MW 50 was not fuel.
It was an antidetonant.
It allowed raised boost pressures without engine damage.
Cooling effects were secondary, and power increase using MW 50 without boost increase were negligible.
You're asking HTC to model something that would not make a big difference, and for which no data exists anywhere.
AFAIK the "overheating" in AH is just a WEP timer. In the manuals for each of these planes you will find time limits for WEP power. These are either recommended limits, after which the pilot should reduce power to improve long-term reliability of the engine, (e.g. Spitfire) or they are hard limits, beyond which the anti-detonant runs out, or the engine control system automatically reduces boost, or both (e.g. P-47D).
In order to force us to respect the WEP time ratings, HTC made it so WEP shuts off automatically at the prescribed time. And it sure looks to me like the temp. gauge is just a clock for this time.

[This message has been edited by funked (edited 05-30-2001).]