What is a rule of thumb on RPM gain or loss per pitch, 1,2,3 or 4 hundred RPM ?

You will lose or gain 200 rpm for each inch of pitch but only if you are staying with the same type of prop (for example going from a Mirage + 23p to a Mirage + 25p in theory you would lose 400 rpm). If you go from 3-4 blades that will effect rpm's too...so will trying a prop with more bow or stern lift...Labbing etc. So many variables.....

on my baja 272 496HO

bravo1 22p=5150 max
bravo1 24p=4800 max
on smartcraft digital rpm

Thanks guys couldn't remember, going to try B1-28P to B1-30P,but going to do a few things to off set the 350-400 rpm loss.
.25 less dia. and slightly less cup with alittle more thining of blade,originals 28P is not very thin,but a true labbed prop.
Hopefully this could get me approx. 200-250 RPM loss, providing i can keep the same slipage percentage.

If all else fails , depitch by .5
maybe gain 2 mph

Thanks again

typically on a B1 prop...1 inch of pitch= 150-200 rpm.

Therefore...going from a 28 to a 30...you will loose between 300 and 400 rpm.

You could sharpen and balance any of these props for an aproximate 150-200 gain in rpm.

Chris

P.S. the lower pitched props are typically more efficient (less slip)