[AMT92]

I have long been a fan of my muffler/secondary cat delete on my 330i, but as of recently it was too much to bear drone wise, which forced me to go back to stock. Granted I am looking to get a new BMW this year, I would still like to put an exhaust on it that can be custom, won't cost an arm and a leg, and is close to drone free.

SOLUTION: I have been browsing the web far and wide and come across J-pipes, also known as a Helmholtz resonator (example below)



The piping is anywhere from 28 to 48 inches long depending on where your peak drone is coming from on your RPM band. The pipe is capped on one side, and the other is typically welded after your last muffler and before your exhaust tips. The piping captures vibrations from the exhaust, funnels it through the J-pipe, then comes out significantly less if at all. The muscle car community and 370Z are crawling with information about it as well, all with great feedback from the J-pipe.

My question is, why hasn't anyone done this on BMW's yet? I haven't found any examples of it on a I6 engine configuration, which makes me wonder if it's only applicable to V6/V8's. Has anyone heard of these/have some feedback?

Threads pertaining:

http://ls1tech.com/forums/cadillac-c...ltz-tubes.html

http://www.camaro5.com/forums/showthread.php?t=102075

http://www.camaro5.com/forums/showthread.php?t=214004

[2fly4em]

I plan on doing this myself. Like the G8 solo performance exhaust.

[AMT92]

Originally Posted by 2fly4em

I plan on doing this myself. Like the G8 solo performance exhaust.

Exactly like that. The Camaro forums mention the G8 SOLO exhaust many times. My only concern is if will have the same effect on an I6 motor that goes from a dual exhaust outlet into a single.

[2fly4em]

We won't know until we try. I want to create my own full exhaust. Right now I have a muffler delete and removed the resonator also. So the 2nd cat is the only thing up.

I enjoy the sound but, I would like to add more growl to it, a deeper tone would be nice.

[2fly4em]

Originally Posted by Joker330i

Exactly like that. The Camaro forums mention the G8 SOLO exhaust many times. My only concern is if will have the same effect on an I6 motor that goes from a dual exhaust outlet into a single.

What I wanna do is.

After the catless down pipe to cat back, I would like to remove the two secondary cats add a 2 inlet 2.5" into a 1 outlet 2.5" weld a resonator to it. Then run a single 2.5" pipe all the way to the mid rear. Add another 1 inlet 2.5" to 2 outlet 2.5. then the solo performance straight pipe with J pipe exit.

I have N54 btw

[2fly4em]

Like this!!

[AMT92]

Originally Posted by 2fly4em

What I wanna do is.

After the catless down pipe to cat back, I would like to remove the two secondary cats add a 2 inlet 2.5" into a 1 outlet 2.5" weld a resonator to it. Then run a single 2.5" pipe all the way to the mid rear. Add another 1 inlet 2.5" to 2 outlet 2.5. then the solo performance straight pipe with J pipe exit.

I have N54 btw

That looks like a great design. Why did you choose to go from 2 into 1 into 2 versus 2 all the way to the rear?

[Kgolf31]

Originally Posted by 2fly4em

What I wanna do is.

After the catless down pipe to cat back, I would like to remove the two secondary cats add a 2 inlet 2.5" into a 1 outlet 2.5" weld a resonator to it. Then run a single 2.5" pipe all the way to the mid rear. Add another 1 inlet 2.5" to 2 outlet 2.5. then the solo performance straight pipe with J pipe exit.

I have N54 btw

2 - 2.5" Pipes into 1 - 2.5" Pipe is not going to work out too well for you

[rhombus]

Originally Posted by Joker330i

I have long been a fan of my muffler/secondary cat delete on my 330i, but as of recently it was too much to bear drone wise, which forced me to go back to stock. Granted I am looking to get a new BMW this year, I would still like to put an exhaust on it that can be custom, won't cost an arm and a leg, and is close to drone free.

SOLUTION: I have been browsing the web far and wide and come across J-pipes, also known as a Helmholtz resonator (example below)



The piping is anywhere from 28 to 48 inches long depending on where your peak drone is coming from on your RPM band. The pipe is capped on one side, and the other is typically welded after your last muffler and before your exhaust tips. The piping captures vibrations from the exhaust, funnels it through the J-pipe, then comes out significantly less if at all. The muscle car community and 370Z are crawling with information about it as well, all with great feedback from the J-pipe.

My question is, why hasn't anyone done this on BMW's yet? I haven't found any examples of it on a I6 engine configuration, which makes me wonder if it's only applicable to V6/V8's. Has anyone heard of these/have some feedback?

Threads pertaining:

http://ls1tech.com/forums/cadillac-c...ltz-tubes.html

http://www.camaro5.com/forums/showthread.php?t=102075

http://www.camaro5.com/forums/showthread.php?t=214004

My E39 stock muffler used this principal. It had a second muffler can (capped) that was tapped in right before the actual muffler. The car was silent with it in place, sounded good without it. I can see this working to reduce volume and drone.

[shadow191]

Isn't this similar to the AA exhaust? It runs a similar chamber; not a dual obviously, but similar concept.

[rhombus]

Originally Posted by shadow191

Isn't this similar to the AA exhaust? It runs a similar chamber; not a dual obviously, but similar concept.

Good point. Its not as long so I wonder what resonant frequency its tuned for.

[2fly4em]

Originally Posted by Kgolf31

2 - 2.5" Pipes into 1 - 2.5" Pipe is not going to work out too well for you

Run (2) 2.5" into a 3.0" then?

[Kirkies328]

I have 3 inch piping the whole way no secondaries no res and no muffler. Sounds amazing. Should give it a try