It would almost have to be very efficient -- they're saying it can do something like 500HP continuous, and it doesn't have enormous fins all over it for cooling.
Looking at the picture, it looks like there may be a liquid input (cooling). Even a very efficient motor is going to need cooling (and lubricant).
Looking at the picture, it looks like there may be a liquid input (cooling). Even a very efficient motor is going to need cooling (and lubricant).