Middle resonator/muffler internal design question
 

Howdy guys. I'm working on developing a sweet stainless 304 exhaust system for our e53's. I'll share some details in a separate dedicated thread. It's something not available for machines as of yet.

Okay, I'm currently hunting down any information on what our middle resonators look like internally. Is there any crossover between banks, any shared chambers, perforated tubing? This goes for both the V8's and I6's.

I added a non resonated X pipe to my custom system between the headers and mid resonator, and for some reason, resulted in a not so good sound. Middle resonator is the only thing stock on my exhaust at the moment. My drone issue became even more exacerbated, and all the burble, and pops are washed out. Just blah. Not what I was expecting. Every part of the exhaust system is integral and connected when trying to tune for performance and sound. It's a pretty complex science/theory that has so many variables.

Anyways, if you have any input to share please let me know. Otherwise I'm cutting and scoping tomorrow.

Sub’d

I have been wondering about this, and have headers sitting here I could bolt on tomorrow. But I haven't for lack of a route to go on that middle resonator. I'd hate to end up with blah.

I was debating removing everything from the headers back and starting over, but you have--once again--already done that.

Hey buddy. So, adding the headers and keeping the rest of the exhaust stock is a safe move. But the rear muffs kill quite a bit of performance and economy and sound. The problem I ran into in cutting out the rear mufflers was the resonators I put in place. To small. It is an Aero AR25, which are used for the S54 powered BMWs to cut rasp, etc. I tried it as a stand alone. My X5 sounds wicked, just about a 2000 rpm drone that bugs after a while. I know from my previous e53 that the magnaflow 4 inch rounds (14 or so inch body length?) sounded awesome and I don't remember any drone, or if so it was very small.

Anyways, I decided that I want to experiment with a few different setups, and then build a 304 stainless system from the headers back. I'm working out tube size and different options on the middle resonator. I've got a super awesome option for the rear mufflers. We have been limited on what we can put back there due to size and angle constraints, etc. More on that later.

X pipe is getting cut out as we speak and two glass packs added to further experiment. I'm getting new hardware for the middle resonator connection, so I can scope the internals. My current hardware is rusted and won't come out without breaking.

The x pipe I chose was not the best design. It was stamped and had quite a bit of internal space. It acted more like a hollowed out echo chamber. You don't need that much space. Honestly two pipes with a ever so slight shared wall or merge is all you need. They don't have to cross over like an X. Ideally just enough to help scavenge the pressure waves/low pressure tail of both banks and increase your volumetric efficiency. The X pipe I put in was rubbish. I'm leaning toward a borla pro Xs dual in dual out with a built in resonated X pipe as a trial.

Hang tight over the next 30 days. Once I have finalized my design, I plan on making a few extra header back sets to sell. Gotta practice my tig welds! 😄 PM me for details.

I'd look for one in a junk yard and cut it open to see how it's constructed.

Dude that would be awesome! Let us know.

You misunderstand. I didn't say I'd do it it. I suggested you do it.

I'm curious on how this pans out...sub'd

sub'd! I have a not so good X pipe with Schiedmann and this is how it sounds.
https://youtu.be/LKfjc0M4peQ
https://youtu.be/GP2PUTQl3X4
https://youtu.be/Ols-ETIEY0M
I like how it sounds. but id there is room for improvement lets do it

I think we lost the Dragon in R&D...