another thing to watch for when racing is the ammount of times you crash or spin.
we have done some testing over here on some sort of a dyno thing or computer system that measures the motors current and temp n everything on a test run.
when you hit walls or barriers or spin, the motors temp and voltage spikes and increases heat substantially and is one of the major factors in motor temperature. and also if you keep your throttle on when stuck in something, that really kills it. the heat jumps up a lot
if you drive really smoothly and nice your motor will never get as hot as it would if you mash it out of every corner and slide n spin and all sorts.
gearing obviously plays a major role, but what ive just said is also something to keep in mind
just my $0.02
Yokomo * HobbyWing * Sanwa