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Old 11-04-2005, 05:05 PM   #1
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Default CE Dyno Question

Hi,
I am trying to figure out how to properly use my Turbo Dyno for 1/12 4 cell stock motor tuning. I have been having lots of trouble making good horsepower consistently.

From what I have read, I should figure out what the average amp draw is of the motor during a race and then run the motor at amp steps and then tune in that range.

I am having a tough time figuring out the best way to set up the motor. Here are two motors for example:

Motor 1
RPM Torque Watt EF AMPS
17372 3.3 43 58 15
15905 4.8 57 64 18
15077 5.7 64 64 20
14265 6.5 68 61 22
13145 7.6 74 59 25
12194 8.5 77 55 28

Motor 2
RPM Torque Watt EF AMPS
21507 2.1 33 44 15
19467 3.4 48 53 18
17327 4.4 56 56 20
16470 5.1 62 56 22
14953 6.3 70 56 25
13672 7.7 78 56 28

Running the motors @3 volts on my turbo thirty shows me that motor 2 draws a lot more amps (with no load) than motor 1.

It seems like motor 1 would be the better choice because of the increased wattage through the middle range of amp steps.

But, can I really compare a torque motor to an rpm motor at the same amp steps? Or do I have to compare the torque motor (motor 1) watts at 20 amps to the rpm motor (motor 2) watts at 25 amps? If that is the case, how do I know how many amp steps to jump for comparison?

Thanks for any help!

Yankey
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Old 11-04-2005, 06:41 PM   #2
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Yankee: Yes, you can compare a torque motor vs. a rpm motor...In fact, that is exactly what the dyno is for.
Look at the watts, (electrical horsepower) at the average amp draw for your application. For 1/12th stock, I like to look at the 20-25 amp range. Motor 1 was 4-8 watts better through that range than Motor 2. Motor #1 will be your better motor, guaranteed.
As for RPM, all you use that value for is gearing. Oh, and more amp draw does not equate to more power. If it did, none of us would need dynos...just our Turbo #35's.
If you need any additional help, feel free to post here or call me at the shop...
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Old 11-04-2005, 07:30 PM   #3
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Todd,
Thanks for the response. How do you go about figuring the gear from motor 2 to motor 1?

If motor 2 was good at a rollout of 1.5, and I wanted to go to motor 1, would a good starting point be to compare the rpm at 22 amps? So if a good rollout is 1.5 with motor 2, I would find a starting rollout of 1.5*(16470/14265) = 1.73? Thanks again for your help!

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Old 11-05-2005, 09:11 AM   #4
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Yankee: You got it pal, that's exactly how you calculate it.
Most important advantage a dyno give is the ability to gear a motor properly. I'd rather run a 77 watt motor rolled out perfectly than an 80 watt motor geared wrong...
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Old 11-06-2005, 04:24 PM   #5
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Mr. Putnam, this info has helped us alot also. Thank you!!
We love your blue and green shunt brushes!!
Every one should try them at least once. after that, they would not be without them!!!!!

Do you have your t-shirts for sale somewhere?
We have looked, but to no avail. If Smoke wears them, they must be cool
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Old 11-06-2005, 06:24 PM   #6
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burgboyz: Glad to help...Yeah, our t-shirts get a ton of recognition...too bad our most famous model is a hairy guy
Maybe I can convince him to wear one instead of his Tux at the Cup Points Banquet...
Yes, our 2005 shirts are available. Contact the shop 9-5, M-F EST...
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Old 11-07-2005, 06:32 AM   #7
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Hey Yankey,
Just my 2 cents, but I would run motor 2. I've been using a CE dyno since they first came out and on most tracks I run at motor 2 would be my choice. I just ran at the Hollowwen Classic and ran a motor closer to motor 2 with a 1.51 roll out and was faster then what I was with a motor with higher torque and wattage. The formula you used to calculate roll out may be off just a bit. I found out that if you use that and go from a lower RPM and torque set up to a high RPM and lower power output you need to compensate a bit more. When you get the gearing correct, it is faster. I started at 11.3 lap time and finished 11.5. If you're off a 1/2 of pinion with the high RPM it gets hot and goes flat.
Wayne
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Old 11-07-2005, 07:48 AM   #8
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Wayne: Intersting post. You said you had better results with a motor that produced less power and torque...could it be possible that you were off in gear with the higher power motor, or ran a weaker pack? If you've been using the CE as long as I have, and it appears you have, I am curious about your findings.
I've never seen that to be the case, that's why I'm asking. In fact, based on the dyno sheets posted, it would be my guess that motor #2's brushes weren't broken in enough.
As far as rollout, the only time I've ever seen that calculation not be accurate is if you are comparing 2 different types of stocks,(two different arm types)...say comparing a Monster Stock to a Binary 2, etc.
Like I said, interesting stuff...
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Old 11-07-2005, 08:58 AM   #9
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Quote:
Originally Posted by sg1
Hey Yankey,
Just my 2 cents, but I would run motor 2. I've been using a CE dyno since they first came out and on most tracks I run at motor 2 would be my choice. I just ran at the Hollowwen Classic and ran a motor closer to motor 2 with a 1.51 roll out and was faster then what I was with a motor with higher torque and wattage. The formula you used to calculate roll out may be off just a bit. I found out that if you use that and go from a lower RPM and torque set up to a high RPM and lower power output you need to compensate a bit more. When you get the gearing correct, it is faster. I started at 11.3 lap time and finished 11.5. If you're off a 1/2 of pinion with the high RPM it gets hot and goes flat.
Wayne
Wayne I'm not arguing with you as you beat me in that race at the classic (I was 5th due to poor driving on my part and a bad start).

But isn't a 1.51 pretty low of a gear? I was more in a 1.70-1.71 range???

my motor was pretty rpmish itself but had torque as well. I'll see if I can dig up a dyno sheet for 5 volts.

I ran it at 7 on EA's dyno and it was 30k rpm at 20 amps and torque was in the 9's at 30 amps watts in the 140's?

can't remember exactly

later

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Old 11-07-2005, 11:58 AM   #10
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Quote:
Originally Posted by Todd Putnam
Yankee: Yes, you can compare a torque motor vs. a rpm motor...In fact, that is exactly what the dyno is for.
Look at the watts, (electrical horsepower) at the average amp draw for your application. For 1/12th stock, I like to look at the 20-25 amp range. Motor 1 was 4-8 watts better through that range than Motor 2. Motor #1 will be your better motor, guaranteed.
As for RPM, all you use that value for is gearing. Oh, and more amp draw does not equate to more power. If it did, none of us would need dynos...just our Turbo #35's.
If you need any additional help, feel free to post here or call me at the shop...
Hi,
If you are looking at 20-25 amps in 1/12th stock, what sort of figures would you be looking at in 1/10th 27t stock?. Many thanks
Phil
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Old 11-07-2005, 05:26 PM   #11
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Wayne,
Thanks for the response. It has been my experience as well at my local track that guys are going faster with a setup closer to motor #2. That's what made me post the question because it seems like more watts should be faster. I'm still wondering, like Todd, if I just plain haven't found the right gear with a motor #1 type setup. Although I have tried a rollout from 1.50 to 1.75 and it just seems slow for the whole race no matter what I do. Do I need to go higher than 1.75 with motor 1?

How hot is too hot for the motor? Also, is it half a tooth either way, or just half a tooth overgeared that heats it up?

Thanks for the help!

Yankey
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Old 11-07-2005, 06:14 PM   #12
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Phil: I assume your speaking of 1/10th Sedan? For a heavier car with more rotating weight, look at the factors at the higher amp loads, such as 30.

Yankey: Depending on the layout, you could try a higher rollout with motor #1. In the past, we've even been able to overgear a motor that had huge watts and torque, (80-84 watts with 8.7-8.9 torque) and just throttle drive it. Conserve the power until you need it, but you have got to be disciplined when you gear to the moon, as well as have a car and driver that is capable of rolling around the infield without scrubbing speed. If you get greedy, pull the trigger and get everything hot, you're done.

If I told you the rollout we used with Smyka one year to win the Snowbirds, you'd be shocked...it was well above a 1.70, and he was about 1/2 a second a lap quicker than the field when he'd pull the trigger...but he's awesome at rolling his 1/12th car around and not showing his hand

Bottom line, you gotta do what it takes for you to be fast...I hope some of my suggestions help...
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Old 11-07-2005, 06:44 PM   #13
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One thing that I cant figure out is why you run these motors at 3volts on the dyno when they will be run at 4.8 on the track. If you have a theory on this I would like to hear it.
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Old 11-07-2005, 07:10 PM   #14
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Hey Todd,
I have my CE set up for amp loads, and set for 5v. I look at 10, 15, 20, 25 amp loads. A typical roar epic motor with a fuller face brush will go 25,000 at 10 amps and 16,000 at 25 amps. I'm sure there is variation from dyno to dyno.. Typical torque number at 25 amps my be 5.8 to 6.2 with 70 watts produced. I've tried different commutator diameters and shaved the brushes down to get less wrap and would get numbers such as 21000 at 10 amps and 13900 at 25 amps with 6.8 torque and 75 watts. You would think a bigger pinion with the better torque and wattage motor would be better, but on most tracks and with the IB3800's I found this not to be true. I tried from a 1.60 to 1.94 roll out with the motor with higher wattage, then I threw in the high RPM motor at a 1.46 to start and went .3 tenths quicker up front and finished the same. As far as the roll out, I don't think there is a set formula. My car dictates what I can run. But I do see that if I plug RPM values and known roll outs that work with one RPM and try to figure out another roll out with the same type motor it's usually off by a pinion.
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Old 11-07-2005, 07:17 PM   #15
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Yankey,
When I go to a track, I throw in an average reading motor and start at 1.60 - 1.65 roll out. If the motor comes back 90-100 deg. after my practice run I go up 2 teeth and try it again. I try to get about 130 deg. armature temp. after 8 minutes. There are some times that you can be way under geared and the arm gets 130+. Try to get a feel of where the car peaks out. I shoot for the car to be peaked out about 3/4 of the way down the straight away. Also, with the higher RPM motors I usually go down an extra pinion.
Hope this helps..
Wayne
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