What's the difference?

[CHEETER-JOE]

between a marine motor and a street motor? I am wanting to build a sbc to replace my 6.2, what do I need to know?

[Moneypitt]

Your bank account balance is important...Other than that just build the hoursepower you want using a camshaft that will work in the desired RPM range. This means the bottom/midrange and the top end. A boat is fairly forgiving when it come to getting into the midrange. You're not trying to move a heavy vehicle on the pavement so the motor can get happy pretty quickly. As with any hipo project the bottom end needs to be bullet proof, don't spare the $ money down there. Once the comp ratio is established,(do you plan on running "funny gas") then you can cam it and work your way in and out from there..........boat weight, gearing, and how wet the boat remains at speed all have a bearing on your HP requirements. Do a little research, look at boats simular to yours and see what they have done, what worked and what didn't.......get the picture? .........Moneypitt

[CHEETER-JOE]

I am looking to build a basic 350 or 400 block with alum heads fully roller nice cam and maybe some sort of fuel injection on pump gas. Maybe around the 400hp or so range. As far as the heads, they are the same for street or marine?

[Moneypitt]

I would say yes, they are the same. However, boats are harder on valve train parts because they don't coast like a street car. If you accelerate up to speed in a car, you can feather the throttle back and cruise. In a boat, you must maintain the rpm s to maintain the speed. I other words you're gonna be reving it pretty hard all day. I strongly suggest the springs used be part of the camshaft kit, and a stud girdle is a necessity...........MP

[CHEETER-JOE]

Thanks for the info MP.

[twistedpair]

This guy used to post here a lot. You might say he wrote The Book (http://www.glen-l.com/books/smallblock.html) on marine performance motors.

[powerplay230]

CHEETER-JOE,
Not sure what they deal is on your 6.2 but if it's in one piece can you build up it. Saves you the cost of the basic longblock or is that motor even worth building up. Not sure what parts are used in them or what is available? Guys??
Rick

[CHEETER-JOE]

There is nothing wrong with the 6.2 besides lack of power, it has only 46 hours on it. I know I can just add a whipple or procharger, but I dont know what is internal in this motor. If I build another motor, I can still have this in the meantime. And it is always fun just to build a motor anyway!!

[Bondo]

Your 6.2l IS a 383..............
350 Block,+ a 3.75"(400cid) Crank............
You've got Problems in Tuning......
You Should have all the HorsePower you Need........

[CHEETER-JOE]

Originally posted by Bondo
Your 6.2l IS a 383..............
350 Block,+ a 3.75"(400cid) Crank............
You've got Problems in Tuning......
You Should have all the HorsePower you Need........
It is a 377 6.2 MPI with 320hp. In a 24' boat. I get about 55-58 mph out of it, but always want more. I would like to get between 65-70 mph out of it.

[powerplay230]

Joe,
If you are going to build another engine while still running your 6.2 you might want to consider building a big-block to go in. Sounds like for your needs you are going to need a pretty generous increase in horsepower, so either a "healthy" big block or really wild small block. I'm guessing the bigger motor wouldn't cost much more to build and will last longer. Just my two cents though.
Rick
:eek!:

[Nucking futs]

I would build a bigblock!About the same price to build a bb as a wild sb.Plus you alawy have room for better upgades later on the big block.You would have to wing that sb alot higher and longer than it likes in a 24' boat.You would get about the same horse power but at a lower rpm in the big block and i say about 550hp it would get up in the speed your looking for and maybe even more.......just my .02

[CHEETER-JOE]

I thought about the big block, but what would it take to change the motor mounts? And would my ehaust be in the same holes thru the transom?

[FOURQ]

I dont think it would be hard to change the mounts and the exaust should work with the old holes especially if you got a set of lightning headers he will custom make them for your aplication.. how does your motor mount?

[powerplay230]

Most small and big block Chevys used the same mounts.