I have a 1996 4100 scr with 420 cummins. at 2650 wot i get 33 knots 2300 cruise 26 knots. boat has trouble getting over the hump and i long to plane. did filters air seps aftercoolers cleaned bottom and reconditioned props with 1/2 inch pitch taken out. when planing i get a ton of black smoke. what kind of numbers are others getting?
i have been told these boat were over propped to begin with. what size/pitch should be used?
That Cummins diesels should have a Max RPM of 2600. If you're reaching 2650, then it already sounds like you're either at the sweet spot or slightly underpropped to begin with.
Prop pitch is fairly basic. Either you Are, or you Are Not reaching the Max RPM range @ WOT. Speed is irrelevant.
performance numbers 4100scr
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