Unfortunately, most people rate the motors by turns or kv (rpms per volt), but there is only 1 true way to rate all motors, and that is by watts of power produced at 7.2V.
Kv rating is no good because it takes torque completely out of the equation. It's a rating with no load. It gives you an idea, but it's not an accurate way to measure power of a motor. It is a common misconception that RPM determines speed. You need to look at both RPM and Torque to determine the power of a motor.
As Big Jim
used to say:
746 Watts = 1 electric horsepower
"Horsepower is horsepower! Speed then, is just a matter of gearing. HP (Watts) = RPM x Torque"
Here is Novak's brushless motors Wattage ratings:
A good example of how Kv isn't a good way of determining power. Look at the SS5800 motor and the HV4.5 motor. Both produce similar Kv (5000 and 4800 rpm per volt). Yet the power is very different. The SS5800 motor produces 225 Watts of power (1/3 Horsepower), while the HV4.5 produces a whopping 750 Watts of power (1 Horsepower!).
Another point to drive this home further. Hank from Hobbytalk was talking with Jim Campbell, the President of Tekin
, while at the Chicago Hobby Show. Jim said that he could make a 13.5 turn motor that would perform like a Novak 7.5 if he wanted. Using a Kv rating wouldn’t work because the motors he has been developing can pull a LOT more gear then the current Novak motors.
It is my hope that ROAR should define the max power allowed in each motor class. That way, it doesn't matter if you use brushed, brushless, bearings, bushings, magnets, or any future technology. Horsepower is horsepower. The laws of physics state that this is the only true way of determining how fast motors are.
For 540 sized motors:
Stock motor class = maximum of 100 Watts of power at 7.2V
SuperStock motor class = maximum of 200 Watts of power at 7.2V
Modified motor class = unlimited watts of power
(or some variation like this)