What size prop are you guys running on your sonics? 26 ft 502 mpi all factory with stainless marine manifolds and tail pipes.

24P 4 blade labbed Bravo on a HP500EFI Prowler back in the day.
Probably a 22P 4 blade Bravo is a safe prop to start on yours.

Have you run anything on the boat yet? If so, do you have any rpm or speed numbers?

Brett

I have a 98 prowler with stock502mag Mpi with eddie marine exhaust and mine came with lab bed 26 bravo 1 four blade when I bought it few years ago

I have a 24 4 blade bravo 1 on there now. But im fighting some issues and wanted to see what everyone else was running boat would only do a best of 50-52mph not sure on rpms guage broke once issues started but if i had to guess 4-4200 rpms so i sent my injectors out to get flow tested and looked over adding a fuel pressure regulator changing exhaust over to stainless marine manifolds and tail pipes, and had my outdrive gone through. Ive never had a solid run out of this boat since i bought it last year. The motor i purchased the boat with poped on first trip out and now i have a fresh 502 in the boat but it was a blue motor (hp 500 i believe) and my old cam was put in the fresh motor (dont ask why) i didnt know until after i started asking questions and i set my mpi fuel injection set up on the long block and it free revs fine good oil pressure good compression, once i get the injectors back ill do the fuel pressure test but i think thats all good and im hoping its the prop and not my cam.

Any help? Im leaning towards a 21 or 22p

If it is a HP 500 and has the 470+hp, you should be able to pull the 24 more than 4200. The hp500's would like to run in the 5100-5300 rpm range.
You need to get all the ducks in a row and also get a accurate tach and then I can be more helpful.
We can send you test propellers without buying one and get you dialed in from there.
Something is up if you can only pull the 24 to 4200.

Brett

The only differance with the hp 500s and the reg 502 mpi motor should only be the cam and he said he put my original cam in the motor so my motor should be 415 hp what prop would that call for?

Even with 415hp I'm surprised you can't pull more rpm. Wait till you can run again before you get too worried. We need accurate numbers to get you where you need to be.

Brett

In my opinion your running the right prop. Its an engine issue. I have a 28' boat and stock 502mpi & 24 pitch. It turns the 24 to the max & I could run a 26 but will kill my quick planing. My boat is heavy. Have to start with process of elimination. RPM guage? Fuel Pressure? TIming? VST/Fuel FIlter?