1997 fountain 38 with 22% prop slip
 

Motors fresh off dyno made 750hp at ozark speed and marine. XR drives with 2" shorties. Running 32 4 blades from bblades. Took it out tonight and ran 83mph at 5300rpm. Slip calculators say that's 22% slip. Was hoping boat would run low 90s.

Any ideas??

Thanks guys

That's way slow. My 2000 Fever, same hull, small steps with -2 imcos, ran 86ish with a set of fresh 525 efi's and stock 32 bravo's turning 5300 then mid 90's with 700 Ilmors turning P5X's around 6000. That boat should also be running mid 90's if not better with 750 HP. How much torque did the motors make? Are you picking up water thru the Imco's or external pickups? Something isn't right. Are you sure about the HP? Have you checked the hull for hook?


My 38 liked the P5-x's and 5 bladed Herrings.

something is not right,a 750 hp engine should spin those props to around 6000 rpm if you have 1.5 gears.do you have dyno sheet?

Do you have a rev limiter on the engines? If so it could be that you are under propped and hitting it.

5 blade props

What speed, rpm, and props did it run with the 625's listed in your profile???

Which way are the props rotating?

Jim's dyno is pretty generous with horsepower ratings.

I was thinking the same thing that the boat should run 10MPH faster. Drives have drive showers. I am not sure what you mean by check the haul for hook. I will do a google search to find out what that means haha!

We are rookies when it comes to boating....we are only capable of swapping motors because of our extensive drag racing back ground. If you want to talk small tire drag radial racing I wont sound so uneducated.

thanks for the help!

Rev limit set at 5800 I believe. Its not hitting rev limit.