your point. Trimming the trailing edge of the brush doesn't change the position of the leading edge, so each segment should energize at the same point of rotation. they'll just turn off sooner. 

With that in mind wouldn't laydown style itself increase the timing to a little as apposed to standup brushes? That would actually energize the segment sooner, wouldn't it?




tfrahm said:


> *The cut I use is designed to be the optimum to eliminate a flaw in the design of laydown brush motors. A full face laydown brush produces a DEAD SHORT 6 times per rotation, as a comm segment momentarily overlaps the trailing edge of one brush and the leading edge of the other. The cut I use is the minimum to just barely eliminate that short. My experience has been that this improves efficiency (by eliminating the wasted energy from the short), keeps virtually all the RPM's of a full face brush, and brings torque up noticably (as you'd expect on a TD45 -- less amp draw and greater efficiency always shows as more torque at a given amp load)...
> 
> *


I'm curious about this. Could you give more details about it?


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## DynoMoHum

I wish I could win the A-main with a motor that's down on power about 2 or 3 watts over a good motor... Lately when I go to the track there are at least 6 or 7 guys that are Natiional caliber racers... Anohter 5 or 6 that are just a couple tenths off of the fastest six... and me... well I struggle... That's probably why I enjoy my dyno so much... 

Next weekend it's going to be even worse were going to have guys from other states come in and race... ahh... 

Anyway... I'd find another P2K with the exact same comm size... start swaping parts till I figured out which compoenent was causing the biggest decline in proformance, then start looking much closer at that compoentent to see if you can figure out what is differnt about it... I'd say if you can't get the dyno numbers up to what the good motors are, it's never going to be a top conenter on the track.

I'm just starting to play with timed/trimed brushes.. what I've seen so far is very promising. Quite frankly I've never felt much need to improve the effciency of a P2K... but perhaps it would help... I'll try it today.


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## tfrahm

Snuffy -- You seem to have picked up on what I was talking about. And, yes, Laydown brushes have a big advantage over standup brushes -- the leading edge is several degrees further around the comm than a standup, and thus give significantly more RPM's. The downside is the overlap/short that happens 6 times a rotation. Most racers aren't aware of this short situation, and that's too bad. Read what Trinity says about the P94 brush design and think about what that means for laydown brushes.. That dead short 6 times a revolution burns the comm, wastes battery and creates significant amounts of harmful heat. 

The thin cut I make on the trailing edge just barely elimintes the short -- I want to keep as much of the duration that pole is energised as possible (the pole "pulls" longer, producing more power), but I don't want the waste... *Please note that Todd Putnam has posted on the "Monster" thread that he does the same sort of thing to the LEADING edge on high RPM motors to intentionally retard the timing to get more torque.* Clearly this idea is worth some experimentation, but so far I haven't done much on RPM motors other than the MVP.

By the way -- the reason the Big Jim MVP brush cut (shaving both the leading and trailing edge) works, and the reason others (I think DynoMoHum has posted about this) recommend cutting the same brush to the same width as the Big Jim cut (0.14"), but doing all the cutting on the LEADING edge (about 1/16" cut) has to do with the design of the MVP (and the Core and the V10) armature laminations. These motors have holes (they call them "power tunnels", etc.) drilled into the center web and the top of the pole. These holes affect the limit to the ability of the pole to be "magnetized" when the coil of wire is energised. These motors normally get super hot because the iron in the pole is "over-saturated" (meaning the coil produces a stronger magnetic field than the iron in the laminations is designed for. By reducing the duration the pole is energised, this over-saturation is reduced or eliminated. Since anything more than the iron can handle is a waste, the motor now runs cooler and actually produces more power.


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## tfrahm

A further note on the "short" situation I describe above... On a modern EPIC motor, the big window in the endbell top/bottom is really handy for observing this. Take a motor, put a pinion on the shaft and SLOWLY rotate it while looking in the "window" -- you will clearly see that each time a segment comes to the window, it will gradually rotate out from under one brush, cross the window and then it will touch the other brush while STILL contacting the first brush. There can be no mistake about it once you see this -- that is solid copper touching BOTH brushes at the same time *ZAP!* a dead short! And this happens 6 times per revolution (3 copper comm segments, and the short happens once for each at the top and bottom of the rotation -- that's 6 dead shorts per revolution)... Think about how much energy that wastes and how much that hurts your performance!...


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## DynoMoHum

Lots of things to report... First a comment in response to Tfram's last posts...

My MVP playing, has not been very controled in terms of brush width... I know for sure I didn't narrow the brush quite as much as is recomened by Big Jim. In fact I probably took slightly less then Big Jim does off of only one side... I took it off the leading edge, but also tried it once with taking it off the trailing edge. It didn't seem to make that much differnace if I took it off the trailing or the leading edge... the basic effect was that Efficiency improved, and peak power either went up, or was not effected. I stil am working on the MVPs... Basicly I think Big Jim's narrowing technique is taking off about twice as much as is really needed. (you loose too much peak power by taking off that much).

I tend to think that taking it off the leading edge on the HIGH RPM motors is best... but still have very little testing on this... 

Basicly I'm agreeing with Tfram on this... a slightly narrowed laydown brush is often a good thing... taking too much off is a bad thing.


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## DynoMoHum

Other stuff... I had a very productive weekend... cut about 15 comms on old stock arms I have... Tested 4 motors of a friend (two GM3s and two Monsters) on the dyno... I built me a killer Paradox out of a average Paradox I had laying around... and I further verified my theorys on gear selection given dyno runs for two differnt motors and a referance gearing for one. (Using Golden's DynoViewer). I also backed up my dyno data for my Monster and this new Paradox setup with on track testing...


I tested two GM3s and two Revenge of the Monster motors for a friend. His motors were all pretty decent motors, I'd call them above average. One of his Monsters looked quite good, and one of his GM3s looked slightly better then his best Monster. Both of these look very simmilar to my Monster's proformance level on the dyno. Basicly I didn't see anything to indicate that his Monsters were any better then any really good EPIC motor.

I went through all of my stock armatures and cut the ones that needed cutting, and measured and sorted them all in terms of comm size. My intention was to start doing lots of tesing... The first motor I actualy put together was a Paradox. I used my newly improved hood alignment technique. I didn't even look at the wear marks, I just completed the alignment procedure stated late last week here, and put the motor together and broke it in. The first thing I noticed was this... this was the first time I ever had a Paradox motor pull too much current for my Turbo35... this was at 2.4 volts, and it was pulling more then 12 amps. I think this had alot to do with the brushes... they were warn in the shape of a much smaller comm... and the brushes were only touching on the tips of the brushes... Eventualy after I got them fully broken in, it went down to about 7.5 amps at 2.4volts with no load (not even a fan)... The motor looked very promising on the dyno... 127 watts peak with the 7.5 volt Robitronic setting. My personal best motor was 128 watts... So this is about as good as I've ever gotten from a motor myself.


I tested the Paradox and my Monster on the track... I was running 4 cell Sanyo 2000 packs with pretty good numbers. On the Robitronic with 5 volt setting, both these motors look pretty good, within 2% I think... On the track... same thing... both motors ran within 1/10th once proper gearing was applied... I forget exacthly how much differnt the gearing was... I'll have to go back and check my notes... but it was in the neighborhood of 4 teeth differnt. In the end I felt the Paradox was the better motor.

So... To me the two most exciting things (besides my race in 19 turn 4 cell oval) was that I verified my gear selection technique using Golden's DynoViewer... and I verifyied that my hood alignment procedure is capable of producing very good results...

My race... Well I lead the A-Main (there were only 3 of us racing 4 cell 19 turn) for at least 30% of the race... I qualified 2nd, it took me about 5 laps to gain the lead, I held the lead for about 10 or 12 laps... I hit a inside corner, lost 1.6 seconds and the lead, I fought back, was gaining about .05 seconds per lap on the leader... wound up loosing by .6 seconds... My wreck caused me to loose... boy was it fun though... best race I've had in a long time.


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## tfrahm

DynoMoHum (I still like 'TMFU'... LOL!) -- I agree on the "Big Jim" cut -- at least to the point that I am experimenting to see if the double cut is too much...

Since the V10 and the Core use the same type of laminations as the MVP, I've been doing some experimentation on them too... 

On MVP's with the Big Jim double cut (cut both leading and trailing edge, making the brush face "centered" and 0.14" wide), the MVP will look strong on the TD45, with high torque and lower RPMs. In fact, they look almost identical to a typical P2K. On the track, they perform well, but the "feel" is very different. My testing has been in sedan and offroad, and the BJ cut MVP turns quick laps, but in spite of the dyno numbers, it never seems to have the raw "rip" I'd expect from those numbers. It's sort of a subjective, subtle thing, but I find I like a Paradox, P2K, or P2K2 better for the raw punch I get from them... 

I have a V10R (raw un-tuned when new), that I tuned by cutting 766's on the trailing edge (essentially 1/2 the BJ cut, making the brush face 0.18"). This motor RIPS! Won the Expert Buggy A-main at the local club last week... At 7.00v on the TD45, 20A numbers are very nice (22,423 RPM, 5.7 torq, 68% eff, 94 watts -- well above average on my dyno). Clearly and "RPM" motor, but when geared down a tooth or two, very good to drive -- strong punch out of turns and over the doubles, fast on the straights...

I have just started playing with a CORE "dyno tuned" (big joke) motor, and out of the package it was sad (smoking hot after a couple of pulls on the dyno, low torque -- "gutless")... On this motor I tried doing the 1/2 cut to the leading edge (brush is 0.18" like I used on the V10), but I wanted to see if this would trade off some RPM's for torque... No track testing yet, but the motor went from 85-88 watts at 20 A (very erratic results when new due to the heat problem) to now being a very solid motor with a solid 92 watts at 20A without recutting the comm... I've now cut the comm but didn't have time last night to dyno it (I wanted to let it cool after reseating the brushes)...

Right now, I'm thinking that the 1/2 BJ cut 0.18" brush may be the "optimum" trade off of efficiency, torque and RPM....

OH -- after recutting the comm, reshimming the arm, and a few minor brush hood recheck/retweak, that problem P2K I posted about a while back is looking better. 93 watts at 20A on the TD45, with 117-119 watts at 28 amps and *less heat buildup*. I'll run this Wednesday night (if we don't get snowed out) in my XXXT-MFE and see if it holds up for the full 5 minutes...

(edit) What I find interesting is that the P2K above now seems to run cooler after the tweaking and shimming and cutting of the comm (which had gone back out of round), but the NUMBERS are about the same... Not a total surprise, since the heat took 3 minutes or so before it would make the motor fade, but I still expected the numbers to come up or something...?


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## DynoMoHum

An observation about hood alighment... The Paradox brush hoods have alot more slop between the holes and the screws that hold them in place then the more Modern EPIC motors. I'm thinking this can be a good thing for a motor tuner. It sure seemed to me, that I was able to move the brush hoods around to where I wanted them to be, much easier then I can on a P2K, P2K2, GM3, or Monster... I'm thinking that maybe this is why I can often get a Paradox to proform as good or better then any other EPIC motor...

I wonder if the motor designers haven't out foxed themselves on brush hood/motor design. It seems that in a effort to make motor tollerances tighter, they've also elimated adjustablity in the motors. Theorteicly tighter tollerances would be a good thing... but not if the tollerances all line up in the wrong direction... Anway... some food for thought.


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## tfrahm

One further note on the "double cut" (Big Jim style) MVP brush setup... The slightly softer punch can be a real "speed secret" in offroad for some tracks or for intermediate drivers. I built one of these for a friend, and his performance has picked up for the same reasons I was unhappy with this type of motor. The reduced raw punch helps him run much more consistent laps, yet he still has the speed he needs for straights, etc.

This is an issue we cannot lose sight of when we discuss motor tuning... Pure raw punch isn't always an advantage, just as huge RPM with low torque isn't either... As I learn more about motor tuning, I think I am starting (only STARTING) to understand that there isn't ONE "best" way to tune motors -- you need a "bag of tricks" that you can draw from to tune a motor to match the type of racing it will be used for...


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## Guest

Yeah, I agree with tfram. I gave my MVP to my father, and he thought it was a rocket. I believe it was the lack of punch that actually made him drive better. I took his GM3 as a trade. Man that motor is fast (GM3). I wish I knew why this particular motor is so different than all my other motors that I've tested.


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## DynoMoHum

Yeah... you've hit on something I've suspected for a long time. That is, I beleive that sometimes people do indeed go faster with less power...

Just for example... I can go faster with 4 cell 19 turn on a Oval then I can with a 6 cell stock setup... Now there is more here then just power... but the fact is that with 4 cell 19 turn I have less power, and I can tell that it's easier to drive then it is in 6 cell stock. (at least for me). In 6 cell stock, I can actualy spin the tires comming off the corners and get loos as a result... I can never do this with 4 cell 19 turn, and my lap times are faster.

Even so... I personaly would never put up with less power... there are other ways to make a more powerfull motor drive better... for one, you could gear it up a extra tooth... This would give you better overall speed, but still keep the low end power/torque managable... Or simply improve driving or car setup to handle more power...

As for the MVP... I am getting really close to the point were I beleive I could go just as fast with a MVP as I can with a good EPIC motor... even in high traction situations... A month ago, I had given up all hope of ever making a MVP run well on a carpet track... I've never liked the MVP with narrow brushes... didn't like them on the Dyno, and didn't like them on carpet (which is all I do). I'd love to be able to run fast with a MVP... One of my problems now is that I don't run stock motors very often... and rarely use 6 cells either.


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## DynoMoHum

Glad to hear you finnaly got that GM3 from your dad... it should be put to good use... that's a awesome motor from what I can see of your dyno data...

So... Mike... have you been doing anything new with the DynoViewer? I like your 'perfect torque' feature... I've been putting it to good use... I'm begining to think it may be possible to use the point of peak power to calculate gearing as well... with very simmilar results. I haven't played with the numbers yet, but on the graph... what I often see is that if you line up the arch of the power output on two motors, the torque curve is basicly paralell at that point. I'm thinking that maybe it might be easier to find peak power then it is to find 'perfect torque'...


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## Guest

I haven't done anything with it lately. In fact, I haven't been running my dyno much lately either. I've been working on driving and setup more than motor. I can out motor anyone at the track as it is now. But if I hit the wall a few times, I loose a lap, and all that extra power has gone to waste. 

I've also been using Monsters almost exculsivly in my TC3. Yes they are slower on the dyno, but I can go faster with them on the track. Maybe its just a gearing thing. Maybe its because they don't seem to drop off as much through out the race as much as my other motors. I'm not sure, but they have been working fine so far.


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## DynoMoHum

A while back somone, I think it was John Stranahan wanted to know if I had some sample data files to use with Golden's DynoViewer...

Well... I have some now, not every conceivable type of motor... but I do have like 2 GM3s, 3 ROMs, a couple Paradoxs, and a MVP...

I never thought I'd see a MVP like this here... it's using brushes with the leading edge trimed a bit. The dyno data for it, looks almost as good as any EPIC motors I've got... I don't have much track time with these yet... but they look pretty good on the dyno...

anyway... have fun with these.

http://www.wiltse.net/zips/robi_data.zip


By the way... the newest DynoViewer can be found at...

http://www.wiltse.net/zips/new_dv_exe.zip

That was just a new program... you'll need the full instal from the previously released version to instal first (if you have not already) The last complete instal, is the same currently as it was the last time it was given in this thread... (a couple weeks ago or so...) If your new you may need this first...

http://www.wiltse.net/zips/DynoViewer.zip


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## Mayhem

I bought one MVP when they first came out, and it set the all-time power mark (stock)on my dyno that still stands today after many hundreds of motors. I know you need to try it for yourself, all i can say is i hope you have better luck on track than I did. I wasted a lot of time trying to get that motor to finish decent.


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## Rich Chang

Hi Glenn,

I should have had you dyno my MHP motor yesterday at JCC to see what it looked like. I finally ran the thing this weekend (after purchasing it over 2 months ago). I had it geared down close to 6 teeth under what I normally ran my GM3. I didn't get to do any track comparisons by running the GM3 since I was trying to battle Aaron for TQ (since I knew I had a pretty good gear selection for the MHP I didn't want to switch motors). 

Anyways, you might want to talk to FredB and see if he can get you one of his MVPs. He and Aaron ran them all last year and they were fast with them. I don't think Aaron has his MVP anymore, but it wouldn't hurt to ask him, too.

btw: What motor did you run in your oval main that had Keith Hamilton in it? Sucker was fast.

-Rich




DynoMoHum said:


> * I never thought I'd see a MVP like this here... it's using brushes with the leading edge trimed a bit. The dyno data for it, looks almost as good as any EPIC motors I've got... I don't have much track time with these yet... but they look pretty good on the dyno...
> 
> anyway... have fun with these.
> *


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## Fred B

If anyone wants a new MVP, Scott has them at the JCC races or one of us can bring one up to Lansing on a Friday or something. If you just want to run some numbers, I have an MVP to try.


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## Rich Chang

Well, speak of the devil. Stop stalking me, Fred!


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## TheBoss

ROM? Am I missing something?


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## DynoMoHum

ROM = Revenge of the Monster

The motor I ran in the 4 cell 19 turn class was a Chameleon 2, with Putnam brushes in it. I have done very little to this motor, it's the only 19 turn I own. It came out of the box with hood alignment that looked pretty good, I tweaked one brush hood and other then trying differnt brushes and springs I haven't done much else too it. I started the day with a 2.22" rollout, and by the end of the day I was at 2.722" rollout. The motor was pretty warm at that rollout, but not too hot. I've dynoed other good 19 turn motors, and haven't really seen any that are much better then this one. I did breifely have a real Putnam Pro 19 turn Chameleon 2 motor, that had very simmilar power numbers, but had way more RPM then mine. At that time, I was not gearing my motor anwhere near the rollout I had at the end of the day on Sunday. Basicly I had been undergearing my motor previously. The finnal note on that run... My GP 3300s came back with just 45 seconds left on them at a 30 amp discharge, even so I wasn't falling off much at the end of the run. By my calcluations that's pushing about 40 amps average... depending on how that pack cycles out...

I really need some test drivers for my work...  my driving needs alot of improvement, and I'm confident that many of my competitors could easily beat me with my own equipment... Heck I've seen them beat me with motors that were clearly slower then mine. 

The MVP in that zip file looks differnt then any other MVP I've ever played with. I should have included a more typical MVP to compare it to. Basicly I've seen some with higher power, but the effciency isn't as good, and the RPM is much higher on a typical MVP. I did test this brush setup one day a couple weeks ago, but only had like 2 runs, and didn't have a whole lot to compare them to at that time. However I was impressed with it on the track, more then I ever have been with any other MVP.

Next time Rich, Fred, and I, get together at JCC or wherever, I'll be happy to dyno some of your motors... Heck I might even give you guys some of my motors to try... because I really would like to see what a good driver or two could do with some of my motors. I'm just now getting a handle on how to gear one motor to another based on dyno data. I'm realtively confident I can get within one tooth of a perfect match, if given optimal gearing for a referance motor. Watch out this weekend... Keith has one of my Paradox motors that was included in that robi_data.zip file. On the dyno it has about 5% more power then his best motor.... I didn't give him my Monster... I'm still playing with that, and it's the only one I own.

Oh, another thing... I didn't realise it... but my Monster is looking pretty awesome now... I've been tweeking on it so much, I never really stoped and took a look at it from a few steps back... I'm tempted to try one more thing with it... if it works as good as it has on some other motors, I might be able to eek out another couple watts. Still... I know there are better motors out there... DGPDX7V in that zip file is the best motor I've ever dynoed... It's not mine, but one of my competitors, I still don't have any idea how he got a stock motor to run like that...


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## Guest

Hi Guys. I've only just recently discovered this thread and been back through it all and caught up to current. 

AWESOME discussion. Really learnt a lot from this (though I don't claim to fully understand everything)so keep up the good work.

One question: where can I buy (on the net) a "fiddle stick" that Dyno says he uses for set the spring tension?

Cheers!


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## Snuffy

tgr,

Do a google search for "sonic fiddlestick" it should be the first match that comes up.


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## Guest

Thanks for the quick reply Snuffy.

Got it on Google.

Thanks again.


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## DynoMoHum

"powerband"... in terms of 'stock' elecric RC motors... what does this mean? Is it simply a refferance to high RPM or low RPM? Or what? 

To, me powerband refers to the location of power, in relation to the motors max RPM. Like on Gasoline engines, peak power sometimes occurs at low, medium, or high RPM, depending on lots of things related to tuning, valve timing, etc... 

In my observations of electric RC motors, peak power ALWAYS occurs at the same basic location. At least this is true of basicly all the electric motors I have dynoed. Some motors have higher RPM, and lower torque, or lower RPM and higher Torque, but the POWER always peaks at the same point, which is basicly at about 50% of the motors maximum RPM. 

Many people seem to think this 'powerband' can be moved on a electric RC motor. So far, I have not seen any evidence of this, at least not in what I consider to be the 'powerband'. I recently have gotten my Revenge of the Monster motor to put out nearly identical power to what I have long considered my best motor, a P2K. I would now like to show you something that compares these two motors of mine. I'd like to have some comentary on this subject of 'powerband' or on the subject of what may or may not make either one of these motors work better then the other in any given situation. I will ask you to ignore the fact that the Monster in this data has slightly higher power... I say ignore it, because it really is a very small differance, and I don't beleive it's significant in any way.

Please take the time to look at the following web page, the text, and both the graphs shown on the page.

http://www.wiltse.net/powerband.htm


A seperate but very closely related topic I'd like to discuss objectively, is... What if anything could possibly make a high RPM motor better then a Low RPM motor? Many people seem totaly convinced that the High RPM motors of today give them some advantage. My personal experiance on the track doesn't really lead me to that conclusion, but I know I often seem in the minority on this issue. I'm seriously trying to figure out if there is any way to explain what I may be missing. My gut feeling is that I'm not missing anything in perticular, and that my own personal observations are not flawed, but then this requires me to beleive that many of you are somehow mistaken in your beleifs... I am sincerly at a loss to figure out what makes so many of you beleive the high RPM motors are and advantage somehow. 

Probably the only way I could ever truely solve this riddle is by doing some exentensive testing with some other people. Sort of sit down with several differnt motors, some top notch drivers, a good selection of pinon gears, and some time to figure it out. I would like to do this, and maybe someday I can get a few locals to help me... until then, I'd like to see if there's any way to figure it out just by talking about it.


By the way... the two motors displayed in that web page are included in the robi_data.zip file I put up previously... they are GROM7V and GP2K7V. If you wanted to look at the current or effciency of these motors, you could look at the data extensively if you want to.


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## Fred B

Dyno,

Could you add efficiency to those? When two motors are that close the differance is usually efficiency. How does each motor run when it gets hot?


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## DynoMoHum

I'll re-due the images to include efficiency soon... Or perhaps add a way to show it as a option... The graphs get very busy when you show more then a couple data items at a time... When I did my last on track testing, I did it with 4 cells. The graphs at 5 volts look very simmilar in terms of equality... but my point is that my on track testing was done at realtively low voltage, and heat was not a big issue for me at the time. It is a good point however that testing with 6 cell application, may very well yeild something slighly differnt then 4 cell.

An alternitive would be to download the viewer and the data... but I'll try to make the data available on the web pages too...


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## Guest

I've said this before, but I'll say it again. 

If we make a stock motor the old fashion way, with a full armature and a no hole can just like a normal modified motor is made, we would end up with a motor that makes too much torque and not enough rpm, so power will suffer a ton. To fix this problem, Trinity invented the slotted armature. It produced a bunch more rpm than the torque it lost, which made more power over all. They then continued this trend over the years by coming out with higher and higher rpm motors. I feel the racer community has been brain washed into thinking that more rpm is always better, and this belief does help Trinity sell more motors. 

Now we have come to the modern era of stock motors. They all produce the same power, and with out any new advances in technology, we will not see any more power from a stock motor. Nothing has changed since the Midnight 2 was made rebuildable (Paradox). The P2K changed the asymmetrical web a little and advanced the timing of the magnets with dents in the holes in the can. The Green Machine 3 was a tri-rotor arm. The P2K2 removed 2 laminations off the arm, but was otherwise identical to the P2K. And now the Monster, which uses even less laminations than a GM3; it is missing the middle section, and it uses triangle shaped holes in the can to advance the timing of the magnets. 

I see nothing in the changes to those motors which would make one make more power over another. So why do people think more rpm = more power, maybe we can find the answer with mod motors. What is the difference between a 20 turn arm and a 10 turn arm? I'd say that the 10 turn pulls almost twice the rpm of the 20 turn. So when it comes to mod motors, more rpm always equals more power. This principal has also shaped peoples opinions of rpm.

When we look at the Power and Torque curves of 2 motors after gearing is applied, we can clearly see that there is no difference between a high rpm motor and a high torque motor. Both motors, after geared correctly, will have the same torque at a given wheel rpm. Because torque is acceleration in a car, both cars will accelerate at the same rate. So therefore both motors will perform identical on the track.


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## DynoMoHum

Ok, I've added efficiency... it looks pretty good (not to busy), so I'll just make this the normal view. 

On my computer it's hard to see the differnt colors of the efficiency curves... but the P2K is the one with the highest efficiency.

I don't see efficeincy as being a problem on either of these motors. Based on my own experiance I would think it would be extreemly hard to notice any real differnce between these motors on the track. (previous experiance related to many other motors included) 

My own expernaces have lead me to trust the my dyno data ALOT. On track proformance for me pretty much always backs up my dyno data.

A side note... I see Josh Cyrul and Jim Deiter have been indicating that some of the Trinity drivers seem to prefer their motors tuned differntly. Josh recently apparenly was running a Monster with trimed brushes, and other drivers prefered motors will full faced brushes and differnt spring and/or cuts on them. I don't know exacly what to make of all this... I think it tends to point out that driving style and getting the most out of a motor is highly dependent on driving style and many other factors.


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## tfrahm

DynoMoHum -- I wish I had "answers", and I don't... But I do have some thoughts, much like Mike did...

Some of it may be the way we "perceive" speed. One example of this is at the local HobbyTown parking lot races. The Nitro sedans ALWAYS get all the OH's and AH's and "Wow that's FAST" comments -- but the STOCK electric sedans turn more laps! The Nitro guys have screaming, noisy engines that just make you 'FEEL' the speed, but they are "soft" on the bottom end and then suddenly come "on the pipe" and shred the tires and get sideways, so the locals cannot get the consistent lap times. The electric (stock) sedans are more "mellow", much "smoother", and thus 'FEEL' slow and look slow to the spectators because they don't make those "zoom-zoom" noizes. (Please note this if for "local drivers" of moderate skills -- I don't want to start a Nitro-vs-Electric fight -- OK?)

The same thing applies to high RPM motors -- even electric motors sound different... On our offroad track, you can almost tell what type of motor is in a truck or buggy by the way they sound in the air over the doubles -- the high RPM motors "sing" with a high pitch whine while the 'torque' motors are much more quiet... Another example -- I believe that CART advertises that their cars are the fastest closed circuit cars, but NOTHING sounds as fast as a screaming F1 car... We are conditioned to associate that screaming with speed...

Now -- if "perception" is part of it, how do you explain guys who swear they are turning faster laps with the high RPM motors... Part of the answer may be in the recent discussion of how the MVP motors with the Big Jim cut dyno strong, but feel "soft" to some but feel like a "rocket" to others. The short version is that if you feel you need low end YANK, then you will only "like" torque motors, since they fit your driving style. On the other hand, if you need a more mellow motor to smooth out your driving (or if traction is in scarce supply), a BJ cut MVP will smooth things out and your lap times will improve dramatically.

Another factor is just a match of motor type to driver style. I know some guys who can do better than me on the oval with GM3's or Monsters because of a compounding effect -- they can drive smoother, carrying more corner speed, which then means they can gear up one tooth more than I could, even with the same motor. So these guys are faster because of their style, and then because of their style, they can gear up and go even faster! I need a 'torque' motor because I scrub more speed in the corners, and need the "grunt" out of the turns...

I know this rambled and is a bit "random", but it's your fault for getting me thinking about this...


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## DynoMoHum

I think I understand what your saying Tfram, but still... my data seems to show that there really is vertualy no differance in where the power is located at on a modern stock motor, once you gear it right.


One of the things I'm thinking is that people don't gear things 'right'... that is that they wind up undergearing low rpm motors, and tend to be slightly on the overgeard side with high RPM motors. It's easy to gear a Monster higher then you would a P2K... by my calcultions, the motors in those graphs are geared 6 teeth differntly. (20% is more accurate) Some may not really beleive they can use their P2K with that much gear.

I'm begining to think that the differances most people see are either due to actual varations in power that is due to slightly differnt tuning of the differnt motors and/or production differances, or simply that they gear the one of the motors slightly differnt and don't really realise how much of a differnace it can make. However I really would like to verifiy this. I'm finding it harder and harder to state my posistion without either offending someone, or them just simply thinking I'm a total nut for thinking the way I do.


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## DynoMoHum

Fuel to the fire... 

Here is a comparison of my newly tuned MVP with the same Monster from the other graphs... In this graph, I see what I would start to call a differnt 'power band'. If you look closely you can see that the Monster shows slightly better power in the middle RPM, and slightly lower power towards the lowest RPM and the Highest RPM. 

Quite frankly I don't see this differance as being significant either, I just wanted to show and example (one of the only ones I've seen) of what I would consider as being a differnt 'powerband'.


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## Snuffy

Think about this Dyno. In your discussions you're talking about the power band with gearing applied. 
I would relate that to the powerband of the setup.
The powerband of the motor would likely be what determins what gear to use with which motor.
If you use stiffer springs on a motor your reducing the RPM and increacing the torque. This is what I'd consider changing the powerband of the motor. 
With gearing applied the powerband of the setup won't change.

Make sense? Or am I completely off my rocker?


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## DynoMoHum

I went back trying to find some MVP data from before I tried triming just the leadinging edge... to try and compare the before and after... 

Well... I found some old dyno runs that looked every bit as good as my new ones. That is with some narrowed 767 brushes, compared with just the leading edge trimed off of a pair of 4499s... Basicly the only real differance was in RPM and Torque... once gearing was applied the power curves looked pretty much identical.

So, Basicly I'm thinking that either way works about the same.

More and more I'm begining to think that with enough time and enough effort, I could make just about any stock motor work pretty well. I may even start playing with a Rage that I have...


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## DynoMoHum

Actualy snuffy, I've got some data that suggests RPM actual goes up when you use stiffer springs... at least to a point. There is a point where the stiffer springs start to cause the RPM to go back down, but they have to be very stiff springs for this to happen.

As for the changing powerband... yes I think that it depends on how you veiw the term 'powerband'... If you simply see it as making more or less RPM and consiquently less and more torque... then sure you can change it...

However in my opion the basic capablitys of any well tuned stock motor remain quite simmilar.


What I was really wondering is this... is there some inherent flaw in dyno data? Something that makes it totaly worthless when you start to compare a high RPM motor to a low RPM motor?

I don't think there is... but I do have at least some doubts. One of the reasons I have doubts is by seeing really fast oval guys go WAY faster then me with motors that appear to be down on power by around 8% or so on the dyno. Now I know this is exactly why we don't race dynos... but still I've dynoed motors from guys who have beaten me quite badly, and near as I can tell it has nothing to do with power as far as the dyno shows it... In this perticular case I was using a very good Chameleon, and the really fast guy was using a Kisbey 19 turn ARCOR motor, presumably with the timing cranked way up on it. On the dyno the Chameleon looks much better then the ARCOR motor.

A side note is that I've also seen REALLY fast guys go REALLY fast with Chameleons that look about like mine does... Way faster then I can go with mine. So... my doubts about the dyno are very small... almost non existant. Last time I spoke with some of the guys in question about ARCOR vs. Chameleon, I was told that the Chameleons are faster, but not by very much.


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## Snuffy

Maybe it's all in how you define Powerband.

I define it as the RPM range that produces the most useable power.

By that definition a low RPM motor and a high RPM motor will have significantly different powerbands even if they produce the same total amount of power.

With gearing they can be made to be equal.


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## Guest

Dyno, about your comments on someone beating you with a weaker motor...

I really have to admit this, but I race stock and mod with the same car on the same track with the same setup and tires, I simply change motors. Now I run a 10 double in the mod, which produces over twice the power of my stock. I'm lucky if I get the same number of laps with the mod. The mod just has too much power to handle. I can put all the power to the track, its just that trying to slow for the next corner is very difficult. But man is fun to go twice as fast through the strait. 

Also, there are guys who beat me almost every race, but their motors suck compared to mine. They are easily 8% off in power too. But alas, we all have to go through the corners too.


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## Snuffy

Mike has a good point. The last few weeks at my track the layout has been a speed track. I really haven't been doing too well. I have to work hard to get into the A main. People with less driving ability are blowing the doors of me because they have better motors.

When the layout is technical, and requires more driving skill, I'm in the top 3. I race in the super stock class.(inbetween novice and Expert)
When I can run within 2 or 3 laps expert guys, I plan on moving up to the expert stock class.


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## rcavenger

DynoMoHum.

Can u make a chart showing power output in wattage versus amp draw (or load)? this is where i see the most difference in 'powerbands' RPM is merely a gearing function. the place where a given motor produces its peak wattage output in comparision to its amp load is the key. that is why a higher timed motor will generally outperform a lower timed one, esp. in stock. using your theory, there would be no point in having a timing limit, since u can gear a given motor to the same wheelspeed. most of the mods done to recent stock motors are done to simulate the effect of having more timing in the motor, given the 24 deg. limit.


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## DynoMoHum

Mike, I'm currious... a day or two ago you said you were now running the Monster pretty much all the time. However you also basicly agree with me that there is virtualy no real reason to expect the Monster to be a better motor. Why then are you runing the Monster and if I understand you correctly, you feel you are going faster with the monster??? What would you atribute this too, ohter then the possiblity of gearing that you've already suggested could be the reason.

Also... your really running something other then your dad's GM3 after you got it from him? How do your monsters compare to that GM3? If you've got the actual dyno numbers post them. From what I could see from your dyno data on that GM3, it was about as good as I would ever expect to see from a stock motor...


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## DynoMoHum

When I get a chance I'll show you the data in relation to amp input... However the effciency curves that are now on the RPM graphs, should give you the basic idea about what the amp load is... 

As for timed motors having now advantage in terms of power... that's simply not true... If you crank the timing up, the power goes up too. Not just the RPM... There is no question that a motor with higher then 24 degree timing will put out more power... however the peak still occurs at something very close to 50% of max RPM. 

Take a look at this web page if you want to see what cranking the timing up on a MVP will do. 

http://www.wiltse.net/Timing.htm

I'll go through that same data, and show what happens when you gear some of those differnt dyno runs. Basicly the overall power will go up as timing goes up. It may take me a while to re-do that whole topic... I need to do it though, because I didn't have Golden's DynoViewer back then.


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## Guest

I run the Monsters, because they seem faster. They may infact be slower. Maybe thats why I'm faster with them.

I think I'm faster with the monsters for a few reason:
1. When I dyno the motors after the run, the Monsters are faster. (Remeber I have twin Monsters. They always dyno exactly the same.)

2. The fact that I have 2 that run the same; it makes the car seem more consistant.

3. I think the Monster spools up faster than most other stocks. I believe this is because it has so little iron mass. But I only have a TD45, so I cannot see spinup times.

4. Everybody else seems to go fast with them too. The fast guys have had to chuck their GM3s and MVPs and P2K's for Monsters. And their lap times have picked up. When I run the monster against them, I seem to run the same speed as them. Note, there are only 2 guys that run faster than me at my track. We are in the Pro class. They consistantly beat me, but noone else does.

5. I just need to learn to drive better. I actually had a run last week where I didn't touch the wall once. And if you've seen our track, its quite an accomplishment. We have sand bags everywhere and open ended PVC pipes. Plus huge bumps in the carpet that throws your car in funny directions when you enter a corner.

6. Simplicity. I have one of every motor out there. It would take me 3 weeks of racing to test them all. And thats just the fast ones.

7. My Monsters seem to run cooler than any of my other motors. I feel that I can gear them 1 tooth higher without smoking the motors, and I only have 60 seconds left on my Sanyo 3000HV @ 20 amps.

Oh, and I think that GM3 is finnaly dead. Last time I trued it, it was at .970. Dad game me the motor a few weeks back, and it smells funny now. I think I figured out why he gave it to me. I haven't run it sense he gave it to me. I wanted to this weekend, but I think its about dead. If it still runs ok, then maybe I'll send it to you, Dyno, for some testing. I'd like to see if it is really that good.


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## Guest

If anyone is wondering, I run Touring Cars (TC3) for 5 mins on a road coarse for 5 min in both stock and modified. I can pull 23 laps with the stock and 24 with the mod (If I'm really lucky). Records are 23 laps in stock (but faster than what I've done) and 25 laps in Mod.


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## rowle1jt

So where does amp draw figure in? If you look at the pic, these are two GM3's pretty similar in power, yet at high RPM's mine (green) just doesn't draw the amps of the second motor? Keep in mind this is a "non" pro GM3, I have cut the comm to ensure its true, put in Reedy 767's and went to town. I imagine w/ a brush and spring change it would only get better. What can I do to bring the amp draw up? If amp draw goes up, doesn't peak power or not?
thanks
Jake


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## DynoMoHum

Mike... the situation you describe with how things are going at your local track is exactly why I wanted to investigate this phenomina... Basicly it seems that every time Trinity comes out with a new higher RPM motor, it eventualy becomes the motor of choice for many people. Yet in all my testing, I just don't see any reason to think that these higher RPM motors actualy do anything in perticular that should make them faster. 

My thinking is that it's just that people buy new motors, and eventualy stop useing there older motors. I also beleive that it's just the nature of things that people continue to get faster over time. Not nessasarly because their equipment got better, but quite possibly becasue they got better... Eventualy people see fast guys useing the new motor, and they decide they have to have one too. Yet... I also know there are very good drivers who also insist that the new motor is faster then the old motor... I can't fully explain the whole thing. 

I really want to enlist some top level drivers to do some testing, amlost a blind test, where I give the driver the car with the motor and gearing instaled without really letting them see what's in it... this would be alot of work to do well... but it probably would be the only way to really sort it all out. I think I could get at least one local oval guys to simply run one of my motors for me, after he's previously ran his... that would be easy to do, and could go along way toward sorting things out... I'm going to ask a guy this weekend if he's willing to help me out... Since it's a really big event, he may not want to get too involved but I'm going to ask anyway... Quite frankly the guy I'm thinking of is a good enough driver that he could win with a realtively poor motor anyway.


Jake... I'll get back with you... if nothig else... I bet Jake would run one of my motors if I let him...


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## rowle1jt

DynoMoHum said:


> *Jake... I'll get back with you... if nothig else... I bet Jake would run one of my motors if I let him... *


 If we are having 4 quals and a Main, I will be trying more than 1 of my motors. LoL Sure, I'll run one of yours.... you think I would say no after seeing how your motors run? 

Ok, as long your gonna answer my question, I can stand to wait...._I guess_.  LoL
Jake


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## Guest

I don't use XP, but boy does it make my app look fancy.

Why would you want to bring amp draw up? For a given motor, if we bring the amp draw down and keep the power output the same, then we have just created a more efficent motor. But to really answer your question, if you advance the timing, you will increase the amp draw. You can also put super glue on the bushings.


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## DynoMoHum

Jake,

I can't fully anwswer your question about what role AMP draw plays. For the most part I've started to think it doesn't play much of a role... 

In my opion your motor and that other motor are so close in every aspect that it would be impossible to tell the differnance on the track. 

Lots of factors effect amp draw, some of them are... hood alignment, broush compound, brush width, brush cuts such as holes, slots, etc...

Timing plays a huge role in amp draw, but we all know that we can't legaly change the timing on a motor... However I'm realtively confident there are some small variations in timing due to production tollerances and other factors. 

Length of wire also plays a part, again this is not anything we can change, but production tollerances do exist.

Basicly the list of things that could effect amp draw are endless. 

At this time, I don't beleive AMP draw is anything we should be trying to minipulate in a motor. Basicly I beleive amp draw is the symptom of some so many differnt things, it can't be used as a defining factor in how fast a motor will run on the track or on the dyno.

One more thing about this... There is a odd behavior that I have yet to fully understand, it has to do with how RPM and current behaive at in the last 20% or so of the RPM curve. A motor with a very fresh comm will have a very linear curve/line, as a motor get's a couple runs on it, the curve becomes more of a curve, and less of a straight line. RPM and AMP draw seems to increase at this point, and I don't fully understand what causes it. I'll try to find a good example of it and show exacly what I'm talking about. GP2K7V and GPDX7V are dyno runs that I would likely use to show this... GPDX7V is the dyno run from a Paradox that has about 3 runs on it... GP2K7V is a motor with a very fresh commutator.


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## rowle1jt

DynoMoHum said:


> *A motor with a very fresh comm will have a very linear curve/line, as a motor get's a couple runs on it, the curve becomes more of a curve, and less of a straight line. RPM and AMP draw seems to increase at this point, and I don't fully understand what causes it.*


 Looking at those two motors I see what you mean, that is odd. Could that be the dreaded "jump" on the Robi where graph goes nuts for a second? I see what you mean.










I know when I dyno stuff on Mel's Fantom, the higher the AMP draw, the better a motor is. Is this just on the Fantom or is it shown on the Robi as well? I understand the efficiencey side it, it seems like a motor that drew more power would make more power to a certain extent. Mind you there is a limit for that, IE putting super glue on my motor would bring up the amps but would kill performance. LoL  Now, super glue on Glenn's motor might give me a fighting chance..... LoL

Mike, I have been playing with the Dyno Viewer for a couple of days now with Glenns data. It is an *AWESOME* program!!! Keep up the good work, your right, it doesn't look to bad in XP. 
Jake


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## rowle1jt

If you look at the pic that I put up, the Paradox has little "jumps" all over the place, I wonder if it was the dyno run? Bumped the table or something? I dunno what would account for that, I don't know enough about the Dyno its self. Out of curiousity, how sure are you that it is related to the motor and/or comm? Maybe the comm gets just slightly out of true about that run? Does it continue to do this until you cut it or does it eventually stop doing? Weird.  
Jake


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## rowle1jt

I need to stop looking at my old GM3 against anything of yours. I'll have you pull my GM3 and my Monster on saturday so we can update those files. Trust me, my GM3 has gotten faster since you ran it on your dyno....... :devil:
Jake


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## DynoMoHum

The little bumps are 'glitches' and that's a minor example of such a glitch... Some motors will almost always have glitches on the Robitronic dyno. It's something that I basicly ignore if they are small like that... If they get big, I ussualy just thow out the dyno run and try for a better run... I can't explain what causes this.


As for amp draw as you speak of it in terms of the Fantom... Basicly that type of thing isn't really available on the Robitronic dyno. I'm not sure that it really says a whole lot about the motor anyway. Mel has just simply observed that motors that show up as being good on the Fantom, almost always also pull alot of current while the dyno run takes place. I think that number is the actual current that the dyno itself is pulling from the 12 volt power sourse during the run. It obviously would be somewhat related to the dyno data itself, but just how closely it's related to actual power output I could not say, and I personaly would not use it as an indicator of motor proformance.

I have found a really good example of interesting behavior I have observed on nearly every motor I've ever dynoed. This following graph reperesents the same motor. M19-I-01(Motor 2) is the motor with a fresh commutator. Motor M19-Iaf2(Motor 1) is the same motor after the motor has had at least one run on the track. I don't know for sure how many runs this motor had on it, but I know it was at least one. I also know that this increase in RPM and AMP draw near the tail end of the dyno run occurs on ALL motors once they have a run or two on them. This is something that I'm just now trying to understand. I have never mentioned it before, because I have no idea what really causes it, or if it is a sign of something good, or a sign of something bad. Recently I've been thinking it's a good thing.... however I can't tell you why... neither why it happens, or why it would make things work better on the track. 

Any opions about what would cause this would be welcome.










The RPM based graph of this same two motors can be seen here...

http://www.wiltse.net/images/M19_BAF_R.gif


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## Guest

It could be due to brush glaze or that the brushes are now fully broken in.


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## Snuffy

rowle1jt,

I allways want to produce the most HP with the least ammount of current.
Raising the current without producing more HP only causes more heat.

I wouldn't worry about the difference in current.


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## rowle1jt

That makes sense. I was just curious, the thing is, my GM3 doesn't run hot like some other peoples do. I have tried changing gearing and then it is apparent that I am overgeared or under geared. So that graph is basically showing me that my motor will run cooler compared to the other one on the graph right? Maybe the efficiency explains the 9 and 10 minute practice sessions..... LoL 
Jake


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## Fred B

If you look at both of the graphs, you can get a little better idea of what's causing the "glitch" in this case. Two things point to the problem being "commutation". What's causing the problem could be a number of things, brush bounce, a carbon deposit on the comm, or my guess is part of the edge of the brush breaking off bouncing the brush as it runs through.

If you look at the graphs, they can give hints as to where the problem is coming from. In the graph you posted on the forum, the glitch lines up with a specific current point. On the other graph you can see that the current draw is the only thing that's jumping around. I don't know if this is a bad thing or not because the motor accelerates through that area so quickly it's not a big affect on performance.

I would assume that the Robi samples at a much higher rate than the Fantom. This is a good thing but it shows any glitches that happen during the very short run-up on the dyno. The only thing that I don't like about acceleration dyno's is how quickly they take data. A dyno with a slave motor holds things steady long enough for these things to stabilize.

Next time you see this, try carefully removing the brushes and taking the edges off. If that fixes the problem, it's my guess from above.

FB


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## DynoMoHum

Actually... in my last graph, I wasn't trying to say anything in perticular about the 'glitch' in that graph. I basicly just ignore those things at this point in time. I could show you a whole bunch of really ugly graphs with huge glitches in them. It may have something to do with commutation and/or brush bits falling off or what ever... I don't know, I've basicly given up trying to figure it out. I do know that on some motors it happens ALOT, other motors it rarely if ever happens. I also know that Robitronic claims it's the bushings causing it, yet I've seen it happen with motors that have bearings too... so I don't buy the bushing argument... My best guess would be commutation... It doesn't seem to have any bearing on the proformance of the motors however, so I just continue to ignore it...


The increase in RPM at the end(near max RPM) of the dyno run... The brushes are fully broken in in on both runs. I've seen this over and over and I know for sure it's not a matter of brush breakin... My best guess is that it has something to do with the little chared marks you get on the commutator after you've run a motor a couple times. When ever those marks are present, you will get this type of 'flip' where the RPM inreases at a higher rate then it had throughout the rest of the dyno run. 

If it were brush glazing, or something like that, I would expect the RPM and amp draw to decrease rather then increase. 

I know for a fact that motors seem to run just fine with this condition, in fact I think they may actualy run better. I'm starting to do motor maintaince much less frequently then I used to, and so far I have seen no ill effects from this decrease in maintaince. I figure as long as the peak power doesn't go down much, I'll take the extra 'kick' at the end of the run, and hope it really does translate into on track proformance, as it would seem it would based on looking at the dyno data.


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## DynoMoHum

FYI...
Good news and bad news...  Good news is there is a new version of the DynoViewer... bad news is that to use it you have to instal the new version yourself... it's not done for you... 


Mike Golden has updated the full instal of the newest DynoViewer. I've put it up on my web site, and it can be found here...

http://www.wiltse.net/zips/DynoViewer.zip


This is apparently version 1.3.3 

I haven't personaly tried this version yet. Some new features... one is the new 'perfect torque' feature that matches up the torque of two differnt motors, and 8 out of 10 times gets you a pretty good starting point for gearing between those two motors. (Sometimes I tweak it a little from that point). Another nice feature that has been added, is the ablity to change the size of the graph as the size of the window changes... this should be cool, I haven't seen it yet though. I think he also has a way to save Fantom Facts II data into a form that would allow you to recall it later by useing the 'load Robitronic data' menu item... No it doesn't make it exactly like Robitronic data, but it does use the same format, so the program doesn't no any differance between the two at that point.


PS... I don't think 'perfect torque' will work with CE turbodyno data... but should work pretty well with either Robitronic or Fantom Facts II data.


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## OffCenter

*Error*

Dyno Ho Hum, Clicking on the above link yeilds a 4.04 error
File Not Found message. Please check and resubmit if incorrect
Thanks:roll:


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## DynoMoHum

Sorry, I spelled Viewer wrong... should work now.

I hate the fact that my 4th and 5th grade teachers basicly taought me nothing about spelling.


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## OffCenter

*GN / B/N*

GN the new speeling got me there........
BN when unzipped and opened in Micro Excel it
looked like hyrogliphix.


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## OffCenter

*Speeling?*

See I musta been lookin out da window when I shoulda been payin attention to what they was learnin me!:wave:


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## DynoMoHum

Not sure what your saying now about the zip file... I downloaded it myself, and un-ziped it... there are like three files that should come out... if you double click on the setup icon, it should fire up the instaler... it worked for me...


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## rowle1jt

Can the Robi and the Fantom handle MOD motors, or do yo just not want to put the stress on them? I understand completely if you just don't want to push your equipment, I wouldn't either. 
Jake


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## DynoMoHum

Theroreticly my Robitronic can handle at least a 10 turn... I've been told that you can also do sub 10 turns with it, if your careful. 

The newer Robitronic dynos are suposed to be able to handle sub 10 turn motors with no problems... My dyno is not new howerver...

I also just basicly don't want to take a chance on doing wild mod motors on mine. I don't run these types of motors myself, and really have very little desire to ever run them... So I personaly don't care that my dyno has a 10 turn limit. I also figure those guys running wild motors can and do have dynos they can use for themselves... 

I'm not sure about the Fantom.


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## Shiloh

I've got one of those newer Robi's. I've spun up a 8 turn double P94 on it, and it had no problems handling the load. I would not try that with one of the older Robi's, though.


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## TOME57

I read some where that the Fantom can handle any motor. In fact it was stated that you could connect the two leads together and it would handle the max amps from the supply source. To date neither I nor anyone I know has tried this (disclaimer). I have spun up 7x2 D5's with no problem.


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## pancartom

i've had my fantom upgraded by al at wizard to what he calls the drag dyno mods.... i've run 6's, 7's, 8's... you name it wothout any problems. bring your ear protection though


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## popsracer

*Dyno Guru's;*

Has anyone noticed over the years of Dyno testing Stock Motors if an Armature that lacks any balancing holes in the laminations will tend to have a stronger field and therefore a higher power output? This would explain the reason for epoxy balancing on Mod Motors. Anyone ever look at this?

Thanks, Popsracer


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## Mayhem

I've only had 1 out of hundreds with NO drill balance holes, so its hard to say. Personally, I dont think a few milligrams of iron is going to effect the motor either way. I know if I were balancing hundreds of motors I would rather epoxy balance. Its much easier, faster, cheaper,and if you make a mistake you can easily re-do it. And if there is anything to the mass thing your covered anyway. Those bits used for drill balancing arent exactly cheap either...


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## DynoMoHum

I too have had very few arms with no holes. 

My personal feeling is that reducing the weight of the arm does very little if anything to increase power. It may very well make the arm have more RPM, but it most surely looses torque. 

Basicly it's the same idea/argument... is there any advantage to today's high RPM motors. Is there any advantage to making them even lighter?

At this time, I don't see the advantage... but I'm still looking.


Well one minor advantage... I can use a smaller pinion, and it may save me $5 from having to go buy another to gear up further with my low RPM motors. 

Actualy... there probably is some therotecical advantage because the pinion is smaller and lighter when you use a high RPM motor... it's probably a extreemly small advantage... Probably less then you would get by reducing the length of your wiring by an inch... and that's a very small help too.


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## DynoMoHum

FYI... I have just beat my previous best dyno run for a stock motor.... I did it with a P2K. I used my recent hood alignment techniques, and some Putnam brushes. I had to re-tweak one of the hoods after my initial alignment procedure, because on brush was wearing really funky. This motor looked like a real DOG when I started, in the end I reach 63 watts at the 5 volt setting on my Robitronic. My previous best was 62 watts. At 7.5 volts, it put out about 131 watts... my personal best before that was my Monster at somehting like 129 watts.

I'm trying to get ready for the Snowbirds warm up race this weekend at the Hobby Hub raceway in Lansing Michigan... Watch out Jake... I've got a 61 watt Monster, a 63 watt P2K, and I'm fully capbably of builing a Paradox that's in that same ball park...  I'm speicificly going to run 4 cell stock this weekend, just to get some track time with all these stock motors I've been building lately. I'd get blown away in 19 turn class anyway...

Put away the dyno... lets go racing...


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## tfrahm

*Re: Dyno Guru's;*



popsracer said:


> *Has anyone noticed over the years of Dyno testing Stock Motors if an Armature that lacks any balancing holes in the laminations will tend to have a stronger field and therefore a higher power output? *


Good question...

I have seen maybe a half dozen or more "no hole" Stock armatures in rebuildables... The ones I've seen DID tend to be above average in performance -- one or two were outstanding!

To be honest, nothing in my physics or engineering background really convinces me it is because of the amount of IRON in the armature poles... I believe the answer is much simpler and subtle (but perhaps "obvious" once you think about it)... A rebuildable stock motor armature that (in theory) went through a balancing process, but has no holes has a secret "hidden" advantage -- *such an armature was WOUND very evenly on all 3 poles...* Think about that -- a heavily drilled balanced armature MUST have had a very uneven winding job (where else would the out of balance condition come from?)... 

So (if I'm right) -- an armature with what we'll call "minimal" balancing (no holes or one or two SMALL holes) may be nearly "perfectly wound". It should have a minimal amount of wire on each pole, and each pole will have virtually the same electrical characteristics as the next. *Such a motor SHOULD(?) be a very good performer...*

In fact -- my BEST motors almost always have no more than 2 SMALL balancing holes, and preferably only one or none... Now this could be coincidence, but....????

What do you think?


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## DynoMoHum

I've heard Tfram's theory before from some locals... I basicly buy into this theory... when I go look for a new motor, what else can I look at? Surely not the dyno lable on the side... 

Actualy I found a Paradox recently with a very small ballance hole, others I had to choose from had bigger holes... I put brushes in the motor, allingend the hoods, etc... it was a dog. 

I think I re-tuned that motor last week and built one of my best Pardox motors ever.

I've also recently taken severa other motors and/or arms I previously though were junk, and re-tuned them a bit and made them run quite well...

I'm begining to think that if you put enough time and effort into a motor, nearly any motor can be made to run well.

I did just look though my stock arms... I found a Pardox arm with no holes... maybe that'll be my next project arm... I need to build another to make up for the good one I let a local guy borrow...


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## rowle1jt

DynoMoHum said:


> *Watch out Jake... I've got a 61 watt Monster, a 63 watt P2K, and I'm fully capbably of builing a Paradox that's in that same ball park... *


 I'm not to worried, with a 60+ watt GM3 and a 62+ watt ROM, I just need to drive a little better than you. 

What happened to letting me run some of your motors to see if some of your theories are true? I'd rather get beaten by you with your motor rather than mine.  Maybe this weekend I will just have to out drive you.  
Jake


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## tfrahm

DynoMoHum said:


> * I've also recently taken severa other motors and/or arms I previously though were junk, and re-tuned them a bit and made them run quite well...
> I'm begining to think that if you put enough time and effort into a motor, nearly any motor can be made to run well.*


Actually, some of my "best" motors used to be my "worst" ones... For me, it works like this... If a motor is strong right "out of the box", then I tend to leave it alone and run it as-is (with nothing more than minor "tweaks" if anything) -- but this means I may be leaving part of it's potential "on the table"...

On the other hand, sometimes I'll get a motor that's a real pig... On a motor like that, I'm not afraid of messing up a "good" one, so I'll really tear it down... I'll tear it all the way down, re-shim the armature, check all the SMD capacitors to make sure none are shorted, check how the caps are installed (sometimes they short on the small "tabs" in EPIC endbells), do a very detailed brush hood alignment procedure (maybe even take 3-4 shots at it before I'm happy with it), try different brushes, different springs, different brush cuts... etc., etc. ... 9 times out of 10, I end up with a very strong motor. Heck -- one of my best is a blue endbell handout I re-did half a dozen times before I was happy with it...

I think the secret is what you have already described... Keep tuning until you can't get anything more out of it and don't be afraid to try different things... Of course, this also explains why 99.9% of the "dyno tuned" motors you buy at the LHS are nothing special...


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## Guest

About the drill holes in the comm. Most of the magnetic flux is built up at the tips of the crown on each "pole". Hardly any of it is where we drill holes for balancing, so drilling holes does not affect the strength of the magnetic field generated. 
Also, most stock arms over saturate the steel armature with their magnetic field. Removing a little material will just reduce the over saturation.


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## Guest

Dyno, you said, "Is there any advantage to making them even lighter?"

When I look for Mod motors, I want the lightest wound arm possible. The lighter the arm is wound, the faster it accelerates. Trust me, there is a HUGE difference between a 10 turn that is fully pack with wire, all the way to the tip of the crown, and a 10 turn with the arm only half filled with wire. Yes the fully packed one does produce more power, but to fix that, we just get an 8 turn that is half packed. 

Here is an example. Lets compare the 10 turn Fully Packed motor to the 8 turn Half Packed motor. For demonstration purposes, lets say that the 10 turn and the 8 turn make exactly the same power and have exactly the same resistance in their windings. (to explain the resistance, 10 turns of large wire can equal 8 turns of small wire in terms of resistance) Now if we install these 2 motors and watch how fast they exit a slow corner, the 8 turn will out accelerate the 10 turn by almost 5 car lengths. Remember that these two motors have the same power. How can this be? Its all due to the fact that the 8 turn has a much lighter arm. 

I think we can see how this can be applied to stock motors, right?


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## Guest

I should note, I run Road Courses with Touring Cars. 

For Ovals, you want the Fully Packed arm, especially if your on a huge track where your geared to the moon.


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## DynoMoHum

Very interesting... I have virtualy no experiance with mod motors... I'm not sure comparing differnt wind mod motors has a whole lot of bearing on stock motors with all the 'same' windingd.... It probably does have some educational value. I'll have to give this some more thought. I do highly value the information.

Next ...

I dynoed somewhere between 10 and 20 differnt motors for competitors and myself this weekend. We were running in Lansing Michigan at a 'snowbirds warm up' race... I didn't dyno too many Monsters, maybe 3 or 4, can't remember for sure. I dynoed some GM3s, some Paradoxs, a P2K2, and a couple P2Ks... My best motor was a P2K, at about 63 watts... I saw at least one GM3 at this same point... and I also saw a blue endbell Paradox that I tuned for fellow hobbytalk patron (Jake) that put out something like 64 watts (a new 5 volt setting dyno record for my dyno). 

Most of these guys were basicly intending to run 4 cell stock, so I didn't dyno anything above 5 volts. I dynoed a few 19 turn motors, but just a couple other then my own.

I still have never seen a Monster that puts out any more power then any ohter EPIC stock motor. On the EPIC stock motors, RPM and Torque change from one to the next, but generaly speaking once gears are applied, there is little differance in them from everything I have seen on the track or on the dyno. At least in terms of 4 cell oval racing and dynoing... Oh... actually there is one interesting notworthy item about Monsters vs. P2Ks.... The Monster seems to run cooler, I can't realy explain why, but that is my observation, and it's not because of efficiency.

My Monster is within a watt or two of my best looking motor on my dyno. On the track, I'd have to say that both motors in my car with 4 cell stock setup, run within a 10th of a second on a 5 second/lap type run... (snowbirds sized track). Basicly in all honesty, I can not tell the differance between my Monster and my P2K on the track in 4 cell stock oval racing. On the dyno, the motors only vary in Torque and RPM, however the power is not all that much differnt. I have no reason to beleive that any of the other motors I dynoed would work any better then my two motors I used on the track... (the Monster and the P2K)

I came in 3rd place in the A-main on Friday, and 1st place in the B-main on Saturday. My car was probably a 2nd place car on Saturday, but the leader got in a wreck near the end of the race, and he wound up 3rd. If my car would have been better on Saturday, I could have easly won the B-main even if the wreck had not occured. I had the P2K in the car for the mains on both days, geared at about 2.50" rollout. 

Monsters used about a 2.18 roll out, GM3s between 2.2 and 2.3" rollout. This all jives very well with what I get when I compare typical motors of these types on Golden's DynoViewer using my methd of matching up the torque curves... 

Chris Ulbrik (13 year old brother to Frank and Mike Ulbrik) won the A-main in 4 cell stock oval both Friday and Saturday. I did not get a chance to dyno any of the Ulbrik motors... maybe someday I'll ask them too let me dyno some of their motors, more then likely they would agree to. I wouldn't be at all surprized if some day Chris will be a national champ... He is one heck of a driver, I was very impressed with Chris. (Frank and Mike were competing in other classes, and I don't know for sure how well they did, I know one of them had problems in their main) I think the Ulbriks told me they had Chris' GM3 at a 2.32" rollout... All the Ulbriks are very fast, and also very nice people...

I did get a chance to dyno a couple Big John Zubak GM3 motors... they were right up there with my best EPIC motors... I never saw any of these on the track... Zubak ran 19 turn I think... I didn't dyno any of his 19 trun motors.... John's fast... and is reasonably nice...  

Oh, and by the way.... Thanks to EVERYONE who let me dyno their motors... I really do love to get a chance to see what other peoples motors look like, espeicaly if I get to compete agaist them on the track as well... makes me fully realise just how little motors have to do with going fast on the track. Jake owes me $5 for the tune up job I did on his Paradox...


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## DynoMoHum

FYI... I'm thinking of ziping up all my dyno runs from this past weekend and making them available to everyone... There are very few notes on them however... I'm trying to decide if I should go back through them and add comments in the Roibtroinc fields... Maybe later I'll zip them and tell you were you can get them.


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## Guest

I wasn't really trying to compare 2 different winds, I was trying to show how a lighter armature will spin up a ton quicker. I only used the winds and resistance to show how the two arms can be made to have the same power. In stock motors we cannot change the wind (obviously), so we need to remove material from the arm to get the same effect. If you look at a monster, you'll see that it has the least amount of material as any other stock arm out there.


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## DynoMoHum

Yes, I understand what you intended to be showing with your example of the Mod motors... I'm still not sure it directly applies to stock motors... but at this point I'll take your word for it...

My observation that the Monster motors stay cooler.... I wonder if the redcution in armature mass also somehow increases the heat disapation? Perhaps more air gets to the wires and such, and the whole motor ends up staying cooler as a result? Either that or, perhaps the can of the Monster somehow also disapates the heat better? I don't know for sure, but I'm pretty sure the motors were alot cooler, and I don't think it was because they were geared incorectly...

Seperate rant I have...

I hate spinup time as any kind of indicator of proformance... To me, spinup time on the dyno is useless. I say this because the flywheel doesn't exactly dupliacte the load a motor will see in a car. If we used multiple flywheels, on for high RPM mtors, one for Low RPM motors, another for Medium RPM motors, then maybe spinup time would tell us something.... or maybe dynos should have a gear box built in them... gear differnt motors differntly, and then collect the data after the gearing... I think if there is any flaw in dynos, this is what it's related to... each motor needs a differnt flywheel...


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## SuperXRAY

In response to armature mass...

Although in theory a lighter armature spins up faster than a heavier one, it is somewhat incorrect. That theory is based identical materials and parallel physics, which do not exist. Take this example:

1.Motor Cans Identical (tested in-depth for mass, resistance, field effect, etc.)
2.Identical and matched magnets
3.Identical endbells and brush hoods
4.Armatures shimmed identical to each other
5.Wire on armatures wound EXACTLY the same
6.Brush Hoods aligned exactly the same

There are other items as well, but that would get you started. I'm pretty sure you would find that if you took (whether you drilled or cut) material out of one armature and left the other one stock, you MIGHT see an increase in both spinup and rpm on a dyno. However, as DynoMoHum said, this does replicate real-world performance. The Mass of the armature (usually three different coeffecients of inertia, which is why you have to balance an armature) is indirectly related to the output of the magnetic field generated by the current through the wire. In other words, removing material will most likely decrease torq, in proportional amounts to the RPM and spinup.

You can watch the same principle in racing real cars. An 800bhp 4-Cylinder Honda has problems taking a 600bhp V8 in the quarter mile. The difference in that case is that, more than not, the V8 is a BUNCH heavier than the Honda. Horsepower (usually higher in high-RPM engines) does not always equal fast.


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## Fred B

It isn't really fair to compare an RC electric motor to a drag motor. There are other differences in full size drag racing that make up for the horsepower differance you mentioned.

One of the major differences is powerband. Fact is, given the same weight and layout (FWD or RWD) the higher power 4 cylinder will be faster in the 1/4 provided it has enough gear ratio's to keep it in it's powerband. Peak power means nothing unless the powerband is wide enough for the available gearing.

In RC, a lighter armature may or may not accelerate faster on the track. Droppong a few grams off the armature is just a drop in the bucket when you consider the entire drivetrain of an offroad truck for instance.

When all is said and done, most of the new motors make the same peak power and have similar powerbands (for me this is the slope of the torque curve). The only differance is what RPM the motors peak out at. In the end, given the correct gearing they produce the same force at the tire and thus perform the same.

Some of the older motors do have different powerbands and can not run the same even if gearing is corrected. Once the slope of the torque curve changes all bets are off.


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## DynoMoHum

Well... my 'expert' test driver has given me the results....

My Paradox I gave him to try rand 10.2 second laps, his Monster ran 10.0 second laps, and his GM3 ran 9.8 second laps... This is in stock Touring Car... I don't know exactly what the track looked like.

The motors he used were in my robi_data I put up last week. GPDX7V was my paradox, KGM37V is his GM3, and KFROM7V is the Monster he ran.


I think those are the correct motor names, I'll correct it later if I find out otherwise.


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## rowle1jt

Glenn, Are you gonna zip all my motor files and send them to me? _Pretty please?_


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## DynoMoHum

Yeah... I'll zip all the motors I did on Friday and Saturday...


FYI... with the help of a Techtalk participant, known as Gee-dub, it's becomeing somewhat more clear, that there may be a flaw in the way I was figuring gear relationships to the torque and RPM data... Mike's working on a feature or two that should prove to be even more helpfull then what is currently available in the DynoViewer... Stay tuned...

(oh, and he already corrected the 'geared motor rollout' bug that I found on Saturday)

Look for the data from this weekend at... 

http://www.wiltse.net/zips/warm_snow_data.zip

Give me at least a half an hour to get it put up...


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## rowle1jt

Cool, Thanks Glenn.


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## Guest

Here is something that I emailed to Dyno earlier today. It may enlighten a few. It is in reference to Gee Dub's data that he sent us.


> He is correct. I never looked at the data from a % increase before. Just load 2 motors and do a gear that lines up the torque. Now if you compare % difference at the low RPM range and the High RPM range, you will see a huge difference in Torque. I will use an elementary example of how the numbers trick us.
> 
> Low RPM:
> 
> Motor 1 - Torque is 130
> Motor 2 - Torque is 125
> 
> Torque diff is 5. Percentage diff is (130 - 125) / 125 = 4% more Torque for Motor 1.
> 
> High RPM:
> 
> Motor 1 - Torque is 10
> Motor 2 - Torque is 15
> 
> Torque diff is 5. Percentage diff is (15 - 10) / 10 = 50% more Torque for Motor 2.
> 
> 
> Now if you look closely, you'll see that at High RPM and Low RPM the difference we see on the graph is 5. Our minds trick us into thinking that it is the same on the High end as it is on the Low end, but when we are only producing 10 Torque on the High RPM end, 5 more is a Huge increase.
> 
> 
> I'm going to add a Percentage Difference in Torque to the DynoViewer. It should really open our eyes. Also, there is nothing wrong with the DynoViewer's calculations. Its just our minds playing tricks on us.


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## rowle1jt

As evidence of Glenn's tuning ability, the red is my Paradox that he tuned! Green is my Green Machine 3, blue is my P2k and the purpleish/girlish color is my Monster. 

I think Glenn is _as good as anyone out there at building motors_, because he is *ALWAYS* fast. It is not uncommon for him to have the fastest car on the track....... 

*Keep in mind, this is zoomed in.*


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## DynoMoHum

Well... Mike's got a new version of the DynoViewer ready...

http://www.wiltse.net/zips/NewDynoViewer.zip

He corrected a bug in the rollout of the geared motor... he also added a feature to display the "percent differance in torque" when you are compareing two motors.

You don't need to re-instal the whole thing, just copy this new DynoViewer.exe file and use it, insted of the older one. If you don't have the full instal done first, you'll need to go get that and instal the older version first.

This newest feature is not as significant as I once thought it may be. It is helpfull, but in my own way, I pretty much took this into account when I did my thing with gearing anyway.

It seems to me, that if you look more at POWER insted of Torque, the whole issue becomes a non issue.

I'm still strugling to understand how some people, including my test driver, seem to go faster with high RPM motors then they do with low RPM motors... Nothing in the dyno data that I can see gives any indication of how this could be. Quite frankly, I also don't see it, in my own on track testing... but then my on track testing was limited to oval racing.


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## DynoMoHum

In refferance to Jake's praise of my motor tuning skills...

My cars may be fast down the stratights... but I have trouble in the corners... so my lap times are often not all that good. I should probably put my dyno away and start working on my car, and getting more hours behind the wheel...


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## Snuffy

We'd probably make a good team Dyno. I can drive better than I can tune a motor.
When I build a motor it comes with a gaurentee.

I gaurentee it to be 5 watts lower than what it was before I messed with it. I wish I could figure out what I'm doing wrong.


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## Shiloh

The only advantage a high RPM motor has is that it feels like it has a broader power band. At least that what guys who like high RPM motors always tell me. Personally, I always prefer motors like the P2k on the track. For some reason, certain people love high RPM motors, even if they look bad on the track. I loaned a buggy of mine a Monster Stock I had tuned that was 5 watts less powerful than my blue endbell motors at every amp step. He won the A main with it, and commented that he loved the power band. Other than having a lot of RPM, I could not see anything impressive about the motor. Power and effeciency were clearly lower at every amp step.


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## Snuffy

Maybe it's the fact that the high RPM motors with less torque make the car a little slower and a little smoother making it a little easier to drive.

Just a guess


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## 300M

Mike/Glenn: Thanks for the update and data. I do my own gearing calc based on performance so this was not an issue. Dyno, like you I need more time behind the wheel. I also build good motor, gave one to a bud who was behind in all 3 qualifiers. It was a tuned GM3, he won the "C" main and beat all 3 that were ahead of him all day.  On the RPM/Torque thing. I am more comfortable with a P2K/P2K2 that with a GM3. My style fits a torque motor vice a RPM motor. But I do drive touring not oval. Even in my 1/12 I like the hellfire with narrowed brushes or a P2K.
Dyno, here the oval dudes run either a GM3 ot the monster. 1 out of 12 runs a P2K2. Wish I had time to go in depth like you guys are, but working part time at the track and runnng the website is eating most of my spare time!


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## DynoMoHum

So... then we wind up back at the question of power band... and where and what it is. I think Fred B. had the most reasonable decription of the power band, that being the 'slope' of the torque curve. Clearly a motor like P2K, has big torque up front, and it slopes down, to near zero, just like every other motor. A motor like the GM3 or Monster has much less torque at 1 RPM, but it's torque doesn't seem to taper off as quickly, because the torque stays longer, the RPM continues to climb.

Still... based on everything I see on the dyno (and for me even on the track) what I see is that once you put a couple gears between the motor and the rear axle, you wind up with a torque curve that has nearly identical shape and slope... so then I'm back to square one, where I don't understand how there can be any differance.

I wonder if it's a little like fishing... If you've ever fished, you probably have a favorite lure, one that you catch most of your fish with. It's likely the first one you put on, and the last one you take off at the end of the day. The question becomes, do you catch more fish because of some magical quality of that perticular lure? or do you catch more fish because you have more confidence in it? Or simply because you give it more of a chance to catch fish?


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## Snuffy

Dyno,

I really think you're confusing the powerband issue by throwing gearing into it. The powerband is a charicteristic of the motor itself. Gearing doesn't have anything to do with it.

Take a gasoline engine for example. 
The powerband of a fuel engine it the rang of RPM where the engine produces the most power. 

The same is true for an electric motor. Yes, an electric motor produces max torque at 0 rpm, but HP is RPM x torque so it's also producing 0 HP. As the RPM increaces the torque decreases. At some point RPM x Torque will peak. This would be the middle of the powerband.

Gearing is used to keep the motor running in it's powerband so maximum HP is delivered to the wheels. A higher RPM motor will have Peak HP at a higher RPM. We use a smaller pinion gear so the motor will have higher RPM at the same speed thus operate in it's powerband.

When proper gearing is applied to two motors that produce the same HP at different RPM's, there should no difference in power at the wheeles.


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## DynoMoHum

Well... I think we are spliting hairs about it Snuffy. I fully understand power band in terms of combustion engines, and especialy how it relates to a vehicle with a multi speed transmission. 

I also understand that a Monster motor will have it's peak power at a higher RPM then does a P2K. 

However the typical electric RC vehicle has but one gear to use at any given time. So, for this reason I think it's totaly legitimate to view things in terms of what happens when you actualy put a gear in line with the motor and the wheels of a electric RC car.

Near as I can tell, when you do this, all stock motors have peak power at the same point. THat is, at 50% of maximum RPM. I've never seen any differnt. One interesting point is... we only spend a small portion of our race at this point were peak power occurs. Normaly we are either above or bellow this point, and only breifly spend time at the point of peak power.

With normal cars with combustion engines, it's a whole differnt thing... and power bands do change significantly depending on many factors. In the end I beleive it's very confusing to try and apply these same principles to 'stock' electric RC racing with single speed gearing. Near as I can tell, the only way to get a 'wider' power band with an 'stock' electric RC motor is to increase overal power, this in effect widens the power band. I see no other way to widen the power band of these electric motors, so they are differnt then combustion engines in this regard. I don't beleive we should attempt to compare the two as if they were the same.


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## Guest

I think Snuffy is getting confused by looking at the Power at the Rear Wheels. No mater what gear you throw into your car, you will always have the same Power that the Rear Wheels. But Power at the Rear Wheels does NOT Accelerate our cars. Torque at the Rear Wheels Accelerates our car. The equation is F=MA, or Force = Mass times Acceleration. If you want me to turn it around, A = F/M. Force here is Torque. We all know that gear ratios drastically change Torque at the rear wheels, and the only way to describe how our cars will accelerate is to look at the Torque Curve produced at the rear wheels. This is the whole reason I wrote the DynoViewer. Originally it was to show DynoMoHum what I was talking about.


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## OffCenter

I too have been bitten by the highRPM bug and noticed a real beating in the corners. All of my understand ing of rollout was near useless but one thing I did note, the package says do to the high RPM gear down more than you are use to. The more I dropped the pinion the faster my corners times were without suffering on the straights. RPMs are nice but tourque is the ability of the motor to reach RPM. If you need to run high RPM motors you have to make up for the fact that they take awhile to reach high RPM's. I attribute this to the lower torque. Gearing down makes up for this, I now run a much lower rollout but go faster.


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## DynoMoHum

Actualy, near as I can tell, Snuffy understand the relation ship of Torque, RPM, and Power. I think for the most part all of us do. However I think it's because we often use the terms loosely, and somewhat inconsistantly then we all get confused. 

If we assume that my Robitronic data is accurate, and that Golden's DynoViewer correctly calculates torque and RPM once gearing is applied, it becomes farily obvious to me that the torque and power of these elecric motor is nearly identical once you get the motor in the car with reasonably correct gearing.

High RPM motors require high gear ratios, this lowers the RPM and the wheels, and increases the torque at the wheels. Low RPM motors require Lower gear ratios, makes the RPM at the wheels very simmilar to a correctly geared High RPM motor, and the torque also ends up very simmilar.

My real question revolves around the following concept... It's fairly hard for me to explain. But basicly a flywheel dyno represents a fixed load, with it's single flyweel. A low RPM motor initialy has a easier time acclerating the flywheel, because it has more torque. A high RPM motor has a realtively hard time acclerating the flywheel early on in the dyno run. Spin up time from 0 to 20% RPM will basicly always be slower with a high RPM motor, it all has to do with physics. What happens as the flywheel picks up in speed, is not as clear, or easy for me to understand. I know that the Low RPM motor reachs it's max RPM faster then does a High RPM motor... Anyway... at some point I'm wondering if it becomes a un-fair test for one or the other of these two differnt motors, simply because of the way everything works. Maybe the high RPM motor would show better power with a lighter flywheel, then a Low RPM motor would... and maybe just the oposit would be true if you had a heavier flywheel... I can't say for sure, becasuse I only have one flywheel and I'm not a physics guru. So... at the heart of my remaining questions is... are we handicaping one motor with the way the dyno run is done...

Or... should I have kept my CE TurboDyno??? (I think the answer is no... but I'm not 100% sure) 

My turbodyno data basicly always agreed with my Robitronic data... so I honestly don't feel there is a problem with flywheels... but then I still can't explain why my dyno data sometimes doesn't agree with other peoples on track proformances.


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## tfrahm

*Another perspective....*

A while back, DynoMoHum posted:


> Oh... actually there is one interesting notworthy item about Monsters vs. P2Ks.... The Monster seems to run cooler, I can't realy explain why, but that is my observation, and it's not because of efficiency.


I want to throw something out on this to see if it offers any clues...

At first glance, a less efficient motor should run hotter, but Dyno has not found that to be the case... Add in the fact that some racers are seeing great ontrack performance from the Monster and others see only average to poor performance...

Consider the fuzzy definition of "power curve", etc. and think of this... If you have a "torque" motor, you gear up to take advantage of the torque and if you have an "RPM" motor, you gear down to take advantage of the RPMs. You can't have both, so you trade either torque or RPM for speed through gearing changes. But -- how does this impact "heat" and/or performace on the track?

Normally, my high torque motors are more efficient, but when I run them in my touring car on the parking lots in the summer, the motors get smoking hot (240+ degrees!). I'm starting to think this is a side effect of the gearing -- when I gear up to get the speed (using the torque), I'm now "lugging" the motor almost constantly. A geared up torque motor doesn't get to "breathe", because I've geared up to keep it down in the strong torque part of the "power curve"...

Now -- a less efficient RPM motor will force us to gear down to gain torque through gearing... This motor may(?) actually run cooler because it gets the chance to rev out and "breathe" -- the gearing reduces the "lugging" of the motor and it runs more "free" in the upper ranges of the RPM part of the "power curve"...

*Please note this is just an idea, but what do you think?* 

I know I'm rethinking things lately... I have never even tried a GM3 or a Monster in a sedan or an offroad vehicle because of the typical lower torque -- I always run P2K's or P2K2's... Well lately, I've tried specially tuned MVP's, V10's and a CORE and I'm finding that if I get the gearing right, they work! 

Some of this is just another way of looking at the gearing adjustment comparisons DynoMoHum and others have posted, but I thought maybe it would be worth a shot...????


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## Snuffy

Dyno,

I think we’re talking about different things. I’m trying to answer the question you had about the powerband and how it can be moved. And how different motors have different powerbands.

If you have 2 motors, both producing the same total HP, one has a max RPM of 5000 the other has a max RPM of 10000, the two motors have different powerbands.

If you tune the 5000 RPM motor to achieve higher RPM with the same total HP what you’ve done is moved the powerband of that motor to a higher RPM.


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## DynoMoHum

Well Snuffy... I don't think you and I have any disagreement... I basicly understand what your saying... However when the power comes out at the wheels, there is virtualy no differnace that I can see. So... I guess I could say, by your deffinition of powerband, the only thing it really effects is gearing.

Many people seem to beleive that a Monster puts out more power near it's highest RPM, and that a P2K puts out more power near it's lowest RPM... but this just simply is not true.

Now, Tfram has a intersting idea... does the high RPM motor cool better, because it turns faster? Sort of like having a built in fan... If you couple this with the fact that on a motor like the MONSTER, you have little or no iron blocking the airflow to the wires. If you look at a Monster arm, you can actualy see air bellow the windings, between the shaft and the wire, thre is air... I've never seen this on any other motors. My best guess is that somehow, this helps the motor run cooler. If this is true, it may be possible to slightly over gear the motor (realtively speaking) and even though it's consuming more power, and wasting more power, it still stays cooler. If this is all true, this in itself may be a advantage, and may also explain most of what I'm seeing and hearing about with people who like high RPM motors.

Incedently... I'm racing mostly 4 cell oval... I beleive tha heat is much less of a problem with this class, then say a Touring car... Touring cars run for 5 minutes, and they use 6 cells... more power, more wasted power, more heat... My experiance in 4 cell oval, probably has very little correlation to someones experiance in Touring Car.

I still say that for a short period of time, regardless of cooling or effciency, a P2K should run just as fast as any Monster. What happens after 1 minute goes by, may be an entirely differnt story.


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## Guest

tfrahm, 

I was thinking the exact same thing. Higher running RPM = motor moves more air and stays cooler. Now, with the 3300's avalible, I simply gear as high as motor temp will allow. If the Monster runs cooler, I can gear higher and go faster.


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## Guest

Oh, and I run Touring cars and not 4 cell oval. I have to deal with very tight corners, short straits, very sweeping corners and very long straits. Gearing taller does not seem to affect the tight corners or the short straits, but it does help a ton in the sweepers and the long strait.


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## DynoMoHum

If all this is true about the cooling effects of a higher RPM motor, then I would say that it is an advantage. Especialy in a class like TC... you could gear up much farther as long as the motor stays cooler. So even on motors with equal power, the motor that stays cooler longer, would have an advantage. This may solve the whole riddle...

Still... why do you rarely see a P2K go up in smoke, but you do see GM3s and Monsters going up in smoke? Is it because people just natruraly push them harder? or what?


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## tfrahm

DynoMoHum -- good points...

IF higher RPM is related to "air cooling", then why...

Well - first, it is easy to over do a good thing. If the RPM motor seems to encourage gearing up because it is cool, and IF the motor is happy in a narrow RPM band, then it would be easy to go a tooth too far and "poof" -- you release the factory smoke... A torque motor normally has so much torque that you can be off by 1-2 teeth and it will still not fry (it's "happy" range is over a broader/lower RPM range). The RPM motor might fry if you are only a tooth "over", but the Torque motor might not fry even if you are 2 teeth over...?

Back to performance... Factor in battery "IR" (don't worry about how you measure it, just include it in your thinking)... 

The torque motor will be geared up, will draw more amps -- thus it gets less voltage from the cells because of the "IR". So even though on the dyno, it produces equal power, on the track it gets less voltage IN, so it puts less power out...?

The RPM motor will be geard down, will draw less amps at this lighter "load", and thus gets more voltage from the cells. So even though it produced equal power on the dyno, on the track it gets more voltage, so it puts out more power...?

Is this a clue or am I off track (pardon the pun)...?


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## OffCenter

Dyno, You hit on almost the same point. If a High RPM motor takes time to reach its peak on the dyno spinning a flywheel it also will take time spinning wheels up to top speed. The higher ratio (Smaller pinion) compinsates for this because one problably run out of track before attaining this desired RPM. A tourque motor, while not revving as high will reach this rev band quicker and propel the car fast. 
Now if you run a large oval the High RPM motor might be fine, but a short course or a road course where bottom end and quick bursts of power are needed would benefit from tourque, not rpm's.

Unrelated to this: When looking at the #'s on say a Fantom what would be the catagory that would tell you which aspect would benefit you the best. Assuming your looking at only one motor but several different versions, like for example a stock with 3 different spring combos. Which set of #'s shows the most improvement RPM, AMPS, Power etc. I mean you change springs and RPM go up but amps do too or power goes down. How do you best determine which # has the most bearing on improvement?


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## tfrahm

Another "smoke factor" is "mechanical"... The more full the armature laminations are, the better the wire is held in place. A P2K lamination stack, combined with the aluminum keepers on the ends keeps the wire pretty firmly in place, so you don't get wires vibrating around (chafing on the stack and shorting out) or "throwing" a wind -- both reduce the chance of "smoke"... 

The GM3, Monster, etc. have a very OPEN design -- not much supports the center part of the wire "wrap". If there is any slack in the wires (remember -- machine wound arms), then the wires can loosen, vibrate, chafe on each other and/or the stack or get "thrown" (greater centrifugal forces at higher RPM) -- all increase the chance of "smoke"...


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## DynoMoHum

I think your getting a little off track... but that's ok...

Actualy the lower the IR, the higher the voltage should be under heavy load. Basicly V = IR, so the more current you pull the higher the voltage drop of the battery (if it's pure resistance) the lower the IR, the lower the voltage drop of the battery at any given current amount... 

The motors should be drawing the same mount of current, and also should be seeing the same voltage as near as I can figure.

I also don't like the idea of wider or narrower 'powerbands'. I see no evidence to support this.

Even the higher/lower torque thing doesn't make much sense to me in terms of motors smoking or not, but there may be some truth in it. Bascily, there surely is a point when you gear a low torque so far over, that it just simply doesn't have enough torque to push the car... but the same is true for a low RPM motor, it just takes even lower ratio to do it.

Think about this.... Just because a motor doesn't feel hot to the touch of the can, does not nessasarly mean the windings are also just as cool. It could be that the heat just doesn't travel from the windings to the can as much on a higher RPM motor. The temperature of the wire is likely to be just as hot at some point as the wire in the lower RPM motor. Under ideal condtions, the cooling effect keeps the insulation on the wire from melting... however if you push too far, the insulation melts and we have smoke... With a motor that doesn't cool as well, we may notice a drop in proformance due to the magnets getting hot, and we may avoid overgearing as a result, because we can see the negitive effects, long before the insulation on the wires melt... So.. this may be why you rarely see a low RPM motor smoke.
( I like my theroy much better , even if it is my own...)


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## DynoMoHum

OffCenter,

It's my beleif that a high RPM motor geared with a small pinion will acclerate just as fast as a Low RPM motor with a big pinion. I personaly don't beleive the mechnics, or elecrical propertys of either of these motors gives it any advantage if the proper gear is choosen for each motor. The torque whould be the same with proper gearing.

Fantom low, medium, and high power factor numbers remain a mystery to me. I have a vague idea of how they are calculated, and given the fact that Fantom dyno users always use the same flywheel, I beleive that these numbers are basicly meaningless. It's all related to the fact that a single flywheel can not possibly correctly represent the actual load seen by a variety of cars and gearing situations. I'm not really doubting the power numbers a flywheel dyno gives, however spinup time on a flywheel dyno in my opion is worthless. My understanding of Fantom Low, Medium, and High power factor numbers, is that it's directly related to spin up time, so I find those numbers to be nearly worthless. (this is just my opion, but I have good reasons for having this opion)

I'm not trying to say the Fantom itself is worthless... just the low, medium, and High power numbers...


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## DynoMoHum

By the way Tfram... I accept your idea about the lack of support for the wire as also being a explination for why there seem to be more smokers from the ranks of the high RPM motors... not to mention the fact that the higher RPM would tend to cause the wire to have more force throwing it towards the outside...


FYI... Mike Golden gave me this link a week or so ago... There is some really good basic information here about motors and gearing...

http://www.geocities.com/budb3/arts/gear/gfun.html


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## Guest

For those who don't know this, it is Illegal for Stock Motors to have their windings epoxied, and they cannot be epoxy balenced. Because their windings are not epoxied, they fly outward under high RPM. This can cause the windings to get caught or cut on the magnets, which will smoke the motor. I've personally wound modified motors myself, and it only took me one try to find out that this happens. Of course it is more pronounced on mod motors, but the same principal still applies.


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## DynoMoHum

Actualy... are you sure it's illegal to have epoxy on the stock motor? It's my understanding that it's only illegal to ballance the arm using epoxy, and that having epoxy to hold the wires in place is not nessasarly against the rules. I think this recently came up, somewhere else around here...

I personaly don't really know for sure which is the correct answer... I guess I should go read the ROAR rule book again.


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## DynoMoHum

The rule book basicly states... 'no epoxy balancing of armatures' this is for re-buildable stock motors. I think that technicaly this does not preclude the use of epoxy for other purposes. 

For instance... the tag in the motors are epoxied in...

Then again, at some point how would you know if epoxy was there for balancing or for securing wires, etc...?

I'm not sure adding epoxy would be a great idea anyway... it would likly impeed air flow to the wires, and tend to reduce the cooling effect that may be taking place on these motors. You may gain stablity in the physical posistion of the wires, but would likely loose in cooling ability.


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## OffCenter

Assumming we dicount the low/med/high #'S I also have these available from the dyno. This is a rev of the monster example:
Max power 60.91 @ 13933RPM
Max Rpm 22366 @5.2sec
Max torque 909gm/cm
Max Eff. 49%@ 14942 Rpm

Which of these numbers changing would show the most improvement that any tuning, truing or changing of springs/brushes make.

Do I only want to see more RPM's? 
Does an increase of power mean more than an increase in RPM would
Would increase in efficiency or more torque be a more important # to be looking at.

I am using the dyno to try see what changes best suit a particular motor and gaining RPM the point of losing some other factor might not be an improvement, I need help understanding what role the power and efficiency play in determining if a change I made was really for the better.

By knowing which #s are most beneficial I think it would also help me determine which of 2 or 3 motors tested would be a better one.


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## DynoMoHum

In my humble opion Max Power is what you want to increase. From what I have seen of other's Fantom data, 60 watts is pretty low for a stock motor. But, it's not really a good idea to compare dyno numbers... Too many variables between one dyno and another.

If you take your data, and put it into a spreadsheet, or Golden's DynoViewer, you will see that Max Power, pretty much uniformly translates into more power everywhere in the RPM range.


POWER is most important... next would be efficiency. Well... lower track times would be most important... then POWER, then efficiency...


If you have the Facts II software, I would highly recomend viewing it on Golden's DynoViewer... I know of no way to get the DOS Facts data into a format that would allow you to transfer it to the DynoViewer without the use of the Facts II software.

RPM is needed only for selecting gearing. The same is basicly true of torque.


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## OffCenter

Thank you. Having the machine and not really knowing what it does was like watching TV with the sound off. You see stuff going on but really don't have an idea of what your seeing. Now at least with any changes I make I can track progress. My only other avenue for info is at the track and there really isn't time between races for lessons. Your help will be appreciated:wave:


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## DynoMoHum

Actually if I had no way to get the data into something like the DynoViewer... I would use Max Power, and the RPM where it occurs to do all my gearing.


Say you have motor X, that has max power of 60 @ 22,366 RPM, and motor Y, that has max power of 62 @ 20,000 RPM. First I'd say Motor Y is the better motor, and then I'd set out to try and figure out how to gear it. 

Using lap times to select the best gearing is the best way... lets say you get the best gearing for motor X, and then want to switch to Motor Y...

Lets say you have a ratio of 5.0 for Motor X... 

( 5 / 22,366 ) * 20,000 = 4.47

I would use a 4.47 gear ratio with Motor Y.

This is based on my newest gearing theroy that says using the point of peak power for gearing is the easiest way... I am pretty confident that if the data is correct, the gearing calculation should work out. If you showed me actual Facts II data, I could illustrate why I have come to this conclusion... I could show you with Robitronic data too, but you might not be as eager to beleive me if your a Fantom user...

I'm not saying this is the absolute best way, but it is easy, and I think 90% of the time or better, it should work.


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## Guest

Have been away for several days, so missed some of the discussion. A couple of points:
1. The max power will always be at 50% of max rpm. The is because power is a parabolic curve derived from the torque and rpm curves, which, at constant voltage, are straight lines. So Dyno is correct, it is alway at 50% max RPM.
2. A flywheel is not a constant load for a dyno. Its moment of inertia gives a maximum load at startup and goes to zero load at maximum rpms. (If it wasn't zero load, it won't be maximum speed, and if it wasn't a heavy load at startup, acceleration to top speed would be "instantaneous."))
3. I think there are some people that are confusing power curves and useful power. If you think about oval racing, when a car goes into a turn, it slows down to some degree. That represents the "lowest" motor speed. At the end of the straightaway, it represents the maximum motor speed. For the car to work well, the motor has to provide the necessary power to get between those 2 speeds, i.e., thru the turn, accelerate down the straight, and maintain top speed. The "size" of the power band needed therefore depends on the track characteristics. The argument can be extended to on-road which is a series of curves connected by straights.
4. I think (3) explains why more people are liking "rpm" motors. If you have a sweeping course, then the motor doesn't change speed much and either a torque or rpm motor will work (with a torque motor being easier to find the right gear). But if you need larger changes in motor rpms, then you need an rpm motor. In either case, you need a motor that makes the necessary power in a "useful" range. This "useful range" appears to correspond to 15-30 amps for stock. You can load the motor up more, but i2r losses due to the increased current usually makes the motor hotter at the end of the race and "soft."


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## DynoMoHum

Well based on my dyno data, and Golden's DynoViewer, there is no differance in this 'useable' power area when you compare a motor with equal power, but differnt RPM. Near as I can tell, the only real way to increase the range of useable power, is to increase power overall. 

When you compare two motors with differnt power levels, then it's easy to see how and where the advantage could be.

I think there is some possiblity that some motors just happen to hit on the best possible 'rollout' for a perticular motor. Even with 64 pitch gears, there are a finite number of ratios that can be obtained. Now you could play with tire size, and swaping both Pinion and Spur gear, but most people don't go to these lenghths. 

Anyway... I still think if there are differances in the RPM and Torque motors, it's related to something other then 'powerband'.


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## Denney

Just bringing this to the front page...

And giving a BIG thanks to Mike Golden for the DynoViewer. I spent a few hours this weekend inputting data front some motor testing. What a great tool the viewer is for us CE guys that don't have a PC link like the others do.

Also - Glenn did you save any dyno numbers from when you had the CE? I was hoping to use some of your better #'s as a baseline for mine.

Thanks, Denney


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## DynoMoHum

No, I didn't really save any of my TD data... well I did, but I didn't do it in any orginzed fashion.

Basicly I was going by much of Big Jim's recomendations. at 7 volts, 20 amps, 100 watts... etc...

Actualy though I did dyno some motors this weekend on my Robitronic and a TD that was at the track... using 5 volt setting (we're all running 4 cell oval).... 84 watts at 30 amps was about the best motor... 64 at 20 amps. I saw a whole bunch of other peoples motors that were barely getting 74 at 30 amps...

These stock motors that were putting out 84 watts, at 30 amps, 5 volts were a GM3, a Paradox, a Monster, and a P2K... (actualy the P2K was the only one to hit 84, but all these types of motors were able to put out at least 81 watts at 30 amps.

I let a local fast guy use my Monster, used the DynoViewer to figure how to gear it in relation tho his really good GM3.... He TQed with the Monster, but basicly his GM3 ran just as good, he ran his GM3 in the main and had a lap on the feild. He would have had more laps, but second place kept him from getting by him, by roughing him up a bit... it was all in good fun really, but he was blazingly fast.... and the guys he was competing against were also very fast... but my personal feeling is that he was beating them with motor mostly. I saw dyno data from the second place guys motor... it was like a 70 watt at 30 amps, 5 volts... I tried to loan my motor to the second place guy... but he apparently wanted to run his own... I gave him a hard time afterwords about getting beat so badly...

On the Robitronic, my Monster was like 61, and the winner had a 61.7 watt GM3.... He didn't want to try my 63 watt P2K... 

I ran 19 turn... I have a 90 watt Chameleon II... up from 87 watts previously. It was flying down the straights, but I just can't get through the corners...

I got me a tire truer now, and I'm going to be concentrating on getting my setup much better for the rest of the season.


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## Tskelton

I have question. I just got a Robitronic dyno. What would cause a bad curve? I made my first pull on a Trinity Monster stock and it looked good. But on the second pull with the same motor some time later it did not look good. The graph was a little jagged at the end. I'm still new at reading dyno reads so any help would be appreciated. Thanks.


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## DynoMoHum

It's a mystery Tskelton...

People from Robitronic have claimed it has something to do with bushings, presuably the bushings causing little voltage spikes or something. However I have seen the same behavior on motors with bearings, so I don't beleive this explination.

My best guess is that it has something to do with 'commutation'... or in other words, I think it has to do with how well the motor is transfering the electrical power to the windings of the motor, via the brushes and commutator. 

However, I see no direct correlation between how well a motor runs and how much it has these 'glitches'. 

I do know that these glitches occur more on some motors then they do on ohter motors. It seems that on some motors, you can hardly ever get a clean dyno run, other motors rarely have those glitches.

I personaly often try to get runs without any glitches, mostly because I often try to display some of my data and findings. This often causes alot of extra effort on my part. If I'm dynoing for my own personal use at the track or something where time is more important then perfection... I ignore the glitches for the most part. If the glitche effected parts of the curve I am most interested in, then I will make anohter dyno run as well.


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## 300M

Denny
I have a TD and punch all my data into a spread sheet. I could send some of my better numbers if you like. Realize that no 2 dyno's will read the same.


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## Denney

300M - Thanks, I would appreciate that very much. I'm not so much trying to compare exact numbers, but relationships between rpm/eff/tq/watts. I have spent a bunch of time inputting data into excel & trying to graph them, but the Dynoviewer is way easier - You could send dynoviewer files if you have them too. I have attached the results of a P2K I've been working on, it's still a work in progress, but looks hopeful.

Denney


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## MIKE VALENTINE

DynoMoHum will you be making it to snowbirds?


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## DynoMoHum

No, I won't be making it to the snowbirds... I have a hard enough time getting my wife to let me go to race on a Friday night where I won't return home till after midnight...

Besides... I'd be like dead last, due to my poor driving and car setup skills.

A few locals will be going... the Ulbriks I'm sure... Big John Zubak... Ted and Bobby Flack, Walter Henderson, and a local guy that's helped me alot over the last couple years... Keith Racknor. I just try to stay out of these guys way when they're all at the local track... If you see Keith there... tell him 'Mr RC' said hi...


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## DynoMoHum

FYI on golden's DynoViewer...

There's a minnor bug I see with regard to CE TurboDyno Data... If you leave a line empty, it seems to have problems with it... Putting in a empty data point, rather then just ignoring it...

Also... You can enter data into a text file, with a format like the Robitronic data uses, and then you can read it by using the 'Load Robi Data' menu item. You may find entering your CE data easier just by editing a text file with the Robi format...


The format is pretty straight forward... feilds are seperated by a ; and a 'tab'... The order is...

RPM; Power; Eff; Torque; Volt; Amp;

You can enter as many or as few data points as you like in this type of file.


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## 300M

Denny: I will post my stuff later tonight as the file is at home 
I will see what I have on dyno files from golden's viewer.


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## DynoMoHum

I recently had someone ask me how I determin gearing using the DynoViewer. In this perticular case, the person was using a TurboDyno... they eventualy gave me a couple TD files to look at.

I found it very hard to explain why I do what I do with my gearing choices... Perticularly when one motor is not really as good as another. I started to go into a long explination of what has lead me to some of my conclusions... 

One of the things it forced me to look at was some TurboDyno data again... ( I sold mine to Denney ) 

I would like to attempt to answer the question more througly... however I'm still trying to figure out how...


One thing that has complicated my thoughts is in trying to explain how to gear when given TurboDyno data... It turns out, that I find it much more difficult, and it forces me to basicly point out some things that I see as problematic with trying to use a TurboDyno to accurately evaluate motors.

More later...


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## DynoMoHum

A hint of what I have in mind...

I'm begining to think that TurboDyno users should normaly use the 5 volt setting, even when they race 6 cell. The reason I say this, is because it is more likely to show you the true nature of a motor when you view data at 30 amps or less. Mainly this is because at 7 volts, 30 amps has not really started to reach the point of peak power. At 30 amps 5 volts, the peak should be pretty close to this... To me, I can tell more about a motor from it's peak power, then nearly anything else... with typical 7 volt TurboDyno tests, I can only guess what is happening at peak power.

Even at 5 volts with steps of 30, 28, 26, 24, 22, and 20... (which is personaly what I would recomend) it's very hard to get a really good idea of a motor's overall charactoristics. But I think I could learn more from these steps, then the 7 volt steps normaly used by many TurboDyno users.


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## 300M

Denny
I was tied up last night and worked late. Will be Friday AM on the data.

Dyno: I do not have trouble gearing mine and I use a TD. You might be reading to much into the equation on this.... Time is my enemy right now so I cannot elorabate right now. Boss is pushing me to do 140% of my capicity


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## DynoMoHum

I understand that it is not all that hard to gear a motor using TurboDyno data... However I also still beleive that there are some issues that need to be understood to do it well. Mostly it can be somewhat difficult at times to see which motor is really best, primarly because you see things from a very small window of the motor's total operating range.


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## OffCenter

Dynohohum, In your opinion when viewing 2 or 3 stock motors what determines which is a good motor. Assuming you use the same dyno for testing each your numbers should be relative to each other. I see power, rpm, torque and efficiency. Now if all three show similar power and torque do you go for the most rpms? I know that some lesser rpm motors stomp higher ones on the track. I realize they could be geared differently and spool up times come into play, but off the dyno numbers how do you determine which is good vs. bad? How does the graph work better than just reading the numbers?


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## DynoMoHum

To some degree it depends on the Dyno in use. 

In general I think Peak power is a very good indicator of orverall useable power. I base this on looking at tons of dyno data, and trying to understand it. 

Next is effciencey and to be honest, I haven't found a good way to determin how much is enough, or how much is too little... Too much is never a problem... basicly with effciency, the more the merrier.... but it does help if it's located in a really good spot. I haven't came to any real conclusions on where it should be either... Basicly I rarely see efficincy as a problem with most motors.

Lastly I look at RPM. Recent observations by me, and others have lead me to beleive that there may be some value in RPM stictly as possibly allowing a little more cooling of the motor, due to more air whirling around inside the can...

Ok... I lied... results on the track are the most important... but we all know that...


As for TurboDyno Data... in absense of knowing the actual point of Peak POWER... I'm thinking that by looking at the slope of the power curve is a good indicator of what the peak power is likely to be... To do this properly, you have to adjust the data to take into account the gearing that is likely to be used... Without gearing, the slopes are fairly meaningless in two motors with greatly differnt RPM. This is what I'm working on now, trying to explain this idea.


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## DynoMoHum

Graphs vs. Numbers... Either works fine... but i'm 100% convinced that if you don't apply gearing to the data, the numbers can easily fool you. You don't have to graph it, but you do have to change the numbers based on gear ratios... 

Viewing things with a graph tends to make it all easier for me, but it's mainly just a personal choice.


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## Fred B

Well, as a turbodyno user, I think I need to chime in on a few things.

First, you should always tune your motors based on what your "best guess" is of "on track voltage" Yes, the normally accepted 7.0v for 6 cell and 5.0v for 4 cell are ok. You can use the standard loads for 4 cell because the motor hits peak power at or before 30 amps.

If you only have a 30 amp dyno, you're pretty much hozed for 6 cell racing. The best compromise is to put trendlines in an excel spreadsheet and extrapolate what the peak power is. I've checked this out on my dyno and it's normally pretty close as long as the comm is in good shape.

As for gearing, oval is pretty easy, I take split times on the track and use the length of that section to see what the motor is running (back the average RPM for that section out using the rollout). I normally gear to go just below peak power at the slowest part of the track (slightly higher current than peak power). Then fine tune with lap times.

On the roadcourses, I split the straight in half and use that as a starting point for gearing. It's easier with the datalogger because I get the peak current at each corner but that's another story.

Basically, you have to run the same voltage as "on track" because that's the only way to figure out what load the motor is pulling. If you use 5 volt numbers you will get fooled because the amp draw will be way off.

The best way to view turbo data for 6 cell is to have the dyno updated and test up to 45 amps.

What I look at on the turbodyno is:

1) Peak power
2) The slope of the torque curve. (You want more everywhere and still have good power)
3) Efficiency. (more is better because there's less heat)

RPM means nothing once you compensate with gearing.


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## DynoMoHum

When I was talking about gearing... I was talking about something slightly differnt then Fred is... Basicly, I've never made any attempt to do what Fred is doing.

The only thing I use the dyno for in terms of gearing, is if I already have one motor that I feel is geared correctly... based on track times... Once I have this referance motor... I use the dyno to gear a new motor in relation to the other motor's gearing.

Reading what Fred has described, fits in really closely with what some of my own personal theorys are with regards to gearing... Basicly I think normal operating range should be between peak power and peak effciency. Sometimes your forced out of that range, but I think that is where things should be centered... From what I can see of what Fred is doing, it makes perfect sense to me.

The reason I was suggesting 5 volt testing might be best, is because it's not as hard on the test motor... 


Typicaly what is the current input when a stock motor peaks at the 7 volt setting on a turbodyno? 40 amps? maybe higher? What about 5 volts? 30 amps?

One thing I see as slightly problematic with all dynos, except maybe for something like the CS dyno... The voltage at the motor is not the same as will be seen in the car under heavy load... With the CE Turbodyno it's too high, and with the Robitronic and Fantom, it's too low... AMP numbers are inaccurate as a result as well. So... I think it would be very hard to make a one to one comparsion of dyno numbers and real car numbers... It's probably fairly easy to get close enough with either of the dynos... but it's not exact.


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## DynoMoHum

Fred... I'm also currious... what kind of settings/steps do you use on the TurboDyno? Can you give me an example of some data you use?

Actualy, I'd like to see other peoples TurboDyno data as well...

Oh... and Denney... I think that P2K you gave data for a few items back, looks like a pretty good motor...


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## Fred B

Peak current at 5 volts is at around 28 amps sometimes 30. I can only guess at peak current at 7 volts but it's around 40 amps.

Both types of dyno's have trade off's. 

The TD does not do a very good job of simulating on track voltage and it builds excess heat during the end of the pull. The motor doesn't see these steady state conditions on the track. The voltage thing is less of an issue with the 3300's because there is less voltage drop at high loads. Heat is a big issue at 5 volts though. I'm going to look at that a little when I get back from Vegas.

The flywheel dyno's have their own set of problems. I'll limit this to the Robi because I haven't seen some of the Fantom results that it would take to lump both together. Judging by the Robi data that Dyno has provided, the Robi has lower voltage under heavy loads (high amps). It's a bit more than what I've seen on the track with the new batteries but it's a start. Flywheel dyno's in general are less accurate due to the short time they spend at each datapoint. I think the Robi samples at a higher rate and is better but that's another story. Typically inertia dyno's are fooled by the weight of the armature. A lighter armature will often show more power than a heavier one because the software doesn't take into account the "flywheel" effect of the arm. This is not a big issue as long as all of the arms are about the same weight.

Posts like this normally start a big argument over what type of dyno is better. Let's try to cut this one short by saying that neither one is better, they are just different. There's nothing wrong with either type as long as they make you faster on the track. In the end they're just a tool and you have to use them properly.


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## Denney

Here's a few more I've run lately. The Mvp I'm basically done with, the GM3 belongs to a friend & I'm still sorting it put, the 19T is a Cham 2 I've had a while & haven't done anything to yet...


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## Fred B

I've been tuning for 12th lately:

5 volts

18-20-22-25-28-30 amps

Not much data here at work... but peak power for a blue endbell is 70-75 watts at 28 amps

I think the peak is actually at 30 amps but the brushes get too hot by then. I'm going to try running the motor at 30 amps first to check it out.


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## Denney

here's the MVP data


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## DynoMoHum

Denney... that's only one motor you just posted... you indicated there were more... what happened to the others?

I don't have any idea what a good 19 turn looks like... although I did see some hitting 115 or so at 5 volts 30 amps recently... that's about the only numbers I remember from the 19 turn motors...


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## Denney

...and the GM3 (guess I can only have one attachment per...)


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## DynoMoHum

I guess I just have to wait a few minutes for you to post the others... 

I'm currious about something else... Big Jim continuely maintains that MVPs will work as good or better on the track then EPIC motors, even though they are down on power by several watts... I personaly have not been able to back that up at all with my testing... basicly I've never had a MVP run quite as good as a good EPIC on the track... And basicly they are always down on power a bit on the dyno... Big Jim will clearly back up the lower dyno numbers... but has anyone ever really seen that the dyno numbers lie about this issue? 

I've always found it hard to understand how this issue could be... For one thing... if it's really true, it would seem to give evidence that the dyno itself is of very little value...

My personal experiance is the MVP is not as good on the dyno or the track... but I'm very currious if others see this. I mean I know they can be close... and quite frankly 2 or 3 watts at 7 volt testing is a very small differance. Typicly less then 3%... You really have to work hard to notice 3% differance in a motor on the track.


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## rowle1jt

Glenn, As I've told you before, in touring, the MVP is an absolute rocket! I have found that narrowing the brushes makes the car feel little better on the track, but it doesn't show up on the Dyno. The MVP I run in my TC3 is 55 watts on the Fantom. Most people wouldn't run it, and going strictly by dyno numbers neither would. On the track (and lap time prove this) I don't have an Epic that will touch it..... Oval is another bag of tricks though.....

BJ tells people that the MVP doens't look good on the dyno, just gear the crap out of it and smoke your competition. I guess it "fools" the dyno? LoL  For offroad it is a toss up for me to run either a P2K or an MVP, touring car its the MVP hands down!


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## OffCenter

Ok let me try to ak this way. Stock motor (PK2, GM3, ROV)
What would a good motor be in terms of Power 60. 65. 68?
What about torque for the same motors High .9'2 or do you go over 1.
and last efficiency? What is the scale.? I realize the higher the better but how low of a # is still a decent motor.
Note: my testing will be based on Fantom #s


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## Fred B

The idea that a motor that makes less power will be as fast on the track is wrong. I seem to remember from my MVP days that it outperforms the EPICS under heavy loads. I had to gear the poo out of it and hope it didn't let the smoke out. The ice cube trick is a must.

I remember pulling Dave Johnson off the corners and all the way down the straights for the first 2 minutes and then they were about the same once the motor got hot. You couldn't compare those motors based on current draw because the MVP needed to pull more current to run well.

The MVP was also the motor that I used to find out what brushes performed well once they got hot. Peak power cold is one thing and peak power hot is another. I'd rather give up 1 or 2 watts up front for 10 at the end.


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## DynoMoHum

Denney... I'd say your motors are all looking pretty good. To me, the GM3 you posted is the best, but not by a very much. Second place, I'd give to the P2K... Third is the MVP... 

Maybe you could get Jake to buy the MVP from you... 

I'll try to go find some of my TurboDyno Data... but based on what I remember, your getting as good or better then I ever got from motors... However, back then I was viewing things a whole lot differnt, and I rarely paid any attention to 28 amps numbers, and now, that'd be the first place I looked... Oh... actualy... I know where I have some data... it's on a web page...


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## DynoMoHum

I found one set of TurboDyno data for what I think was likely a P2K... it was just over 100 watts at 20 amps, and about 125 at 28 amps... (7 volts)

Basicly, I think your motors look quite good Denney. If your not keeping up with most guys at the track, it's very likely it is due to something other then your motors.


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## Snuffy

OffCenter,

If you get a 68 watt motor on the fantom not using the production version of the software AND your fantom is working correctly, put that motor in a SAFE plase and only bring it out for special occasions.

55 watts isn't even a good practice motor because it's too slow. 
If I have a choice I won't run a motor under 60 on the fantom. I often don't have a choice.
63 is a really good motor. Anything above that is treated special.

I've seen some Monster motors 65+. I'm beginning to think a bad monster is about 60.


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## Denney

I'll find out tonight how well I keep up. Most of these motors I was running when they were 6-8 watts lower & they seemed fairly fast then. I have been thinking about the MVP vs Epics a bit lately though...& was thinking about dynoing just before I race & immediately after - while the motors are still hot. Maybe this will show that a narrowed MVP may appear weaker when cool, but could close the gap when at racing temp. Anyone out there done such a test??

Denney


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## DynoMoHum

Offcenter... I've seen quite a large variation in Fantom numbers, depending on the dyno... 

Having said that... 

I beleive anything in the neighborhood of 65 watts is good for peak power. I've heard people say somethig about 70 watts for peak on some motors. My motors rarely saw 60 on the Fantom I had access to. 

Effciency seems to be much lower then with other dynos, I think better then 50% is accpetable from a Fantom. 

Torque... I've never seen one go over 98... in fact at one point I questioned if the torque number is some how realtive... realtive to a max of 100 or something... I've never seen one hit 100, and never really seen them lower then 80 or so... The really strange thing with torque is that often the lower RPM motors have lower Torque numbers as well... this is just the oposit of what is seen on other dynos I've worked with.


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## Fred B

The MVP's didn't run well at 5 volts for me, you needed the extra voltage on the dyno to make them look good. I'm thinking that they're more efficient at higher voltage.


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## Snuffy

Dyno,

I've seen torque numbers over 1 but not with a stock motor.


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## DynoMoHum

What do you run Denney?

My best guess is that you might notice a couple tenths of a second at the most with a 6 or 8 watt increase in power... asuming you get the gearing right...

I've given people motors to use that are 10% better, and their lap times don't improve at all... Alot depends on driving... If a persons driving isn't up to speed, the extra power seems to do nothing...

Even good drivers sometimes see very little differance in a motor that is less then 5% differnt... at least that's my experiance with motors.


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## Snuffy

I'd have to agree with you on that one Dyno. Where I race some of the fastest guys on the track are using batteries and motors no better than I am and some times even worse than mine. they're still one hell of a lot faster than I am though.


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## Denney

These motors will all be used in a Losi xxx-s touring car. I have only raced about 15 times total (just got into r/c two years ago), about half of that was with a touring-converted HPI Rally. So...I'm usually about a second or slightly less per lap slower than the fastest guys, so I have a bit of work to do there. When it comes to straight line speed I'm very close - it's just the whole driving thing I am sorting out. Mostly all I really wanted was to know that I could be competetive when it comes to power, the rest is just getting more driving and set-up experience...

Denney


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## DynoMoHum

That's basicly the reason I bought my dyno... I wanted to know why I was getting beat on the straights... now that I'm up to speed on the straights, they just go by me in the corners... I do know for sure that I'm not getting be by motor... and I still have fun, so that's all that matters...

Actualy, I easlily see a couple tenths per lap on a fairly small increase in power... but it's only like on my best lap... all my other laps are still pretty crappy.


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## OffCenter

Thanks for the help. I'm new at using a dyno and I was primarily using it to track changes that truing, and changing of brush & spring combos would make. I've been running an ROV with power in the 65+ 21,000-24,000 rpm .935-.953torque and 48-50% eff. (everytime it sees the dyno I see a slightly different #'s) This motor loves a small pinion. It never seems to run out of speed on the straights and the smaller the pinion the faster the corner speed seems. While not the fastest I consistently run in the top three if no bumps or crashes.

I have a GM3 64.5,19,933,.958,52% I think I want to try this weekend.
Having a better grasp of what to look for will certainly help- thanks again.


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## rowle1jt

The only place I have run an MVP in the last 6 months is in touring car. I'm not taking BJ's side, but say what you want about the MVP's or "_I won't a race a motor under X watts!_" LoL Some people really crack me up. What are you gonna say when I pass you down the straight with an MVP that sucks? I think some of you are so far into thinking every race is won with a motor and a dyno that you have forgotten to see what things feel like on the track. I think we all need to take Glenn's advice, and starting working more on the car and our driving rather than getting another watt out of a motor. 

Don't get me wrong, Dyno's are an important tool for going fast, but I still agree with a lot of other people, *WE DON'T RACE DYNO'S!* So go ahead, say what you want about the MVP and how it looks on the dyno. If I had never raced some of my motors that don't look good on a dyno, I would be missing out. Put a few runs on a "bad" motor, and sometimes they improve on the next re-build. 

Glenn, why should I buy another MVP when most people think they are crap and will give them to you for free?  I think the 4 I have is plenty, I only ever bought one.


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## Denney

Here's the race report from last night (we run a Thurs night series, with 2 heats & a main):

First heat I ran the GM3 (belongs to a friend), geared 90/22 (Losi xxxs). The car was really fast. At least as fast as all but the Pro-match sponsored guy that was there.

Next heat I ran the MVP, geared 90/23. Not quite as fast as the GM3, but I needed more gear...so for the main I ran 90/24 & it was better, but I think I can go 90/25 & be as fast as the GM3 or faster, but I didn't try gearing up the GM either. Either way speed is not an issue, the 6-8 smacks into the boards are slowing me down more than any power deficiency. Also, the MVP at 90/24 was no hotter than the GM3 after the race either.

Denney


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## OffCenter

My info was based on what is working on my local banked oval.
I only have to go fast and turn left 4 times per lap!:thumbsup:


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## DynoMoHum

Bascily... I find it hard to belive that motor is more then about 10% of the total picture in road course racing.

In oval it might be 20% or maybe slightly more...


Basicly I think there are many many reasons why people go faster or slower with one motor vs. another motor, perticularly in road course and even more so in off road. I beleive it's entirely possible for typical club level driver to actualy go faster with less power in road course or off road... there are so many variables involved in that forum of racing, I personaly wouldn't use it as a judges of actual 'power' of a motor.

In oval... the same is basicly true, but to a lesser extent. Here beleive that a good driver can pretty easlily see even small changes to motor proformance in a oval situtation... It's like off center says... you have two straights, and two corners... (Offcenter says 4 corners, and I guess you could call it that...) Basicly I think in oval it's much more likely that motor proformance will be seen on the track... even so... I still say it's probably at best 30% of the big picture in oval racing. Motor is probably slightly more important on a banked oval, then on a flat oval.

Right now... I think my dyno's most valuable use is in helping me to switch from one motor to anohter and still be confident about getting the gearing close. That, and continuing to re-enforce the fact that my motors are not causeing me to go slower then the fastest guys...


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## Guest

Sorry for getting into the conversation a little late. I have a MVP and it does about as good on the dyno as my other motors, it is just a little off. On the track, it is not up to speed. I do race touring and I cannot gear high enough to go fast. I've taken it off the track at over 250 degrees. I've also geared it lower, no help. But my Monster kicks its butt every time, but it only does a little better on the dyno. 
But I should say that my Dad loves the MVP. I believe it is because he goes so slow and hits the wall so much, that having a power curve like the MVP is very benifical. Now don't get me wrong, I don't think that the MVP is for people that suck. The fastest guy at our track occasionally uses his MVP and beats us all. I just find that my dyno data usually backes up my performance. Execept that my Monsters seem to do a little better than what they say on the dyno, but I believe that has to do with the fact that I gear them tall and they don't over heat.


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## Guest

*hoping for help*

what i'm looking for is what kind of #'s should i be looking for on a ce dyno on a 19t arcor motor in a 4 cell class.i know the fantom "s but not on a ce dyno.


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## DynoMoHum

I don't have ARCOR motor numbers on a TurboDyno, but do have some memory of 5 volt 30 amp numbers for Chameleon motors... 116 watts at 30 amps, 5 volts, is all I remember... It's not much, but that might give you something to go by.

My best guess is that the ARCOR motors would be a few watts less then a really good Chameleon... I base this on seeing both ARCOR and Chemeleons on my Robitronic dyno... On my Robitronic, 90 watts is about as good as I've seen for a 19 turn Chameleon, ARCOR motors have always been lower then the Chameleons I've dynoed, perhaps 85 watts or slightly higher.


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## 300M

Denny: I remember the file  I cut out 6 runs and pasted into excel sheet for you on the TD data I have. I added the 6 v files to the viewer and included in the zip file. IF you want to see the remainder of the excel files on the motor let me know. I have about 100 runs on that ssheet.


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## rowle1jt

Glenn, I know that Mels C1's pull 119 on Keith's TD.


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## DynoMoHum

Yeah? those are likely cranked C1s... Not acusing anyone of cheating... but my understanding of all the C1s that get used around here arebascily all cranked. I guess the fact is, with the way we run around here, it's not considered cheating... but then people don't generaly use them unless they are just having fun... Even so... I wouldn't think it's unheard of to achive 119 watts even without changing the timeing a bit.


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## rowle1jt

I'm positive they weren't cranked! He can tune a 19t like no ones business! I think he only has one that is cranked, it wasn't cranked until after I saw the numbers. I saw these numbers in late nov/early dec.


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## Denney

Thanks 300M!!


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## OffCenter

I know this might not be the best place to ask but the results I saw were on a dyno so..... Has anyone ever heard of a brush deglazer. I watched a motor pull another 10 watts and several thousand rpm gain after one drop. I don't know what was in the bottle but it definatly showed some higher #'s. Could it have been water, or denatured alchol? it appeared clear. The guy wasn't telling what it was. Maybe someone out here knows. It wasn't comm drops.


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## DynoMoHum

I wasn't going to comment because I have no info on the type of product your asking about. However since no one else has yet to respond I'll make a comment or two about what I see as being related.

My experiance is that some motors will look really good on a dyno when first built/tuned, yet after you run them in a race they will come back and be down on power by 10% or more. A really good motor will not see this kind of decrease, or is less likely to have this kind of decrease. I can't say for sure what all is involved if/when a motor sees this kind of proformance decline after use. 

Other motors will run really well before and after a race, these motors will generaly will work well time and time again. Often comm drops do very little to improve the proformance of a good motor like this, basicly they are just really good motors. 

Back to the topic at hand... If a motor gains 10 watts by just putting some liquid on the brushes and comms, it probably was one of these motors that didn't run consistantly well. I seriously doubt that you'd see this kind of behavior on a motor that was truely in top notch conditon as far as tuning goes.

I am currious about the liquid, but I suspect it's not as miraculous as it may sound. I don't mean that as an insult to you OffCenter, or to anyone, it's just that generaly when a motor is REALLY good, things like that just wouldn't be likely to happen. At least not in my opion.


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## DynoMoHum

FYI... There is a Robitronic dyno up for bids on ebay right now. Opening bid is like $475... I don't know the person or anything like that, I just thought if someone is interested in a Robitronic dyno at this time, there might be an opertunity to get one at a reasonable price...

Based on the photos this dyno appears to be in good condition, and if I didn't already own one, I'd be interested in it.

I hope I didn't get anyone into a bidding war on a item they already knew about... but since there are currently no bids, I'll assume it's not been seen by any who are truely interested in it...

I make no claims about the condition of this dyno, other then the photos make it look like it's all there and in good shape.


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## Mayhem

I think what you may be talking about is a product called "conducta" which was clear and sold by a compamy called "aero tech' if my memory serves me correct. If it is the same I dont think it is sold anymore.
I used it for years with success it really added to efficiency #'s.


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## Tskelton

Mayhem said:


> *I think what you may be talking about is a product called "conducta" which was clear and sold by a compamy called "aero tech' if my memory serves me correct. If it is the same I dont think it is sold anymore.
> I used it for years with success it really added to efficiency #'s. *


You can get it Tower Hobbies. It's made by "Aero-Car".

http://www2.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=++&FVSEARCH=conducta&FVPROFIL=++


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## OffCenter

Thanks for the info. We got people here that think Comm drops are Windex, So if this was some simple homemade stuff I thought that someone out here would know. 
Unrelated to this but on the subject I ran a G3 which hat lower Fantom #s than my ROV but with the right gearing turned out to be a happier combo for the track I race at.
One thing mentioned here I have noticed is that after a practice, 3 qualifiers and a Main with only a spray out before the main I dyno my motors after a day at the track to record #'s before a teardown and comm cut and the #'s are higher than before my day of racing. They actually go down slightly after truing and cleaning. I use the dyno as a guide, and the track to gain results.:roll: :roll:


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## DynoMoHum

Offcenter.... I see simmilar things on my dyno... Well... notthing to do with your GM3 with lower numbers out proforming the ROV (what is that? I'm assuming Monster?)

What I am seeing is that when I have a fressh cut comm, I get lower RPM and good peak power, after a run the RPM may go up, power may go down just slightly, then after another run, power may even come back up and RPM go up as well... Basicly what I'm seeing lately is that a fresh cut comm may not be all it's cracked up to be... I think sometimes a motor will run at it's best after at least one run, and maybe even better after 2 or 3 runs... My experiance is with 4 cell oval racing... 

So far I have not found out exactly how many runs I can make before the proformance declines significantly. Mainly becsuse I basicly will cut the comm the night before a race day, and rarely have more then 4 runs on any motor.

I have run my EX-Spec motor for as many as 8 runs and noticed no indications of proformance loss. But this is a standup brush with low timing.


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## Bodido

I'm trying to follow this killer thread. Ton of info.

One question.... What is an ROV?


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## OffCenter

That would be the "Revenge of the Monster" but do to my spelling I chose to abbreviate. Also, I had also seen the monster referred to as a ROV elsewhere in here and wanted to look more hip with the proper jargon.
Dyno, I agree and do the same, I would really hate to find out it only had one more good run before a tuneup since I usually don't drag a lathe and dyno to the track. I also am far better at tuning at home with more space to work and the pressure of the next heat etc.


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## DynoMoHum

I vaguely remember ROV... but wasn't it ROM? I don't remember... ROM would be the way I'd refer to them... but sometimes I simply use M... M1, M2, etc... So far I only own 2...

I did notice something that is somewhat odd... I still am strugling to get a Monster motor to run how I really like it to... I am like 98% a 4 cell oval guy. The best I can get out of my Monsters is about 59 or mabye on a good day 60 watts. This is not bad... but I like at least 60 and prefer 62 if I can get it... 

Well what I noticed is that one of my Monster motors puts out 130 watts on the 7.2 volt setting of my dyno... Typicaly 125 is the start of a good motor, 128 being what I shoot for... 130 is the best I've personaly been able to acomplish. I do have some Paradox motors that do 130 as well, but my surprize is that when I tune my Monster for it's best output at 5 volts, it really doesn't impress me that much, but when I happend to test it at 7.2 volts, I was somewhat amazed that it ran as good or better then most any other stock motor I have. I've tried everything to make one of these exceed 60 watts on my dyno at 5 volts, but I just can't do it.

I wonder if maybe these are better suited for 6 cell racing for some reason.


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## OffCenter

See what I mean about spelling. I don't know where ROV came from, hell the " V " isn't even next to the " M " I meant to write ROM. I too run 4 cell (ARCOR packs)in an open wheel SK modified class on a 190' banked track. The ROM ran good and the smaller the rollout # the better, but the G3 with proper gearing seemed like a happier combo. The guy to beat also runs a G3. I did also note that tires on the fast cars are very low profile. I run mine now at about 2.15 - 2.175 and though they wont'last as long this seems to be how the fast are fast. I still am playing catch up with them and I attribute 1/2 the difference in my driving, but there has got to be some more speed in there somewhere. I have gone to teflon coated pviot balls up front and freed up the rear and smoothed out the diff with better balls, and rings. I'll see the results this weekend.


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## DynoMoHum

The fastest guys at are local track are still running GM3s, I have seen a few trying to run Monsters but as of yet haven't seen anyone really fast using them in 4 cell stock. I did loan my first Monster to one of the guys who's generaly one of the fastest 4 cell stock drivers in our area. I did so after dynoing his motor, and I was confident that my Monster was as good as his GM3. I told him what to gear it at compared to how he was runnig his GM3, and he had identical lap times with both motors. Later he brought his GM3 back to me, and he had it tunned up a little, and it was showing better then my Monster at that point. He TQed with my monster motor that night and ran his GM3 in the main... he won by 2 laps over another guy who is also extreemly fast... the other guy was trying a monster... (it was not as good as my monster however). 

Bottom line really is that there is nothing magical about a Monster motor as near as I can tell. It's not a bad motor, it's just not what some people have attempted to make it out to be. At least that's my opion.


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## Guest

Mine have always worked great in 6 cell touring.


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## DynoMoHum

Well... like I say, my second one is showing pretty good 7.2 volt numbers, as good or better then most any other stock motor I've tuned... but I just can't get it to do the same with 5 volts applied to it.


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## DynoMoHum

I'd like to request the help of some fellow dyno owners... There seems to be some confusion about what happens to a stock motor in relation to spring tension. For a long time, the general idea has been that sping tension reduces RPM and increases torque... or at least that's what I heard back a couple years ago when I first started learning about motors, and I keep hearing others that have that same idea...

Well my testing shows otherwise. I've tried to document this before, and have previously shown my work. However, it seems some doubt what I am saying. 

So, it seems to me, that one of the only ways I could defend my posistion without just simply saying... 'trust me'... is to ask others to conduct tests and share there results with us all...


What I recomend for a test is this... take a modern stock motor... I believe anything from a P2K2 to a Revenge of the Monster stock motor will work. Get three sets of springs... two greens, two reds, and two purples. Make a dyno run with the greens on the motor, record the data. Next put the red srpings on the motor, record the data. Finnaly do the same with the Purple springs...

Idealy you should find some way to measure the spring tension, because springs can often vary greatly in their tension even when they have some perticualr color... Also make sure you control your tests pretty closely... let the motor cool between tests, and give each test the same conditions... or at least as close as you can get.

Report back with the data...


My posistion is that the red springs will yeild RPM that is higher then the green springs. Purple will likely yeild higher RPM then the Red springs, when doing 7 volt (6 cell testing), but at 5 volts, you may not see the increase in RPM and may either be very simmilar then the Reds, or slightly lower.

Better yet... use the fiddle stick to measure the spring tension of the three sets of springs you use... In my testing I started out with springs that were about 4.5 on the fiddle stick, medium springs were about 6.5, and stiff were about 7.5... Purples springs are like 9... and I personaly never use purple springs or tensions that high, and also don't recomend it... but most of all my own personal testing never used springs higher then 7.5 on the fiddle stick. I fully expect that at some point exsessive spring tension will indeed cause RPM and power to go down... but in my testing I never saw this, because I never used springs that were that strong...

http://www.wiltse.net/springs.htm


I really would like for others to conduct tests and report back... I think we need to clear up the confusion and what I beleive is mis-information. However I really don't expect people just to take my word for it, and it would be very good to have others conduct simmilar tests.


By the way... my test showed that a P2K did not change much at all with my variation in springs... The higher RPM motors responded to a larger degree then lower RPM motors.


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## rowle1jt

Glenn, talk to Jamie this weekend. He is a firm beilever that the lighter the spring the faster the motor in 4-cell.


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## OffCenter

All my testing was done on a Fantom dyno, I believe it is at 5 volts Your mileage may vary! All power #'s were 62-65, Rpms were 19,5 to 24,000 (ROM) and eff was in the 48 to 52% range for both motors. Unfortunately the records of these tests were lost but the best combos are on the motors now. Have you expierimented with holes or cuts in the brushes? I've been using Zubak Speed juice with better results.


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## OffCenter

Dyno, I think my first post got lost. I have done what you had just suggested with a G3 and ROM. The G3 worked best with a black+ silver- and the ROM has a purple+ silver- I don't know the tension #'s, But all the numbers across the board were highest with these combos.
I tried Red Green (almost as good on both) red red, green green, purple green, black silver, etc. My P2K is such a slug that nothing helps it.


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## DynoMoHum

Fastest on the track is not what I'm looking for here... Fastest on the track has too many variable... like for instance gearing, and many other factors...

What I'm looking for here is RPM of the motor as it relates to spring tension. Any other data that can be provided would be even better... 

What I really would like is actual dyno data. Howver if you don't have the data and just want to report to us what the data said, that is fine... 

I would however like to avoid just pure speculation on what happens.


Jammie can go fast with anything... including a motor that I personaly tune... My motors all have spring tension that is between 6 and 8 on the fiddle stick... I have never found any reall need to gou outside of this range myself.


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## OffCenter

I'm sorry my results are not available but i do recall that green on the + side was alot less rpm than red or purple on +. I couldn't try silver on + because I have one for that side. purple + gave the best results with a silver but only slightly better than with a green. Red red, did nothing, green green was no good, red green was the second best. The results were similar with both motors except the G# liked the black + better than it did a purple. With every improved RPM change power seemed to improve as well. Efficiency varied but my concern was for Rpm and power,. The computer puked and had to get reloaded so those tests were not saved.


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## DynoMoHum

OffC... I've experemented with a few brush cuts, but basicly I use just one at this time. I cut a couple notches in the side of the brush, basicly what is called a H-cut. I also trim the trailing edge of nearly every laydown brush I use. Even in Monsters, or P2Ks... or what ever... The P2K doesn't seem to care much what the cut is... other motors seem to like trimed brushes... basicly to reduce brush overlap and increase efficeincy... 

What I do to trim a small amount off the trailing edge. Dyno... if I feel I still could get better numbers I might trim a little more off, and dyno again. If the power starts going down, I know I've gone too far. Not much you can do at that point, except maybe start over... mostly I just try not to take too much off... about 1/16 or less is what I end up with.


More on the test I'd like to see... I'm not looking for what is the 'best' combination... what I want is to see the trend that takes place when you use progressively stiffer springs.


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## DynoMoHum

Aside from the tests of progressively stiffer springs and what happens....


I have found that nearly every motor I play with prefers slightly differnt springs. I also find that springs dirctly from the package rarely have tensions that are consistant with what they are suposed to be. For instance, you can often find green springs that are just a strong as other red springs, and red springs that are often just as stiff as purple ones... etc... if you don't have some way to measure the actual tension, you're really just hoping that the spring is what you think it is... The fiddle stick is not perfect, but at least it's somehing to work with... If you practice with it, you can get pretty consistant results.

Differnt brushes also seem to like slightly diffent springs as well... There are many many variable that go into the perfect spring package for a perticular motor. It seems to me that the higher the RPM the more picky the motor is about springs...


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## OffCenter

As far as brushes go I am at the mercy of what is available at the track on Sun when I race. I've got Putnam green/high silver in the G3 now and Trinity 4499 in the Monster. I'm just starting with cuts and so far just a vertical down the brush about 1/8 was what had been suggested. It doesn't seem to do much on the dyno but I have yet to note whether it will improve racing. I played with the timing trimming of the brushes as I had read about somewhere and definately lost significant rpm/power #'s on the dyno.


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## DynoMoHum

I think I've resolved the issue of the spring tension and RPM with the person (Tempest2000) that was questioning my comments and/or findings...

It turns out that I think he and I basicly agree with one another. The sticky point being that there is a point where too much spring tension does indeed decrease RPM. My findings were based on 7.2 volt dyno testing on my Robitronic and 7 volt testing on a CE TurboDyno... Tempest's observations were on a Fantom dyno. Basicly he indicated that yes RPM was lower with lighter springs, but that anything above a red lowered RPM... or something close to that...

Anyway... I don't really dispute his observations and I dont' think they conflict with my observations at all. The reason I was able to see higher RPM with even stiffer springs I attribute directly to the voltage differances in the testing. Higher voltages require and/or will allow for higher spring tension before you get to that point where too much spring tension will start to decrease RPM and power....

I think I may eventualy do some further testing, where I do one set of tests with 5 volt setting, and another set with 7.2 volt setting.... I think it will become more clear then, that motor setups for 6 cell will work better with slightly stiffer springs then are needed for optimal power at 4 cell voltages. This will likely help make this issue more clearly defined.


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## Tempest2000

voltage would definately have a direct effect on the results. The higher voltage would definately vary the results pertaining to spring tension, RPM, and power/torque. All it really says is that with more voltage there is less RPM loss with heavier springs than with 5 volts. At least I think that is what we determined. :thumbsup:


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## DynoMoHum

For sure... the gray/blurry line is what is too much spring, and what is too little. Clearly there is a point at which light springs cause RPM loss due to loss of input current, and another point where too heavy a spring causes RPM loss from too much friction.

The point where the spring is just right is what we all are looking for I think.


Just recently I sent a motor to a guy to test... He dynoed it on his TurboDyno, and the numbers were not impressive. On my Robtronic at 7.2 volt setting it looked pretty good. It also looked quite good at 5 volts on my dyno. Basicly I felt it was perfect for 4 cell racing and thought that it was likely to be good for 6 cell as well. Based on the new data I have, I'm thinking that for 6 cell I needed stiffer springs on this perticular motor.

I really am now very curreious and determined to figure out just how much differance there is between the ideal spring for a 4 cell motor, vs. the ideal spring for a 6 cell.

Basicly I'm moving to a new point in my learning as a result of  this discussion and other recent observations I've made.

I don't know for sure when I will get a chance to do more extensive testing at a variety of voltages... probably at least a week off, maybe more. However it's basicly going to be my next motor project to figure it out.


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## Tempest2000

I mainly run 4 cell so 5V is perfect to test with for me... I can see where 7v would be beneficial to 6 cell racers.


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## OffCenter

Dyno, Unless you think there is something wrong with your dyno stick with using it. Trying a motor on different dynos will net different results. I'll bet you already new this but I couldn't resist.


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## DynoMoHum

Well what I mean is that I sent a motor to a guy to do some track testing with... I had several of his motors myself for awhile... anyway... my motor didn't show to well on his dyno compared to other motors he has... yada yada yada... He's going to do some track testing and then wei'll go from there trying to figure out why the dyno says what it says.... I have my theroys... He runs both 12th scale and Touring car, so he has a need to have motors that run well for both... I felt farily confident that the motor I tuned for him to try would actually work well for both. However now I'm not as sure as I was.... I know my motors work great for 4 cell... but I don't have much experiance with 6 cell... but I really want to be able to know what it takes to tune for both types of racing... so I'm going to do what ever it takes to figure it out... that's what I have fun doing... well that and racing, but I really want to figure this out. Given some more time and some more testing, I'm confident that I can figure it out.


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## 300M

Dyno: There is a differance. I run both TC and 1/12, but I use different motors. If I use one of my 1/12 tuned motors in TC they will arc at the high loads. Punch is down. I tend to use lighter springs on the 4 cell tuning than I do on 6 cell. About 1/2 FS unit in general, but most are motor specific. Working on a monster now for 4 cell just to see for myself. Best motor is still P2K2. This one has the best power numbers and pulls well.


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## Guest

Pretty new to this rc thing and even newer to a dyno, though I have recently got a robitronics. I have a couple of questions/observations 

1.When you cut the brush trailing edge, how much? I think I read a couple of posts back, 1/16" though that seemed quite a lot to me. Do you always cut both brushes?

2.When I dyno a motor (P2K2, 6 cell, TC) with new brushes #4499 I get a particular graph and results, naturally. After 5 min race the serrations are all but gone and if the motor is dynoed again the graph is markedly different, usually a gain in power in the low amp numbers and a near equal loss in the higher amp range (25 ish). When both results are put into goldens dyno viewer the gearing usually changes by upto 2 teeth, and the resulting rpm plot is near identical. Thus I assume that the gearing change would result in two pretty identical motors (I realise it is the same motor, but you know what I mean). Therefore would you assume that the 'gearing' of the new brush motor would change during a race and that it may be more consistant to not reserrate the brushes?

3.Would a hole in the center of the brush have similar results to the serrations and any info on how this works with a cut trailing edge? I was going to try it but incase someone already has.

Sorry for the ramblings but if you don't ask you don't .........


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## DynoMoHum

You've asked some very good questions, it seems you are also very observent, all good things.

I generaly break in a set of brushes for quite a long time, I like to get some visual indication that the brushe is indeed making contact with the full surface before I dyno anything. If brushes are only partialy broken in, the dyno results will change. Even 90% broken in is not good enough. 95% isn't really even good enough... This is not a direct reponse to any of your questions, but you should be aware that dyno results will vary a great deal as the brushes get seated.


Motors that have higher RPM will show lower power at low amp rates... at least in a general sense. If your motor picked up power at low amp rates, it was likely becuase the RPM went down. Don't ask me how or why this works like this, becaus I don't know why. It's not just something to do with the Robitronic either... You'll see the same thing on a CE TurboDyno if yo look at it closely.

What your seeing seems odd to me. In someway's it makes perfect sense, but it's not really like what I see most of the time on the motors I call good. To me, a motor should run just about as good after one run as it did before the run. I personaly see my motors pick up a little RPM, and loose a very small amount of peak power. What I see and what you are descirbing are almost just the oposit. I don't know if I've ever seen my motors change so much that a two tooth gear change would be in order. 

My observations have been that even when the RPM changes, the gearing really doesn't change on the same motor I'm working on. This is hard to understand maybe, but it really boils down to the fact that the motor really is the same as it was before, it just has slightly more or less power and RPM. I guess there are cases where this isnt't true, but my feeling is that something is wrong if that occurs.

I'd like to see your data. Maybe I could offer more comments if I actualy had the data.


Triming the brush.... I break in the brushes fully first, dyno... to get a benchmark. If the motor looks like it could use a little more efficiency, then I will trim the triling edge by about half the thickness of a dremel cutoff wheel. I'll dyno again, and if I'm still not happy, I'll take the other half the thickness of the cuttoff wheel.... (to get one full thickness trimed off) My estimate was that this was 1/16th... I've never actualy mearuesd it... I'll do that now.... hold on...

Opps.... I'm sorry... my mistake my cuttoff wheel is just .025" of an inch I guess I have to re-state my measurments... A 32nd of an inch is about the most I ever tak off... I start with about .015 and go up to maybe .030 

Sorry... I really never measured, and obviously my estimation and memory of what a 16th was like were way off... Glad you aksed the question....

Take a little bit off at a time, if you see peak power drop, you've taken too much off. In my opion, if you want to learn about dnyos and what numbers mean, what happens when you take a small amount of material off the brush etc.... work with brushes that don't have serrations left on them, or very small amounts of serrations left... If you try and work with serrated brushes while your doing dyno work, you'll constantly be fighting with consistancy problems related to the serrations and/or brush breakin.

I can make a non serrated brush work just as well as a serrated one, and to me, the only value in serrations is to allow quiker brush breakin. On the dyno, serrations are just a pain in the you know what to work with.


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## Northerner

does anyone break in motors while dipping in water anymore? i have heard this is a very fast way to break in the brushes and get them seated very quickly? 
do you just hook up a 4 cell pack to the motor and dip the endbell in some water?


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## Guest

It will eat up your brushes in less than a sec. Try it once. I did it on an old motor with hard brushes once, and it actually worked quite well. But remeber that all our newer brushes are very soft as far as brushes go for electric motors. We may call them hard in the RC world, but they are actually soft.

Also, I hear it works for those spec motors with hard brushes.

4 volts should work, and you shouldn't be able to shock anything at that low of a voltage.


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## DynoMoHum

I've done it recently on a Ex-Spec motor. I do it with a old Tekin Dyno, at 5 volts,... my Spec motor was pulling about 18 amps when the brushes were fully broken in. I have had stock motors pull more then 20, and had to turn the voltage down to keep the amp bellow the 20 amp limit of the Tekin.

Depending on the brush, a couple minutes or so will get them fully broken in, even with realtively hard brushes, and a great deal of differacne between the contour of the brush and the commutator.

Just hook em up, dip them and check them once in a while.


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## Fred B

For some reason, water dipping doesn't work as well on the new brushes. It takes a little longer. In the old days, you would only dip the motor for a few seconds.

Want to speed things up? Add some salt...just clean it out after.


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## Guest

Pepper too?


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## 300M

Nah, that just makes you sneeze. Hot stuff, Texas pete raises the temps though   
:lol:


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## Fred B

Just helps the water conduct...


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## DynoMoHum

Well, I took some time and played with thee old dyno last night...

Started out wanting to explor spring tension some more. I also played with voltage a little...

My spring test sort of started out where my other older spring test left off. The lightest springs I used this time were like 7 on the fiddlestick. Those were some new greens I recently purchased. I had reds that were 8, and purples that were 9 fiddle stick units. THe stiffest springs in my old test were 7.5 on the positive, and 7.0 on the negitive side...

My new test was not nearly as dramatic as some of the results I observed on the older test. Basicly the green springs had slightly less RPM then did the red springs, power was very simmilar. Purple springs were almost indistiguishable on the dyno from the red springs.... This was all on a Monster stock motor with brushes that had the Trailing edge trimed and a H-cut... I did some testing at 5 volts, and more at 5.5 volt setting on my Robitronic dyno. 

Probably the more interesting part of what I did last night was when I started playing with voltage increases from 5.0 up to 5.5 in 0.1 steps... The inrease in peak power appears to be somewhat logarithmic, rather then linear. There probably is some perfectly reasonable explination for this, it may be as simmple as the fact that peak power moves toward higher and higher amp rates along with the increase in voltage.

For example... on this perticular motor with two red spring on it... at 5.0 setting, Peak power was about 59 watts, at 5.1V it was about 60, 5.2v was 62, 5.3 was 64, 5.4 was 68, and finnaly at 5.5 volts peak power output was around 71. 

What does all that mean? Well for one thing... the more voltage you have, the better off you are. But basicly you can't do much about that with motor tuning, so you left with finding better batteries, speeed controls, and wiring to get improvments there.

It may come as very little surprize, but spring tension around the level of a red spring is about as good as things get for a 4 cell type setup... Purple doesn't seem to be much differnt howerver. 


Also... at 59 watts at 5 volt setting... my Monster still doesn't really run all that great... not terible, but it's certianly not my best motor (62 is a good motor, 64 is the best I've ever seen) I do know however that it seems to do quite well at higher voltages, at 7.5 volts it proforms about as well as any motor I've ever had. But this is somewhat unrelated to springs... I don't know what I could do to make my Monster work better at 4 cell voltages... I'm still trying to figure that out.


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## Fred B

Dyno,

You might want to try running the same test with a different motor (GM3 or whatever). Just from what I've heard, the ROM seems to be good in 6 cell but not as good in 4 cell. Oval might be a different story but you might want to look into it.


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## Guest

Dyno, there is a reason why the power out increases like that. The answer electrically is that V=IR, where V = voltage, I = Current, and R = Resistance. By that equasion, you should be able to see that holding the resistance constant and increasing the voltage, the current through the circuit will also increase proportionally the same. So, if you increased your input voltage by 10%, then the current in should also increase by 10%. And because overall power in has increased, power out should have also increased.

I don't know the current you put into the motor, but the generic equasion would be (New_Voltage / Old_Voltage)^2 * Old_Power. The "^2" means Squared. 
Using your numbers (5.4 / 5.2)^2 * 59 = 68.8 Watts. Its a little off, but the efficency has changed.

Hope that helps.


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## Guest

Also, people have recently been talking about the new GP cells that have that 1.17 voltage over the usually 1.15. Lets find the difference in power for a 6 cell pack. I'm assuming a mod motor that puts out 200 watts.

(1.17 * 6 / 1.15 * 6) ^2 * 200 = 207

Thats a 7 watt increase.

If it was a 100 watt stock motor, it would now be 103.5, and a 3.5 watt increase on a stock is very noticeable.


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## DynoMoHum

Also consider that actualy some of the older GP 3300s were 1.13s with average being about 1.14 just a few months ago... I've heard of 1.178s being availble to people who are not even sponsored... 

Now is .01 volt per cell worth X dollars? Only you can decide... but if someone tells you voltage doesn't matter, there confused or trying to mislead you... 

Of course then you also get into that old battery debate of wether run time or voltage is better. However at some point it doesn't matter that much... a 1.141 420 second cell is not as good as a 1.178 420 second cell... and it will make your motor run better too...


I know for sure my Monster doesn't run as well at 5 volts as it does at 7.5 volts... I have seen a couple Monsters that looked pretty darn good at 5 volts... (better then mine anyway). Next chance I get I may do a simmilar voltage test with another motor just for kicks...


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## chicky03

Keep in mind that unless you can somehow look at the discharge curves, a 420 with 1.165v might actually be even voltage or possibly higher to a 390 with 1.175v as far as actual voltage that you motor sees in a run. Of course a 420 1.175v will be better than a 420 1.165v. Batteries with 420 and 1.145 for me seem to run equal 390 1.155v. Runtime and voltage together = King. Just some thoughts. 

Paul


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## vented

*fantom dyno tuning*

with the fantom dyno what are some things to look at when tuning stock motors? what are good numbers and where shoul i look for them?


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## tfrahm

*Test of LEADING edge cut on CORE Stock*

I know this is going to "stir the pot", but I felt this was the proper thread to post this... I have always been a believer in shaving a bit off the TRAILING edge of laydown brushes to improve efficiency and to eliminate the dead short which their escessive "wrap" creates. This has been true for every motor I've ever had until Big Jim introduced the "MVP" cut with BOTH the leading and trailing edges shaved down to produce about a 0.140" brush face width. When I got my first and only Orion CORE STOCK motor, I noticed the armature looked exactly like the MVP... This led to an "experiment" -- I tried sort of a 1/2 MVP cut, shaving only the LEADING edge of the brush... To my great surprise, it WORKED, and worked well! Just to prove to myself what was going on, I ran the motor on the track and then did some testing (see notes)...
NOTES: 
1) This was an attempt to prove to myself that this motor (and so far it is the only motor for which this seems to be true) REALLY "likes" to have the LEADING edge of the brushes shaved down a bit rather than the usual trailing edge.
2) ALL tests were with the same brushes (this was a major pain, but I thought it was best for a "scientific" test). The change from leading edge cut to trailing edge cut and back was done by simply "flipping" the brushes in the brush hoods and then very diligently re-seating them.
3) The actual brush cut used is sort of 1/2 the "Big Jim" MVP cut, shaving one edge of the brush only, which brings the brush face width down from 0.185" to 0.163".
4) THIS MOTOR "LIKES" THE LEADING EDGE CUT! -- Note that the first test (fresh motor with full face serrated brushes) is pretty similar to the trailing edge cut test, and that the two leading edge cut tests are very similar, implying that the determining factor is the effective timing change introduced by cutting the 0.022" off the leading edge. I believe this has to do with the armature design (visually identical to the MVP), which becomes over-saturated with a full wrap, 24 degree timing, but is "happier" with the partial reduction in timing introduced by the leading edge cut and also with the reduced "wrap" of the now narrower brush face...
5) DON'T compare dyno's -- mine has always produced lower numbers than every other TD45 I've seen, but it's consistent, so it doesn't matter to me. On my dyno, the strongest motor ever tested was 98 watts at 20 amps at 7.00 volts, and I consider any motor with 90 watts or more to be a decent motor, with most of my race motors being in the 90-94 watt range...
6) All testing was at 7.00 volts, with the motor starting "cold", with each test consisting of 2-4 "pulls" until I got two back to back pulls that were essentially equal, with the last one in the series being the result "of record" for this test...

COR#1 -- TOP/Orion CORE RS "Dynotuned"
Brush: Stock 41200 (w/'1' in circle stamped on back)
Springs: (TOP/Orion)Red+/(TOP/Orion)Green-
7 Total Runs, with 3 Runs since Re-Build

Test: 20030111c -- Raw "Out of the Box" (uncut serrated brushes seated to the corners)
25507 2.7 51 49 @15A
23600 4.3 75 60 @18A
22423 5.3 88 63 @20A 
21205 6.2 97 63 @22A PwrBand(15A-28A): 7,178 RPM
19742 7.5 110 63 @25A
18329 8.5 115 59 @28A

Test: 20030206b -- Raw After 3 Runs in XXX-KE, w/0.022 shaved off LEADING edge of brush
21979 4.1 67 64 @15A
20845 5.3 82 65 @18A
20025 6.1 90 65 @20A 
19300 7.0 100 65 @22A PwrBand(15A-28A): 4,970 RPM
18184 8.1 109 62 @25A
17009 9.2 116 59 @28A

Test: 20030318d -- w/0.022 shaved off TRAILING edge of brush
27225 2.3 46 44 @15A
25111 3.7 69 55 @18A
23540 4.7 82 59 @20A <<<< [email protected] 
22244 5.6 92 60 @22A PwrBand(15A-28A): 8,456 RPM
20461 6.9 105 60 @25A
18769 8.2 114 58 @28A

Test: 20030322b -- w/0.022 shaved off LEADING edge of brush (As in 20030206b test)
22840 3.8 64 61 @15A
21593 5.1 82 65 @18A
20723 6.1 94 67 @20A <<<< [email protected] 
19969 6.9 102 66 @22A PwrBand(15A-28A): 5,189 RPM
18808 8.0 111 64 @25A
17651 9.1 119 61 @28A


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## Fred B

Interesting,

We've tried the same thing in 12th scale. It seems like if you're running a motor that has less useable RPM (Either a high torque low RPM motor or a 4 cell motor with lower RPM) reducing the timing will generally produce more power.

Just as a note for everyone, the reason that we advance the timing in our motors is to compensate for the "rotation" of the magnetic field while the motor is running. A motor that runs at a lower RPM will need less timing to compensate. This seems to hold true for stock motors.


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## DynoMoHum

Interesting.... I didn't see this last bit of discussion till just today, I happed to be searching for some other info that I new was in this thread, and noticed that there were a few new posts i had not seen.


Up untill a month or two ago, I never cut any brushes except for a few cuts I made using the 'big jim' cut that trims both sides of the brush. Months ago now when Tfram started discussing brush overlap and shorting, is when I first got into it. Prior to that I really hadn't given it a whole lot of thought or consideration. Since then, I don't run any full faced brushes any more. When I first started playing with it, it was on a MVP. I first tried triming the leading edge, going with the my on guess that the MVP basicly had too much RPM and could stand to loose a little, and that triming the leading edge would be better. My first testing both on the track and the dyno was very promising, my MVP had never ran so good. (I've always hated them, but I only run 4 cell racing and I think that is part of the reason they didn't work so well for me). Later for kicks I tried reversing the brushes, to my surprize the results for me were very simmilar to when I had them in with leading edge trimed. I didn't really attempt to document any of this, I was just killing time one day at the track basicly.

For me, P2K motors have always ran good, and what I've come to beleive is that they don't seem to mind runing a full faced brush, and triming either edge of the brush doesn't seem to effect things very much at all. I've also observed that spring tension also doesn't seem to effect the proformance of P2K motors as much as it does on other motors. I'm not sure why this is.

I've played with quite a few Paradox motors as well, and they do seem to be more effected by triming brushes one way nor another, and also by spring tension, at least more so that I had observed with the P2K motors I played with. To be fair, I've probably spent more time on Paradox motors then any other motor, simply because I have a whole bunch and they just make a good motor to test with since the hoods are easy to tweak, and again I have a bunch of them. 

Basicly I have never attempted to document what Tfram just reported on. I find it interesting, and ceritianly worthy of futher exploration. 

Here is one of my current quandrys... I'm basicly really looking at moving on from stock racing and moving toward 19 turn racing. Mostly because I'm still a oval guy, and quite frankly 4 cell stock racing is kinda slow, and 19 turn is appealing simply from a speed factor. Now ROAR is apparently making 4 cell 19 turn oval a offical class. Basicly addopting the ARCOR motor as the standard if I understand it correctly. The reason I'm telling you this here is... I'm really looking forward to learning more about timing and how it effects motors and racing. 

I expect I'll also still do some 4 cell stock racing, simply because I know that I have not even come close to mastering it, and would like to be able to do much better at it then I currently can. Stock motors are also still very fun to play with, and try to find ways to EEK out one more watt of power, etc... What I'm thinking now is that rather then playing with reversing the brush and such, why not just play with timing? Is there any real differance between changing the timing and triming the trailing or leading edge of a brush in a fixed timing motor? There may very well be a differance, but exacly what it is, is not very clear to me at this time. 

In direct comment/question of what Fred and Tfram have just discussed... Other then trial and error, how would you know when a motor is likely to need more or less timing? (or when to trim the trailing or leading edge?) I mean Fred says timing is not needed as much on lower RPM motors, and is needed more on higher RPM motors... where is the line that determins when to switch...


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## DynoMoHum

Moments after I posted that last one... I got to thinking... What effect does voltage have on the perfect timing and/or brush overlap.

We know that RPM increases with voltage, so it's likely to have some effect on these issuses if for no other reason then the RPM is significantly effected by voltage.

Somewhat simmilarly... I continue to beleive that a Monster motor is a better 6 cell motor then it is a 4 cell motor. But I'm really unable to understand why.


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## tfrahm

HI Dyno...

About the question of when to trim, where to trim, etc...

What I have seen so far (again, based on a limited sample), is that motors with strong magnets (MVP, CORE for example) with the "MVP" armature (both the MVP and CORE use what is visually identical armatures) with the holes drilled in the laminations are ones that are "different". I blame this on the hole drilled in the center web of the lamination -- my theory is that it disrupts/weakens the electromagnetic field by eliminating the "iron mass" right at the center of the wire coil. The net effect is an "RPM" motor because the motor is now a poorer generator, thus reducing what is referred to as "back EMF". The negative side effect of this method of getting higher RPM's is that the lamination core can easily become over-saturated by the magnetic field generated by the windings. Once the laminations are saturated, all additional energy just produces HEAT and loss of efficiency. By reducing the "wrap" (and especially by trimming the leading edge and reducing the timing), it is possible to "tune" this so that you still saturate the armature without over-saturation. This optimizes power, efficiency, etc. and reduces heat. Since the MVP seems to have stronger magnets than the CORE, the MVP seems to "like" having both the leading and trailing edges trimmed while the CORE seems to "like" just trimming the leading edge...

Other motors, either due to weaker magnets or a non-drilled armature lamination (EPIC motors seem to "play" with the crown of the lamination, which affects the effective timing of the electromagnetic field but doesn't reduce the ability of the laminations to avoid over-saturation) seem to be MUCH more tolerant of a full face brush or a trimming of the trailing edge. 
EXAMPLES: 
1) I have a pair of C2 19 turns from Todd Putnam, and he barely shaves the trailing edge (brush face is 0.180"), but this is for an EPIC with a solid armature with no gaps...
2) P2K's have a altered lamination crown , but a nearly full stack (only about a 1/16" gap), so they can also tolerate a full face, but can benefit from a slight shaving of the trailing edge to gain efficiency by reducing the "short".
3) P2K2's have an altered lamination crown, but different (less alteration) from the P2K, but they also have a bigger gap (around 1/8") in the laminations, so they can saturate easier. I find they NEED some form of trimming the trailing edge (I use a 0.163" brush trimmed on the trailing edge). They seem to really be happy with this as they keep full timing, eliminate the short and seem to just reach full saturation without over saturation...
4) GM3's and Monsters have a greatly reduced armature stack, making them very sensitive to brush face size. I'm finding that they do NOT like the "MVP" cut, but that a trimming of the trailing edge (0.163" like the P2K2) combined with a thin dremel cut slot maintains optimum "wrap", eliminates the short, and reduces the brush face enough to flow just enough current to saturate the arm without over saturation..

*"As always - Your mileage may vary"*

OH -- I have an ARCORNITE that I have done some tuning/testing on if anyone is interested, but I have NOT gotten it on the track yet.


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## tfrahm

OK -- I'm still sort of new at adjustable timing motors (used to run "lizards", now testing an ARCOR motor)... Just "FYI", here are 5.00v TD45 dyno pulls for my one and only ARCORNITE with serrated 4383s, and springs equivalent to typical Red + / Green -:

MotorID: ARC19a 

Test: 20030330c Desc.: 36 deg retest 19t
25166 1.8 34 32 15A
23313 3.1 54 42 18A
22185 4.1 67 48 20A 
21186 4.9 77 50 22A 
19789 6.1 89 51 25A
0 0.0 0 0 28A

Test: 20030327d Desc.: w/24 degrees 19t
19336 3.7 53 50 15A
18209 5.0 67 54 18A
17365 6.0 77 55 20A 
16832 6.8 85 55 22A 
16060 7.9 94 54 25A
0 0.0 0 0 28A

Notice that, within the test range of my TD45 (power supply limitations, etc.), the 24 degree test shows much better numbers, but when I look at gearing, I'd have to go to a HUGE pinion gear to get the needed rollout. By using the 36 degree setting, I can use a more reasonable pinion. I should note that some racers have had great success by going to a very small spur and big pinion so that they can use the 24 degree timing setup...


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## DynoMoHum

I'm kind of in the same boat with 19 turn motors. I've got a Chameleon 2 that I think runs quite well, but now ROAR using the adjustable timing in 19 turn, I figure that is the one to start working with to figure out how to make them run. Currently I can run any 19 turn I want basicly because our local racers basicly don't really care what kind of 19 turn you run. 

I know my Chameleon requires a pretty big low ratio to use it's power... Others running ARCOR generaly have the timing cranked just about till the ring won't hold the endbell on. They seem to have less total power then a Chameleon, but they still seem to do quite well on the track. I don't fully understand why, and it has me really currious and wanting to understand more about timing and such.

It seems like this has basicly just given me a really good excuse to buy a ARCOR 19 turn and start playing.


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## tfrahm

*My ARCORNITE*

Although I don't own a Fantom dyno, I was given the oportunity to put my ARCORNITE on one at an area track Saturday...

The pull was done at 36 degrees of timing, and they declared the motor "a keeper", so for that dyno, it looked good. Here are the numbers:

92.06 power @ 12623
23,800 peak @ 2.9 seconds
1.130 torque
65% Eff. at 16,713

For their track (flat carpet oval, around 135' racing line, 19t track record is 60 laps), the Fantom says to gear for 1.815" rollout... (Last time I ran a C2 on this track, before they went to the ARCOR motors, I geared at 1.837" rollout for a Putnam tuned C2 motor...)

Guys running TI based ARCOR's at 24 degrees are using a rollout of around 2.45"....!


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## rowle1jt

Thats inline with what my Arcornite pulled on a Fantom, RPM's were the exact same, and my power was 94. So atleast we agree on what they get, and that was at 36 degrees of timing.


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## tfrahm

rowle1jt said:


> Thats inline with what my Arcornite pulled on a Fantom, RPM's were the exact same, and my power was 94. So atleast we agree on what they get, and that was at 36 degrees of timing.


I found it very interesting that the "spin up" time was so good too. I was worried that all that timing might drop the torque enough to make it take a while to spin up. But a 2.9 sec. spin up time looks pretty good to me. On short flat tracks, sometimes the spin up time can be a VERY important number. I know that with stock motors I've had some that looked decent on power and RPM, but had a 5 sec. spin up time and they just never performed -- when you turn a full lap in 4-5 seconds, a motor that takes 5 sec. to spin up never gets the job done...


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## rowle1jt

Yeah, I hear you on spin up.  Mine was 2.90 as well. :thumbsup:


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## DynoMoHum

Well... I've got me a Fantom Ti based ARCOR motor now... and I'm thinking about buying a Trinity Arcornite motor tomorrow... So I should be able to get some of my own data soon.

I know I raced some others with my Chameleon this past weekend. At least one other guy was using a Ti based ARCOR motor. By the end of the day We were all running very simmilar lap times, I had my Chameleon 2 geared at 2.74" rollout. I know one ARCOR Ti guy had a very simmilar rollout, but I'm not sure what he had his timing set at. One ohter that I think was using a ARCOR motor had a significantly lower rollout, and yet he too was running very simmilar lap times. This was on a rather large oval...

My Chameleon 2 is about a 88 watt motor on my Robitronic. I can't remember for sure what it was on the Fantom. 90 is about as good as I've ever seen on my Robi. If I remembr correctly, some locals have 19 turn motors that show well over 100 on a Fantom.


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## DynoMoHum

I spent about an hour last night dynoing my new Ti based 19 turn ARCOR motor. I'm starting to get a better picture of what happens when you increase the timing on these motors. At this point I don't have a detailed aynalisis of what I see, but I beleive this is one of those situations where viewing motor proformance in relation to amp input is really quite misleading. 

What seems to hapen when you increase the timing of these motors (and it's probably simmilar to what happens with any mod motor) is that the shape of the power curve changes significantly in relation to RPM. Peak RPM increases with timing, yet the point of peak power in relation to RPM doesn't change quite as much. So... lets say at 24 degrees of timing peak power occurs at 45% of maximum RPM, but at 36 degrees it is more likely to uccur at 40% of maximum RPM. This may seem like a very trivial thing, but I don't think it is really.

What also happens is that peak power declines slightly, like 1 or 2%, but power near the peak RPM increases more like 30% or more. When you apply gearing (based on looking at data with Golden's DynoViewer), you see that say at 10,000 RPM the 24 degree motor puts out 123 watts and the 36 degree motor puts out 120 watts. Yet at 20,000 RPM the 24 degree motor puts out 52 watts and the 36 degree motor puts out closer to 69 watts. So, it could be said that when you increase the timing from 24 degrees to 36, you give up like 2% of your power in the corners, yet you gain like 30% more power at the end of the straights.

The question becomes this... which would you rather have? 2% more in the corner, or 30% at the end of the straights?

When I first started racing 19 turn, and started dynoing guys ARCOR motors who were really fast, I couldn't understand how they mangaged to be so fast, because at the time I was looking at data in relation to amp input, and peak power was clearly lower, as was power at every other amp step along the way. It just didn't make any sense to me. Well... if you look at it in relation to RPM and you apply some gearing, it becomes more clear.

Don't think you gain 30% at higher RPM for free... Amp input at those higher RPM is also higher then it is with the 24 degree timing, but it's still realtively low... At the same point where I told you the 36 degree motor had 30% more power then the 24 degree motor, the motor was also consuming 42% more current. The 24 degree motor was drawing just 13 amps, where the 36 degree motor was consuming 18.5 amps. Just be aware that at peak power these motors are consuming more or less equal amounts.

In short... there's more to what first meets the eye when you strart cranking the timing on a motor. I'm no expert on this, as I've just recently started looking into it... but I know for sure in many cases a motor with 36 degrees of timing will beat a 24 degree motor, even when it has slightly less peak power.

I'll try and document this as best I can soon. I will also say that higher RPM in a fixed timing situation like stock motors, doesn't ussualy look quite the same as what I see when higher RPM comes as a result of higher timing. RPM is not always created equaly.


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## DynoMoHum

I should also warn that apparently this situation I describe is pretty hard to see on a TurboDyno. I've entered Tfram's data into Golden's DynoViewer, and I see that it's virtualy impossible to see what I see when using my Robitronic data. with the CE TD data, it appears as if gearing alone will take care of the RPM differances. Part of the reason for this I beleive is because at 5 volts, the loction of peak power on one of these motors is higher then 40 amps. Tfram's data only shows a small portion of the total picture. I don't really mean this as an attack on TurboDynos... I'm just pointing out what I see, and if you try and see what I'm describing with Tfram's data, it's going to be impossible from what I can tell at this point.


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## Fred B

Dyno,

You can place a trend line on the turbodyno data in excell. I forget exactly what I was using but it actually comes out pretty close to what the motor would put out on the dyno. You can use the equation of this trend line to extrapolate approximate performance at peak power. I used some 5 volt stock data to prove it out and it's surprisingly close.

Looks like I used a 2nd order polynomial for power and EF and just a straight line for torque and current.


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## Fred B

It looks like TFram's data doesn't go up far enough to show the curve for power. I think we might need to go to at least 30 amps to get a reasonable curve. The power trend does follow what you are saying.


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## tfrahm

*Fred and Dyno....*

As I mentioned in one of my posts, my power supply doesn't let me go far enough into the power curve, so I agree with your observations... I'm using a heavy duty 30 amp supply, and for 6-cell offroad testing, where actual amp draw seems to average around 20-22 amps, I'm fine for stock class motor tuning. BUT -- for "Mod" or for 4-cell oval, it's different. In the last year or so, 4-cell oval around here has gone from using efficient, "torque" motors to amp-sucking RPM motors, and even for stock, average amp draw is more like 25-30 amps... I should be able to add a 28 amp step to my TD45 with my current power supply, but I know from experience that a 30 amp step is "out of bounds" (the dyno seems to complete the pull, but the LCD display goes blank during the 30 amp segment!)... 

As you have noted, for modern stock motors and for "mod" motors, I'm clearly not getting the peak power point...

By changing the power source to a 12 battery, I should be able to go all the way to the dyno's 45 amp limit, but I've purposely avoided that up to now...

Since the Robi and Fantom use a battery type power source, they can map out a more complete power curve... Sigh... I still prefer my TD45, but....


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## Fred B

I think what you have is fine for general tuning in mod. A small battery would do a good job but, it's kindof a pain.

I prefer the TD as well...I just need to send it in for the 45 amp upgrade.


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## DynoMoHum

If you have the DynoViewer and would like to see some of the data I collected last night, I've zipped up 4 text/data files that represent my Fantom 19 turn ARCOR motor set at 4 differnt timing settings. 24, 30, 32, and 36. 

THe files are ziped in the following file

http://www.wiltse.net/zips/timing19.zip


At this point I'm thinking I might start out with a bit of a compromise and run like 30 degrees of timing.

If you look at those files with the dyno viewer, you will see that if you look at the data in relation to AMP input, the 24 degree timing appears to be better all the time. Yet if you swtich to the RPM based graphs, that's when things get interesting. What I see, is what I would call a 'wider' power band (wider RPM range) with the higher timing.


----------



## DynoMoHum

For those of you who don't have the DynoViewer, or simply don't want to download and look at the data... I have thrown together a very quick web page with 3 differnt images, and a very breif explination of what they are.

http://www.wiltse.net/timing19.html


I would really encurage you to look at the data more extensively with the DynoViewer, I simply can not begin to show you all the subtle differances that can be seen between the various timing settings and how it effects torque, current, RPM, power, etc...


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## David Root

*This stuff is great!*

Perhaps I can get my answer here. What RPM is max on a 4 cell stock motor with a light load. All I am trying to figure out is top speed of my carpte knife. I don't have a clue what the RPM is of my motor at the end of the straight. Its a P2K2. Rollout is in the real low 40s.

I asked in a different forum and aparently there I am stupid.

Thanks all you dyno guys, I am learning a lot about power from all this stuff with out owning a dyno or spending the time you guys do.

And YES mister MO Hum, it seems to me a little more tension on the brush springs bring on a little more torque. So thank you.

David Root


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## tfrahm

David Root said:


> Perhaps I can get my answer here. What RPM is max on a 4 cell stock motor with a light load. All I am trying to figure out is top speed of my carpte knife. I don't have a clue what the RPM is of my motor at the end of the straight. Its a P2K2. Rollout is in the real low 40s.


Well -- The only stupid question is one you don't ask because you don't know you don't know... LOL! You are welcome here... We all started at the beginning too...

Based on what I see with 4-cell stock 12th scale onroad (I also have a 'Knife 3.1) and in 4-cell stock oval, here's my guess...

Even with small rollouts to let the motor "breath", and even with a long straight, the friction and aero drag will probably never let the motor get past around 17,000-18,000 RPM for a P2K2... That is a typical range for my good P2K2's at a 15 Amp load on my TD45 dyno... These motors almost pull that much amperage with NO "load" so I figure that's a real world max RPM range... I'd say use 17,000 as a "typical" value...

Does that help?


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## David Root

*Thank You!* It was my guess too. I figured some where between 17 and 22, closer to the 17 because it is 4 cell.

I have learned much on that other message board, but seem to have out grown it. I am as fast or faster than most on the straight when I am racing stock. Now i am working on my driving skills. That is why I jumped into the 12th scale. I love it. Simple and straightforward Yet the most difficult to master for me so far.

Off Road starts here in a month or two, I can't wait to use what I have picked up over the winter in knowlege and driving skill.

Thank You 
David Root :wave:


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## tfrahm

David Root said:


> Now i am working on my driving skills. That is why I jumped into the 12th scale. I love it. Simple and straightforward Yet the most difficult to master for me so far.
> 
> Off Road starts here in a month or two, I can't wait to use what I have picked up over the winter in knowlege and driving skill.


I've always found that 12th scale hones driving skills more than any other form of racing -- it's all about smoooooth, "the line", carrying momentum in the turns, etc... I've found that stock offroad on a tight, technical track is a close second for many of the same reasons.

My first love is Oval (mostly 4-cell stock now), but I don't get to do as much of that lately....


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## mattlyness

Slightly off topic but does anyone have any Robi dyno data for modified motors particularly the Orion Core Touring 12x1, or indeed for a P2K2.


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## DynoMoHum

I've got lots of Robitronic data, not for 12 turn Orion modified motors, but alot for stock motors, and some for 19 turn motors. I for sure have some P2K2 data somewhere...


What exactly are you looking for in the data?

I may have some 12 turn arms somewhere and could possibly throw one in a can and make a couple runs. However I'm just recently getting into modified motors, and I can tell you at this point the results are highly dependent on the timing and that interpetation of just exactly what is good and what is bad is not really known by me at this time. 

Go back to my last few posts about my 19 turn ARCOR motor and you will get some idea of why I consider modified motors to be whole new chapter in my own personal quest to understand motors and dyno numbers.


I will add that my latest experiance in 19 turn racing was a very positive one. I'm very much looking forward to playing with timing and 19 turn modified motors. My first race experiance with adjustable timing motors was very good.


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## 300M

Dyno: What is the latest version of Mike's Dyno viewer? I have 1.3.5 Would like to be able to print my TD 45 data. Just now getting into oval. My calculations showed a rollout, but motor was flat. Put the data into DV and rollout dropped 1.6 teeth! Showed me what I missed.


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## mattlyness

In relation to the P2K2 it was just for comparison on my motors which are standard. I wanted to see when I start fiddling with them that I am moving in the 'right' direction, or is it just a question of max power and then gear it to suit?
As for the modifieds again it is the same as above, but what would be good power figures for a 12x1, std timing. I only got the motor and didn't get to dyno it before using it and was wanting to gauge if it had gone off much (187 Watts at present, seems low?).


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## DynoMoHum

300M, the newest version of Golden's DynoViewer is 1.3.5. I'm not sure what you mean when you say you put the data into the DV and the rollout droped... The DynoViewer really only helps to gear a motor in relation to another motor. If you line up the torque and power of two motors, then you can refferance the gearing for the second motor if you do it right it works pretty good. When/if you start talking about mod motors, then it can get kind of interesting in trying to do this gearing if you start playing with timing.

Mattlyness, for fixed timing motors like a stock motor I recomend tuning for peak power. A good stock motor at 5 volts is about 62 watts peak, with the highest I've ever seen being about 64 watts. At 7.5 volts the start of a good motor is about 128 watts peak, and I've seen a few up towards 134 watts peak. 

As for the 12 turn... I can't comment much on that at this time. I will see if I can find a 12 turn arm to play with, but my recent experiance with 19 turn adjustable timing motors is that it can get very tricky trying to decide what makes the best motor once you start chaning the timing. The best I can do at this time with regard to mod motors is refer you to my recent posts where I played with the timing on my 19 turn motor. When I ran that motor this past Friday I ran it at about 28 degrees, and then once cranked it up to about 30. It ran better at 30 then it did at 28... On the dyno, it's very hard to see exactly why. The reason why seems to be in the basic shape of the torque curve.

If you don't have Golden's DynoViewer yet, I recomend getting it....

http://www.wiltse.net/zips/DynoViewer.zip

I'm not 100% sure if that is the latest DynoViewer or not, install it and then check to see if it's version 1.3.5, if it's not then down load this other file and use the .exe in it insted of the .exe the instaler put in place. (you won't need to re-install however, just use the newer .exe)


http://www.wiltse.net/zips/NewDynoViewer.zip

PS... if you download the DynoViewer soon, and find out for sure if the main zip file has the newest version or not, please let me/us know... I can't remember for sure it's been so long since I did it myself.


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## 300M

DynoMoHum said:


> 300M, the newest version of Golden's DynoViewer is 1.3.5. I'm not sure what you mean when you say you put the data into the DV and the rollout droped... The DynoViewer really only helps to gear a motor in relation to another motor. If you line up the torque and power of two motors, then you can refferance the gearing for the second motor if you do it right it works pretty good. When/if you start talking about mod motors, then it can get kind of interesting in trying to do this gearing if you start playing with timing.


Thanks Dyno. I still green on the oval so I am still in the seek and find on general rollout. I do a comp of 20 amp number to ge the rollout. What the DV showed me is something I forgot about one of my P2K2's. That one likes less gear, like a monster does. If I max the numbers out without looking at the curve the info is not evident. Looking at the curve the power/RPM dip from high to low in the 20 amp range. So I geared wrong. Could tell in the final as power was off.


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## DynoMoHum

In 4 cell stock racing with a pan car, typicaly we have been running between about 2.3" and 2.6" rollout. I beleive I was told that the track had about a 190' run line. Last time I ran stock my fastest lap times were with about a 2.32" rollout with one of my Monster Motors. I beleive I'd be pushing 2.5" with a P2K2, I might push 2.65" with a P2K if I were to run one. However I also know some very fast guys that can run close to 2.5" with a Monster, to some degree it depends on your ablity to keep the speed up in the corners and/or your driving ablity. I don't think I'd go much lower then this, unless the track was really short and wouldn't hesitate to go higher if the track was longer.


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## David Root

I find this interesting, I gear my 1/12 on road for a rollout of 1.62 or 41mm. Nothing to do with Dyno Data, but I would never go near 2.5" or 63mm. All I would do is go slow or smoke my motor. This is stock P2K2.
I go as fast as everyone else on the straight. The guy that held the track record was geared about the same. I have NO idea what the oval guys use for rollout. the track is 40 X 80 or 40 X 100.


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## 300M

Like David, I was using 42mm rollout on my 1/12. 23x53 track On the oval higher, from memory, the oval numbers are considerbaly higher. Not 100% but like Dyno 2+ David, the 1/12 weight is 28 oz. 1/10 Oval weight is 39.8 That will drive up the rollout. I use the same motors in 1/12 and 1/10 P2K2 or P2K. Monster I have I am not impressed with.


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## Fred B

Are you running Roadcourse in 12th? That's just a little lower than what we were running the ROM at on the roadcourse but pretty close.


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## DynoMoHum

If not already clear, the rollout numbers I gave are for 4 cell stock oval racing. I don't beleive I've ever ran any less then 2.0" rollout this year even on the shortest track. It seems that the rollout that is typical for many of those I race with has gotten higher over this year's racing. If I remember correctly in the begining of the year we were running around 2.2", and lately as I say, even with the Monster motor and it's big RPM we have been running higher then that.

We average about 30 amps, maybe even slightly higher, or I supose slightly lower depending on lots of factors. Near as I can tell we are operating at very close to peak power for about 90% of the race. The cars really don't accelerate that much from the end of the corner to the end of the straight, mostly because the fast guys get through the corners at a very high rate of speed. 

We are running a flat carpet oval that I am told has more or less the same dimensions as the track that was used at the snowbirds this year. I think the track record was like 52 laps in 4 cell stock. My personal best was just 49 laps. The fastest guys are capable of doing 4.5 second laps in the opening laps, and typicaly slow to like 4.7 seconds near the end of a race. My own personal best lap was like 4.7 seconds, typicaly I go about 4.9 or 5.0, my goal has always been to achive some consistant 4.8 second laps and really never quite achived that goal this year. I've spoken with all the fastest guys and my rollout is very close to what others are running, as are my average amp draws. Bascily my problem is driving and car setup. I still don't feel all that bad about my own situation because many of my competitors are really more or less capable of speeds that would do quite well in national events, also because this is my first year of really competitive oval 4 cell pan car racing.


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## 300M

Fred: Yes, road course with the 1/12. Oval with the 1/10 (KSG).
rollout for the MVP is lower. I do not use the moster as it is a RPM freak and I am not partial to those. Prefer the P2K2 as a good all around motor.

Reading my last post I was not clear. For Oval I run 2.0+ rollout. Depends on the motor. 

Dyno, we have a big shootout at our track next weekend so I am not going to give my actual rollout number. Have to have some advantage of my labor and they did not give theirs when we were at their track.  I understand the increase in rollout. In TC we were raising the bar more with higher numbers and more speed. Motors were really getting hot.

I just looked back through my dyno data. Rollouts for my T1 were ~28mm (1.12"). 1/12 was ~42mm (1.68") My KSG, 4 cell stock, the number are over 2.0. I have not checked the discharge nunbers as I have 2 new 3300's I have not cycled. Humm add that to the to do list.

Our track is 132' race line with 7 degree banking in the straight and 14 degree in the turns. Track record was set last week in masters stock. 67 laps 4:02 min In my 2nd week of racing I went from 51 laps to 55 laps  I improved, and had fun. Record laps are 3.5 sec, my best to date is 3.9 My bud did a few pratice laps with the car and did 3.7 sec laps. So I am close on motor, car was tight. The guys are giving me hints on stettings and I am trying to get smooth running the line. I enjoy the racing and that is all that matters.


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## Fred B

300M,

That probably is pretty close for an MVP in 12th. I too dislike the ROM for 4cell roadcourse. It always feels undergeared on the straight and overgeared on the infield.

FWIW, my all time favorite motor for 12th onroad is the GM3. We're running 767's and narrowing up the brushes until we stop dumping. Usually about 7 amps at 3 volts.


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## 300M

Fred: I use the MVP to pratice with and P2Pk to run. MVP is a dog, low on power. Was a freebie and not worth the time to make run. Using 768 in that as it likes them better or the narrow 766. I use the 769's in the GM3's they seem to like that brush.


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## Snuffy

Just thought I'd bump this up to the front.


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## DynoMoHum

Wow... a long lost thread... Seems like we had all exausted our selves out of dyno discussion...


I will say... I started getting into 19 Turn ARCOR motors near then end of last winter's indoor season, and I came to the conclusion that there is MUCH more to judging a motor with adjustable timing then there is in judging one that has fixed timing... 


I'm really looking forward to this fall's indoor action... I'm going to more or less exclusvely run 19 turn class, and more then likely will be using motors with adjustable timing... So I fully intend on going to school on just what makes them tick soon.

Also... I intend to really look closely at a Quad magnet Reedy 19 turn vs. a Two Magnet Reedy 19 turn as soon as possible. I'm VERY currious what if anything can be seen on the old Robitronic dyno with these new fangled Quad magnet motors...


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## PizzaDude

ttt
ttt


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## DynoMoHum

Still waiting on a Quad magnet 19 turn spec motor...

I got me a SIB - MVP stock armature in the mail today... Hopefully I can get some testing done on it this week... 

My RC season is just weeks away, I haven't touched a dyno in about 6 months... I've got to get started soon...


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## PizzaDude

Glenn,
I'm also very interested in your test results. (SIB)
Can you please keep me posted!

Regards,
(Dutch) Pizza


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## tfrahm

Glenn -- This thread is like an old friend, isn't it? That's one of the truly great things about HobbyTalk -- threads don't vanish...


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## vwal

> Also... I intend to really look closely at a Quad magnet Reedy 19 turn vs. a Two Magnet Reedy 19 turn as soon as possible. I'm VERY currious what if anything can be seen on the old Robitronic dyno with these new fangled Quad magnet motors...


That is an accelerometer Glenn!!! Anyway, most of us have found BIG springs and max timing to be good on those Arcor motors. I am looking forward to seeing your results wwith the SIB stuff as well. Also any info you find with the quad mag stuff. I didn't find much difference but I also didn't try much and I know of some who found it better by quite a bit. Keep us updated.


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## DynoMoHum

Ok, vwal... Accelerometer... from here after when you see me type "dynometer" when I refer to my Robitoronic ProMaster Motor Checker, you just convert it in your head to "acelerometer"... That way I can just type 'dyno'... 

One problem I think I'm going to have... I don't seem to have working MVP motors anymore. I either gave them all away, or used the armatures as loads for ESC testing... I guess I'll have to dig one up from somewhere.


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## vwal

No big deal!!! I just think it gets old when "people" call the Fantom that. It is a dyno to all who use it. That is what I am going to be tuning the motor for the contest on so I guess we'll see how close it will get me. There is another guy using one as well that I am sure will be toward the top of the list. I can't wait!! Later.


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## MARSscrutinizer

For the record, Big Jim atached the term "accelerometer" to all accelerometer "flywheel" dynamometers. In reality, it's nothing more than the type of dyno.

An accelerometer is a device that measures acceleration. Nothing more. Nothing less. They're used to measure anything from vehicle acceleration/deceleration (ex:airbags) to part vibration.

There is absolutely nothing wrong with the concept behind any of the flywheel dyno's out there. The theory is the same as what is used in real world dyno's for automotive testing. I might not agree with the way that they are used or made but...they are dynamometers none the less. The Robi/fantom/CS all do provide useful info.


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## Fred B

Dyno,

If you can't find a motor, let me know and I'll get you one.


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## DynoMoHum

Thanks for the offer Fred... I'll keep it in mind. I figured I could find someone who'd let me borrow one. 

I bought a T4 this weekend, and spent most of my spare time building it, so I didn't do any dyno/motor work this past week. I have to do some soon... although the SIB/MVP motor test thing will be pretty low on my priority for now... There is a ROAR Region 5 oval race localy in one month and pretty much all my RC spare time will be devoted to preparing for that. However once I get the dyno out... I may force myself to give the SIB arm a spin...


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## Fred B

I have a new motor that you can use. If you want I can drop it off at Lansing today.


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## DynoMoHum

Sure drop it off with Nick and/or someone and let them know I'll be picking it up, I'll likely be up there next weekend...


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## DynoMoHum

FYI...

Mike Golden has updated his DynoViewer application at my request... (He's really a very helpfull guy)...

A few months ago Matt Lyness sent me a message indicating he was having some troubles opening some Robitronic dyno files with the DynoViewer, he sent me copys of the files. After playing around for a while I discovered that the files that would not open, appaently had not been saved "with line breaks". I stumbled upon this by accident really, but anyway I figured out that if you opened them with Microsoft Word, and then saved them 'as' "text with line breaks" , then you could open them with the DynoViewer. 

It seems that etither the newest version of Robitronic software and/or the newest versions of Microsoft's windows OS save the Robitronic TXT files without 'line breaks'...

To make a long story shorter, I contacted Mike yesterday about this... Today he has given me a new DynoViewer build... I beleive he may have fixed one other issue related to entering TurboDyno Data with less then 6 data points that I just told him about... 

So... if your a fan of Golden's Dyno Viewer, then you may want to download the latest version of it... If Mike actualy updated the version number in the software, this new version is... 1.3.6 (that's what shows up in the 'about' window)

One thing is for sure... this version has never previously been released to the public before today...

http://www.wiltse.net/zips/DynoViewer.zip


Thank you for your time... and thanks Mike for your willingness and ablity to write and maintain this fine piece of code...


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## Denney

Thanks Glenn (and Mike)...this is a great program for us TD users.

Denney


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## DynoMoHum

So Denney... did you get your SIB/MVP arm? Have you had any chance to test it yet? If so... what'd you find out?


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## Denney

I did get it (got a Quad Mag 19T too!). Cut the com (was badly out of round - had to take off 3 thou.), plugged it in a decent MVP (Fantom), and in the 10 minutes I had to make Dyno runs, it looks like it _might be _ good for 2-3 watts @ 20 amps...I'll be able to make a much better analysis tomorrow night. The new QM 19T shows some promise, but the hoods are way out & I didn't get time to align them, but at 28 amps it's only down about 5 watts to one of my better C2's. 

Interesting notes: 
On the SIB arm - sounds really quiet and smooth when I was breaking in the brushes - almost no arcing at all. I'm going to try some other brushes & see if this holds true.
On the QM 19T - until I took it apart I thought it had adjustable timing (I just got the spec version), it has timing marks and a "0" indicator line, nut the lock tab was hidden under the flame sticker. Looks really cool too!

More to follow, Denney


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## DynoMoHum

Cool... 2-3 watts addtional at 20 amps is really nothing to sneeze at. Seems right in line with what I would have expected based on what I've read about the concept and/or patent that it's all based on. If the comm wears less and you get a 2-3 watt improvement, I'd say that's every racers dream... Makes one wonder if/when we might ever see somethign like this in a production motor from one of the Big RC companys... (but they may very well have to deal with the patent holder if it ever does happen) Also makes me wonder why something like this has been around for at least 2 years and hasn't already made it's way into RC racing...

I hope to have a Quad 19 turn this weekend, my timing lock/notch will be gone more or less as soon as I get it.  I also hope to have a MVP can/motor to put my SIB arm in this weekend too... and I hope to have some time to dyno all of what I end up with..


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## vwal

This may just be me but my regular 19t stuff makes it power around 30 amps and my KR can with the same arm in it make the power more around 40 amps. The SIB thing is interesting, now if they would make it for a good stock motor!!! That is personal preference by me, I never have liked any Reedy stock stuff, but the mod stuff I like. Later.


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## DynoMoHum

Well, by most accounts the SIB arm is not legal for something like ROAR, so I'm not sure it matters too much what 'stock' arm they should use. Even so... I bascily agree, that I've never really seen a MVP that I liked much, at least compared to many other stock motors. 

I will also say that I beleive it would be really quite easy for anyone to solder on their own diodes, so you could make your own probably quite easily. At this point I don't know the exact diode that is used, but it's probably pretty easy to get.


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## DynoMoHum

Well... I finnaly got me a 'new' Reedy Quad-Mag 19 turn 'spec' motor... I haven't had time to run it on my dyno yet... however I did break in the brushes (766s) and run it on friends Fantom... 76 watts max at like 10,000 RPM with something like 20,000 max RPM. For those of you firmilar with Fantom numbers and other 'spec' motor... those are NOT good numbers...

I haven't done ANY work on this motor yet, other then breaking in the brushes. I've been told that 766 brushes won't work very well on this motor and/or for 4 cell racing, so I'm not perticularly surprised that the Fantom didn't like this motor. I hope I get some time today to fire up my Robitronic and run this motor on it.


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## HOOPD1

76 watts  was the timing at 0???


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## vwal

Umm HOOP, what was that Bulit arm you had last year?? 78????  :devil: I am sure it needs some tweaking, or maybe a lot for a quad mag deal. I take it, it uses laydowns since it had 766's in it. I put 767 in a KR with a Fantom ARCOR arm and it was a ways over 100. But like I said before the power was made at 40 watts!!!!!


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## HOOPD1

Yeah it was a bulit arm.........thick web paper weight.it ran ok on the track as long as it was geared right.
But not even close to a d5 based one.cough cough putnam cough cough
:thumbsup:


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## vwal

What are you saying?? Maybe you should log onto MSM and we can talk!!! Later.


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## DynoMoHum

The Quad-Mag 19T 'spec' comes with laydown 766 brushes, it has a typical timing lock/tab on the endbell. Up to this point I have only tested the motor at 24 degrees timing, as it comes from the factory.

Ok, on my Robitronic... with 5 volt setting. My only Chameleon 2 that I own is like 89.5 watts peak, with 21,400 max RPM. After cutting the comm on my only Quad-Mag 'spec' motor, it is putting out 86.8 watts, with 19,500 max RPM. Before I cut the comm it was just 84 watts peak, with 19,800 max RPM, this was the first run I had made with it on my Dyno, the only other use it has seen was the single run I made on my friends Fantom.

One of the best Chameleon motors I have ever seen on my dyno was about 90 watts peak, with like 23,750 max RPM. Sorry I don't know what the Fantom numbers were on these...

I beleive I can work with this motor and make it put out more power then my Chameleon2, however... it appears to be a rather low RPM motor. Fantoms may not like it as a result of it's low RPM.


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## DynoMoHum

First off I have to thank Fred B. for providing me with a brand spanking new MVP so that I could do some testing on the SIB MVP armature.... Thanks alot Fred, I really appretiate this a great deal.

I've done a little more testing on both the Quad-Mag 19 turn 'spec' and the SIB Mvp armature with diodes attached to it.

My initial thoughts are that neither of these items seems to show any significant differances on my Robitronic motor checker...

I've ran the Quad-Mag motor and compared it to a Arcornite 19 turn motor, a Chameleon2, and ARCOR/ROAR legal Ti based Fantom 19 turn motor. I've also compared the Ti based ARM and endbell with both the Ti can and the QUad-Mag can. At this time, I must say... I can not see any differnace between the Quad-Mag can and the Ti can... I intend to do more testing, but I really don't see how anything is likely to show up that would convince me there is any advantage to the Quad-Mag for 19 turn motors... at least as far as my dyno testing is concerned. I will do track testing at some time too, but that is going to have to wait while I prepare for a ROAR race where I will not be able to run the Quad-Mag anyway.


The same thing with the SIB/Mvp armature... After a very lenghty breakin period I was able to get the MVP's 766 brushes to seat fully on a .298 commutator. I cut both the stock MVP arm and the SIB diode attached arm down to .298... Initial dyno runs were almost indistiguishable from one another. I'm still in very early stages and in all honesty what I'm doing is not as scientific as I'd like it to be... unfortunately to do something that I would consider more scientific, I will likely have to remove the diodes from the SIB arm... (to do a before and after test on the same armature). Even so... just don't see this to yeild much that I would consider to be truely significant.


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## McLin

You may not see a performance difference with the SIB deal. What they are claiming is that you will get more brush life because of less arching. If that is true or not is to be seen.

From what I have been told (so far) the Epic version of the Quad motor is the lick for 19t. The dyno numbers are not that impresive but the track runs are. I have not personally done either yet.


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## DynoMoHum

I've done another dozen or so dyno runs on the SIB arm and also on a stock MVP arm. It does apear as if there may be less arching and/or comm wear on the SIB arm... However in the case of my two test armatures... the stock MVP arm is always comming out just slightly higher in overall power... even after it's comm gets warn a little... 

Now it could simply be that the SIB arm I have is not quite as good as the stock MVP arm, for reasons that are totaly independent of the diodes attached to the SIB... As I said before, for me to do anything more 'scientific' I will basicly have to disable the diodes on the SIB arm, and I'm not sure I can do that without damaging the thing beyond my ablity to repair it. I can try sometime, but for now I'm just going to sit tight and think of other things I can try to do with it... One of the things I'm interested in is if it does any better or worse with differnt timing settings.

I'm not sure I'm willing to buy a Trinity Binary 19T, simply to test with... but then again... For the sake of full personal knowlege of what may or may not happen with various 'quad' magnet designs... I may have to . If these things were legal for ROAR and/or ARCOR use, I would have more desire... 

But then again... my local tracks stated policy is that in club racing (which is what I do 98% of the time) we can use ANY 19 turn motor... basicly if it's got a tagged 19 turn arm... it's good. So, it's not like I won't be able to use these motors down the road...


----------



## MARSscrutinizer

From what I've heard, the new Reedy 19's need to be trued when they're new. They have to bake the arm when they epoxy the tag in and that distorts the comm. Rumor has it that 767 brushes are the way to go.

I'm not all that surprised that the SIB thing doesn't work well with the sib diodes running to the arm. One question though...does the SIB arm make more mid range power? The high speed switching at lower current draw might be too fast. At lower speeds it might help more.


----------



## DynoMoHum

My testing really shows nothing very interesting really. On the first dyno runs I did, I literaly was unable to notice any differance between the two armatures when I compared the dyno data. Later I cut the comm on both a second time, then for some reason the stock arm started to show maybe 2% increase in power over the SIB arm. Eventualy I will put up the dyno data so that others can look at it, it's just on a differnt computer that is hard to get it transfered and onto my web server.


I was truely amazed and somewhat shocked that I literaly could not tell the differance between the data when I used my ARCOR/Ti arm in both the Quad-Magnet can and in the Ti can... No mater what timing I set them to, the dyno data was within 1% of what it was when the other can was used. With all the talk I had previously heard of the Quad-magnet design yeilding such differnt profromance, etc... I just don't know what to think... I would have fully expcted something differnt... I was so puzzled, I more or less gave up for the time being, with the intention of trying to figure out if I was doing something wrong, and/or if I could think of some other way to test...


----------



## erock1331

Dynomohum, You got mail


----------



## TeamGoodwrench

Hey -- I'm sure this is buried somewhere in this thread, but I didn't have time to dig it out.

If you are comparing motor "A" to motor "B", what is the correct baseline to use ??

i.e. do you look at each motor at different amp draws ?? for example, motor A vs. B at 20 amps, motor A vs. B at 21 amps, etc. etc. and compare watts and torque at those points (knowing that the rpm will be different between them at those points) ?

OR

do you look at each motor at different rpm points ?? for example, motor A vs. B at 10000 rpm, motor A vs B at 15000 rpm, etc. etc. and compare watts and torque at those points (knowing that the amp draw will be different between them) ?

Thx


----------



## BadSign

TG-
No matter what, more watts= more horspower. You just need to know what kind of amp draw you'll be pulling, depending on your type of racing. For stock motors and 6 cells, look at the 20-28 Amp range.

If the motors have different RPM, and you have one geared well, simply change the other motor's gear ratio so they have the same axle RPM.

Just remember your motor pulls the most amps from a dead start, or at least exiting the corner. As the car accelerates, the amp draw drops. A motor with higher 28A Watt #'s will pull harder out of the turn, A motor with higher 20A Watt #'s will be faster at the end of the straights.


----------



## DynoMoHum

I personaly use Golden's DynoViewer and compare power in relation to RPM after gearing has been applied.


----------



## DynoMoHum

I've been searching for a place to post this, I searced the General section of Hobby Talk looking for discussions on brush width, perticularly as it relates to brush overlap, and/or what the ideal width of a brush should be to prevent brush overlap, most of that type of discussion too place on this thread...

For a while, in the back of my head, I was thinking the basic answer could come from math, and/or geometry, but I really don't like to mess with that stuff unless I have to. So I didn't persue it much.

Last night I got to thinking about it again, and today I did some research... I have come to the conclusion that the answer is very simple... 

Ideal brush width is aproxiamately equal to the radius of the commutator. 

I say aproximately mainly because it's really slightly larger then the radius due to the width of the slots cut in the commutator. Adding .005" or .010" to the radius is likely a good number to start with. Best of all... it's easy to remember.

Why? well... its all math and/or geometry. The sine of 60 degrees is one half. Equalaterial Triangles have 3 sides of eqal lenght and all the angles are 60 degrees, etc...

Now there could be reasons why it may not be all a bad thing to have some brush overlap... but too much is not likely a good thing. And what is ideal in terms of actual motor proformance can likely be debated untill the cows come home, and all of us wouldn't agree. But that's a whole seperate issue...


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## TeamGoodwrench

Hmmmm....

Well... if the comm is .285 diameter, then you are saying the brush width should be rougly .143 ?? seems pretty narrow for that size comm.

I've never run brushes narrower than .175


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## DynoMoHum

Aren't standard size laydown brushes like .175" when they are new?


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## DynoMoHum

Does anyone know off the top of their head how big the gap is between comm segments on a typical motor? I'm trying to draw a detailed drawing that illustrates the comments I made earlier, and/or verifiy that my + .005 to .010" is a vaild assumption.


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## vwal

.010 is probably pretty close for a stock motor, maybe slightly larger, .015??


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## pancartom

i just measured a couple of monster stock arms lying on the bench, and they were .020"


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## DynoMoHum

Comm slot width x (sin 60) x 2 + radius of comm.

Sin 60 = .866 

So if the comm slots on a .285" comm, are .020" wide, the largest brush width with out any shorting would be .178"

Goodwrench wins the prize... 
My estimation of how much the slot size mattered was not very close... I apoligize...


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## pancartom

damn, i never win anything


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## TeamGoodwrench

What did I win ???


----------



## DynoMoHum

Exactly what are the actual dimensions of a typical brush?

I thought they were like .175", but that is just from my bad memory....

Using my last formula... the 'ideal' width for a .270" comm is .170"


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## TeamGoodwrench

So what you are saying then is that the benefit from the reduced shorting is greater than the power/torque you give up by making the brush face area smaller.

Hmmmm... now how to prove that is the case ?


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## DynoMoHum

What you won is me stating that I was wrong... Publicly, with an apoligy... Posted a couple posts back...


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## TeamGoodwrench

I believe they are .190 new -- at least that was what the Putnams were the last time I checked.


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## DynoMoHum

I don't think I ever stated that you'd gain anything by reducing the shorting... at least not in this go around...

many of us have been reducing the width of our lay down brushes, with very good results... but I think it's very debatable still if you should have absolutely no shorting, or if you should not care if it shorts... 

I have my opion... that is that reducing the shorting often makes a motor run better... unless you go too far... I also feel triming just the trailing edge is perferable to triming the leading edge....


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## DynoMoHum

Oops.. I now think the formula should be...

(width of comm slot X (sin 60)) + radius of comm

which is (.020" X .866)+ .143" = .160" for a .285" comm...

I'll let Goodwrench keep the prize however... I may owe him more before I'm done... When I draw things, I get a better understanding... I may find more problems before I'm done. Even though I think I'm correct now.

That still doesn't mean that a little overlap is not good... so .175 still may make a faster motor...


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## TeamGoodwrench

.143 is a DARN NARROW brush ! -- esp for a .285 comm

That's .050 off of a new brush -- I've never trimmed more than about .010.

I liked your first formula better


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## erock1331

Hey guys question for you.
I have the putnam jig, that allows you to drill holes in the middle of the brush. When I get brushes that are a fraction wider that are tough to get in the jig my motors all dyno and run better on the track, versus brushes that slide right into the jig.
This is with Putnam and 767 brushes.

Anyone else experience this? 

Which brings me to another question. if the ever-so-slightly wider brush works then why would you want to time the brush. i have tried taking some of the trailing edge off and it only reduced the numbers on my dyno.


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## TeamGoodwrench

It's probably because those tight fit brushes are getting less brush cock then the looser ones.


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## David Root

*In MY expierence*

I work on large DC motors in the 300 to 600 amp draw size with many segments on the comm. The one thing that is for sure if we want to increase RPM and Reduce Torque, we have a SHUNT across the fields to weaken the magnets and create a larger amp draw to the motor.

SO, think of the reedy MVP, its a high RPM motor. Reduce brush overlap like Big Jim recomends and you have torque again. I think this could work on the moster stock too. 

All this makes sense to me. Strong magnets make more torque, Lots of brush overlap makes for more RPM. Cut down on the magnet strength and RPM comes up while torque goes down. Cutting brush overlap will reduce amp draw (ask any 1/12 scaler trying to make run time) and torque will go up. "narrow the brushes and gear it to the moon"

David Root


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## HOOPD1

tourque x rpm= power,so you have to find a happy medium as far as brush overlap is concerned.
I hope the new reedy stock motor is decent the MVP was a sad specimen indeed.


----------



## DynoMoHum

Here is my preliminary drawing...

No explination of the Trig yet... but I have a start, and it should make some
things clearer I hope.

http://www.wiltse.net/nb.pdf


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## DynoMoHum

.148" X .190" is what the first 6 or so brushes measured when I picked some old ones at random from my box.

.020" comm slot on the first arm I looked at...

TRinity 4379 dual shunt P-94 brush... .175" X .200" ( I thought those were suposed to be square?? )

Goodwrench... that last formula comes out to .160" brush width... .143" is for a comm with comm slots that have no measureable width... when you figure the .020" slots, it adds about .017" to the imaginary brush size. Imaginary because there is no way to have a comm slot that is .00000" wide...

I still think that having some overlap can be good, so .175 is probably pretty good in many cases... what's .015" ??? less then the width of the comm slots themselves...


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## DynoMoHum

Ok, I've got a slightly more detailed drawing and explination of how I come up with my formula... I've also created a new term that better describes what I'm really after... Non Shorting Brush Width (NSBW)

http://www.wiltse.net/pdf/nsbw.pdf

Looks like I'm going to need a second page to explain how I'm accounting for the addtional brush width that comes about by figuring in the width of the comm slots. I'm not done with that part yet.


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## McLin

Dyno - You have way too much time on your hands LOL


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## erock1331

I was thinking that same thing, LOL
My question is if you cut the brush width down so it doesn't short does it make the motor better? if not then why all the work trying to figure this term out?
You would think brush manufacturers would have caught onto this and design brushes like that.


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## DynoMoHum

Page 2...

http://www.wiltse.net/pdf/p2nsbw.pdf


Narrowing the brushes down from full size lay down deffintely helps the proformance in many cases. In my humble opion, one thing is for sure... taking a brush down to less then NSBW is not good, and should be avoided at all costs. 

Some manufacturers have though about this... Trinity came up with .175" wide P-94 brush... how they came up with .175" is not known to me. 

Reedy made a 'mid sized' comm to match their comm to the size of a laydown brush....

They've thought about it... maybe not as much as I have , but they have thought about it.


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## DynoMoHum

By the way... my Reedy Quad Magnet 19 turn motor has a .350" comm, the comm slots are .025". Using my calculations... the non shorting brush width would be...

.197" The lay down brush is .190" wide which is too narrow in my opion.

The comm will have to get smaller then .336" before it starts to have any overlap.


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## Mike Wilson

Why not just turn it down to about .335 or so and run it there. Just a curious obversation.


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## DynoMoHum

Well... I could do that. However I think at that point, at least half the life is gone out of it. My understanding is that the thickness of the metal on those comms are not any diffent then the thickness of the metal on a standard comm. Standard coms start about .300 and can go down to .270... If I can go down .030 from .350 on the big comm, that means .320 is about as low as you should go. 

You can always cut a brush down to size, it seems like it'd be better to start with a brush that had slight overlap, and allow the user too cut it down as needed.

I'm going to be doing some testing on some P-94 brushes soon. Not many people have much good to say about these... I'm thinking they offer lots of possiblitys in terms of cutting them in differnt ways, etc... The 4379 compound seems to be fairly easy on the comm, and produces good power too.

Oh, another interesting tid bit I noticed while making my drawings... the width of a .020 comm slot is about 9 degrees on a .300 comm. If you trim the leading edge of the brush by 20 thousands, your losing around 9 degrees of timing. I don't know many people who'd willingly give up 9 degrees of timing. So I highly suggest if you do try narrowing your brushes... stick to triming just the trailing edge, that way you won't be losing timing... 

I've tried triming just the trailing edge on just about every stock motor there is. None suffered at all as long as I didn't remove more then about .020". In my opion, even MVPs will run better with just the trailing edge trimed. P2K2s, GM3s, and Monsters all do well with .015" to .020" off the trailing edge.


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## Topstrap

Been intereesting reading all of this. I have a Fantom and I take it to the track every weekend for anyone to use. If they don't know how I'll run the motor for them. I have seen everyones motor and the numbers they produce including a couple of really fast racers that place well at National events.. at first glance their motors don't seem any better than what I or most of the others run.. I've been watching one fella in particular and try to question him about what he's looking at when he runs a motor. He's not after the highest power number or the highest RPM. The last ROM he ran had a 53% effeciency with 21,000 max RPM. The higher effeciency number he has the more gear he can put to it and it'll perform the way he wants. He's fast, very fast and always has the track records where he runs. 

A fella that pits beside me brings his CE45 occasionally and he's also used mine.. he's used to the data his spits out but also knows by the numbers he gets on mine what to do to change his motor or gear his car at. I'm still a rookie at the DYNO info but it's been a really good tool for working with motors.


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## DynoMoHum

I've been doing more contemplating about NSBW... I've got a slight flaw in my formula, probably causes a error of less then .001" when the comm size is close to what we have on our motors. I've got a solution... though... 

It's really insignficant for our purposes... so don't no one loose any sleep over it... I do that, so you don't have to. Seriously... last night about 4AM i woke up thinking about this flaw... Man I need a new hobby to get my mind of this stuff.

But MiniCAD has become my new hobby...


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## vwal

Is it because you can't just measure brush width, you have to measure the curve length?? I was looking at all your diagrams and that is the only thing I didn't see. To me it looks like you are figuring width for a flat object riding on a curved surface? Just curious.


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## DynoMoHum

It has to do with the way I'm calculating the additional brush width allowable as a result of the comm slot. It's slightly more complex then what I did... the error between the way I did it, and the way it needs to be done is proabably something like .0001" or something that's basicly very insignfiicant for our purposes. I just want to get it right, so that no one points out that I'm wrong...  

For our puposes 

NSBW = ( (slot width * .9) + radius of comm)

heck... " NSBW = radius + slot width " is close enough...

The first part where calculating NSBW without considering the width of the slot, is fully accurate as far as I know...


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## Topstrap

Didn't get to finish last night, power went out and I sent the post before the battery backup died... 

He also looks at the 18 amp settings, seems to be the one he's most worried about.. Will have to corner him this weekend and get some Dyno secrets as to what he's looking for when he runs a motor. 

Topstrap


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## DynoMoHum

Dyno numbers can be inerpeted many differnt ways. The numbers from one dyno to another can not be compared directly. This forces you to learn more about the dyno you are using and try to understand the numbers it gives. All dynos give numbers that could easily be misinturpted, if the user is not carefull. I know my Robitronic numbers pretty well by now, but I don't think I could tune with a Fantom to save my life. If I had a Fantom, and no other dyno, I'm sure I could figure out a way to use it eventualy. I've owned a CE TurboDyno, and I could use one of those right now pretty well if that was my only option.


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## stevent

What dynos are still being produced?
Stevent


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## DynoMoHum

Robitronic, Fantom, and CS are the only dynos I know of that are still in production. However there are plenty of CE TurboDynos for sale used, and you can still get service on them.


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## DynoMoHum

Ok, for those who just can't wait for the new improved formula...

"Non Shorting Brush Width" = D * sin((arcsin(S/D) +30))

Where...

D is the Diameter of the comm
S is the width of the slot between comm segments

The error in my other formula would result in about .00033" on a .300" comm, about .00037" error on a .270" comm... Now that would have ruined your whole day if you'd had that kind of error, wouldn't it? 

Pictures to follow...


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## DynoMoHum

Yup I think that last formula is about as accurate as can be...

"Non Shorting Brush Width" = D * sin((arcsin(S/D) +30))


I sure am glad I don't have to write math text books for a living... Here's my best effort at explaining this...

http://www.wiltse.net/pdf/p3nsbw.pdf

For all those skeptics... do the math... or just trust me.


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## vwal

Now just make a handy chart for us with all the NSBW of all the comm diameters!!!!! Thanks.


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## Mitchman

When DynoMoHum listed the three dyno's still in production, what does the "CS" stand for? Do they have a website.

I used to own a Robitronic...I sold when I got out of the hobby 5 years ago. Now that I'm back in, I really wish I still had it. I do have access to two Fantom dynos that their owners never use. I've just never used a Fantom before!

Thanks for keeping up a great thread!

Mitch


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## Green

Problem fixed...


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## DynoMoHum

CS is CS electronic, the dyno is known as Power Check. It's basicly a poor mans Robitronic. I don't really mean that in a truely offensive way. People who own them tend to like them, they are cheaper then the Robitronic, which is a big attraction because as we all know the Robitronic is not cheap.. (about $750 new these days I think). My understanding is that the CS can be had for about the same price as a Fantom when new. (something like $450 or so.). The CS does not have a regulated power source, it basicly is designed to use a rechargable RC battery as the power source for the test motor. They seem to market this as one of the most desireable features of their dyno... that it uses the same power source as the motor would use in your vehicle... That's all interesting in concept, and may indeed have some value as a test... However in my opion, it's also a draw back to the dyno, and potentialy a problem for the users. It's also very likely the reason they are able to sell the dyno much cheaper then the Robitronic.

http://www.cs-electronic.com/CS-Produkte/Power_Check/power_check.php

Anyway... potential users of the CS dyno should be prepared to deal with the fact that the power souce's voltage may not repeat itself very well, depending on what exactly is used as the power source. If it's a rechargable RC battery... the voltage will drop with each dyno run you make, untill you recharge the pack. Some users report they get at least 6 consistant runs, and maybe even more. Other users use two packs in paralell, so the voltage stays consistant longer. Still others use 6 volt lead acid batterys that they keep a trickle charger on, etc... Many ways to try and deal with the issue...

Then there is also just buying a differnt dyno that doesn't have the issue. 

I fully admit that it would be nice to be able to ocasionaly test a motor with the RC battery pack as the power source. I just think it's better as a option, then the norm.


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## Guest

DynoMoHum, It's nice to see someone that sees things the way I do. I came to a simmilar conclusion 6 years ago (the last time a raced). The only problem with your equation is that it is right on if you trim the same amount from each side of the brush, however if you "time" the brush by removing only the trailing edge of the brush the numbers are not right (the brush orientation is no longer at 90 deg to the comm, it has now advanced several deg.). My equation as follows takes this rotation into account. I know it could be simplified however it is stored in my calculator. I also know I have way to many operators however this is to make sure my trusty calculator doesn't choke on it.

Where
B = Brush width
D = Comm diameter
G = Gap between poles of the comm

(sin(180-(arcsin((B/2)/(D/2)))-(60-(arcsin(G/D)/2)))*(2((D/2)sin((60+arcsin(G/D))/2)))

This equation will yield a brush width of .1489. As I said before it is really great to see someone on the same page as me. I hope to be racing again soon. My oldest son will turn 7 early next year and I think santa will be bringing him his first rc car (ok so that will just give me a reason to get back into it, I miss it).

Dave


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## DynoMoHum

Well thank you for doing what I wasn't going to do... Figure out what it would be if the brushes weren't trimed evenly on both sides... I knew my equation didn't work, but I had made up my mind that it was close enough... and I wasn't going to do any more math to figure it out... It's not really something I enjoy all that much, and I just simply had, had enough... 

Thanks for the follow up on the issue.


----------



## DynoMoHum

Oh, one more thing... if your still in the mood... Think about what happens if/when your brush hoods are not aligned perfectly...


----------



## calvin

Or when your brushes get shorter and cock more


----------



## Guest

Well, lets see. This is a set-up I would only use at a large race. At these races when you only make several runs a day and they are hours apart you have plenty of time to make sure your brush hoods are aligned properly. If you are looking for a formula to describe intentionally shifting the brush hoods to advance timing it would be fairly complicated as many times the misalignment is caused by a slightly deformed brush hood and not just the gaps between the screw and the brush hood and the spring perch and the brush hood being uneven. Also to the best of my knowledge this would be illegal by ROAR rules. ROAR states that the brush hoods must be aligned at 90 deg. As far as the brushes getting shorter and cocking more the result would be similar with or without the brushes being cut as the depth of the cut would not have to be deep enough to actually enter the brush hood. Also I wouldn't expect to run a set of these brushes more than two runs before changing them or shelving the motor. By the way, the following equation will tell you how much the cut of the brush has advanced the timing of your motor.

arcsin((B/2)/(D/2))+(60-(arcsin((G/D)/2)))-90

In the case of our comm being .285, brush width being .190 and the gap being .020, the new timed brush width would be .1489 wide and the advance would be 9.7995 deg. If you were to cut the comm to .273 and your brush to .1419 you would then have a 36 deg motor in a 24 deg can. Just something to think about.

Dave


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## DynoMoHum

I don't have any disagreements with what you've said. However experiance tells me that reducing the brush width to .149", even when it's all removed from the trailing edge... will reduce power output when compared to a brush width of say .170" or so.

I'm just bascily saying that a little bit of brush wrap doesn't seem to hurt much, in fact it seems bennifical in many cases. Even so... my personaly opion is you should never trim the leading edge, as that will clearly retard the timing and I really don't see any point in doing that.

One other thing I've observed... as a motor wears and gets pitted near the comm slots, the motor tends to behave as if the timming is going up. My thinking is that the comm slots are effectively getting larger (as a result of the pitting)... The reason I bring this up here now, is that I'm thinking that when this happens, the brush width can get wider without shorting. So... I think it's best to be conservitive when you start triming the brush width, start small, and maybe none at all unless you feel you need more effciency or have some other purpose behind your desire to trim the brushes.


----------



## Guest

Wow, I never thought of the pitting actually simulating the increased gap, but I can see that it is logically possible. One thing I do know is that thinking like this can give a huge advantage on the track over others who do not put this much effort into the process. I know that similar thought allowed me to finish 5th at the 91 US Indoor Champs (12th stock) while using 1400SCR's that were like mid 290's (20A) with good voltage (The expensive 1400SCR's were probably 310's - 320's at the time). Most people were using 1700SCE's or the P-170 Panasonics which both had far more run time (and they were using it all even in stock). It just kills me the way people will chuck up big bucks for the best packs on the market while ignoring things like brush overlap which in all actuality is taking the gains from the mega batteries and producing less output (on the track) than using average batteries with an efficient motor. Dyno, What classes do you race. Most of my experience has been in 12th on road and the now almost extinct 10th on road (pan cars). Also the pitting you have noticed, is it only on one side of the comm pole or both. Is it possible that the pitting is actually caused by the huge load of the shorted portion of the comm pole. As far as the Robitronic dyno you use, what do you think of it? That may be a purchase for me when I get back into it. My dyno experience was mostly with the Fantom unit (I was sponsored by them in the early 90's). The Robitronic seems pretty cool the way you don't need to have your laptop connected to use it, and I think i read something about using it as a battery charger. Is it possible to change the voltage to simulate a 4 cell pack as this is what I will be doing again? Nice talking to you again.

Dave


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## DynoMoHum

I race 4 cell oval. Lots of stock last year, this year I've moved to 19 turn class with adustable timing. I'm at best a average racer, my cars tend to go fast in a straight line, but I get beat in the corners on a regular basis.

The pitting occurs only on one side of the comm slot, I don't remember which side off the top of my head. Typicaly you will have to cut the comm about .001" or more to remove all the pitting on a motor that has more then a run or two on it. Some times you have to remove .005" or more if you really let your motor go. I never let mine go that far. I know for sure it makes the motor proformance change as this pitting changes (grows). Quite frankly, I think it can actualy inhance proformance in some cases, if it hasn't gone too far. Knowing when to cutt the comm and when to not cut the comm is tricky as a result. I personaly think it's not nessasalry a good thing to cut the comm after every run. Most people don't anyway, but sometimes at big races they will, and I actualy think they may be hurting themselves sometimes if they do that.

I've done some recent dyno runs that I will post sometime soon. Where I took a fresh motor, clean comm, broken in burshes... then ran like 20 consecutive dyno runs... you can see the RPM increase with each run... I've noticed this previously, but I've never really attemted to document the phenomina. 

In my opion, the biggest draw back of the Robitrnonic dyno is it's price. THey are about $750 new, and you rarely see them for sale used. I have seen some go for like $400 to $500 on ebay. I personaly bought mine used for $500 about 4 years ago. I have absolutely no regrets with my Robitronic purchase. You can adjust the voltage from like 4 to 8 volts. They claim they 'simulate' the voltage drop of a NiCd, so the higher the load, the lower the voltage as you run the test. In all honesty, the voltage drop of their 'simulated' NiCd is too much... For sure it doesn't simulate a modern NiMh internal resistance, and I'm not even sure it did a very close simulation of a NiCd... But to me it's a very minor issue, I just set the voltage so it achives the voltage I want at a perticular load. For my 4 cell racing, I've found that the 6 volt setting yeilds 4.8 volts at the motor as it is pulling 30 amps. I average 30 amps in my racing, and a modern NiMh cell will easily put out 4.8 volts with a 30 amp load on it... at least for the first 3 minutes or so of the batteries discharge...

Anyway... All dynos have their own pros and cons. For my purposes, the Robitronic suits my needs best.


----------



## Guest

Oval huh, I only did that a few times (I ran for wood racing for years and Mike Sr and Jr talked me into it a few times). What I can say about oval racing is that if your car is not dialed in perfect all the motor in the world will not help. I always had problems with this. I could take my car out, feel like it is rippen (it may have been fast, but not dialed) only to find I would be like .5 sec / lap off the pace. oval races (in my opinion) are really won in the pits with countless hours spent working on the chassis and motor. I almost think, believe it or not that the chassis is more important than the motor. You can be the best driver in the world but without the car being dialed you'll probably be in the middle of the pack. In other words if you are not the fast guy it's probably not the driving (with your thoughts on motors it doesn't appear to be that either) it's probably the chassis (just some thoughts).

If you get a chance try using my equation on a stock motor and see if the pitting still occurs. If it works for a 4 cell oval racer I'll know for sure that it makes power.

As far as the dyno goes, thanks for your thoughts. I do have one other question though. Which curve on the Robitronic best relates your motor's ability to accelerate. For example on a tight twisty track I would probably be looking at this curve to be the highest (in relation to other setups/motors) from 1/4 to 3/4 of the RPM band as where on a more open track 1/2 to 100% would probably be the area to look at. Which curve am I most interested in. Thanks again.

Dave


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## SpeedBump57

Hey Dyno!
I have been reading this therad since the begining. I just wanted to thank you for all the great info and wanted to ask you a question.
I'm haveing a hard time understanding this formula. I have put it in excell and can not make it work. =sin(arcsin(.020/.275)+30) Is this how it should go in? What am I missing? Please Help.

Again Thanks for all your effort!
SB


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## DynoMoHum

Somewhere I had a typo... I know on the pdf file I last posted there was/is.... I'll go back and look at my postings here and correct if needed.

the formula really should be what you have... times the diamter of the comm...

'NSBW' = D * sin(arcsin(S/D)+30)

Where D is diameter of the comm, and S is the width of the slot.


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## SpeedBump57

Man I am sure glad there are people out there like you because math wizzard I'm not. If sin=.866 what is arcsin. I think this is what I am missing!
Thanks
SB


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## DynoMoHum

man you had to ask that didn't you? Me, I'm no math wizard... I barely made it though college algabra, and a intro to calculus... I rarely do math in my daily life. I strugled just to get as far as I did...


arcsin is the inverse of sin, more then that... I can't say...


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## SpeedBump57

LOL you sound like me! I have been playing around with Excel and found out that arcsin is not listed as a function. Instead you have to use ASIN which the same thing I think. Here is its definition (Returns the arcsine of a number in radians, in the range -pi/2 to pi/2. If I enter this formula "=SIN(ASIN(0.02/0.27))+30" this is what I get (30.074). When you have time do a copy & paste and see what you come up with. That formula is right out of your PDF file. Which is very nicely done by the way. You ever have one of those things’s you just have to figure out or it drives you nuts!
Thanks
SB


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## highster

Hi all,

I just purchased a Fantom dyno, even though I haven't got it yet, I'm looking for some advice on set-up and usaage. I have never used a dyno before so anything that you could offer is greatly appreicated. If you know of a web site or something that would be great also. As I have no idea of what I'm even going to be looking at. If it matters we run mostly oval.

Thanks,
Tom


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## highster

I have been reading alot of the older posts here, and I downloaded the DynoViewer, from Mike, my question is how do I get some of the Fantom data, that I also downloaded into it? I just can't figure it out. I know it's so simple, but I'm lost.

Thanks,
Tom


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## amainiac

I'm not sure if this thread is strictly motor dyno's but I just recently got a Thor chassis dyno (without instructions) and need some help with it. If anyone wants to share some instructions, it would be most appreciated.


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## chicky03

1Loosenut,

Email me at [email protected] with your address and I will send them to you.

Paul


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## amainiac

Chicky, I sent you an email and thanks for the help. Also thanks to Hobby Talk for such a great forum. This site has helped me tremendously :thumbsup:


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## DynoMoHum

Anyone know anything abuot this?

http://www.land-and-sea.com/images/dyno/auto/chassis/chassis_dyno_rc-car.htm


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## vwal

No, but that is pretty cool though!!!!


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## highster

Looks cool. Did you call them for info yet?


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## DynoMoHum

I didn't call them... I thought maybe someone could tell us more before I called... 

The caption reads something like... ' a customers RC_dyno' it sounds like someone custom made it, and for all I know it may not even be functional. Since I'm not really in the market for a dyno... I wasn't really in too big a hurry to spend any time investigating it... I guess I'm just plain lazy in this matter...

It really does look cool...


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## DynoMoHum

FYI...

EPIC Bin2 'outlaw stock'... 

Mine ran like crap out of the box. I did manage to get it running for 4 cell voltages, and I can see where this motor deffintely has the potential to be very fast if geared right. 

So far I haven't been able to get mine to look good at 6 cell voltages, but I haven't really tried too hard just yet...

I have been told by a very reliable friend of mine that racers at the champs were able to get them to run well even at 6 cell voltages... In fact from what I've been told, at least one guy had one that was puttin out 135 watts peak on a Robitronic dyno at the 7.5 volt setting... The best motor I've ever seen on my Robi at that setting was about 134 watts... a typical good motor is 128 or better... 

Where this and other high RPM stock motors really shine however is at the high end... My early data tells me this thing really puts out near it's max RPM... My early impression was not so good for this motor, but I guess it takes a little time to figure new things out... but from what I'm seeing, and from reports I've heard... this motor should be faster then a Monster... 

On the ohter hand... I'm not sure these high RPM beasts are very good for the novice... my experiance is that the more RPM a motor has, the pickier it is about everything... from gearing to spring choice.... Probably see alot of these babys go up in smoke... by either people pushing them a bit too hard, or by people who don't know what they are doing...


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## pepe

DynoMoHum said:


> I didn't call them... I thought maybe someone could tell us more before I called...
> 
> The caption reads something like... ' a customers RC_dyno' it sounds like someone custom made it, and for all I know it may not even be functional. Since I'm not really in the market for a dyno... I wasn't really in too big a hurry to spend any time investigating it... I guess I'm just plain lazy in this matter...
> 
> It really does look cool...


Hmm,looks very interesting.I couldn't find out anything about it on the website though.Looks like a true dyno though.


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## SpeedBump57

A while back in this thread we talked about trimming the trailing edge of a brush. I think I might have been confuesed as to which edge that is! So which edge is the trailing edges so I can make sure I've got this right.
Thanks
SB


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## DynoMoHum

See if this answers your question about the trailing edge...

http://www.wiltse.net/pdf/tet.pdf


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## SpeedBump57

Dyno and company you guys are the greatest!

That is exactly what I needed. I have been playing with trimming the edge of the brush for about a month. My motors have been improving but a couple of times some of them have been running a little hot, which is not normal for me. I thought maybe in my head I got the wrong edge filed. After seeing your drawing this is not the case. Thanks very much for the file! About the same time I started to play with trimming I also replaced the Schottky diodes on my motors for the Novak in line version. The thing of it is I don’t have a Novak ESC. I have an LRP 7.1 and LRP quantum sport, the package says it will work on any ESC. I don’t have any problems with hot motors with the quantum just the 7.1. So now I am thinking either I got a bad inline part or the 7.1 does not like this setup. Has anybody here run this inline setup with an LRP 7.1? If so any problems.

Thanks
SB


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## Fred B

*Data Acquisition and Dyno's*

With a real acquisition package just around the corner from Eagle Tree, what does everyone think the best way is to compare Dyno data to track data? I've been playing around with some spreadsheets and was wondering what others would do.

The main thing that I'm thinking about is how do we use the on track data to calculate what the correct gear is for that track and motor based on dyno data?


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## DynoMoHum

First for SpeedBump... I personaly never use a Schottky... but I race oval, and my understanding is that the Schottky mostly comes into play under braking... I tell you that bit of info, mainly because what I'm going to tell you next comes with virtualy no experaince with a Schottky diode on a RC motor...

I see no reason why a Shottky diode would casuse a motor to run hotter... 

Narrowing a brush should make a motor run cooler in almost all cases that I can think of... The more you trim off, the cooler the motor should run.. In ohter words I don't think your triming the brushes are the cause for your motor to heat up...

I'm not sure what else to tell you at this point... perhaps somoene else has something for you...


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## DynoMoHum

As for Fred's question/comment...

Well... I wish I had me one of them data acquisition systems, maybe I'd have more of a opion... Having said that... I still have a comment... 

Clearly the way you use the info is going to depend on the dyno you use... My Robitronic is going to give alot differnt info then will a TurboDyno... so it seems I'm almost just going to have to wait and see, use trial and error to figure it out.

In the mean time... I'll have to think a bit more about this... I do like your question alot... 

I just can't wait to get me one...


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## TeamGoodwrench

I have a Quantum Competition... I quit using the Schotty thinggies completely.

I know the instructions say to put them on the motors, but I had radio glitching with one of them and that did it for me. There are 19-turn mod guys at our track that run that speedo too and also do not use the diodes.


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## Fred B

Just so everyone can get an idea of what the data would look like from the logger, I'm going to attach some data from the old logger that is currently available. I didn't have the amp data at this time but it runs from 35 amps off each corner down to 15 amps at the end of the straight. You have voltage and RPM so you can figure the current from the dyno.

Sheet one is a graph of one lap (4 minutes in), sheet two is the raw data and some calculated data in red, and the final sheet is a crude sketch of the layout. Each turn is marked on the graph.


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## PizzaDude

That looks great.
Better then the cockpit look posted earlier?! IMO

Data in graphs, data in tables, summary and a track explination!
Only one important quastion to this.
Will there be a compare(baseline-new test) function in it.
to test run 1 and 2.
By putting the graphs upon another!?
Is a deffeinative MUST have.


I want the DAQ ASAP...Full options!


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## PizzaDude

Also V at battery and at motor ould be interesting. as well as temp battery, temp motor..

But aren't we getteing off topic on this thread.
Oops


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## SpeedBump57

Thanks Dyno!
I really wasn’t implying that the Shottky diode it self was causing me to run hot just the way I had it installed. As for the trimmed brushes I thought maybe I had the leading and trailing edge mixed up and was actually trimming the leading edge by mistake and thought maybe that would make it run hot. The file you posted confirmed that I had it right Thanks. I think I have found my problem though. I have a Losi XXXT and have been playing with different diff setups mainly the diff balls. I have been using all grade 3 silicon nitride balls (Ceramic Balls) which really make a difference. They last much longer and are much smoother. Anyway last night to prep for this weekends race I did a rebuild and took a real close look at all the diff parts and discovered that the thrust bolt was slightly warped. I replace the bolt and have no more problems. My guess is that was causing the diff not to work properly and maybe with to much drag. I really wasn’t running to hot just hotter than normal. I usually run around 150-160 and had jumped to mid 180 and could not figure out why.
Thanks for all your help!
SB


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## hankster

PizzaDude, The new DAQ will only check voltage at the battery and amp draw. But then at full throttle the battery and motor voltage should be the same. It can check temp. in 2 places. Anyways, there is a thread on the new unit at http://www.hobbytalk.com/bbs1/showthread.php?p=628998 Might be best to take this discussion there not to clog up this thread.


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## Roadsplat

Just wanted to bring this thread back up for more discussion


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## MarcosGraveyard

Sorry for bringing up an ancient thread but I have bought an old Robitronics Dyno to test and compare the Tamiya Black Can motors that I race in Tamiya Mini's over here. 
I have just read all the previous 816 posts and have learned a lot.
Is Mike Golden's DynoViewer program still available anywhere ?


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