so we recently had to remove our buschur cat back exhaust and put the stock pipe and muffler back on due to some traffic violations. the strange (or maybe not strange and im just a dumb girl) thing is that when we put the smaller stock exhaust pipe and muffler back on the car makes more power than it did with the larger buscher exhaust system

comments suggestions ideas?

would it be better to keep the smaller pipe and just get an axel back muffler to replace the stock?

 

It's because you got your scavenging back. With an NA motor the pressure from the cylinders pushes the exhaust out and then the exhaust sucks it out. I don't believe NA exhausts should be larger than 2.25" at the downpipe and the rest should be 2".

There's an article I'll try to find that was written by an exhaust engineer and was posted on impreza.net and mirrored on the suzuki swift forums. He describes how the ideal turbo exhaust would be developed and says in the first paragraph that Na motors need an exhaust that is the exact opposite of what he's going to describe. He says turbo exhaust need to be big and get bigger on the way out to reduce "backpressure" on the cylinders, backpressure slows down the turbo spooling. So he basically says, in ver simplified terms that turbo should look like this: < and NA should look like this > (progressively smaller diameter to promote scavenging).

Like I said, I'm paraphrasing him, but if you search for exhaust posts with my name, you'll see that I've been saying that for a while- and I was a little more articulate in another post.

 

thank you engineer boy thats a perfect answer. how large is the stock piping on the lancer anyways?

 

1 7/8 i think

 

I would suggest that you don't trust the butt dyno for gains. If it's not on rollers it's not a credible statement imo.

Again, dyno proven gains across the powerband with the BR cat-back.

 

lancer exhaust has got to be smaller than 1 7/8, I upgraded mine to 2 and made a hell of a difference. I think it's actually closer to 1.5 inch diameter. cuz when I hit 3200 RPM, it kicks up a bit and really starts hauling.

 

I noticed the same when I did that with my car. I had an AEM CAI and a Cat Back...I took it off and gained power.

 

Does anyone know if the buschur or magnaflow exhaust system would produce more hp gain?

 

It will produce more high end power but lose low end torque if you're NA.

 

when i was NA i noticed the same thing. all i had was a sri and header. when i installed my catback exhaust i noticed i lost some low end. but then again you cant really trust the "butt dyno".

 

taking off an exhaust will increase the low end a little bit, thus feeling quicker...but your high end will such...it all depends on what you want...i love the sounds of my greddy and its pretty much the only reason why i still have it