maybe it's ur batteries.. gears.. bushings?... :)

Kulang Do you think you may have got the wrong motor? Mistakes do happen. Some thing don't add up with it. Have your tried to figure up if you had a 9 or 10s if it works out right.

Well, I know it's not my batteries because I have tried four different sets of matched GP3300s. When I charge them on my Integy 16x4, they still get about 3200-3400 mah charged at 5 Amps.

Gears, bearings, etc .... I know there's no binding and it sounds fantastically smooth, much smoother than my e-maxx.

Wrong motor? That's an interesting thought. Reverse calculations on Lipomax's spreadsheet show that my motor is performing as if it has a kv between 3400-3600, not the 4436 that's stamped on it. The Feigao 10S has a kV of 3549. Interesting thought! My truck is running exactly as if it had a 10S in it according to the spreadsheet.

Is there a way that I can find out if this motor was incorrectly labeled/stamped by the manufacturer?

You can do it if you have an oscilloscope. I wouldn't be able to tell you how to measure the kv even with one. If you are really interested, a search on Google might help you out.

Another idea would be to get a Venom Speed meter. Use it to gauge your speed while your car is off the ground, and when at full throttle, measure the speed of the car and the voltage of the batteries. You can use this measurement in determinging what the kv is by using your gearing (assuming you put the sensor on a drive shaft). This isn't as involved as using an oscilloscope, and should be pretty accurate, but you will have to pay for the speed meter.

You could measure the amp draw under no load situation. Each motor draws slightly different amps under no loads. You can find the data at motocalc for the no load draws. In addition, are you sure you got the right gear ratio for the tranny? The right size tires?

My tires are Pro-line dirthawgs that are exactly 4" tall.

The Rustler final drive ratio is 2.72:1.

I am seriously beginning to think that I have the wrong motor. I think I have a 10S that's marked as an 8S. That would explain everything.

I don't know how to measure amp draws under no load. I think my multimeter only measures in volts and ohms.

This is making me crazy! :C:

If your multimeter has a DC amps setting, you can measure the motor's no load amps. What you would do is hook your multimeter in series with either the positive or negative wire to the controller. Then rev the motor and see how many amps the display shows. Feigao's website has the no load amp ratings on all of their brushless motors.

The rpm/volt on the Feigao motors is also under no load. The loaded rpm/volt of the 8s is actually slightly less than 4000(3990?). This, and some battery voltage drop makes a lot of sense to me. With aggressive gearing, the voltage is probably .9-1 volt per cell. This, along with the 3990 rpm/volt figure probably makes a lot of sense on paper(spreadsheet). I would certainly expect higher speeds than you are getting, though. I am curious how well your batteries are deliovering the voltage under load(not all gp3300s are created equal-mah after charging has nothing to do with voltage under load, either).