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      09-27-2019, 05:30 PM   #1
RevNev
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This is how you make an S55 engine sound good!

The S55 M3/M4 engine sounds farty and raspy for 2 reasons. The farty V6 twin exhaust sound is caused by the exhaust manifold split with twin turbos and isolated outlets and the 2 midpipes needs to be joined into 1 to blend out the farty V6 note and this is what AA etc do with the single midpipe.

The raspiness is caused by stock resonator being too small and not packed with sound deadening so it's an open chamber resonator with an H pipe that emphasises raspiness. To get rid of the raspiness you "must" use perforated tube resonators packed with sound deadening preferably stainless wool as it doesn't burn out like fibreglass.

With catless downpipes, you need 4 12" resonators 4" diameter in the midpipe to control noise with the valves open and create a smooth rasp free note. The reason all the aftermarket exhausts sound nearly as bad as stock but louder, is they don't use resonators or the resonators they use are too small and not packed with effective sound deadening material.

This setup sounds magic with catless downpipes and stock rear muffler but unfortunately it seems that everyone is trying to get a decent note out of the S55 exhaust with straight un-resonated pipe and it's impossible! This is simply "old school" exhaust technology I've used to make V8's sound great that works just the same on the S55 engine as I expected.
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Last edited by RevNev; 09-27-2019 at 05:45 PM..
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      09-27-2019, 05:48 PM   #2
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Post a sound clip.. that proves your point best

Seems like the modifications you did increases flow restrictions over OEM.. not exactly what most people want to do.
The single mid pipe is the only tried and true way to get rid of most of the rasp while deleting factory secondary cats, even with straight pipes.

Please post a clip.
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      09-27-2019, 06:23 PM   #3
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Haha what a tease! How can you post all that and not post a clip! Can't wait to hear it!
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      09-27-2019, 07:08 PM   #4
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Quote:
Originally Posted by JamesGames View Post
Post a sound clip.. that proves your point best

Seems like the modifications you did increases flow restrictions over OEM.. not exactly what most people want to do.
The single mid pipe is the only tried and true way to get rid of most of the rasp while deleting factory secondary cats, even with straight pipes.

Please post a clip.
How does it increase flow restrictions over OEM with no cats and 2.5" perforated tube resonators? Tell us how you think the OEM system flows better?

The single midpipe doesn't get rid of the rasp at all. It blends the sequential pulses from each turbo outlet and gets rid of the V6 farty sound the same as joining the twin pipes into one. Raspiness is the metallically sound of a mechanical muffler or straight pipe that only perforated tube packed resonator removes.

How to do think a V8 sounds with a twin 2.5" system, no mufflers and balance (X-pipe)?

I'll post and audio clip soon.
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      09-27-2019, 07:43 PM   #5
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Quote:
Originally Posted by RevNev View Post
How does it increase flow restrictions over OEM with no cats and 2.5" perforated tube resonators? Tell us how you think the OEM system flows better?

The single midpipe doesn't get rid of the rasp at all. It blends the sequential pulses from each turbo outlet and gets rid of the V6 farty sound the same as joining the twin pipes into one. Raspiness is the metallically sound of a mechanical muffler or straight pipe that only perforated tube packed resonator removes.

How to do think a V8 sounds with a twin 2.5" system, no mufflers and balance (X-pipe)?

I'll post and audio clip soon.
Adding 4 packed resonators with cutouts like that seem to cause disruptions to flow as compared to the stock exhaust which has been shown to flow extremely well - just saying that most people are trying to get away from those, which means aftermarket pipes that aren't "packed" and usually deleted for higher flow rates.

And really? You're going to compare a v8 sound to the s55? Let me tell you man.. you can do a hack job and just chop off any rear muffler on a V8 car to hear sounds that you will never, ever hear from our beloved S55.

You're so quick to dismiss the AA mid pipe reducing rasp, which leads me to believe you haven't heard the setup in person...

I hope your method sounds so great so I can do the same thing because AA mid pipe is the only setup to me that got rid of the rasp significantly.

Last edited by JamesGames; 09-27-2019 at 07:52 PM..
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      09-27-2019, 07:56 PM   #6
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I stopped reading after you said V6 😂😂😂
      09-27-2019, 08:06 PM   #7
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Nothing with a turbo will ever sound good. At best, it'll sound ok.
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      09-27-2019, 08:46 PM   #8
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Let's give the guy a chance to post the exhaust clip.
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      09-28-2019, 12:43 AM   #9
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Quote:
Originally Posted by LOW4LYF View Post
I stopped reading after you said V6 😂😂😂
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      09-28-2019, 01:12 AM   #10
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Guys, I don't think he was saying the S55 was a V6, he was saying it makes a sound like a farty V6 with twin exhaust. Kinda like when you modify a V6 Camaro with dual exhausts it sounds like sh*t lol.

I actually really enjoy the way the S55 sounds with just a mid-pipe, if you drive the car and hold the revs till the upper revs like 4-6k before shifting, it genuinely has an exotic tone to it.
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      09-28-2019, 01:32 AM   #11
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Let's keep the thread going because I'm in the market for an exhaust setup
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      09-28-2019, 08:09 AM   #12
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All that and no sound clip?
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      09-28-2019, 10:03 AM   #13
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The S55 sounds the way it does because of the unequal-lengthed downpipes because the engineers wanted a symmetrical turbo inlet/outlets so packaging prevented having equal-length downpipes.

If you want that smoother "V6" like sound (or an N54 sound for that matter), you simply need to re-package the mid-pipes to create a equal-length piping prior to both banks merge into either an H-pipe or an X-pipe.
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      09-28-2019, 10:12 AM   #14
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Your exhaust build looks good. Would love to hear a sound clip. Even if it's just a quick video on your mobile phone.
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      09-28-2019, 01:57 PM   #15
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Quote:
Originally Posted by LOW4LYF View Post
I stopped reading after you said V6 😂😂😂
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      09-29-2019, 12:20 AM   #16
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Quote:
Originally Posted by spool twice View Post
The S55 sounds the way it does because of the unequal-lengthed downpipes because the engineers wanted a symmetrical turbo inlet/outlets so packaging prevented having equal-length downpipes.

If you want that smoother "V6" like sound (or an N54 sound for that matter), you simply need to re-package the mid-pipes to create a equal-length piping prior to both banks merge into either an H-pipe or an X-pipe.
BINGO!
You are correct sir. I did that with an old F80 M3 I had in 2016. I just bought another one and I'm on the path to 'fixing' the sound my new to me 2016 M3.
BMW also shot themselves in the foot with the placement of the secondary cats, because they aren't equal distance from the primary cats, then on to the resonator where all that unequal horseshit blatty noise gets to mix together so everything on the F80 is garbage sound wise. And every exhaust maker hasn't ever come up with a solution except to make it louder.
I can't wait for a single turbo kit to come out so I can get rid of all that crap....or make one myself

I'll be done with my F80 sound project later this week, and I'll post pics/video
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      09-29-2019, 12:58 AM   #17
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Quote:
Originally Posted by Brasko View Post
Your exhaust build looks good. Would love to hear a sound clip. Even if it's just a quick video on your mobile phone.
Agreed, I also want to hear a good sounding s55, has to be a unicorn
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      09-29-2019, 02:55 AM   #18
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Quote:
Originally Posted by JamesGames View Post
Adding 4 packed resonators with cutouts like that seem to cause disruptions to flow as compared to the stock exhaust which has been shown to flow extremely well - just saying that most people are trying to get away from those, which means aftermarket pipes that aren't "packed" and usually deleted for higher flow rates.

And really? You're going to compare a v8 sound to the s55? Let me tell you man.. you can do a hack job and just chop off any rear muffler on a V8 car to hear sounds that you will never, ever hear from our beloved S55.

You're so quick to dismiss the AA mid pipe reducing rasp, which leads me to believe you haven't heard the setup in person...

I hope your method sounds so great so I can do the same thing because AA mid pipe is the only setup to me that got rid of the rasp significantly.
Perforated tube straight through mufflers the same diameter as the pipe when ram packed with stainless wool DON'T disrupt anything but noise. The downside is you need a decent length muffler for noise control as they're louder than mechanical baffled mufflers.

What's wrong with the AA midpipe aside from single 3.5" flows less than twin 2.5"; they're too loud on a road car with catless downpipes and there's no room left under the car to fit resonators. With the valves open, catless downpipes and an AA midpipe, there's virtually no muffling capacity at all.
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      09-29-2019, 04:19 AM   #19
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Here's a stationary video clip valves open

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      09-29-2019, 06:10 AM   #20
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I think my car sounds great with the M performance exhaust.
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      09-29-2019, 10:39 AM   #21
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Quote:
Originally Posted by RevNev View Post
Here's a stationary video clip valves open

Thanks for posting that clip. I don't hear any raspy sounds. Very smooth and like a proper European car. Nice work!
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      09-29-2019, 05:31 PM   #22
RevNev
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Here's an M4 GT4 race car with an Eisenmann X-pipe, resonators on the back and sounds great

The point is; if you don't join the midpipes in an X or collector and the exhaust doesn't pass through resonators with the valves open like most aftermarket systems, they'll never sound good and will retain the farty and raspy sound.


Last edited by RevNev; 09-29-2019 at 05:39 PM..
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