overclocking (if high efficiency ie thin lamination's ) like the aussies have been doing to 400hz and over volting (they take a 400 v motor and rewire it to 100v ) running with volts/hz or as the hz is increased so is the voltage counteracting the back emf so torque and amps remain constant as the RPMs go to 5000 on a 1750 motor . They ended up with less heat then stock (1/3 or 1/2 hp) to 5hp overclocked .