When choosing a brushless system for your RC car, truck or buggy there are a few things to consider:
- The size of your vehicle
- The weight
- How quick you want the car to go (FASTER right?!)
- The voltage you wish to use.
The size and weight of your vehicle is the biggest factor. You would not want to run a small motor in a large vehicle. For example, a brushless system designed for buggies or touring cars will not be suitable for use in a large monster truck or short course truck
Lighter, smaller cars can run higher kv motors and use less cells as they do not need the torque that you’d need for a heavier vehicle.
What’s KV All About?
In simple terms, KV = RPM per Volt. So higher KV motors will spin faster for the same voltage. So you just want the highest KV possible right? Wrong…!
In practice, the lower the kv the more torque the motor has and you can then use a higher voltage battery and be geared more aggressively to deliver more power overall.
Motor Sizes
The next factor is the size of the motor. Usually this is listed in the description, or can be part of the part number. For example a 3652 brushless motor is 36mm diameter and 52mm long. That’s a pretty typical size and replacement for a standard 1:10 “540 sized” brushed motor.
Most 1:10 scale vehicles use a 36mm diameter motor with varying lengths depending on the weight of the vehicle. Higher length can often mean higher torque. Monster trucks and short course trucks usually run 3660 motor or longer whereas buggies and on road cars tend to run 3652 motors.
When upgrading cars there may be much bigger motors that can be fitted which can handle more voltage and power. For example the Traxxas Slash 4x4 can accommodate a 42mm diameter brushless motor without much in the way of major modifications. 42mm diameter motors are a 1:8 scale motor which will take more voltage and deliver more power - and ultimately speed!
Common Brushless Motor SIzes and Applications
Heres a quick run down of common motor kv and voltage examples. Note these are general examples - we’re always happy to provide more specific details if you get in touch with our team.
- 4000kv or more usually run 2S (7.4v) lipo max
- 3500kv -2600kv usually run 3S (11.1v) lipo max
- 2600-2200 usually run 4S (14.8v) lipo max
- 2200kv-1650kv usually run 6S (22.2v) lipo max
- 1650kv-800kv usually run 8S (33.6v) lipo max
This is the general industry standard although there are some motors designed to run higher kv and higher voltages for speed run applications.
Research, Research, Research!
When upgrading a motor in any vehicle the key thing is research. Ask questions and read about what others have done before you commit to a setup. A little research may save you a lot of money if you put the wrong motor in the wrong application and damage a very expensive motor or esc (speed control)! Ask away on forums and Facebook groups, or ask our team!
Match Perfect
Usually motors and esc are matched for instance most midrange 1:10 motors run a 60-80 Amp ESC and most 1:8 scale motors run a 120-150 Amp ESC as a general rule. You cannot damage a motor by running a high amp esc as long as the voltage the motor can take is observed. However you can damage an ESC by running a motor that pulls too many amps for the esc to cope with.
