The heat is from run time build up. A smaller motor would get hotter. A larger one would run cooler, but weight more and get shorter run times. I chose this one for weight and run time ballance. In the summer time I might run a Neu 1515 2.5df. keep in mind, I'm not using any fans or vents on the body yet. I will be playing with that in the future.

Sorry, i was thinking a lower kv not the actual size

Yes, I think a 1512 1,5y would work a little better. I would have bought that one, but there was not any in stock.