Help on flying the 109

[Viper2000]

2500 rpm max for one minute. 2400 rpm for 5 minutes, or 2300 rpm for 30 minutes.

If the oil gets too cold then the oil pressure will get too high & you'll break something. If the coolant temperature is too low then opening up to high power would probably cause thermal shock.

The reality is that once the aeroplane is flying you're quite unlikely to overcool it unless you're descending at idle power or something.

You obviously want to keep the radiators as close to closed as possible to reduce drag, whilst keeping temperatures within limits.

I don't know what the actual limits for the DB601 were off the top of my head, but generally coolant <120º and oil <90º is a good guess for a WWII piston engine.