Jonlxa415

It’s a Berkeley pump and jet drive.

originally had a 454 bored 30 over in it

MikeGyver

iTrader: (5)

Isn't sizing a jet pump similar to final gearing on a car? So your statement implies that if the boat used to reach 100 mph at 7000 rpm with a 999 horsepower engine, it will reach 7000 rpm if your cam is designed to peak at 7000. I'm pretty sure that the rpm limit won't need to be set in the PCM, other factors will limit the rpm.

MikeGyver

iTrader: (5)

Or maybe your idea of a "crazy" 454 is different than mine.

joom

Impeller pitch is more like gearing . Pitch and pump size do go hand in hand though .

MikeGyver

iTrader: (5)

So my point is, shouldn't it limit the rpm if the new engine has less power?

smokinlmm

It will, that’s why I asked. If the pump and impeller were setup for 1000hp a stock 5.3 will not be very much fun.

joom

​​​​​​There are "prop shops that re- pitch impellers or propellers , You wouldn't wantt the same prop for say skiiing as you woul top speed .

Jonlxa415

so I’m gonna take a guess and say it roughly about 450-maybe 500 hp so I’m guessing that a 5.3 with a cam should be good to have a little fun

RDF1

Thats what I was getting at earlier. The torque vs rpm will be substantial different from a 5.3 to a big block. ​​​​​​​I helped a guy go from a 502 carb big block to a EFI LS3 in a fan boat and had to change the pitch quite a bit to get it back drivable. Where they had the big block pitch setup to only turn 3000 rpms. The LS3 didn't make near the torque so changed the pitch so it could turn at 4000-4500 where it made peak torque. It worked really good that way and even used less fuel than the 502.

jet boat stuff I'm sure is similar. The LS will need the rpms to make the power.

Jonlxa415

yeah thats what im guessing and if i need to change the impeller then so be it I will change it up