5.7 Mercruiser ???'s

[cj41foley]

I didn't see a boat section so I put this in offroad motorsports. Someone can change it if it needs it. Is a 5.7 Mercruiser the EXACT same as a 5.7 GM? Anyway, I was wondering if anyone knows anything about marine engines on here. I'm gonna rebuild my 5.7 Mercruiser before this summer and wanted to know if I can just go down to the parts house and use regular GM parts or if I have to use Mercuiser parts for some reason? I'd like to maybe put a little bigger cam in it and maybe a different intake and a little head work. Anyone have any experience here? Thanks.

[cj41foley]

[StarDriver]

It may be, do you have any pictures of it.

I know of a Mercruiser engine that will get your boat on the water.

[Mustang1989]

Some GM parts you can use, and others you HAVE to use marine spec parts. I'm not exactly sure which stuff though. My dads been a boat mechanic at a marina for nearly 30 years. He also fixes boat engines on the side. He always shakes his head when someone uses a carburetor made for a car on a marine engine. Something about the way the exhaust is vented, and how easy it is to blow up you're boat if you do that.

[cj41foley]

I bought a 1988 Chaparral 200XLC for $2,900. It looks very good, but needs the motor built. No problem since my dad has been a GM mechanic and master tech for like 30 years. I want the boat to be pretty quick but can't afford a real gas hogg. I'm sure it'd take a pretty strong motor to make the boat run at least 60 or 65mph. I'd probably be doing good to get into the 50's with a stock 5.7. I guess I just need to build it and go from there. Maybe a decent little towing cam for torque and some head work to let it flow. The boat already has the thru hull exhaust and sounds mean. I just wanna go ahead and get it ready for summer.

[SteveKran]

haha There's an easy fix for ya

[mdub707]

My buddy had the 454 in his 21' boat, and we couldn't get 50 out of it, so dont get your hopes up... though most of it is all hull design.

Some basic parts will swap, but for the most part its a good idea to get marine specific parts, the motors are essentially the same and work the same, but they are both purpose built, usually a marine motor needs to run higher RPM's consistently, not like a car motor. Even if some parts fit, they may not work well for that application.