Best power for a TIO-540 is definately not 50 degrees rich of peak EGT. It's 125 degrees rich of peak EGT (PA31 POH). Also, just for your info. The company that I work for specifies 30 in MAP and 2200 rpm for cruise and 37 in MAP and 2400 rpm for climb. You don't get much "oversquare" than that.
A propellor is more efficient at lower RPM's. Reason; as a blade passes through an area of air, it leaves a wake, just like a wing. The faster the next blade gets to that same area of air, the less time the air has to smooth out again and therefore the next blade passes through more turbulent air. Just like an aircraft flying very close behind another aircraft would experience rough air and therefore be aerodynamically inefficient. The more blades, the more this is true. ie. a two blade prop would have to turn 180 degrees to get to the wake of the other prop. However, a 3 blade prop only turns 120 degrees before it's blades pass through the wake of the other blades, therefore it would be more efficient at a lower RPM, even if it's on the same type of engine. The highest possible (allowable) MAP therefore gives more "oooomff" behind the prop. More power, same RPM/fuel flow.
...ummmmmm..........get it.........?
Have fun......................................................... ........H
