Motor cooling questions:
With the stator shown in cinergi's post, the outer corrugated layer could be used for liquid cooling, but how do you cool that solid chunk o'metal stator that TEG linked to?
Also (separate question) - how do you effectively cool the rotor? It should look similar in concept to the stator -- copper bars (instead of multiple distinct windings) embedded in steel laminations. You don't want liquid in the rotor/stator gap (too much drag). Is it worth trying to get liquid into the rotor somehow (hollow axle etc)? I doubt it. I guess cooling around the bearings/axle on either side of the motor would have to do...