Marinizing a monster...

[Bubba1235]

Ok, so I have customer I've done a lot of work with over the years and he called this weekend wanting me to take on a new project for him, repowering his boat. (Again) The existing engine is a Chevy 454 Big Block and is cranking out around 390 H.P.

So what does he want? He bought a Chevy 572 Cubic Inch monster that dynoed at 657 H.P.

I've done some checking and no one builds marine parts for this beast. I can use a lot of things from the 454 (starter, water pump, alternator, etc.) but the big sticking point is the exhaust manifolds, no one makes a marine manifold for it. I am looking at having a set custom built from stainless steel but would LOVE it if someone has a source for an off the shelf manifold.

Currently the boat is running a Volvo DuoProp and it looks like its going to take some creative machine work to couple the drive to this new engine. The outdrive will be sent to another shop over the winter to change gearing and going through the drive. (I am not set up with the needed tools or place to do it.)

Yeah, should make for a very interesting project this winter...

 

[mthieme]

Re: Marinizing a monster...

Here are the MerCruiser part #'s to get you started...
manifold 821137
manifold gasket 841234
elbow 821139
elbow gasket 847934

I googled the manifold # and boats.net carries them....$3,572 per manifold.
I take your customer has deep pockets.

 

[oops!]

Re: Marinizing a monster...

most of those big monsters use headers, the exaust is run thru hull.

water is drawn in thru seperate pumps......

as far as the dist and alt, starter, ect...ect...ect...you might have to have him take the parts to a rebuilder.....they might be able to rig somthing......

but....if it aint marine....its got no business on the watter.......or BOOM

 

[ne7800]

Re: Marinizing a monster...

maybe i'm wrong but i heard that the 572 is a bored out 502 so couldn't you use manifolds from a 502? again i'm just basing this on what i've herd

 

[Tiwaz]

Re: Marinizing a monster...

The 572 is based on the same block as any other Mark IV big block so accessories such as water pumps alternators and such from any big block should work.
Essentially its the same difference as there is between a 305, 350 or 383 small block.

 

[ne7800]

Re: Marinizing a monster...

he want all that power but dosen't want people to here it? i would go with the thru hull

 

[zaroba]

Re: Marinizing a monster...

please forgive my ignorance on the matter, but out of curiosity, why can't it just use all the hardware it would have in a car with the exception of turning a prop instead of an axle?

in other words:
toss the whole engine into the boat as it would be in a car, maybe keep the radiator etc for a closed cooling system (which would have its benefits), put the exhaust as vertical mufflers (unless he doesn't want em like that), and depending on what the guy wants, either direct drive it, or use a manual transmission with the shifter hooked up next to the drivers seat. attach the motor or tranny to a regular drivetrain that goes threw the hull and is modified at the end with universal couplers etc so it can hold the prop and still utilize trim etc adjustment via controls also next to the drivers seat. as for the overall size, that's what saws are for. with the proper tools and enough time, you can pretty much make any motor fit in any vehicle.

 

[redfury]

Re: Marinizing a monster...

he want all that power but dosen't want people to here it? i would go with the thru hull

Maybe he wants he boat to be a sleeper

 

[redfury]

Re: Marinizing a monster...

I can think of at least 100 reasons without even trying.

How about the most obvious....Marine grade parts do not produce spark and are designed to not create hot spots that could ignite fumes built up in the engine compartment ( not to mention better quality so you don't get left stranded due to parts failure because of contact with water, etc ). It's that simple. It's also the reason why if you have a bad ignition switch, you buy a MARINE replacement switch.