Why the high usage of Mercruiser and Volvo engines?

There must be something they are doing to them that makes them better suited for marine use, but I dont notice anything in the build sheets that I see! What would stop someone from building a regular small-block or big-block and dropping it into their boat? Even alot of the GM crate motors seem like a great deal compared to what Mercruiser and Volvo charge!

Some examples:

GMPP LS2 6.0L EFI Engine - $5500 - 400hp
GMPP ZZ4 350ci Carb Engine - $3800 - 355hp
GMPP 454ci Carb Engine - $5000 - 425hp
GMPP ZZ502 502ci Carb Engine - $7500 - 502hp

those motors won't last in a marine enviroment...

swoop

Do a search on "crate engines' for starters. THere has been a lot of conversation about this. I have same thoughts you do about what really makes a marine engine different beyond some of. the USCG requirements on alterntors, starters, distributors. There is also a possible issue about capacity of oil pan and some cooling system issues but it seems like an adaptation of a closed cooling system would resolve a lot of those issues.

Anyway--been discussed a lot and a lot of good info in the board.

i heard something about vortec engines being used in offshore racing a little while back. as a mercury alternative. any info on that?

GM was using the Vortec in a marine app. Merc is also doing it, but they were not promoting it like GM was. I believe that program has since ended. A couple of board members had a very winning season with the Vortec. I believe a certain board moderator also had them in his boat. Rest assured, these were not a stock engine out of a 2500 series pickup!

marine engines 101.....

well first of all the only stupid question is the one that isn't asked!!!

Now on to your question. 1) Merc and Volvo both use GM marine production motors for most of there applications, are they the same as you car or truck? no. The reasons are a) when your car is doing 65 down the hwy your rpms are about 1500 give or take, when you are cruising around in your boat your rpms are between say 3500 and 4400 so you need a different power curve and heavier components ie cam, carb, timming curve, injector pulse with ect, now add to that a salt water environment you need brass freeze plugs water cooled exhaust manifolds, oil coolers and power steering coolers ( because of the rpms ) there are other differences but these are some of the basics!

If I'm not mistaken there is a difference in cam specs as to reduce the possibility of water reversion.

overlap is a little less but not a major factor cam is differnt more so for the power curve then any thing

I've seen people running non-water cooled headers, is that bad? Could you just ceramic coat regular headers or do you need a water-cooled setup?

Only possible in open engine compartment like jet boat etc. Otherwise it would be foolish and no legal