Motor turns
Both brushed and brushless motors are typically classified by the number of turns (or winds) of wire they use. Brushless motors are also classified by their Kv constant (more common in 1/8th scale applications.)
Here is how the turns of wire affect the car's torque and speed:
Fewer winds
- More Kv
- More top speed
- Less torque
More winds
- Less Kv
- Less top speed
- More torque
Motor Kv rating (brushless only)
Kv constant (not to be confused with kilovolts, kV), expresses the number of RPMs a motor will generate when 1 volt is applied to it with no load (when not attached to anything.) This number goes up proportionally, so 2 volts will give roughly twice the RPMs, and so on.
Higher Kv rating
- Higher top speed
Lower Kv rating
- More acceleration and torque
Motor timing
The timing of a motor is another option you can use to fine-tune your motor's acceleration and power. The impact of changes to timing is the same for both brushed and brushless motors.
Increased / advanced timing
- More rpm / top speed
- Runs hotter
- Less torque
- Less efficiency / run time
Decreased timing
- Less rpm / top speed
- Runs cooler
- More torque
- More efficiency / run time
When using brushless motors, the timing can be altered electronically by the electronic speed controller itself using settings known as boost and turbo.
Rotor size
Another factor that affects the performance of a motor is the rotor diameter. Read our article on rotor diameter for more details, but these are general guidelines:
Smaller rotor diameter / shorter rotor
- Higher rpm (top speed)
Larger rotor diameter / longer rotor
- More torque
Spec/Stock motors have large rotors, so you'll usually see racers use very large pinion gears with spec motors, so they can take advantage of the torque and turn it into speed.
Overheating
When doing any sort of tuning with the motor or gearing, it's important to check the motor and ESC temperature often, to ensure that they are not overheating. If they overheat due to timing changes, dial back the timing. If you have not made timing changes, try changing your gear ratio.
