“A sum of 48 equals 75% power (such as 24" MAP and 2400 rpm), each reduction of 3 is a reduction of 10% power, so 45 would be 65% and 42 would be 55%.”
So 24” at 5000 rpm on my machine would = 165%, nice!!!
I have the benefit of up to date instrumentation and tend to set power based on fuel flow at a set RPM. I usually go for 4900 rpm at 18.5lph (CS prop) at around 4000 ft.
Rod1