Why aren't all 17.5s the same KV?
 

I'm looking to get into on-road racing, and I was comparing stock motors. It seems like even the same manufacture offers several different 17.5 540 can motors all with different KVs. What's the deal?

Each motor can be made slightly different within the roar rules and specs id suggest the orca 17.5 it comes with a ht rotor and is FANTASTIC

Kv rating is basically useless. There's no standard whatsoever between companies so there's no standard of measurement.

+1 to the orca 17.5. I'd also recommend a Team Powers Plutonium.

Different rotor strengths, rotor diameters, air gaps, etc.

Its measured unloaded. Turn the timing up, fit a smaller rotor, and the revs will increase.

Its a useless measurement

OK, so KV rating is useless for a camparison, can watts be used as a standard measurements?

Bb

No, as the same issues apply. Crank the timing up and you'll get more peak watts, but at the expense of low-end power and current draw. That's if the watt numbers are even from a dyno and not just invented.

The cheapest and simplest way for most people to find out if a motor is decent is to ask the people who are winning at the tracks you race at, in the class you race. In reality there's not much between any of the top motors, which is why you see all of them up in the A final at some point or another.

If you want a true comparison "number", you'll have to build a dyno and buy/borrow a lot of motors, and even then you end up comparing power curves which isn't always simple.

Thanks Dale

Bb

there are certain companies that build motor dynos my buddy has one, and when he sets the motor to be the most efficient it IS the most efficient because the motors are always good the trail and error method however its not always the best he messes with the motor timing and rotor placement i give him the rotor i want to use ( i run the orca 17.5 tx with stock rotor (a ht rotor)). He sets it to where its the best and it is its like a rocket for each motor he sets