I have an 18' donzi with a SBC and Merc TRS drive.
I have a 22" trued, Michigan Wheel "Rapture" 22P.
If I go to a 23P or a 24P, Rapture, how much faster can I expect the boat to go with each additional inch of pitch? Currently running 58 mph on speedo, with lots of drive trim, w mild chine walk, 60 MPH with significant chine walk.

Incidentally, when I went from a 19P to 21P cleaver, and then to the 22P Rapture, I didn't loose any RPMs, this is w a flat tappet, solid lifter, mild Crower cam still turning 5000 RPM with all three of these props.

Your opinions please.
Thanks
Evan

At what RPM is your peak HP produced? This will determine the pitch you need to run. If you are hitting the same RPM with all props I suspect you are in the Rev limiter with all of them. Where is your Rev set?

Julie

There is NO rev limiter,
This is a 1976 Donzi/ SBC all analog

At what RPM do you believe that the peak HP is being produced?

Julie

As a general rule each inch of pitch turning the same rpm, same model prop results in a speed difference of about 2.5-3 mph.

Matt