Yay, won a 3.0i exhaust for £150!

[Mr Whippy]

Just pondering.

Do the chamber 3 tubes that feed from chamber 2, have any perforation in them, or is chamber 3 isolated from the exhaust except via chamber 2?

If so, we could probably just block up the chamber 2<>3 perforation panel to get only chamber 1/2 active...

That might just give it a bit less boomy wooflyness, and get us some crisper and sharper sound... and a bit more volume... hmmmm

Dave

 

[EdButler]

Just pondering.

Do the chamber 3 tubes that feed from chamber 2, have any perforation in them, or is chamber 3 isolated from the exhaust except via chamber 2?

If so, we could probably just block up the chamber 2<>3 perforation panel to get only chamber 1/2 active...

That might just give it a bit less boomy wooflyness, and get us some crisper and sharper sound... and a bit more volume... hmmmm

Dave

Chamber 3 is only accessed by the perforated wall between it and chamber 2. The tail pipes only access chamber 2 directly so yeah your plan would work. I've totally gutted mine and re-welded it, but I think its just best without; with 4 Cats and 2 resonators, its just overkill... I do have some clamps ready to change it though, as it'd only be a 30min job. Just need some nice weather and a pit ideally!!

 

[Mr Whippy]

So right now you just run a hollowed out back box?

What does it sound like etc?


I agree, all those cats and resonators already silence it up a fair bit. The secondary cats are on my radar for removal, but I'm very tempted by back-box adjustments first.
My main task will be before/after recordings in and outside the car to get a gauge of sound level and sound quality change... also useful for others for reference

Dave

 

[daveg]

I misled Dave before as hadn't had a proper peek. A couple of new photos for those interested.

It's getting late so no words but should be able to work out from Ed's posts.

 

[th30d0r3]

From what I understand of the flap mechanism on the 330 (same as teh E36 328) it's purely for sound purposes (so BMW claim), however as you've said it also increases back pressure for low down torque when closed. it's operated by a vacuum feed of the airbox, which forces air into the flap to close it upon idle and light acceleration and opens it when you gun it. It's a simple yet effective method many car makers use.

The 330 has the loudest stock exhaust of all the E46's and is considered the most free flowing, chopping that J pipe so it feeds into the middle chamber will only make the pipe redundant I think since the air will take the path of least resisitance and head straight out the exit.

 

[daveg]

Very interesed in any ideas anyone has to improve the box.

I want a little louder but tone is OK at the moment. De-cat should restore just a little rasp from what I understand so happy to leave back-box tone as is.

Considering sleeving the inlet tubes, but can't get to them easily. Any suggestions?