454 to 496?
09-08-2008, 01:11 PM
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454 to 496?
i just aquired a 06 496 out of a truck and wanted to replace my 454 mpi it with my would it be better to change the whole to motor out or put my 454 mpi top end on the 496 block
09-08-2008, 01:45 PM
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I don't believe you can put the 454 parts on the 496 engine. I believe the new gen engine is a slightly different animal.
That being said, I'm not sure putting a truck engine in your boat is the best thing to do either. As you'll find by doing searches on here, a marine specific engine and an automotive engine are different. Internal clearances, materials used, and other things can doom an automotive engine to an early grave when run in a boat. The load put on an engine by a boat is much more severe than the load put on it by a car or truck. Sustained higher rpm operation (higher end being 3000+) can really take its toll if not prepared for.
Other things to be careful of are cam profile/computer program. Is the truck cam made such that reversion won't be a problem. Reversion is the act of water being sucked into the engine from the exhaust manifold as the piston is on the down stroke and the exhaust valve is not yet fully closed. I know you can have the engine "marinized" which involves dissembling a part or all of the engine to bring it up to marine specs, but I really don't know much about what they do in that process.
That being said, I'm not sure putting a truck engine in your boat is the best thing to do either. As you'll find by doing searches on here, a marine specific engine and an automotive engine are different. Internal clearances, materials used, and other things can doom an automotive engine to an early grave when run in a boat. The load put on an engine by a boat is much more severe than the load put on it by a car or truck. Sustained higher rpm operation (higher end being 3000+) can really take its toll if not prepared for.
Other things to be careful of are cam profile/computer program. Is the truck cam made such that reversion won't be a problem. Reversion is the act of water being sucked into the engine from the exhaust manifold as the piston is on the down stroke and the exhaust valve is not yet fully closed. I know you can have the engine "marinized" which involves dissembling a part or all of the engine to bring it up to marine specs, but I really don't know much about what they do in that process.
09-08-2008, 01:54 PM
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if this can be done im going to rebuild the top end on either motor new cam and bring to a dyno for tuning i just want to get the 496 in the boat this is a fresh water boat only
no replacement for displacement
no replacement for displacement
09-08-2008, 02:03 PM
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This is Mr. 496- http://www.offshoreonly.com/forums/member.php?u=48805
PM him.
You're going to have to do quite a bit to the engine to marinize it. The cylinder clearances on an automotive engine are too close, unless you FWC it. Going to need larger valve stem clearances as well as different valves & seats. Definitely need a different cam. I believe you have an exhaust flange issue too. Don't forget brass freeze plugs.
PM him.
You're going to have to do quite a bit to the engine to marinize it. The cylinder clearances on an automotive engine are too close, unless you FWC it. Going to need larger valve stem clearances as well as different valves & seats. Definitely need a different cam. I believe you have an exhaust flange issue too. Don't forget brass freeze plugs.
09-08-2008, 02:27 PM
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About the only thing "compatible" between your 454 and the 496 is the exhaust. But I hesitate to even share that little detail, because you don't want to use a stock 454 exhaust on the 496. If you go forward with this, find Merc 496 exhaust takeoffs to use. FWIW, the 496 is a Gen VII tall deck compared to your Gen V or VI engine. Virtually nothing will swap over. I'm not sure about the flywheel, but the bellhousing bolt pattern might be the same. So you got that going for you... 
Quoted from this thread, on the difference between the truck 496 and the Merc 496: http://www.offshoreonly.com/forums/s...ad.php?t=89952
Quoted from this thread, on the difference between the truck 496 and the Merc 496: http://www.offshoreonly.com/forums/s...ad.php?t=89952
the engines are the same except for a few minor things. First one is that you would need the marine ECM, MEFI or similar. Second the marine 496 uses a 8 qt. long deep pan, the truck pan is too deep and small for boat use. The water crossover is diffent as well as the thermostat. The injectors would have to be changed to the marine injector ( larger output). The marine duty fuel injector which is 35% bigger than the truck injector. As for crankshafts, some of the early 2001 and 2002 496's came with a forged crank that GM changed over to a newer cast unit in late 2002 that is supposedly is as strong as the forged unit. My advise, don't take any of these cranks above 575HP in a 496, our tests support this finding! If you simply wan't more power from any 496 call us or visit our website. You can bolt on our parts and with truck 496's you will have more power than stock Merc 496's. We also have a some forged cranks, crossovers,marine pans, etc. You can easily set up some nice 525HP 496's for any boat without denting your wallet.
Good Luck
Ray @ Raylar
Good Luck
Ray @ Raylar
09-09-2008, 08:40 AM
#7
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Raylar is really the only game in town.
I'd strongly suggest doing the numbers on this conversion before you start amassing charges to your Visa card. I think you're going to find that you can get moving a whole lot faster for a whole lot less $$ with any engine other than the 496.
Turning the 496 into something it's not is going to cost a fortune. Doing it any way that doesn't cost alot of $$ is going to result in your boat going slower. That truck-based 496 doesn't put out what your 454 does now. Making it do that, reliably, in a marine environment, is going to be a chore.
Throw a 1/4" stroker in the 454, get a better cam, intake, exhaust, etc and ditch the 496.
I'd strongly suggest doing the numbers on this conversion before you start amassing charges to your Visa card. I think you're going to find that you can get moving a whole lot faster for a whole lot less $$ with any engine other than the 496.
Turning the 496 into something it's not is going to cost a fortune. Doing it any way that doesn't cost alot of $$ is going to result in your boat going slower. That truck-based 496 doesn't put out what your 454 does now. Making it do that, reliably, in a marine environment, is going to be a chore.
Throw a 1/4" stroker in the 454, get a better cam, intake, exhaust, etc and ditch the 496.
09-09-2008, 09:34 AM
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The only people that have done anythng with the 496HO that I am aware of is Raylar and Innovation Marine. I know that Innovation and JimV were working together for a little while before they stopped their R&D.
http://www.offshoreonly.com/forums/s...innovation+496
http://www.offshoreonly.com/forums/s...innovation+496
