Cars in general run at a low power setting for cruise - I believe at 20%
max output, so the heat dissipated would be much lower compared to
aircraft use where we start at 65% and go up from there. 

Robert M. Simon
ES-P N301ES

Robert,

 

That's correct. What's more, when comparing thermal efficiency between the two engines at part throttle, the diesel is quite a bit better due to the pumping losses of the throttle body on a gas engine. This increased efficiency would reduce the radiator size requiremnet somewhat more on the diesel than the gas engine.

 

I was simply pointing out that in comparable applications, the radiator sizes aren't greatly different. I've only made one tape measure comparison and that was on two tractors and the gas tractor actually had more cubic inches of radiator per hp than the diesel. Tractors typically operate at high output levels just like airplanes.

 

Rob