I have a 1999 Volvo Penta 7.4 GI PWTR in a Chris Craft Concept 27', with a stainless steel F7 duoprop the maximum RPM at WOT was 3100 rpm, I've recently fitted an Aluminium D2 duoprop and I'm getting to 3100 rpm at around 75% throttle, after which the engine is cutting out. I understand this...
