I thought I would repost this here as this gearing maximum power for average speed was discussed earlier in this thread but on the oval.

**Gearing**
The best way to gear your car is to start with a fast guys gearing. Some other things to note. An electric motor has its peak power at about 1/2 of its maxium amp draw. Amp draw at peak power is usually a big number and results in a lot of motor heating as we strive to gear the motor for peak power. So another trick we use is a temp gun and gear for 160-180 F. This should not be an absolute as on some tiny tracks you may just have to gear lower and not develop so much heat. In low traction you will not develop as much heat either.

**Gearing Maximum Power at the Average Speed**
I have used this method on the oval to good success. I thought I would explain it here as it turns out my TC4 is geared pretty close to this after some trial and error gear testing on the track and in my driveway.

I paced out my runline on the track with a 3 foot pace, 82 paces, 246 ft run line. A good lap is 10.4 seconds. Dividing gives my average speed of 23.6 ft/s (16 miles per hour). I will change this to inches per min for convenience

23.6 ft/s x 12in/1ft x 60s/1min = 16992 in/min

If I divide this by the wheels circumference I will get average wheel RPM

wheel circumference = (diameter x pi)

16992 in/min / (2.375 x 3.14) = 2280 RPM

Now to see what my wheel RPM is at Maximum Power. I look at the dyno sheet at the Red line. It peaks pretty close to 10,000 RPM, Maybe just a little past. If I divide this by my gear ratio I will get my wheel RPM at max power.

10,000 / 4.72

2118 RPM

My average wheel RPM is 2280 That is within 7% of my Wheel RPM at max power. To get closer I should gear up.

10,000/2280 = 4.38

Anyway the concept would work to gear maximum power at the average speed even on this small touring car track. Note that this dyno run came from my homemade novak Sentry dyno that we developed on a thread by the same name. Most 13.5 motors are going to be very similar to this one where they develop maximum power. I am running a speed passion 13.5. It would be interesting to get a dyno run. I stole the dynos speed control for this car, though, so its not so convenient.

**Maximum Amp Draw**
Check out that green line, amp draw. Our sentrys were specifically modified to get good number here up to 220 amps or so. This motor is pulling 110 amps soon after startup. You need good connectors and fat wire to get this to the motor. You only achieve this on the track with good traction.

John

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