3 to 4 blade too much drop in RPMS

[mikesnowman]

I appreciate any help as I hate to spend money!! The boat is a 96 Mariah 5.7 non vortec with an alpha one 1.62 ratio. Weight is 3200 fully loaded. With the rapture 19 I spin 5000 rpms at 50 gps. I am trying to pick up some top end. I tried a 4 blade Solas SS 21 pitch. Everything was nice but the top end went to 47 and rpmas were 4100 to 4200. My thought is probabaly a 21 pitch 3 blade or a 20 pitch 4 blade, but which prop?

 

[Tail_Gunner]

Re: 3 to 4 blade too much drop in RPMS

50@5000 with a 19 is 11% slip
47@4150 with a 21 is 8% slip

Looks like the Solas is doing fine just to much pitch....lets see if the numbers work out on your boat.

19@5000 SS
alum add...200... drop for the 4th blade 100..So a 19 pitch 4blade alum gets 5100....20 gets 4900....21 gets 4700 those numbers reflect 11% slip

21@4150 alum....20p 4350.....19 4550.....18 4750... 17 4950 @ those numbers reflect 8% slip

18@4750 gets 46 mph @ 8% slip Some of the benefits should be improved hole shot improved midrange..lower planing speed...and top end loss

I believe your at the peak of your boats performance....and it seems to benefit from stern lift ......


You could always drop on some vortec heads...and a 4 barrel carb.. If perfromance is what your looking for