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gunflint

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I haven't seen any posts on improving horse power in a stock outboard. Is it cost prohibitive? You always see people modifying cars,sleds, ATV's,etc, why not outboards. Other than prop changes is there a way to change gears or modify carbs, put in oversize pistons, etc. It might be kind of fun to blow by other 25s with a 25 modified to 40hp.

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Nitrous Oxide!

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I was reading on about that on a boating forum and the general concensus was it would be cheaper to just plain buy a bigger outboard.

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Seriously, I don't know how a guy could do it economically and really gain anything. If you are running a 4 stroke motor you could maybe get a custom ground cam but even if you gain 5%, what are you gaining? If you have a 2 stroke you could send the block away and have it ported but then again, what would you really be gaining, and you would for sure lose your idle quality.

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There have been many articles in Bass and Walleye boats magazine (they have a web site also) about just this. Check it out.

Also be aware that modifying outboards newer than maybe 1998 or so is against the law.

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Quote:

Nitrous Oxide!


Turbo !!!!

Seriously, where's the TurboDiesel Outboard ? Can you imagine the take off and torque grin.gif

More seriously as they already replied the costs to increse power and reliability issues are so large it is not convenient. If you think about the difference in speed from a 15hp to a 25 hp will be probably 4mph... and same for most other outboard size, you realize any extra expense is not worth it.

They have race motors, yes but cost of them is prohibitive and they are very unreliable.

If you had an inboard though you could have more "room to play" but watch your outdrive....

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Valv, a turbo would be the thing to do but to take an existing outboard and re-engineer the exhause manifold system to make it external to mount a turbo then route it back into the lower unit would be a major undertaking. There has to be a reason why we have turbo snowmobiles and PWC's but not outboards. Maybe thats why Mercury went with a blower instead of a turbo on the Verado. That and the holeshot would pretty much suck with a turbo in a boat. Not that easy to load it against the converter! grin.gif

A turbo diesel would be pretty sweet but the weight/size would be a major factor for an outboard.

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Darn, I though I was goint to see the sticker "Lund powered by Cummins"

Also I was gogin to get a sticker like I have on my truck that says "Real trucks (boats) don't have spark plugs" grin.gifgrin.gif

I am just giving you hard time John, I am bored this afternoon.

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Valv,

I wouldn't expect to see a pull start on your turbo. grin.gif

I didn't know it was illegal to modify a newer outboard. You learn something every day here. That dang sierra club has every angle covered. smirk.gif

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Quote:

Valv,

I wouldn't expect to see a pull start on your turbo.
grin.gif


Gunflint, as a famous comedian says "..that's funny right there..."

I would like to see somebody face expression with a Powerstroke reading manual where it explain how to pull start the motor in case of failure.... grin.gif priceless !!!!

Now that I think of it, when I was young (very young, which means a long time ago) I had a French car that had a cranking handle with spare tire carrier, if your battery would fail and you needed to start it you could have used the hand crank....brand was Citroen and they were actually pretty good cars.

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I have a Merc 40 and my buddy runs a Merc 30, both four strokes. They are identical, with the only difference being a different computer modual.

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Quote:

I have a Merc 40 and my buddy runs a Merc 30, both four strokes. They are identical, with the only difference being a different computer modual.


So one of you too paid too much for the same motor....shocked.gif

It's not that simple, most of the outboards share same block size and heads, the carburation/fuel injection is the difference.

If you check any V6 they all have same CC size, but they vary from 150hp to 250hp.

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This was on the Merc. web site.

Quote:

EPA regulations prohibit changes to engines that could affect emissions limits. Per the service manual, "The dealer and/or consumer is not to modify the engine in any manner that would alter the horsepower or allow emission levels to exceed their predetermined factory specifications." The only changes permitted are carburetor jet and gearcase/gear ratio changes for high altitude operation as detailed in applicable Mercury Marine Service Manuals


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I'm sure that even though the block and head is the same, the cam would be different, along with the injector(s), fuel rails, probably the piston(s) and intake as well as the ignition and fuel programming. You don't just get a 25% HP increase with a programming change.

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I looked into mods on my 90 Optimax to make it 115. All it took (allegedly) was 115 injectors and a 115 computer. However, that was to the tune of about $2000, and the motors warranty would be voided. I suppose once the warranty expires I could try to find a junked 115 Optimax for parts.

I still think Cretliner should have rated the 1850 Fish Hawk tiller for 115.

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