Quote:
Originally Posted by skyking
the higher RPM's do work, because the energy required is divided among more events. The heat is less concentrated, and as stated before the cooling system is running at a better flow for the heat.
I deal with this phenomenon with my Cummins-powered Dodge truck.
It makes huge amounts of torque at 1700, but the heat will build rapidly on a hill. If I get it to 2100 or so in the lower gear everything is cooler.
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Yeah, I have seen this happen many times as well in diesels as well as gasoline engines. Recently I went with my father in law to pick up some Holstein bulls from Wyoming. We took his half ton Chevy and pulled his lead sled stock trailer (I offered to take the 1 ton and my aluminum stock trailer...but there is no arguing with some people). When loaded that truck would heat up even during slight grades, but shifting down always alleviated those problems.
3rd gear pulled something like 2600 rpm going up hill at 55, as opposed to 2100 in OD. Moral of the story was to leave it in 3rd and avoid watching the temp.