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looking for input on performance parts for genV 454 merc
I am in the process of rebuilding my merc 454 and just looking for some advice on what other people are doing to them for a little extra performance. the boat is a 1996 baja 208 islander (roughly 21ft) open bow. motor did not really have any problems it was just starting to use some oil so time to go through it. I am looking at different cams but not sure what to go with. I also have been wondering about different intake manifolds and also other peoples input on self tuning efi or if I should just stay carbureted. I bought a set of IMCO power flow exhaust manifolds about a month agao and plan to put them on. as for the moment the boat is all stock. has factory thru hull exhaust. any input would be greatly appreciated. thanks guys!
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I have two sest of 500 EFI intakes with injectors, harness, and computer. would make a great upgrade to the 454. They MerCruiser take offs.
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Is this a 330hp/350hp ? Not a magnum I assume?
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Originally Posted by tunertech
(Post 4614908)
I have two sest of 500 EFI intakes with injectors, harness, and computer. would make a great upgrade to the 454. They MerCruiser take offs.
Originally Posted by convincor
(Post 4614910)
Is this a 330hp/350hp ? Not a magnum I assume?
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Mild performance upgrade is easy.
Significant performance upgrade basically tosses away everything but the block (and the Gen 5 block is the least suitable for serious performance). Your 330 horse Gen 5 will respond to all the usual tricks. You do have peanut port heads, so choose a fairly mild cam. An intake upgrade is also recommended - (the 500 EFI setup mentioned above is for rectangle port heads, which you don't have - but it would technically work) You also need to decide if you plan to boat in freshwater or saltwater. A saltwater boat can't use a lot of the usual hop up goodies without you promising to become a dedicated flusher.. An aluminum intake like the Ebrock Performer is a good upgrade, but it won't tolerate salt like your cast iron stocker. List exactly WHAT your motor and outdrive are right now - as well as whether it is seawater or freshwater cooled right now. Then list the percentage of saltwater usage you plan. Then list your intended result - how fast do you want to go, how often and for how long do you want to run wide open. Do you plan on pulling tubes or skiers very often? etc.. <MC |
Originally Posted by tunertech
(Post 4614908)
I have two sest of 500 EFI intakes with injectors, harness, and computer. would make a great upgrade to the 454. They MerCruiser take offs.
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Originally Posted by mcollinstn
(Post 4615471)
Mild performance upgrade is easy.
Significant performance upgrade basically tosses away everything but the block (and the Gen 5 block is the least suitable for serious performance). Your 330 horse Gen 5 will respond to all the usual tricks. You do have peanut port heads, so choose a fairly mild cam. An intake upgrade is also recommended - (the 500 EFI setup mentioned above is for rectangle port heads, which you don't have - but it would technically work) You also need to decide if you plan to boat in freshwater or saltwater. A saltwater boat can't use a lot of the usual hop up goodies without you promising to become a dedicated flusher.. An aluminum intake like the Ebrock Performer is a good upgrade, but it won't tolerate salt like your cast iron stocker. List exactly WHAT your motor and outdrive are right now - as well as whether it is seawater or freshwater cooled right now. Then list the percentage of saltwater usage you plan. Then list your intended result - how fast do you want to go, how often and for how long do you want to run wide open. Do you plan on pulling tubes or skiers very often? etc.. <MC |
330's never came with rectangle port heads.
The '92/'96 Gen 5 Bravo3 and Magnum motors DID have rect port heads. The other Gen 5 motors had peanuts. Do you have a B3 boat? |
The Crane 731 or 741 are pretty popular for mild builds. I’m really curious about the Holley Sniper FI unit. For an application like yours (and mine) I personally like the simplicity of the throttle body FI on a normal manifold. The Air-Gap Performer RPM is an impressive manifold, but I just went with a Victor JR on my ~500hp build mostly because Merc puts single planes on their 500 engines and figure they’re smarter than me.
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My personal experience over the last 30 plus years now is mild performance upgrades are hardly worth while. Speed gains are minimal. Some worked over oval port 269 runner aftermarket cast heads, cam, intake, carb and roller rockers will get you an easy 150 plus hp. Just cam intake and carb type deal just doesn't cut it as far as I'm concerned anyway. Maybe 30 to 40 hp gain which is fine if your just looking for 2 mph or so. All on what your end goals are. |
If its a mag motor in good shape, drop a blower on it, 5 lbs boost, a 731 cam and a some stainlessmarine exhaust...if thats not enough bolt on better heads.
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Whats your budget ? I have these for sale, just need to add fuel pump
https://www.offshoreonly.com/forums/...i-hp-ecus.html |
Rly curious on what you have for sale but the page will not open. It just says page not found. Now on to the bad news... I started rly cleaning up the block and it’s junk. Someone must not have winterized it at some point and it cracked and they had it welded. Even worse news it’s cracking again and there a lot of stress cracks in it... not what I wanted to find. |
Check his f2's post/threads. I think it's the holley sniper efi with intake and throttle body set ups. |
Dane I don't relish in the fact that your 7.4L engine is trash. However it is a blessing in disguise.
Hopping up your engine would be expensive and the gains mediocre at best. I too am a runabout owner and did a 7.4L MPI to 502 MAG MPI switch years ago and never looked back. I am now 18 MPH faster and the total cost was about 5K. A mechanic did it all and if you have the facility and knowledge to do the work yourself you can save $1000 - $1500. Find a good take out 502/454 MAG MPI or a 496 HO or even one of the newest 502 Mags or HOs and save yourself some headaches. Salvage and sell the parts from the hurt engine to offset costs. OSO is not that "small boat friendly" so it does not surprise me that your thread is not getting the attention it deserves. Too bad Speedwake is dying but it still has the best small boat hop up thread ever invented. It's a good read filled with great ideas and results. Microboats - can they run? - Speedwake 2.0 |
If you're wanting to end up with a dragster...I have a 256 blower/chiller setup for sale in the swap shop...couple that onto a 502 mag or 454 mag and you could easily double your stock 330 hp...just a thought :ernaehrung004:
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