Prochargers on Merc 7.4MPI
#11
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Joined: Feb 2004
Posts: 3,710
Likes: 2
From: MT. JULIET, TN.
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
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
#12
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Joined: Jan 2004
Posts: 4,480
Likes: 43
From: Tennessee
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
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
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.
Let me know exactly what you have and we can come up with a plan of attack and a budget. Eddie
#15
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Joined: Jun 2005
Posts: 726
Likes: 0
From: Hendersonville, TN
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
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
#16
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 !!
The plus side,,,, left alone and maintaned they about run forever !!
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#17
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
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-Wally
Money can't buy happiness, but it can buy horsepower. And I've never seen a sad person hauling a$$!
-Wally
Money can't buy happiness, but it can buy horsepower. And I've never seen a sad person hauling a$$!
#18
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Joined: Jun 2005
Posts: 726
Likes: 0
From: Hendersonville, TN
#19
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Joined: Mar 2008
Posts: 1,181
Likes: 2
From: Vancouver BC
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..
#20
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Joined: Jan 2004
Posts: 4,480
Likes: 43
From: Tennessee
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
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




