am I loosing power ?

[Dave_106gti]

I have a stainless steel cat back exhaust which was custom made for my AE111 BZ-R.

Its just a pipe from the cat to the back box (no center box)

A few people were saying to me I am loosing power is this true?

Would putting a center box back into her help or increase power ?

any help appreciated
Thanks
Dave

[nobbie]

i noticed a power driop when i changed my exhaust too. I remedied this by putting the cat back in to increase backpressure.

It would appear that the blacktop engines need a reasonable amount of backpressure to maintain the power.

[badassmofo]

Hey, a little off topic.
But Dave, I see you have 106GTI in your name, do you own one? They are great cars!!

[Ae92typeX]

Why do you need back-pressure?, one of the ideas behind a multi-valve engine is to get all the exhaust gasses out and eliminate back pressure. This is also why extractors are fitted. From my understanding a four stroke engine does not require or want back pressure.

[Ae92typeX]

http://auto.howstuffworks.com/question172.htm

thers a link to what I am saying...cant be bothered copying anything out of my books at the mo...

[Monsterbishi]

You're quite right AE92TypeX - backpressure is a age old myth, there's only one thing you can do with exhausts, and that is tune the size to get the gasses flowing out faster at either low rpm, mid range or high rpm, all dependant on what you're wanting...

ie, there's no point in putting a 3" exhaust on our tow car, a 1996 Holden Vectra, it makes it's peak power(torque) at 2600rpm...

Peak torque would be shifted up the rpm band if we put any bigger on, but the top end torque would be barely affected.

[Dave_106gti]

@ nobbie - Do you have a center box in your exhaust ? or did you remove that also ?

@ badassmofo - yep I own a 106gti also some car alright great handling and awesome power to weight ratio

ok I'm now a bit confused about the exhaust situation !!! should I put center box into my exhaust ? or would the hassle be worth the power gains ?

the cat is still in the exhaust and I just have a back box at the moment

Dave

[Ae92typeX]

so was it just a resonator you had taken out?
as long as the pipe is the same size i'd leave it. if anything I'd take out the cat also as they restrict flow a little. Power wise it wont be much really, more a placebo feeling than seat of the pants gains

[Dave_106gti]

had the standard system from the cat back taken off and replaced with a stainless steel system . Which is just a pipe from the cat back to the muffler at the back

Dave

[Ae92typeX]

Keep that as is then in me opinion...

[nobbie]

Mine is 2 1/4 inch system, very straight, has cat, then big resonator (the long skinny one) and then a stainless steel oval shaped muffler.

I have a small bit of pipe I can replace the cat with just by undoing the bolts. I may change my cat at somne stage in the future but for now I am quite content with the power its making.

Sorry cant help you any more on this....