MPI Short-Runner Intake Manifold
12-09-2002, 11:54 AM
#2
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Short runner intake
I have a 454mag EFI with Imco powerflow Exhaust, Rex Marine air filter, MSD 6AL, , and was going to purchase the short runner intake from Arizona Speed & marine too. I t works and gives about 25hp. I bought a ported lower intake , adj fuel reg, and computer reprogramed from a guy on OSO, but it will not fit my engine , it is for a 97 back 454mag efi, and he wont give me my money back, I paid $400. So now im stuck with it and all its parts, if interested please call me 1-302-249-1595
12-09-2002, 04:05 PM
#3
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Ric,
As you may remember from earlier contact, I have the same exact engine as you (7.4 MPI 310 hp). If my memory serves me, the ASM intake is for the 454MAG engine, not the 7.4 MPI. These are completely different intakes. I have been toying with the idea of swapping to a MAG style intake manifold and throttle body. This would require some custom reprogramming of my ECM of course. I have been researching options for getting more horses from this engine. The general consensus is this engine is about at it`s peak already and further mods will net very little difference. I have just about decided to concede to this notion and start building a new engine from scratch, using a carburetor. I bought a few nick nacks from Vortec (adj reg, flame arrrestor) and gained nothing (although Vortec assured me 200 rpm). Basically I`m just saying research all your available options before tossing money at this engine.
After some lengthy discussions with Audacity, he has pretty much talked me into leaving the engine as-is and concentrating on my prop to gain my desired extra speed. This is my current train of thought, for now.
Good Luck!!!!
As you may remember from earlier contact, I have the same exact engine as you (7.4 MPI 310 hp). If my memory serves me, the ASM intake is for the 454MAG engine, not the 7.4 MPI. These are completely different intakes. I have been toying with the idea of swapping to a MAG style intake manifold and throttle body. This would require some custom reprogramming of my ECM of course. I have been researching options for getting more horses from this engine. The general consensus is this engine is about at it`s peak already and further mods will net very little difference. I have just about decided to concede to this notion and start building a new engine from scratch, using a carburetor. I bought a few nick nacks from Vortec (adj reg, flame arrrestor) and gained nothing (although Vortec assured me 200 rpm). Basically I`m just saying research all your available options before tossing money at this engine.
After some lengthy discussions with Audacity, he has pretty much talked me into leaving the engine as-is and concentrating on my prop to gain my desired extra speed. This is my current train of thought, for now.
Good Luck!!!!
12-09-2002, 09:34 PM
#5
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DonMan,
I've got the 7.4 MPI as well. I see you're in Texas too. Bob at Full Throttle Marine has mine and is doing/has done some work to it. Mine should be done in the next few weeks pending testing and tweaking etc.
If you really do want to go carb, or even aftermarket EFI, 425HP or so isn't out of the question. Bob can do it, and is getting a lot of good data doing mine. We're sticking with the GM EFI that's on it. The EFI is where the tweaking and experimenting is coming in right now, the engine work is done. Bob's taking his time and doing it right so once mine's done, he'll have even more knowledge of what he can get out of one without going too far. It looks like with mine we'll end up with about 375HP or so but we'll see how much more there is without junking this EFI.
It's well worth at least talking to him. I towed mine 270 miles to him, that's how much faith I have. Others (even on this board) have towed theirs 1000 miles or more. He's on Lake Travis. Full Throttle Marine
I've got the 7.4 MPI as well. I see you're in Texas too. Bob at Full Throttle Marine has mine and is doing/has done some work to it. Mine should be done in the next few weeks pending testing and tweaking etc.
If you really do want to go carb, or even aftermarket EFI, 425HP or so isn't out of the question. Bob can do it, and is getting a lot of good data doing mine. We're sticking with the GM EFI that's on it. The EFI is where the tweaking and experimenting is coming in right now, the engine work is done. Bob's taking his time and doing it right so once mine's done, he'll have even more knowledge of what he can get out of one without going too far. It looks like with mine we'll end up with about 375HP or so but we'll see how much more there is without junking this EFI.
It's well worth at least talking to him. I towed mine 270 miles to him, that's how much faith I have. Others (even on this board) have towed theirs 1000 miles or more. He's on Lake Travis. Full Throttle Marine
Last edited by SeaRay Jim; 12-09-2002 at 09:45 PM.
12-10-2002, 08:07 AM
#6
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I am just wondering where the bulk of your mods are to get 375hp out of this and retain the MPI? Camshaft and head mods I would guess. Bob has offered to work on my boat, but I`m a DIY kind of guy. I`m really just thinking that instead of spending $$$ on the 7.4, I would sell it and go to a carbed 502. I`m just going to wait it out till next fall and make a decision then.
