Engine cooling cannot be discussed of course without its relationship to power settings. Pilot's Operating Handbooks are written with an eye for compromise between power (hence need to dissipate heat) and engine life. The Allison engine left the P40, P38, P39 very underpowered; so for survival purposes, the pilots often had their crew chiefs modify throttle controls so that they could have a fighting chance against a faster or more nimble enemy fighter. Search and you will find lots of criticisms of the Allison engine, so please let's not try to change history and glorify this power plant. http://www.wwiiaircraftperformance.org/p-38/p-38-wayne.html