Is torque related to size or power at all in electric motors? And what about gas motors too?
I have a go kart that is 2.5hp and it's 50cc and its about 1ft x 2ft x 1ft in size. I also see online there are .21 cubic inch gas motors for R/C cars that are also 2.5hp, the difference being that the R/C motor spins at 32k rpm while the go-kart motor spins at 12k rpm. If I were to put a gear reduction on the R/C motor, would it preform more or less the same as the go kart motor? Why is there a size difference?
Same for electric motors. I can buy an RC car electric motor that's 10hp and the size of a pop can. The CNC machine at work has a 10hp motor the size of a 5 gal bucket. Again, the only difference is the RPM.
If I were to reduce both setups so they spun at the same RPM, would they preform the same?
The only reasons I could think of is 1. Cooling and 2. RPM control (For PID loops and sensors)