Looking for more HP

[350cavi]

I'm a new member here so please bear with me .

I have a 1997 4cyl 40hp Magnum Mariner. Right now it sit's bone stock and runs pretty good. I am now not happy with the amount of hp it has, so right now I am looking to squeeze more perfromance out of it. What exactly could be doen to get more power but keep longevity of this engine?

Since I have to pull the power head off to put new upper motor mounts in, I was thinking that this could be the best time to do some motor mods. I was thinking of throwing in a set of Boysen CF reeds and do some porting as well. Also thinking I could maybe bore all the cylinder holes out .040 and run a set of Wiseco pistons in it. Also though about putting some velocity stacks on it. If there is anything I can do to the tuner as well let me know.

Thanks for your help guys!

[Mark75H]

In order:

1) Boysen carbon fiber reeds won't make this motor run any faster or improve accelleration and have a much shorter life than the factory steel reeds (probably need to be replaced every 25 hours or so)

2) Porting ... the venerable 44ci 4 cylinder powerhead has generous port timing and area from the factory. Hogging it out more will only slow it down and make it use more gas

3) $400-$500 worth of machine work and $500 worth of pistons will make no noticible difference on a pleasure boat (probably not on a racer either)

4) There are no velocity stacks made for these motors .... adapting stacks from another motor won't help either

5) The original designers had 40 years to optimize the tuner ... don't mess with it

The best advice to get more power would be to trade it on a used 60 hp OMC while you have it off. You have already talked about spending more money than the trade would cost.

[350cavi]

The motor is on a lighter weight voo doo, if that would help. Well I geuss it sounds like I'll be looking for either a drop on 60hp power head, or find a direct replacement motor. Thanks Mark75H.

[JohnsonM50]

Ive found that when upgrading engines that you will see the most difference in acceleration and it will be moderatly faster. If you want to work with what you have [or a new motor ] proper tuning, set up and prop choice are where youll best optimize.

[outboardjetboater]

don't listen to mark. go to this website.
www.scottcraftboats.com

[Mark75H]

Not much active on Dave Scott's site, email him directly: David Scott

[7500Blizzard]

Daves motors run excellant but they will not push a VooDoo no matter how light it is. It won't even mount right with a 9" mid. He's even in your backyard cavi he's in Kanata. Velocity stacks do nothing for any outboard if they did Mercury racing would've used them on thier factory boats.

[Fast Fred]

hears a VooDoo, it kicks it

[tthibodaux]

Find you a 3cyl. OMC. Be realistic, none of those old Mercs will have the power of the old 75 Stingers or any 3cyl.OMC for that matter. Just a thought. I know some will dissagree but its true in your case with the boat you have and those old motors are a dime a dozen with lots of internal hp to be found.

[tthibodaux]

Hone the cyl. to get the glaze off. There is NO hp advantage to boreing a 2cycle outboard. For HALF the money find you a OMC(3cyl.) off some old fishing boat put fresh rings in it and you'll be miles ahead of where you are now.