Equal-length exhaust discussion: new S55 sounds

[jfritz27]

Hmmm, will see if I made wrong decision. Have a non-res AA EL waiting to go on my stock CS this weekend. From my reading it seemed the consensus has largely been to go with non-res with stock DPs, and various clips of that combo have always sounded good to me. Can't be worse than stock!

[Soul Coughing]

Originally Posted by jfritz27

Hmmm, will see if I made wrong decision. Have a non-res AA EL waiting to go on my stock CS this weekend. From my reading it seemed the consensus has largely been to go with non-res with stock DPs, and various clips of that combo have always sounded good to me. Can't be worse than stock!

I have the same setup and it sounds good. I wouldn't be worried.

[RugbyBro]

Originally Posted by jfritz27

Hmmm, will see if I made wrong decision. Have a non-res AA EL waiting to go on my stock CS this weekend. From my reading it seemed the consensus has largely been to go with non-res with stock DPs, and various clips of that combo have always sounded good to me. Can't be worse than stock!

You'll be good - resonators are really only required with a hi-flow or catless DP setup (basically any non stock DP). Both non-res and res sound pretty much the same under WOT on track, the non-res just sounds more raw/guttural in a day to day context

[WAMx]

Originally Posted by jfritz27

Hmmm, will see if I made wrong decision. Have a non-res AA EL waiting to go on my stock CS this weekend. From my reading it seemed the consensus has largely been to go with non-res with stock DPs, and various clips of that combo have always sounded good to me. Can't be worse than stock!

Should be good with Stock DP, if you go high flow or catted you'll get this tinny rasp at 2k rpms

[ntg44]

Originally Posted by McBobby Jr

It’s been brought up before on this thread but I’m not sure if anyone or any shop actually has tried developing a set. ntg44 could you comment? If I’m not mistaken, Top Gear tried to make a set of equal-length downpipes?

Wow, been a while Hope everyone's been doing well.

EL downpipes was one of the first things I discussed with TGM. You wouldn't necessarily need the full 14 inches offset at the downpipe, but from what we looked at, if it could be done at all, it would need to be catless only, you'd probably need to drop the subframe to install them due to the wacky bends required, the fitment tolerances would be near impossible to do on a production scale, at least with TGM's resources, and it would probably make the exhaust flow much less efficiently than stock with the bends required to accomplish EL in that location and with those space constraints.

I had no interest in having catless downpipes at all, so it was not something that we attempted given all those constraints and unknown feasibility. The initial R&D was on my budget, so I wasn't about to throw money at something that the fabricator didn't even think was possible haha.

Hope that helps.

[canaus]

Really wanted to get some information regarding Bimmercircuit's equal length exhaust but I sent them a message/email from their product page and have received no response.

Makes me apprehensive to say the least.

[McBobby Jr]

It looks like on the Bimmercircuit Equal-Length exhaust, a single midpipe could be mated with a equal length exhaust pulse. According to Bimmercircuit, their equal-length exhaust is a true equal-length midpipe and system. “Bimmercircuit has developed an equal-length exhaust, which is not only equal-length from turbo to the X-Pipe (patent pending), but both banks are equal from turbo to the inlet of both race mufflers.” Although clips are sparse, it sounds good from what I can hear. But it would be interesting to hear how it would sound if a single 3.5” pipe was introduced after the x-pipe.

[RugbyBro]

Who needs titanium anyway?

[Juras]

Never understood the titanium hype on this platform. It just emphasizes that shitty S55 note by giving it more of a fart can pitch. Equal length or single turbo. The rest, as a performance sound, is pretty much useless.

[IceCaps97]

I just installed the AA EQ non-resonated midpipe this past weekend and so far after a few days of running it I am loving the new tone of the exhaust. However, as some other users here and on the M2C forums have pointed out, there seems to be some kind of rattling or resonance sound coming from the exhaust during the first minute after cold starts. I've got stock DPs + non-res EQ midpipe + ZCP muffler, without any tunes or any changed valve behavior.

The rattling/vibration sound first occurs right when the engine starts and roars, then again when you're in first gear or reverse pulling away at around 2.5k RPM. You only hear it briefly, but it's consistent every time you go through that RPM spot. Then after a minute, I assume after the cold start sequence is done, it's completely gone and otherwise sounds amazing. If you start the car again shortly after it's been run there's no issue, again I assume because the car is already warmed up so there is no cold start sequence.

From what I've read, there doesn't seem to be a definitive answer as to what might be causing this since not everyone experiences it. Some people say that it's only an issue when starting the car with valves open, and by leaving them closed during startup those rattling sounds get absorbed by the muffler (not sure that's the issue here since I always start the car in efficient mode and I think the valves stay closed). Others have reported clearance issues, but I'm hesitant to think that's the case here since I already went through the exhaust and re-seated everything twice after I installed the midpipe touching the brace, plus the issue is only when starting the car. That would leave only the cold start as the problem, I guess because of a strange interaction between the waste gates or something else and the exhaust.

Has anyone experienced this issue with their setups or have any insights as to what might be the most likely cause? I'm planning to take another look under the car this weekend to make sure everything is still sitting correctly, so I'll take some extra time to make sure there are no clearance issues anywhere. I'm also thinking of messing around with starting the car in different forced valve positions using Bimmerlink to see if the valves really do impact this specific sound or not. It would really suck if this is just how the exhaust is during cold starts, since coding that out is a $600 purchase through BM3. Maybe I'll get used to it by the time I convince myself to spend that much lol.

[RugbyBro]

Originally Posted by IceCaps97

I just installed the AA EQ non-resonated midpipe this past weekend and so far after a few days of running it I am loving the new tone of the exhaust. However, as some other users here and on the M2C forums have pointed out, there seems to be some kind of rattling or resonance sound coming from the exhaust during the first minute after cold starts. I've got stock DPs + non-res EQ midpipe + ZCP muffler, without any tunes or any changed valve behavior.

The rattling/vibration sound first occurs right when the engine starts and roars, then again when you're in first gear or reverse pulling away at around 2.5k RPM. You only hear it briefly, but it's consistent every time you go through that RPM spot. Then after a minute, I assume after the cold start sequence is done, it's completely gone and otherwise sounds amazing. If you start the car again shortly after it's been run there's no issue, again I assume because the car is already warmed up so there is no cold start sequence.

From what I've read, there doesn't seem to be a definitive answer as to what might be causing this since not everyone experiences it. Some people say that it's only an issue when starting the car with valves open, and by leaving them closed during startup those rattling sounds get absorbed by the muffler (not sure that's the issue here since I always start the car in efficient mode and I think the valves stay closed). Others have reported clearance issues, but I'm hesitant to think that's the case here since I already went through the exhaust and re-seated everything twice after I installed the midpipe touching the brace, plus the issue is only when starting the car. That would leave only the cold start as the problem, I guess because of a strange interaction between the waste gates or something else and the exhaust.

Has anyone experienced this issue with their setups or have any insights as to what might be the most likely cause? I'm planning to take another look under the car this weekend to make sure everything is still sitting correctly, so I'll take some extra time to make sure there are no clearance issues anywhere. I'm also thinking of messing around with starting the car in different forced valve positions using Bimmerlink to see if the valves really do impact this specific sound or not. It would really suck if this is just how the exhaust is during cold starts, since coding that out is a $600 purchase through BM3. Maybe I'll get used to it by the time I convince myself to spend that much lol.

Waste gates are open on the turbos whenever you start the car (only time they aren’t is if your cats are already hot), that’s the rattling/rasp you’re talking about. That is pure, unfiltered S55 sound based on the exhaust manifold design. If you do a cold start delete you will not have this sound. The sound exists with a single or UEL setup too, it just blends with the monotone nature of UEL a little better but rest assured it is still there. If it was touching then the sound wouldn’t go away after cold starts.

[Soul Coughing]

Originally Posted by RugbyBro

Waste gates are open on the turbos whenever you start the car (only time they aren’t is if your cats are already hot), that’s the rattling/rasp you’re talking about. That is pure, unfiltered S55 sound based on the exhaust manifold design. If you do a cold start delete you will not have this sound. The sound exists with a single or UEL setup too, it just blends with the monotone nature of UEL a little better but rest assured it is still there. If it was touching then the sound wouldn’t go away after cold starts.

This is correct. I recently removed the cold start sequence on my car, and it no longer rattles at start up -and if I start to drive immediately there's no booming in the lower RPM. I'm assuming it's leaning out the mixture, opening the wastegates (might be vibrating a little at specific RPM's) and changing the load that you'd usually be adding at low RPM/low loud situation when accelerating.

It'll be 2 years in July that I've had my EL mid pipe installed and I wouldn't change a thing. I really do love the way it sounds!

[IceCaps97]

Originally Posted by RugbyBro

Waste gates are open on the turbos whenever you start the car (only time they aren’t is if your cats are already hot), that’s the rattling/rasp you’re talking about. That is pure, unfiltered S55 sound based on the exhaust manifold design. If you do a cold start delete you will not have this sound. The sound exists with a single or UEL setup too, it just blends with the monotone nature of UEL a little better but rest assured it is still there. If it was touching then the sound wouldn’t go away after cold starts.

Originally Posted by Soul Coughing

This is correct. I recently removed the cold start sequence on my car, and it no longer rattles at start up -and if I start to drive immediately there's no booming in the lower RPM. I'm assuming it's leaning out the mixture, opening the wastegates (might be vibrating a little at specific RPM's) and changing the load that you'd usually be adding at low RPM/low loud situation when accelerating.

It'll be 2 years in July that I've had my EL mid pipe installed and I wouldn't change a thing. I really do love the way it sounds!

Ahh now it's starting to make more sense. That pure S55 noise that you mentioned is indeed present on my car and that's the sound I want to keep, but after comparing my exhaust sound to the many other videos floating around online of the same setup, there is definitely a higher pitch tin-can note that comes through. I think mentioning the cold start and waste gate from the other discussions was a red herring.

My buddy pointed to it sounding like a muffler problem like some kind of metal vibrating under specific resonance. So I went under the car again today and had him cold start it while I was up against the exhaust, and lo and behold the tin-can noise was coming from a small gap in the straight 65mm clamp connecting from the EQ midpipe to the muffler on the driver's side. The one on the passenger side was better sealed and didn't produce the note, and neither did the two ball clamps. The problematic clamp ended up getting pinched slightly where the bolts are, so tightening it more ended up making the gap bigger. I guess as the exhaust heats up it expands slightly and makes the gap just small enough to stop the specific note from occurring, which made me think of the cold start.

I'll have time this weekend to properly re-seat the exhaust pieces and fix the pinching clamp, hopefully that fixes the sound and I can report back with success. Guess I should have held off on posting unfounded theories until after I took a closer look at my own exhaust for what I was looking for haha, thank you guys for your help!

[HotRodM4]

I’m looking to replace the two exhaust ball clamps. Which ones or where do I find them to buy?

[RugbyBro]

Originally Posted by IceCaps97

Ahh now it's starting to make more sense. That pure S55 noise that you mentioned is indeed present on my car and that's the sound I want to keep, but after comparing my exhaust sound to the many other videos floating around online of the same setup, there is definitely a higher pitch tin-can note that comes through. I think mentioning the cold start and waste gate from the other discussions was a red herring.

My buddy pointed to it sounding like a muffler problem like some kind of metal vibrating under specific resonance. So I went under the car again today and had him cold start it while I was up against the exhaust, and lo and behold the tin-can noise was coming from a small gap in the straight 65mm clamp connecting from the EQ midpipe to the muffler on the driver's side. The one on the passenger side was better sealed and didn't produce the note, and neither did the two ball clamps. The problematic clamp ended up getting pinched slightly where the bolts are, so tightening it more ended up making the gap bigger. I guess as the exhaust heats up it expands slightly and makes the gap just small enough to stop the specific note from occurring, which made me think of the cold start.

I'll have time this weekend to properly re-seat the exhaust pieces and fix the pinching clamp, hopefully that fixes the sound and I can report back with success. Guess I should have held off on posting unfounded theories until after I took a closer look at my own exhaust for what I was looking for haha, thank you guys for your help!

Also check the hangar bolts - those are easy to miss but can cause obnoxious rattles

[f82_spooly]

Anyone have a sound clip of NON resonated EL + downpipes + stock/ZCP exhaust? Been combing through these pages and can’t find anyone running this set up

[rumzh]

Originally Posted by f82_spooly

Anyone have a sound clip of NON resonated EL + downpipes + stock/ZCP exhaust? Been combing through these pages and can’t find anyone running this set up

Check out F80Ho on youtube, I'm pretty sure he ran the setup initially.

[imperfectluck]

IceCaps97 I believe the issue with the driver side clamp maybe my similar dilemma not on cold start but when around 2.5k rpm I hear the thingy sound that I didn’t have a few months after installing me EL pipe. I blend E mixes and I realized a bit of water on the floor out the clamp section on the driver side going towards the back box and noticed the passenger side didn’t have it. The shop even have orange markings on where they clamped it originally and it hasn’t moved a bit but I suspect the issue is there as well because it’s more pronounced on the driver side vs passenger.

The pipes do of course expand with heat which helps alleviate it but hoping my next trip in it can be sorted out once and for all because at around 1800-2k rpm is where I hear the resonance the most that is coming from air escaping that one section.

I’m full Active from downpipes back for reference. (AA catted DP, EL resonated mid, AA valved exhaust)

[HotRodM4]

How much weight does the non res equal length midpipe save over oem mid?

[M4orza]

I still think the Valvetronic designs off the shelf system, is the easiest solution to eliminate the terrible factory sound of the S55. Listen from the 10.45 min mark.

[HotRodM4]

In case anyone is curious to hear how the AA EL Non Res Mid Pipes sound with a muffler delete (AWE Track rear section).

I paired it up for some sound clips before I get a new exhaust system and sell these.

https://youtu.be/wr5WK8EbD8o

[mike@x-ph.com]

Originally Posted by HotRodM4

In case anyone is curious to hear how the AA EL Non Res Mid Pipes sound with a muffler delete (AWE Track rear section).

I paired it up for some sound clips before I get a new exhaust system and sell these.

https://youtu.be/wr5WK8EbD8o