What bl motor to use with 3s lipos

[BrianG]

If running it on 7 cells, then go with the 5700. If 3s or 10 cells, go with the 4600.

To calculate motor speed, simply multiply the voltage by the motor KV. So, 4600kv * 8.4v = 38,640rpm. The idea is to use the lowest kv motor you can for the voltage you are using. Higher kv motors means more current, which means more losses, which means more heat. Basically, it's better to develop high power with high voltage and lower current than the other way around.