# Stock motor amp draw



## Ernie P. (Aug 30, 2003)

I have some questions for all you guys who know more than I about how RC motors work:

Assuming a properly asembled and moderately well tuned Stock Class motor; what kind of amp draw do you expect to see, while running in the brushes at 2.0 volts, on a Turbo 35?

What, if anything, does the amp draw predict, as far as motor performance?

Same questions for Spec and 19-turn (both 0 degree and Open motors). Thanks; Ernie P.


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## MARTIN (Feb 26, 2004)

Monsters/epics Seem To Run Best Pulling Around 8 Amps
19turn Flat Track Around 8amps At 24 Deg...banked Track 12plus AMPS AT 36 DEG.


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## DynoMoHum (Sep 25, 2001)

Stock amp draw under no load... predicts almost nothing... Many people will argue otherwise... The ones who argue otherwise, basicly will tell you... the more the better...

Personaly I think of amp draw is like this... Does knowing how much gas your car burns at a idle tell you anything about how fast your car will go? or how much horse power your motor produces? Well no... well maybe... well sort of... but not really.


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## bsracing8 (Dec 14, 2004)

The more the better i never seen anyone dump in stock so i dont think 2 much amp draw will make you dump. 

Brandon


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## Z-Main Loser (Nov 17, 2004)

High amp draw doesn't mean alot. Its like dyno #s. Just because it has high amp draw doesn't mean its fast. No you won't dump in stock but a motor that draws higher amps will make the lap times slow down as the race progresses. Another thing amps can tell you is how well the brushes are seated. When start with new brushes the amps are high. As the brushes break in and seat the amps will go down. Todd Putnam has said that if the amps are over like 9.5 then trim the face down alittle. Thats with a broke in motor. I'll try finding the post so you can see exactly what he said. I don't want to put words in his mouth.


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## Z-Main Loser (Nov 17, 2004)

It depends on amp draw more than comm size. More amp draw does not equate to more power...
We start at about .180" (+/-) with the comms in the .290-.295 range. As the comm get smaller, we'll take more off if the amp draw increases. The max amp at 2 volts is 9.5 amps with a fan. Any more than that any your batteries are being wasted and excessive heat is the result...

Regards,
Todd Putnam
Putnam Propulsion
www.putnampropulsion.com
518-452-0422


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## Ernie P. (Aug 30, 2003)

*Amp draw*

Thanks for the tips, guys. I appreciate the info. Thanks; Ernie P.


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## jbm38 (Jun 1, 2002)

I'm curious as to why my best stock motors always had a draw of 10+ amps? That was on the turbo 35 @ 2v with fan.


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## bsracing8 (Dec 14, 2004)

john all mine are like that and they run good. maybe we can get a good stock class going at marshalls when you come back!!


Brandon


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## Racin'Jason 8 (Nov 19, 2002)

Just because a known good motor pulls high amps is no foundation for saying that all high drawing motors are fast. Amp draw can come from many different places such as tight bushings or shorted windings - it does not necessarily mean that the motor is producing efficient power.


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## HyperformRacing (Apr 28, 2005)

No load amp draw means nothing. Same with no load "dynos"... A motors characteristics change drastically under load. The monster I'm running in sedan right now pulls around 7 amps at 2 volts once fully broken in and it is a BEAST on the track... 

It's a tough mind set to change, I know. My eyes still light up when I see a stock motor pulling 12+ amps during break in. I have to stop and kinda slap myself...


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## jbm38 (Jun 1, 2002)

Whatever happened to the "load" dyno??? I remember way back someone made a dyno that you put the car on and run it to get the output numbers.
Wish someone would make something like it again. Maybe Fantom or Competition Electronics could make a NEW chassis dyno for touring and oval cars. I think that would be great!


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## erock1331 (Apr 1, 2002)

jbm38 said:


> I remember way back someone made a dyno that you put the car on and run it to get the output numbers.


Thor Chassis dyno 
Some still use them at our local track.

Supposedly the way it worked, and I could be wrong (this is what the owners of the dyno told me).
Say you had a really good run with a super stout motor. Well the dyno gave you 3 numbers on the volt meter to look at. Then the theory was you were supposed to put another motor in and it would tell you how to gear that particular motor so it would run like the motor you ran when you were fast. 

But I don't care if you hit that motor's perfect gearing, if the motor is a dud, its still going to be a dud on the track. Otherwise we would never worry about putting the best motor in our box in the car for a race. The way this dyno supposedly works you should be able to take your practice motors and theoretically run a track record. I didn't get it.


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## erock1331 (Apr 1, 2002)

HyperformRacing said:


> No load amp draw means nothing. Same with no load "dynos"... A motors characteristics change drastically under load. The monster I'm running in sedan right now pulls around 7 amps at 2 volts once fully broken in and it is a BEAST on the track...


Do you use a CD Turbo dyno then to test your motors?

I just wanna know how you determined that 7 amp motor was a good one?
Did you dyno it on a load dyno or did you simply let it's track performance do the talking?


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## HyperformRacing (Apr 28, 2005)

I use a turbodyno 45 on all our motors...


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## Ernie P. (Aug 30, 2003)

*Turbodyno 45*

Would you mind sharing the setup you use on the Turbodyno, to test motors? Thanks; Ernie P.


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## dave w 1 (Apr 28, 2005)

i have a turbo dyno to and many a "killer" motor from a fantom have fell victom to my turbo dyno . the 30 amp load makes it a player or a pimp! ps i use putnams steps for stockers !


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## HyperformRacing (Apr 28, 2005)

My setup is pretty standard... For stock and 19turn 6-cell, I test at 7 volts with a 15, 18, 20, 22, 25, and 28 amp load. For stock and 19turn 4-cell, I test at 5 volts with the same load settings.

Dave w 1-the fantom always seems to show the highest rpm motors as being the best.


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## erock1331 (Apr 1, 2002)

I know many do not put faith in the front page of the Fantom dyno's numbers.
But how accurate to on the track performance is the "4-1" screen.
Where it shows the amp steps....can they be relied upon??


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## erock1331 (Apr 1, 2002)

I ran into the same deal with my Robi dyno. They could be 70 watters on a Fantom, but a turd on the Robi. For a flywheel dyno I had to give the robi credit.
The dyno usually predicted what ran good on the track.


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## bsracing8 (Dec 14, 2004)

dave w 1 said:


> i have a turbo dyno to and many a "killer" motor from a fantom have fell victom to my turbo dyno . the 30 amp load makes it a player or a pimp! ps i use putnams steps for stockers !


Yo you have a turbo dyno sweet!!!! And you are a ~PIMP~. 595!!! 

Brandob


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## Z-Main Loser (Nov 17, 2004)

Erock, for the most part it is accurate. I always look at the 20 and 30 amp steps. The closer the rpms are the less it will struggle in the corner. The max power should come close at 30 amps. Of course the higher the rpms are at both 20 and 30 the better. I've seen motors with high front page #s but because they didn't look good at 20 and 30 amps they didn't run good and motors that ran good looked bad but had the numbers at 20 and 30 amps.


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## TnOvalRacer (Apr 17, 2005)

erock1331 said:


> I ran into the same deal with my Robi dyno. They could be 70 watters on a Fantom, but a turd on the Robi. For a flywheel dyno I had to give the robi credit.
> The dyno usually predicted what ran good on the track.


I also got a Robi. Can you share your setup for stock motors for oval use, please !!!! I want to compare my readings later on with your setup. Thanx :thumbsup:


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## erock1331 (Apr 1, 2002)

TnOvalRacer said:


> I also got a Robi. Can you share your setup for stock motors for oval use, please !!!! I want to compare my readings later on with your setup. Thanx :thumbsup:


Dyno was set at 7.5v input.
When I had the robi on the main screen I looked at Watts, Max RPM, Max Torque. Then I would also set the preferences so it would calculate the average watts for the 18-26 amp range (this is the number I thought was the most important).

Some benchmark numbers:
Monster motor:
On the main screen:
Max Watts -- 
128+ (75 degrees or less in the room) 
124+ (is a good number if the room you are in is real hot over 75 degrees)
RPM -32,500 (decent) - 34000 (awesome) 
Torque - 78 (decent) - 80+ (awesome)
Average watts (18-26 amps) - 100 (If you can get the number 98 or above it usually rocks on the track)

On the 22 amp step on the bottom table, this is what I used to gear, every 800 diff in RPM was about a tooth:
RPM - 23,500 (decent) - 24,000 (good)

A good Epic Roar Stock motor:
Max Watts - 125-126+
RPM - 33,000+
Torque - 75+
Average Watts (18-26 amps) - 96+
22 amp RPM - 24,000 decent - 25,000 (good)

The reason I sold my dyno was the Epics with lower dyno number's were outperforming my Monsters with higher dyno numbers on the track. Only thing the EPIC's had more of was RPM.


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## "Frank Ulbrik" (Oct 21, 2004)

*....*

I always have rip in stock on flat tracks with this amp draw at 2.0 V with a finishline fan.
EPIC=9.3 to 10.5
quad=10.0 to 11.8
:dude:
Another hint for stock= without insane batteries your going nowhere. It sucks but that about sums it up....:thumbsup:


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## HookupsXXX4 (Dec 4, 2003)

Hey I just want to put in my .02 cents. The guy I pit with has a dyno, and I use it once in a while. When I do a motor, I check the amp draw with no fan. My motors come out to 9-11 amp draw. That is all I need to know. On the other hand, I am running stock truck, and I know that I will have have to pay to look at dyno numbers this fall for 12th scale. What should I look for?

Jerry
*************
TEAM ShOrT BuS
MAXAMPS.COM


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