Lamar, what motor are you running in the sc10 4x4? I think you have an sc4x but just want to make sure. Anyways I dont think heat should be an issue unless the gearing is off. I ran an sonic 8.5 540 at the trophy race and it was running 160.

That was a borrowed motor (thanks again Kyle), now I have a pro4 4000kv in it and it runs cooler.