new prop help, 4.3 Mercruiser

[Wyomingman]

I recently bought a 2002 1950 Lund Tyee with a 4.3 MPI Mercruiser. The boat was bought in Iowa(lower elevation) and came with a 14 3/4 x 21 Ballistic stainless steel prop. I had the boat out for the first time last week at an elevation of 5000 feet and the boat took about 15 seconds to plane with a top RPM of about 3900 and once going the top speed was about 40mph. The motor ran smooth with no stuttering. I have looked on the Mercruiser website and it recommends a Vengeance stainless steel prop 14 1/2 x 17. Does this sound about right? I think the boat weighs about 2900 dry.

Can I expect 900 more RPMS out of this, better hole shot and more top speed?

 

[Wyomingman]

Re: new prop help, 4.3 Mercruiser

Forgot to add above the gear ratio is 1.62 Alpha One.

 

[wmhob]

Re: new prop help, 4.3 Mercruiser

I've got a Hurricane deck boat (4500 lbs.) with the same set up as far as the 4.3 MPI with 1.62 and I run a 19 pitch prop that puts me just below 5000 rpm at WOT. I had a 17 pitch MI Wheel Stainless on it that gave me great hole shot but RPMs at WOT were too high. I just recently changed to a 19 pitch HighFive and love it. I'd say the 17 pitch would most likely get you up where you need to be.