Originally posted by siulung100
but i was wondering when you buy a better engine like more powerful you have to buy another speed controller
Essentially yes, you'll see that electronic speed controllers are rated for a minimum number of turns. Mechanical speed controllers are good for very little.
but what about the motors with the turns or something like that like a 30 turn motor?
This is the number of times the wire is wound around the inside of the motor. Fewer turns means a faster motor.