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Discussion Starter #1
My 68 Chevy II, with 250 inline 6, is factory rated at 155 HP.

I think the Mercruise (boat) is basically the same engine, but rated at 165 HP.

How does the Mercruise gain an addditional 10 HP over the Chevy engine?
 

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My 68 Chevy II, with 250 inline 6, is factory rated at 155 HP.

I think the Mercruise (boat) is basically the same engine, but rated at 165 HP.

How does the Mercruise gain an addditional 10 HP over the Chevy engine?
Just a guess on my part.

I would guess that the cam has slightly different duration and lift. Most boats with that motor would assume that they will run at a constant rpm, usually in the mid to high 3k range.

My other thought is that the exhaust is a bit more free flowing than a car system.

Doesn't take much to get 10 hp.
 

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Cam and exhaust Are different then that of a car . But the exhaust alone would make that much difference If not more so.
 

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Discussion Starter #4
I have the Langdon cast headers on my car, so I probably picked up a few HP myself.

Guess I could check out the cam spec's to see the difference between the two.
 

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Agree with the cam & Exhaust

But...don't think that putting that merc cam in a driver is a good idea, because it isn't. Merc and the aftermarket suppliers are real proud of their parts. The engines need a totally different power curve and have vastly different stresses. A boat engine operates a constant speed and constant load. Think dragster engine. If you are looking for more power, get with your local speed shop, machine shop or the folks at Summit/Jegs/etc to develop a total engine system.
 

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Tom Langdon sells alot of those merc. cams for use in daily drivers. And nobody that I know of has not had any issues with useing it.
 
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