t500hps

I am buying a boat with M-3 Procharged 500efi. I don't want the Prochargers so they will be for sale this fall. I really want to stay above the 600HP mark but can it be done by:

Punching it out to a 540....
keeping the stock EFI system?
keeping the stock Heads?
staying with 87-89 octane fuel?

Is it possible to hit 620-640HP?

These engines will be our fall/winter project and am looking for some direction.

ActiveFun

Keep the Prochargers. Tune down their output.

t500hps

Suposedly they are running 5psi rated at 765HP. I'm more interested in cruise speed vs top speed. Since these "kick in" at higher RPM's wouldn't they have little effect at 3200-3400 RPMs and then provide all the additional power as you approach WOT? My thinking was more cubic inches would provide the midrange punch to cruise at a lower RPM.

offshoredrillin

Russ, Jeffy is finishing mine now, on the dyno as we speak or this week, will still be reliable. Call me later and I'll fill you in... yes 600+ is possible and still relaible...Rob

SkiDoc

iTrader: (4)

With my single procharged 502 in a 25 ft boat, the centrifugal did help some with planing, etc.....It was a very nice package. Did use more gas than stock. I read in a previous post you need to open up the motors. My advice is you've got some good parts there. If you find you have to go through them, do it and put on better head gaskets, make your valve train bullet proof, get rid of the boost sensitive fuel pressure regulator in favor of dyno done computer reflash and appropriate injectors. Why not send them to R-tech. Bet you would be money ahead, more HP, similar fuel efficiency, and have little worries this way.

SB

iTrader: (1)

The gear ratio and pulley sizes for marine engine's let the centrifugals build boost/power at much lower rpms than you think.

Remember, a street engine designed for 5-7psi at 6500rpm will make less boost at lower rpms than a marine engine that is designed to make the same 5-7psi but at a much lower 5200-5500 rpm. So, yes, the marine set-ups typically have a big impact at the 3200-3500rpm range.

Also remember, your ultimate power 'decider' is your right hands. Cutting off airflow/hp with the throttle is cutting off airflow/hp.

t500hps

A company in Alabama called HESCO did the installation. I've spoken to the and from everything I've seen they have done a great job. Dash has oil pressure and temp guages, water pressure/ temp guages, boost pressure, flowscans for fuel and even pre-lubers for the engines. I know the computer was re-programmed and the fuel system switched to accomadate the needs of the Procharger. (Seems like the install was done with a blank check from the owner)

Now the problem......the motors have been "hurt". They have been run hot and "patched" recently. I'm told several of the pistons are discolored from the heat but the owner didn't want to spend the money to do a complete re-build. Not knowing what is in there I feel I HAVE to open them up this winter. The builder states it runs fine now, but he cannot guarantee it like it is. (Based on the deal I'm getting I'm perfectly happy knowing I need to open them up, I just want to do this ONCE!

BajaRunner

540 cubes will get you 620-640 with reliability.

Canada Jeff

Thats what I want to do when I get over 400 hours on my 500efi. trade the good running engine in on a new 540 ci , maybe efi, maybe not. Don't really want to phuck with my engine if it is still running well. There is value in it, may as well take advantage of it.

Pat McPherson

In this months addition of Powerboat Mag you will find a 540 cude engine that makes like 675HP using the same AZ Speed MPI found on your HP500EFI. Darby in TX builds them I believe.
I'm quite sure there are other builders that have rebuilt 500EFIs with similar specs. Precision EFI or Tyler Crockett for sure...