This will sound stupid ,but here goes. Being a engine is nothing more than a heat pump, will it stress the cooling system more working a weak engine to the gills pushing for all its worth or lightly working the same engine that has been turned up at say half throttle? but yet is capable of producing much more HP at the same rpm.

 

More fuel equals more pwr right? more heat..........more stress...more everything.

 

Thats what I told him, er, the dumb one