[IvanK]

Hmm !

just done some quick testing aimed and engine destruction. Ignored Overheat message.
Just went balls to the wall to maintain Vmax for as long as possible. Note Overheat message does NOT mean damage imminent ... its just a heads up to keep an eye on things.

TA152H
Sea Level Normandy Map, Midday, Rad Full open Max ATA, Max RPM, MW50
Overheat message appeared at 1min 33 secs elapsed time
No engine damage noticeable until 5min 58secs elapsed ... feint grey smoke
At 8min 38 seconds significant damage ... RPM reductions in the order of 100RPM
Progressive performance deterioration until at 10min 19secs insufficient power to maintain level flight.

P51D
Sea Level Normandy Map Midday,Rad Full Open, 67"MAP (WEP) 3000RPM,
Overheat message illuminated at 2min 4 seconds elapsed
Slight performance degradation (loss of 10Kmh IAS) after 5min 4 seconds elapsed
Oil splatter at 9 min 10 seconds elapsed

You will get slightly different results from test to test as a randomness factor is also at work.

EDIT: since some card read. Start was at Sea level or the closest QMB would give i.e. 100metres.