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miatex
08-10-2018, 07:26 PM
Hello to all! Its been a while since I last posted... that doesn't mean I haven't been using the site to get ideas and solve problems...

Recently my exhaust pipe broke and I removed the rear muffler...

I watched some videos about Audis gaining horsepower just from removing the rear muffler due to the very restrictive nature...

With mine removed I decided to open it up and see it for myself. Upon inspecting the exhaust flow inside, it appears the design makes the exhaust gases travel quite a bit before they exit at the tip...
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At first I thought about removing the whole thing and attaching a piece of perforated pipe and cover it with stainless mesh to help with absorption of sound waves while being straight through.

Then I read a bit about mufflers, glasspack, chambered, turbo-style.... and understanding how each operates, I thought we can use what we have, do some minor modifications and hope that flow improves while sound stays pretty OEM...

The flow initially starts through a small resonator (Inside the muffler), then it needs to make its way back through perforated baffles, all the way back so they can reach the pipes that actually make it to the atmosphere...

By simply cutting the lead pipe, and reducing the pipes that lead to the tips... all the exhaust is then dumped inside the first chamber (Where the pipes lead to the tip and to atmosphere) while still retaining the baffles and lots of surface to help soundwaves bounce and cancel each other... The idea is that if a high pressure area is created in the first chamber, then the exhaust will find the easiest way out...
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I haven't put the muffler back on the car, but thought this could be an idea others could find insteresting to pursue.

My idea is to do something similar with the middle resonator, but haven't yet found an image of how that one looks inside to see if it is worth the trouble to open and modify. If you have one, or where I can find one, let me know, to take a look!!

Have a great weekend!

Federico

turbo3
08-10-2018, 09:23 PM
I did this and I was so disappointed. I wanted all that time for no real results. Maybe because the resonator kills all the sound, idk.

miatex
08-10-2018, 09:41 PM
Sorry to hear that! but what were your expectations?
Sound or power? both?

Personally I am looking for maybe a bit more power, with very little variation in sound... This is my DD and I am a father of two kids! so looking to have a quiet family car... (The kids provide the soundtrack [:D] )

My car is currently stock, so there isn't much power anyway hehehe

Once the muffler is installed I am hoping to have before and after soundclips... Right now with stock cat, stock piping and middle resonator the car has a deeper sound with no drone... with this frankenmuffler back I hope to have a quieter sound.

we'll see how this goes!

Federico

turbo3
08-10-2018, 10:24 PM
Sound was the expectation since you're not really gaining much power from an exhaust. You're not really gonna be able to get power without sound. Don't know how quiet you want it.

miatex
08-12-2018, 07:39 PM
I am looking for a close to OEM sound, if it sounds deeper, then great, but looking to have zero drone...

Fasterd
08-13-2018, 04:22 AM
Exhausts are tuned with flow simulations via Solidworks etc., you will spend so much time and money fucking with that thing.

Buy a new muffler if it bothers you that much, you can get a milltek 304 stainless for $750 which is what you will have into stainless tubing/flanges/muffler not including labor (at any shop worth a shit)

But prove me wrong and be that pioneer, just my 2 cents regarding time vs return.

miatex
08-15-2018, 09:17 PM
Exhausts are tuned with flow simulations via Solidworks etc., you will spend so much time and money fucking with that thing.

Buy a new muffler if it bothers you that much, you can get a milltek 304 stainless for $750 which is what you will have into stainless tubing/flanges/muffler not including labor (at any shop worth a shit)

But prove me wrong and be that pioneer, just my 2 cents regarding time vs return.

It didn't really bothered me, since the exhaust pipe broke and I removed it... I decided to open it up an hopefully let the thing breathe a little better by changing how the exhaust flows inside the rear muffler.
I like the way the car sounds without it, I'm just going to put it back on, and see if I like it better. If not, remove it again (I won't be soldering it) and simply run a pipe all the way back with a tip.

I sadly don't have the means to get the milltek and ship it to where I live (Venezuela). Just for reference, I could live well for 4 months with $750... That's how bad things are around here! [:(]

Have a great week!

Fasterd
08-16-2018, 03:02 AM
Iím suprised you have an Audi there at all, between the threat of violence and parts spurcing. I was hooking up with a student from there she was saying you have to be careful where you go and what you wear

miatex
08-17-2018, 07:36 AM
True, you have to be careful... The car is a 1998 A4... It is better to bring an old car back in shape, instead of buying a newer car... Audis are not sought after like Corollas, so surprisingly its a safer choice...

I should be installing the exhaust this weekend, will let you know how I like it!

Cheers a have a great weekend!