Ok. I have a Baretta 17'3" supersport with the Volvo aq131a and the 275 od. The prop is a 14x19L. In the driveway with the muffs on it will turn 4500 rpm easy,with no heat issues. I ran it for 30 minutes at 3500 rpm and it hit 195f. In the lake it gets 3200 rpm wot and builds heat, slow it down...