newer 3.0 power upgrades

G-man

Recruit
Joined
Dec 2, 2003
Messages
2
Currently searching for viable information concerning additional horsepower for a 2002 3.0 Mercruiser. Cust. would like to exceed 200 HP without transplanting a V8 into his pontoon. I have seen the port matched phenolic spacers available from Holley but they only offer 10-15 HP. He would truly love to mount a smaller four bbl onto his existing manifold. Any tips, hints or general speculations would be greatly appreciated.
 

bluewater19

Chief Petty Officer
Joined
Apr 25, 2003
Messages
505
Re: newer 3.0 power upgrades

I don't know of to many mods for this motor. I think 200 hp out of a large bore 4 cyl is asking alot. Gm makes those motors for industrial applications and they were converted for marine use. They are low RPM motors. You need really to spin a 4 banger to make that kind of power. You could turbo one maybe. But we are talking big bucks and poor reliablity. I love hotroding stuff. But you got to pick something with a aftermarket following or you will pay through the nose for custom machining ect.....
 

G-man

Recruit
Joined
Dec 2, 2003
Messages
2
Re: newer 3.0 power upgrades

I was surfing around the other night and saw one site that can mate a 5.7 head to a 181cid or the old 153 block. That sounded expensive to me so I thought I'd look elsewhere. This fellow is competing with the "Johnsons" so to speak and doesn't want to exceed a grand doing so. Right now he gets 31 mph out of his 21' tritoon Odyssey pontoon that I sold him two years ago. I'm sure a turbo kit would shoot the price limitation he set and would probably also require a new set of slugs as well as a cam.<br /> A buddy of mine, an avid offroader like myself, suggested a small nitrous injection; he has a 30hp nitrous setup on his Willys. Any thoughts on that.
 

Doug Durako

Chief Petty Officer
Joined
Nov 17, 2002
Messages
519
Re: newer 3.0 power upgrades

Check your customer's insurance policy before adding Nitrous-Oxide. Many insurers consider that a "racing" application and exclude it. Could be a serious problem if he has an accident.
 
D

DJ

Guest
Re: newer 3.0 power upgrades

G-man,<br /><br />You're simply not going to get anything else out of that engine without SERIOUS modifications with poor longevity.<br /><br />If the same boat is/was available with a 4.3L V-6, the swap might not be too bad.<br /><br />It's the ONLY way.
 

bomar76

Lieutenant Commander
Joined
Jun 27, 2002
Messages
1,963
Re: newer 3.0 power upgrades

Customer and mechanic need to do a reality test....while 200 HP out of the little 3.0L 4 banger is technically possible, the result would be a miserable, unreliable, rod throwing piece of junk.<br />Forget that whole idea and either A: Repower (remembering that drive ratio will most likely need to be changed) or B: Sell it and buy something with the power he wishes.
 

Doug Durako

Chief Petty Officer
Joined
Nov 17, 2002
Messages
519
Re: newer 3.0 power upgrades

There was a thread here awhile back about a three-log pontoon with a 350 mag and it is only making about 45-48 mph.<br /><br />If he wants a fast pontoon, he needs a couple big outboards bolted on the back, and that will cost more than he paid for the whole rig!
 

cobra 3.0

Lieutenant Commander
Joined
Jul 31, 2003
Messages
1,797
Re: newer 3.0 power upgrades

I'll ring in the same tune as the other boaters here. I have the 3.0 Cobra in my 16ft bowrider. It is not an engine designed to handle more than it already does. If it doesn't have electronic ignition, you may gain 2 mph more by putting one in and you may want to try a good stainless prop. You might even try synthetic oils for the engine and drive...more than that and you are looking for trouble. It isn't designed to rev much higher than it does.<br /><br />Go with a bigger block if speed and power is a concern.
 
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