All else the same, what does a longer motor do for you?

[arrover]

I'm trying to learn more about the brushless motors that are in our boats. If you have two motors with the same specs except that one is longer than the other, what pros and cons are there to the longer motor? For instance, if you had 4074 and a 4082 from the same manufacturer, with the same KV rating, and same winding, what are the results of using a longer motor? More amp draw? More torque? What else?

[Fluid]

Power is watts which equals amps times volts, going faster means a higher amp draw. The longer motor will be more powerful because it can draw more amps efficiently. The shorter motor will reach a point where drawing more amps will saturate the stator and any additional amps will be turned into heat, not power. The longer stator on the longer motor will "process" more amps before overheating.

Too, the longer motor has more mass and will handle more amps before getting too hot. The longer motor makes sense in larger boats which must use larger props. In small boats it is really just extra weight.



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[ray schrauwen]

Power is watts times volts, going faster means a higher amp draw.
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There is a typo in there... Just sayin'

[Fluid]

Thanks Ray, darn tablet keyboard and lousy proofing..fixed!



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[arrover]

Thank you Fluid for the info. I appreciate it!

[NativePaul]

A down side of having more magnet is that bigger motors have Higher IO (no load amp draw) so you use more power just spinning the motor, and the higher inertia of the bigger rotor, will pull more amps accelerating itself. Bigger motors are better, but so are smaller motors.