Suzuki Exhaust Modification

[prattvan]

OK. Please educate me.
I did a google search on modifying an exhaust system on an 4 stroke outboard. I found alot of info stating not to do it, that you would burn your pistons.

Maybe the thought I was referring to a 2 stroke engine, controlled by a carburetor. BUT, I'm referring to a 4 stroke outboard, fuel injected, controlled by a ECM.

So.........I'm kind of new to outboard engines, but have worked on car/truck engines, and go-karts for about 20 years (not professionally, just as a hobby).
For as long as 100 years, people have modified combustion engines in search of more power. If you buy a new car or truck, one of the first things some people do is change the exhaust system (because most stock exhaust systems are restrictive). And also change the intake system (such as adding a K&N cold air intake). Therefore, making the engine breathe better creating more power.
So I'm kind of confused on this. If someone puts headers on a 4 cylinder or V-6 engine in a car, you get more power. But, if you open up the exhaust on a 4 stroke outboard, it will burn the pistons ??

I'm open to all comments.

[prattvan]

I have gotten alot of comments when I posted this on another forum about 2 stroke outboards. I'm not interested in that. It's a totally different engine. It's carbureted and a 4 stroke is fuel injected.

Take a 1998 SUZUKI DF70 for example. It's practically the same engine that was in the 1998 Suzuki SWIFT car. Engineers made a modified intake manifold, a modified oil pan, put the fly wheel on the front of the engine instead of the back, no harmonic balancer, a cast aluminum modified exhaust manifold with water jackets to keep it cool and from melting the hood/engine cover, and the engine is mounted vertical instead of horizontal, like in the car.

I received several comments (and I welcome ALL comments) that stated if you opened up the exhaust on a 4 stroke engine it would melt/burn the pistons.
First, many assumed that one would remove the water cooled exhaust manifold and replace it with open headers or something to that effect. Not the case here. Simply put, I'm thinking of modifying the stock water cooled exhaust manifold.

If opening up the exhaust to create more power would cause a lean condition resulting in burnt pistons, then the person that put headers on a 4 cylinder Honda Civic, or V8 Camaro, or any other 4 stroke fuel injected engine........ would have burnt up their engine a long time ago. The computer(ECM) compensates for the added air flow and adds more fuel.

[Moonlighter]

Interesting concept!

I suspect that not many people, if any, will have attempted what you are considering, perhaps because of the limited space in an outboard leg compared to under the hood of a car. Like you, I modified exhaust manifolds, added extractors etc on my cars in days gone by (a frighteningly long time ago, now!) and it was the first thing we all did in search of better horsepower and torque.

I think that its likely that the only ones to have tried it would be the race boat engine builders, and its a pretty small spe******ed group. Might be worth searching them out.

I will have a word about it with my mate who is the local Suzuki outboard guru, in years gone by he was involved in developing engines for what we call out here the "Thunder Cats" - small, 14 foot rigid inflatable cats that run 50hp short shaft outboards. The more standard versions are used as surf rescue boats by beach lifesavers, and the hotted up ones are raced by crazy lifesavers on their days off! The boats come standard with 2 x kidney belts for the crew members! Will post back if I find out anything useful.

Anyway, good luck, and keep us posted on what you find out or what you end up doing yourself!!

[prattvan]

Thanks for the comment. I'll look forward to see what your mate says.