I have a fin 7XL motor running 5s2p A123 (crazy power), with heavy bashing on hard pack, after 15 - 20 mins (runtime), the highest I saw the motor at was 150F, that was with a diff problem too, it was binding gears, and the outdrives were seized because I forgot to grease them (it locked diff)

That was geared 51/18 with about 45mph topspeed (Brian's calc)

I wish my motors would run that cool. I'm always in the 160-170 range. What's the temp like where you guys are running. I'm down in Louisiana and it's always hot down here. I don't even own a winter coat.

I would like to see those kind of temps as well, my smooth 7XL gets 170 - 180 after a hard 20 min run, even with the RC-Monster heatsink (cools fast once you stop though).

Yeah, I've taken to making sure that I have a good thermal path from the motor, to the mount and then to the chassis. I've given up on running a fan on the motor. It doesn't seem to do anything for the heat. I think that sufficient sinking is the key.