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 they were 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 ??
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'm open to ALL comments.
I have gotten alot of comments when I posted this on another forum.
They posted alot of comments 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. If you modify a carbureted engine to breathe better by creating more intake air and/or free flowing exhaust, you have to add more fuel. You either install bigger jets or a bigger carburetor all together. When doing the same to a fuel injected engine, it's a whole different animal. The ECM senses more air coming in and/or going out and increases fuel to the injectors........to a degree. If you modify the air intake/exhaust more than just a little, you change to bigger injectors.
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.
Maybe they were 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 ??
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'm open to ALL comments.
I have gotten alot of comments when I posted this on another forum.
They posted alot of comments 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. If you modify a carbureted engine to breathe better by creating more intake air and/or free flowing exhaust, you have to add more fuel. You either install bigger jets or a bigger carburetor all together. When doing the same to a fuel injected engine, it's a whole different animal. The ECM senses more air coming in and/or going out and increases fuel to the injectors........to a degree. If you modify the air intake/exhaust more than just a little, you change to bigger injectors.
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.