# 17.5BL compair to stock brushed



## jlfx car audio (Nov 11, 2007)

as it said we have a local oval carpet track and i run turing the driveline is about 110' the straits are about 50'each but they become a arch after the first lap anyways novak prints that a 13.5 is equal to a stock brushed and i have drove the track with stock powered cars and i am running a 42-45 roleout and they are about the same speed 1 or 2 anyways (the fast guys) so what should i expect when i change to a 17.5 (because the track folks will only let 17.5 run in the stock class) 
also what kind of roleout should i run for this SS17.5 ?
with my 13.5 it is about 110f after 5min and i hear it should be 150 to be at its best do the same rules apply to the 17.5


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## Fred B (Sep 26, 2001)

If you're going to race, you need the sintered rotor in the 13.5 and 17.5. The stock rotors (nonsintered) lose their strength quickly and tend to run hot when geared for lap times.

I just ran a 17.5 with the sintered rotor yesterday and it was a little overgeared at 3.46 (12th roadcourse) so I would probably start at 3.4-3.5 on oval and play with the gearing for best laptimes.

I always gear the higher wind motors based on lap times and use the temperature as a maximum. I try not to run mine above 170 degrees with the temperature taken on the label of the anodised ring. If you measure off of the sticker it will give odd readings.


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## briano_72 (Jan 21, 2006)

17.5 is to be considered the same as a 27 turn. 13.5 is normally a few laps faster than 27 turns depending on the track size. 10.5 is like a 19 turn. all the 17.5's come with sintered rotors. our track is about 155-160 and 17.5 would be rolled out at about 3.90-4.00. thank god for prs gears !!!


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## Butters16 (Dec 14, 2002)

flat track 88 foot run line 17.5 rollout around 2.90-3.10 depending on how effinent the car is.


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## jlfx car audio (Nov 11, 2007)

thanks for the info are these roleouts in a TC in niches" so i woul be running a 
45t pin ,111t spur,1.77 drive with a 2.5" tire (with my 13.5) = a 44mm roleout


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## L4OvalRacer (May 27, 2007)

Well would have to disagree with everybody saying 17.5 is equivlent to a stock 27t motor. I raced with a few 17.5 guys and dident have a chance. If you want to be anywhere close to a 27t motor you have to have a Perfectly built motor. Theres a couple things diffrent. For one a brushless has the power to get up to speed very easly where a brushed motor takes 2-3 laps to get up to speed. Also brushless has the constent speed to get in and out of the turn faster than a brushed motor. Thats just what i have seen in a 17.5 motor. Its perfect for any track wanting to have a slow sportsman class but I would never run 17.5 with stock 27t motors.

Taylor


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## Josh Keller (Mar 2, 2006)

.....


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## 98Ron (Jun 14, 2004)

Josh, I agree with what you have said, but there is one thing that seems to make a real difference. The track, it seems that the BL motors vs. brushed motors difference may show up much more at different track, it seems that the longer the track the more difference there might be. But in you case they seem very close. Also so what we have seen as guys get more time with there bl stuff they get it faster. Down here we started out in one brushless class running 7.0 laps and thought we had it worked out, then within a month we had the same cars running 6.4 once we learned more about these bl things.


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## 420 Tech R/C (Sep 15, 2006)

A stock CAN hang with a brushless car, especially on a tight roadcourse.I have been running all year with a 17.5 in my 1/12 car on a tight, smaller track(hobby sports .com) and have been beat by guys running brushed stuff.Ihate to say it , but it sounds like a lot of guys are getting upset at the thought that if brushed motors dissapear it will take away their edge because they can tune the crap out of a brushed stock motor.They need to look at the name and ideals associated with the class they are running-STOCK-.which is supposed to be freindly towards the beginning/intermediate racer. Brushless motors cannot be tweaked, or tuned to the point where the 27 turn motor is running as fast as a box stock 19t. That is why I am all for picking a BL motor(be it 17.5, 18.5, 21.5) and making it THE standard for stock class racing, both on and offroad.It would bring close racing like it should be, not 1 guy running away from the pack because he can tune a motor even though his driving is mediocre.I for 1 have always felt that there needed to be a tighter reighn on tuning rules for stock motors just for this reason.There are rules in every other type of racing to govern the amount of tuning that you can do to a powerplant,so why not r/c. And BL motors are the perfect, cost efective way to do it without overloading our tech. people. Brushed guys always say ' BL stuff is SOO expensive' , but they forget to take into account that the own comm lathes and dynos, and BOXES of springs and brushes and spare arms. i mean look at all the stuff you have to do to be competitive with brushed stuff. You know what I have to do to be competitive with my brushless stuff?? Make sure my gear ratio is appropriate, and my batteries are charged, and DRIVE. so which one really sounds more beginner/ intermediate freindly?Since i switched over to running BL I now have more time to focus on chassis set-up,and driving, And even have time to relax and enjoy a day of racing instead of trueing comms, and prepping motors, and rushing to get things ready to get to the line on time.BL has brought things back to where I was when I started racing 20 years ago when we were running sealed can motors that you could only tweak with brushes and springs. FUN. Brushless is the future of r/c racing whether people like it or not. The period we are in right now is a transitional period, where people will need a minute to give up the old and step into the new, but once they do I think that it will be one of the best things to ever happen to our sport.


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## jlfx car audio (Nov 11, 2007)

i like the way you think


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## tuftiger (Jan 2, 2007)

*17.5 vs 27 turn brushed*

Our local track has made the switch form touring to oval this year. It is a flat 160' drive line. We have a very active group of 1/12 car (8-10 each week). after a couple of weeks of running brushed, the drivers voted to allow 17.5 in the class. About half of the class switched to BL, with the balance staying with brushed. 

Several of the brushed racers have very intimate knowledge of what it takes to make the brushed motors fast. In this particular situation, the brushed motors racers are faster than the average 17.5 racer. I am running BL and don't plan to switch back to brushed.


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## Fred B (Sep 26, 2001)

It doesn't matter what we do, you'll never have an "equivalent" between brushed and brushless. The 17.5's seem to be pretty close and that's what ROAR has gone with.

In some classes the brushed is going to be faster and in others, the brushless is going to be faster. In the end, it is what it is.

Personally, I would have slowed stock down even further for both brushed and brushless. But that's just my opinion.


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## 420 Tech R/C (Sep 15, 2006)

I totally agree with you fred, they will never be the same.Like i said I dont care which BL they pick as the standard. Maybe after the brushed motors are phased out in a few years(hopefully sooner) we could drop back to the 21.5 as a stock BL motor.Stock has gotten out of control the last few years and it would be nice to slow stuff down in this class just due to the high voltage output of today's batteries.BUT I dont think dropping to a 5-cell standard is the way to do it.


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## trailranger (Feb 9, 2006)

what did roar say about 17.5T and 27T? I thought I heard they could be ran together during 2008 but in 2009 say bye-bye to the 27T


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## 420 Tech R/C (Sep 15, 2006)

God that would be too sweet if that is the case!!!


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## jlfx car audio (Nov 11, 2007)

so for i only hear about 4cell 1/12th scale what about 6cell tc would it be the same difference their is a couple good motor builders at you track i just hope i will still be competive


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## hopper (Oct 12, 2006)

We are starting a 17.5/lipo class at the Grove in sunny SC. It is a 400 feet tri-oval that is almost a full throttle track, except turn 1 is tight. Some guys are starting to test. No racing yet. However----THEY ARE FAST!!! 27 turn six cell (back in the day) would do 6.0 to 6.3 laps. These guys are already, with little practice, doing 5.7 and 5.8 laps.


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## jlfx car audio (Nov 11, 2007)

that is cool what about on a small track


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## 420 Tech R/C (Sep 15, 2006)

6 cell with the 17.5 seems to be a trade off. at the start a brushed has the advantage until about the 3 minute mark when heat affects the motors performance and efficiency and thats where the 17.5 equipped cars really shine. I been playing with one in my dirt car for off road season this year, and just like 1/12, its all about gearing,and using the slipper to your advantage. use the temp gun to fine tune it and your set.I am expecting to be very competitive with it.it seems to be just as fast as a 27 turn but like I said there is no fall of due to heat at around the 3 minute mark. In a TC expect to gear the crap out of it. The 17.5 is a torque monster, iit doesnt produce the rpm's , but the torque it produces is outstanding.good example is on my 1/12 car with a 27 turn motor I was running a 3.125 input ratio.(32/100). with the 17.5 I am running a 1.8 input ratio(81/45) to get the same top end, and have room with the temp to go up on the pinion at least another 4-5 teeth if I need, and the punch out of the pocket is still better than a 27t.


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## jlfx car audio (Nov 11, 2007)

that is what i needed to know thanks


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## Fred B (Sep 26, 2001)

420, I ran 50/76 with the 17.5 in 12th last Sunday. You've got some catching up to do.

3.46" rollout was a little big though.


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## 420 Tech R/C (Sep 15, 2006)

your running on a MUCH bigger track fred.I am sure that was awesome for up there.not to mention your running smaller diameter tires.We are running the prisms untrued out of the box, so on that track at hobby sports 45- 48, 81 works good enough that I have TQ'd every week for the last2 months, and usually finish 1st in the main.But I am sure if was to go run at josh's I would be right up there with you on the gear ratio.but on that small tight track @ hobby sports any more than what I have been running heats thinngs up a little much


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## twistedone (Aug 17, 2007)

anybody running these in tc that can give some advice on where to start with pinion/


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## jlfx car audio (Nov 11, 2007)

well if i am running a roleout of a 42-44mm on a 13.5 what would the 17.5's be?
i would think that a 17.5 would have more torque and if that is true i would need to run a ligher roleout correct


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## Tdevil (Feb 15, 2004)

trailranger said:


> what did roar say about 17.5T and 27T? I thought I heard they could be ran together during 2008 but in 2009 say bye-bye to the 27T


 Roar stock class is now 27t and 17.5. There is no mention in the minutes of eliminating 27t or any other brushed motor. In fact, ROAR is hoping the brushed motors will be faster and people will continue to choose them over the brushless in all classes. 

Perhaps the change you saw is that super stock (19t) will allow 10.5 for 2008 along with 13.5 and 19t. For 2009 it will be only 13.5 and 19t. Again, 10.5 is being eliminated in 2009 to encourage racers to choose the "faster" 19t brushed motor.

17.5 is stock and will stay stock this year and beyond from what I read. 13.5 is super stock and will stay super stock this year and beyond. 10.5 is super stock this year, but will become modified next year.

We run a track in Grand Rapids, MI. It is an combination oval/off-road indoor clay track during the winter and have an outdoor off-road for the summer months. We have not yet made decisions as to where we are headed, but currently allow any brushless motor with a KV rating of 3300 or less in the stock class and have been allowing lipo batteries in all classes with no exceptions.

I have been keeping separate track records for 13.5 and 27t on the indoor off-road and the brushless appears to be a bit faster. Lap times for the 13.5 are low 16s dipping into the 15s. Lap times for the 27t are mid 16s at best. Difference is about a lap in 5 minutes.

John
www.battlefrontgaming.com


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## 420 Tech R/C (Sep 15, 2006)

JLFX- The set-up I described earlier is running tires @ 46-47 mm (as the prisms come out of the box) we are running a very tight, short track. Usually turning between 46- 60 laps in an 8 minute run depending on the track layout.As the tire od decreases I have been adding 1 tooth on the pinnion per MM of decreased od, and that method has been working very good for me, starting with a 45t,and increasing as the tires wear. we( my son and I) opted to run the tires at a large od to decrease the size of pinion needed to run at pace since the larger size pinions can be kinda hard to get your hands on(50t and above)plus it makes it easier to have some adjustment to the motor.I am running a hyperform razor and he is running an IRS rugrat neither car was designed with enough space to run the gears required to run at pace with smaller od tires with the 17.5.Most hobby stores dont really carry the gears needed to run the 17.5 at pace. The track FRED B. is running at is owned by Josh Cyrul (CEFX Raceway) so since josh is a 1/12 racer they do carry all sorts of 1/12 stuff that most hobby stores are lacking. It is areally nice facility, And i only wish the guys where I race actually carried the stuff we Need.


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## swtour (Oct 8, 2001)

jlfx

The 17.5 only spins about 2/3rds the RPM of a 13.5, so you'll probably need to increase your roll-out accordingly to get close.

If you are using 48p gears, I think from tooth to tooth you are looking at what - about 3.5% gear change per tooth - so you'd need to go up equal to 9-10 teeth.

(Base Kv of the 13.5 is 3300 rpm per volt "unloaded" and about 2200 on the 17.5 motor)

By the time you load them down the RPM on the 17.5 is pretty low, but it has a ton of torque and makes more power than a 27t brushed motor.


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## twistedone (Aug 17, 2007)

I ran a tc5 today with 93 spur and 47 pinion and was running 11 second laps 
and I need about 2-3 more on the pinion 
to be where I want to be


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## jlfx car audio (Nov 11, 2007)

well last night i ran my x-ray T1FKO4 with the 17.5 and a couple hot 6 cell packs (1.234 Vavg) and at the end of the night we all were running 66-70 laps around the oval in 4min i was running 64p 53t pin with 100t spur actual roleout was around a 55mm! it was about 2/10s faster than the pack for the first 10 laps but then fell off to about a 4.1 sec lap for the next 35 laps then droped to a a 4.3 for the remander i am sure some of it was my driving at the end of the race the motor was running 148deg on the very to of the purple stripe near the wire end and about 100deg around the center
my lap times were almost the same as the brushed i was running a fastest lap of 3.89
and the fastest brush guy ran a 3.809
all in all it is worth it to not to have to rebuild every other race and it is so quiet


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## brian0525 (Jan 17, 2005)

Tdevil said:


> Perhaps the change you saw is that super stock (19t) will allow 10.5 for 2008 along with 13.5 and 19t. For 2009 it will be only 13.5 and 19t. Again, 10.5 is being eliminated in 2009 to encourage racers to choose the "faster" 19t brushed motor.


Totally untrue! If you are going to post info atleast make sure you have something that resembles the facts!



Quote from Dawn about motors:


> yes, that means in 2009, 13.5 BL will be the motor in Super Stock. No brushed motor in Super Stock.


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## Tdevil (Feb 15, 2004)

brian0525 said:


> Totally untrue! If you are going to post info atleast make sure you have something that resembles the facts!
> 
> 
> 
> Quote from Dawn about motors:


 And you have to be rude in your response for what reason?

I was reading directly from the posted minutes and it was talking about two brushless motors and allowing only one in 2009. 

So ROAR has created a strictly brushless class for 2009. Good for them. The minutes did not make that clear at all.

Could you share where your quote from Dawn was obtained. I just find it hard to believe that ROAR is doing away with 19t brushed motors.

EXCUSE ME!!!!!

John


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## swtour (Oct 8, 2001)

We did a Oval Touring class today at out 'local race' (www.centralcoastrcracing.com) and we we basically invited everyone who wanted to participate in the class to 'Run Whatcha Brung' and the plan was to do either a Break-Out lap time for the mains or what ever we needed to to closer group the cars.

Two of the guys did show with the 17.5 motors - and the response from all involved was "What a Perfect Motor". 

These guys were a mix of 'old timers' who had semi retired, and Newbies, a couple of which ran their VERY FIRST oval race today.

The 17.5's showed good speed on our nearly 280 ft. track - I don't know what all kinds of TC's were being run - but they were having a BLAST....and at the end of the day - all they could talk about was how much fun they had - and how the group of guys were awesome to each other.


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## Tdevil (Feb 15, 2004)

brian0525 said:


> Totally untrue! If you are going to post info atleast make sure you have something that resembles the facts!
> 
> 
> 
> Quote from Dawn about motors:


 No need to let me know where you found the quote. I found it over in the RC Tech forum. You are correct, no brushed motor in Super Stock in 2009, just 13.5 brushless.

Congratulations on being the superior intellect. Hope others are just as kind to you when you are mistaken.

I will leave this thread now.

John


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