The original RR's run an approx 3000kv outrunner motor which was picked by Steve to run in his prototype. I am pretty sure you can order with or without the motor, he does also or used to sell a type of cooling device that he developed with the littlescreamers guys, it is basically a block of ally that has a couple of ports drilled in and some nipples on each end to attach the hoses. Goes between the motor and the mount. Obviously outrunners cannot be cooled using the conventional cooling cans, the bit that usually gets really hot is the stator which is located on the inside hub of the motor and you want to keep that reasonably cool, I have had success using a brass motor mount with a tube soldered on it and run water through that. Same diff, just not as fancy.