Ok, thanks for the replys, I will do some more testing. I was able to climb to 15000 feet with +6.5, 50% rad and 2600 rpm, changed to 2400 rpm at 12k, I had mixture fully backwards. After a while I increased the rpm to 2800 and almost instantly got an engine failure.
If I try the same with +11 boost amd mixture fully forward (to get it to run clean) I have a engine failure after a couple of minutes in a climb (keeping speed at 230mph). But the same settings at sea level not climbing I do not get an engine failure. But as soon as I increased rpm to 2800 at sealevel I got an engine failure again.
So the 2600/50 looks like a magic number, good find Dutch!
