Originally Posted by Diller
Cylinder temperatures and water temperatures are very different. You can have stable water temps but have the EGTs vary greatly. It is the high cylinder temperature produced by heavy loading that burns off the soot on the injectors and turbo and helps burn the fuel more completely. Efficiency for the sake of my argument basically getting the most energy from the fuel. This can only be done if all the fuel is burned in the cylinder.
I forgot about the EGT. Now I understand.