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Quote:

Originally Posted by Tote-N-One (Post 2511579)

Hey Eddie,

I have the same motor in my boat, and was wondering. If I rebuilt the engine, used original crank, rods with 7/16 bolts, forged pistons and maybe a little biger cam, would i be able to prop the boat for 5k RPM max? Would my HP gain be worth the effort? I'm not looking to make this boat fast, just a couple more MPH on top with reliability. The engine has over 700 hrs on it and I know the end is near!

Thanks
Charlie

You could do that cheap. Rods are damn near free. It's a slippery slope though!!!!!!!!!!!!

Quote:

Originally Posted by Tote-N-One (Post 2511579)

Do I understand right that you have a 7.4 MPI.(310hp)? If you do, then I don't think you would want to put 7/16 rods and forged pistons on that crank. I haven't done it but would think it would be tough to balance with the added weight. Sure you could add Mallory, but the heavy metal would cost more than the crank.:D If you already have a steel crank and 7/16 rods, then go for it. You would probably need to turn it a little more than 5K rpms to take advantage of the larger cam. With a little added compression, slightly larger cam and roller rockers and a few other odds and ends, you could easily bump the hp by about 50. That would be worth about 4 mph on the average v-bottom. There is more hp to be had with a little more work and of course, a little more money.:D Let me know exactly what you have and we can come up with a plan of attack and a budget.
Eddie

Quote:

Originally Posted by kennyo (Post 2511817)

It's a slippery slope though!!!!!!!!!!!!

And you're sliding down it out of control!!!:D:D:D

Quote:

Originally Posted by Young Performance (Post 2512476)

And you're sliding down it out of control!!!:D:D:D

No sh*t! That was my point!

Eddie

It is a 310 horse. Its a shame that this platform is such a weak starting point. I heard recently that this engine is a 2 bolt main. If that is correct, I might as well just look for a 454/502 MAG, and ride this one until it goes.

Thanks for the input Eddie

charlie

As said above,,,, that is just a bad starting platform for mods,,,, thats before you even consider the heads and injection limitations.

The plus side,,,, left alone and maintaned they about run forever !!

Anyone have pics of a procharger setup on an MPI? I have the task of putting a box of parts together back onto a rebuilt motor...would help to have a little reference :)

Quote:

Originally Posted by obnoxus (Post 2512614)

I guess we will see. Got a little over 750 hours on it now.

:boat:

Quote:

Originally Posted by Tote-N-One (Post 2512605)

There's no problem making big power with a two bolt block, it's just every other part of that motor that's a little weak..

Quote:

Originally Posted by Tote-N-One (Post 2512605)

That's correct, it is a 2 bolt main block. Just another good reason not to modify it. You have to remember, that was built as an entry level engine to put in cruisers that needed torque and not a lot of rpm. Hell, they had small blocks making more power than the 7.4 mpi.Now the 454 Mag and 502 Mag are both good platforms to start with. They have the same parts, except the pistons. The 454 has a 4.250 bore and the 502 has 4.467 bore. It would be better to start with the 502 since it has almost 50 more inches to start with.It can go all the way to 565 inches with a 4.25 stroke crank. Let me know if I can help, Eddie.