Marine vs Auto Engine Application Question

[tahoejag]

I bring this to the forum. In general there is a diff in a marine and auto engine, and thats as far as I know. Talking the other day, I was asked "what exactly is the diff"? I guess I was unable to come up with good enuff specific answer, ie. the cam and rods...maybe??? He insisted that there is absolutely no diff and that he could take his auto engine and swap out without modifying anything...??? He did quote the 4.3l vortec as an example. Sitting here with morning coffee thought I'd ask the experts and gain some knowledge in the meantime.

edit: Did a search and read alot that they are diff....cam, rods, etc..maybe lookin for specifics though, for the next time I'm asked...I can say...................

Make it a great day!
John

 

[Georgesalmon]

Re: Marine vs Auto Engine Application Question

internally they are the same, differences are mostly in the things like exhaust, intake, cooling, and electrical stuff. IMHO

 

[matt167]

Re: Marine vs Auto Engine Application Question

Fuel pump/ water pump are different, gaskets are marine type, core plugs are brass, ignition and fuel systems are Marine spec. Camshaft is slightly different, but a truck cam will work.

 

[southkogs]

Re: Marine vs Auto Engine Application Question

The one's in cars typically don't float on lakes, rivers and oceans ...

 

[Bamaman1]

Re: Marine vs Auto Engine Application Question

I had a friend that worked in the GM foundry that Mercruiser rents for a couple of days per year. He said that marine engines use a different metalurgy mix--to Mercury specs. I assume the reasons for using different metal is for strength and salt water use.

GM does the rough castings, but they're then sent back to Mercury for cleanup and substantial machining. They're less Chevy than one would expect.

Mercury engine builders are some of the most meticulous engine builders in the industry. You might find 5 different bearing sizes on a crankshaft. Some of the higher performance, huge cubic inch engines are assembled just about as well as a NASCAR engine.
These engines are built for endurance at higher rpm's, and are simply different from auto or truck engines.

Someone with an oversized 383 truck engine might find good performance in marine use from sheer horsepower, but they really need specialized marine camshafts. Marine engines need a very smooth idle and high torque at low rpm's. Their redlines are relatively low, too. Since they're not turning 7500 rpm's, marine engines don't often need really large carbs or the most expensive heads. They're just special use engines--closer to an industrial engine than a truck engine.

 

[Fishermark]

Re: Marine vs Auto Engine Application Question

Mercury engine builders are some of the most meticulous engine builders in the industry. You might find 5 different bearing sizes on a crankshaft.

???

 

[Bondo]

Re: Marine vs Auto Engine Application Question

I had a friend that worked in the GM foundry that Mercruiser rents for a couple of days per year. He said that marine engines use a different metalurgy mix--to Mercury specs. I assume the reasons for using different metal is for strength and salt water use.

GM does the rough castings, but they're then sent back to Mercury for cleanup and substantial machining. They're less Chevy than one would expect.

Mercury engine builders are some of the most meticulous engine builders in the industry. You might find 5 different bearing sizes on a crankshaft. Some of the higher performance, huge cubic inch engines are assembled just about as well as a NASCAR engine.
These engines are built for endurance at higher rpm's, and are simply different from auto or truck engines.

Someone with an oversized 383 truck engine might find good performance in marine use from sheer horsepower, but they really need specialized marine camshafts. Marine engines need a very smooth idle and high torque at low rpm's. Their redlines are relatively low, too. Since they're not turning 7500 rpm's, marine engines don't often need really large carbs or the most expensive heads. They're just special use engines--closer to an industrial engine than a truck engine.

Ayuh,.... Yer talkin' 'bout the motors used by Mercury Racing div...
Not the standard run of the mill production motors used in the barges that most of Us own...

Aside from the accessories bolted on a Long Block motor,....
The differences 'tween a Standard production truck motor, 'n a Standard production marine motor is Zilch....
As 99% of the production run truck motors are comin' through with brass core plugs, 'n composite head gaskets, Stock...

 

[Silvertip]

Re: Marine vs Auto Engine Application Question

And there is no difference in metallurgy. If there was, the engine would cost twice as much as they do because of the limited production runs.