...that I'm trying to understand the ratio of pump RPM/suction/nozzle whatever to speed..
My friend and I have the same boat. 20.5 Elim sport cruiser. Mine is factory orig (WITH water in the @#% damned oil...) His on the other hand:
Bare hull, no interior whatsoever, no carpet, no side panels, nothing. No deck hardware. Two bucket seats only. We checked the bottom with a 4 foot straight edge. the bottom is still straight. (It had been straightened when it was painted 3 years ago)
The engine: 488 inch Ford, Major head work, Steel rods, big ass roller cam (sorry, don't know the specs) MSD ign, 10-71 Mooneyham, 2 Barry Grant 850's, Rewarder headers. SUPPOSED to be about 850 hp. It makes 12 lbs of boost. Cost $25,000
The Pump: Berk JC with a loader and Place Div. the impeller is a Berk SS AA. The pump is unmodified.
We live at 4500 feet elev.
My boat, 4600 RPM, 55mph.
His boat, 6500 RPM, 74mph.
He thought that with that much engine he could hit 90. He is soo disappointed in the boats performance that after 4 outings this year, he has parked it. I know that you guys are going to jump up and down and say, "The Pump... MPD the pump"...but do you really think there is that much performance to be gained there?
He spent a shit load of money on the motor, and he is really unhappy with the results, so he is very reluctant to spend another 3 grand on the pump.
The way he feels right now.....
"Eliminator for sale...big ass motor... kinda slow...$15,000.00"
I've been trying to convince him to spend a little more on it and keep it. Help.