Equal-length exhaust discussion: new S55 sounds

[ntg44]

Originally Posted by JamesGames

Getting better! Sounds good and tips look way better, just needs moar loud personally.

Thanks. Luckily the valved version is planned to have a muffler bypass. I’m surprised how a muffler as small as this with a single exit does this good of a job. Usually singles are droney as hell. But my needs are stricter than most. Needs to be wife approved. I was getting sick of the crazy cold starts anyways.

[erik_m3g80]

Originally Posted by spool twice

I think the stock muffler will sound the best, I will try to get mine done later this week or early next week, but mine likely wont' happen until after the new year. Can't wait to hear your sound clips, especially on a normal muffler!

I personally think it will sound better than the CS-tipped OE cans. Larger inner diameter tips that are single walled typically deepen sounds. The actual tips of the regular cans are smaller in diameter, but have an outer cover (or "exhaust finisher" in chrome or black on the ZCP) tend to accentuate higher frequencies, exactly what is needed to highlight an equal-length design.

Here is another pic from a member that better shows what I did. He didn't have his painted black so visually its easier to see what was done. He uses an H-pipe though, where I used a Flowmaster "x-pipe" crossover:



I like how they angled his H-pipe design, it gives a better opportunity to merge sound waves. However if you do use an H-pipe, my recommendation would be to place it closer to the differential, because the pipes are closer together, which will maximize merging sound waves even more.

Is there any soundvideo of this Setup?

[Velon]

This thread is awesome, I'm going to make this mod later in April on mine I recon, got 2nd cat and resonator delete right now. -14 F80 😊

[Flange]

How would doing this affect those cars with opf’s?
Would it cause issues with back pressure that would throw warning lights?
( I’m thinking particularly about modifying a non oe exhaust system).

[spool twice]

Originally Posted by erik-f80

Is there any soundvideo of this Setup?

the video's arent the best quality because I made them from the video's he sent me.

Before/After of his car

Before Mods:
Turbo Upgrade (VTT or Pure Turbo's?)
catless downpipes
OEM mid-pipe
OEM muffler

After Mods:
Same as above except center resonator/crossover delete, the U-bend mod + H-pipe section

Slightly raspy due to catless downpipes, but it's probably one of the better before/after video's that captures the difference in tone and sound character by simply adding that equal-length section and then crossing the pipes together

[spool twice]

Originally Posted by Flange

How would doing this affect those cars with opf’s?
Would it cause issues with back pressure that would throw warning lights?
( I’m thinking particularly about modifying a non oe exhaust system).

It shouldn't be any different than those who add an aftermarket OPF-back exhaust since you aren't modifying anything that happens before the exhaust gases reaches the OPF system.

Reach out to this member here who did this on his M2 Comp w/ OPF system https://f87.bimmerpost.com/forums/sh....php?t=1679214

[erik_m3g80]

Originally Posted by spool twice

the video's arent the best quality because I made them from the video's he sent me.

Before/After of his car

Before Mods:
Turbo Upgrade (VTT or Pure Turbo's?)
catless downpipes
OEM mid-pipe
OEM muffler

After Mods:
Same as above except center resonator/crossover delete, the U-bend mod + H-pipe section

Slightly raspy due to catless downpipes, but it's probably one of the better before/after video's that captures the difference in tone and sound character by simply adding that equal-length section and then crossing the pipes together

To be honest, in this case I like the first sound more than the second. But all in all I prefer of course the equal pipe story way more than the raspy oem sound

[Kilabyte]

ntg44, are you working on something that keeps the stock muffler/ valves in place or no?

[ntg44]

Originally Posted by Kilabyte

ntg44, are you working on something that keeps the stock muffler/ valves in place or no?

The TopGear exhaust will be a complete system, from down pipe connection-back, based on the same philosophy as my V2 exhaust. The stock muffler has too many compromises to achieve the tone from my experimental system.

The exhaust is planned to be dual exit with OEM valve integration. As for the final specs, I won't know anything more until they take my car and complete the design. My car is going in 2nd week of January. That's all I know at this point, and any further details will be available once they finish up on my car.

[erik_m3g80]

Originally Posted by ntg44

The TopGear exhaust will be a complete system, from down pipe connection-back, based on the same philosophy as my V2 exhaust. The stock muffler has too many compromises to achieve the tone from my experimental system.

The exhaust is planned to be dual exit with OEM valve integration. As for the final specs, I won't know anything more until they take my car and complete the design. My car is going in 2nd week of January. That's all I know at this point, and any further details will be available once they finish up on my car.

Im so excited to see the final result from Topgear and I will order it for sure to Germany I think a lot of people here will like it aswell

[ntg44]

Originally Posted by erik-f80

Im so excited to see the final result from Topgear and I will order it for sure to Germany I think a lot of people here will like it aswell

You and me both! I still cannot believe that I owned the right car, found the right fabricator/company, at the right time, and convinced them to turn this into a mass produced product, all from an experiment that I had no idea would work or not. Things like this just don't happen to me.

[Kilabyte]

I can't wait that long!

[ntg44]

Originally Posted by Kilabyte

I can't wait that long!

Use that time to sell off any aftermarket exhaust components you have. Market is going to completely tank once this exhaust releases

[MyFragileHalogen]

(at 0:12)
Just for fun I brought out my guitar and compared top musical note of the V2 exhaust and MPE below. top note is still similar- the V2 ends up at about E right below A(440Hz) and the MPE go up to about F#. I guess it's due to tone- different harmonic components that make it higher pitched.

EDIT: I listened to it again and actually MPE is about on octave lower overall in my ears. V2 rocks!

(at 3:19)

In the meantime (also for fun) top note of GT3 is only slightly higher, about quarter step above G# (almost close to 440Hz A).

I guess it's the 'tone' that matters a lot more.

These are new things I read and learn about so appreciate all the discussions and info.

https://www.caranddriver.com/feature...erent-feature/


p.s. I like MPE that it made big improvement over stock exhaust and there are tonal characteristics I like about; but yeah, having that said, I also have my eyes on the new exhaust development. :cool!

EDITED: MPE is about one octave lower in pitch actually!

[aBMWfan]

Originally Posted by erik-f80

Is there any soundvideo of this Setup?

Yes I have a new sound clip of this

[Montaver]

Originally Posted by ntg44

In the mean time, I recorded a few standing revs. After a couple hundred miles, my exhaust is breaking in really nicely.

Smooth, rich. mellow. Lovely tones. Don't normally associate those with the S55. Completely removes that harsh 3 cylinder sound. Dammn I want this exhaust.

Looking at pictures of the M2C under carriage does seem like there is slightly less space to work with in the diff / muffler area due to the reduced wheelbase. Hoping something like this is still possible!

[ntg44]

Originally Posted by Montaver

Smooth, rich. mellow. Lovely tones. Don't normally associate those with the S55. Completely removes that harsh 3 cylinder sound. Dammn I want this exhaust.

Looking at pictures of the M2C under carriage does seem like there is slightly less space to work with in the diff / muffler area due to the reduced wheelbase. Hoping something like this is still possible!

Judging from this photo, seems like there's plenty of room for an equal length exhaust:

https://f87.bimmerpost.com/forums/at...1&d=1472896424


It won't be a direct fit from M3/4, but it looks like at the very least a passive system like mine can be made pretty easily.

[spool twice]

Originally Posted by aBMWfan

Yes I have a new sound clip of this

I can't wait to hear this! did you get that x-pipe crossover installed now?

[jimbob123]

Originally Posted by spool twice

I think the stock muffler will sound the best, I will try to get mine done later this week or early next week, but mine likely wont' happen until after the new year. Can't wait to hear your sound clips, especially on a normal muffler!

I personally think it will sound better than the CS-tipped OE cans. Larger inner diameter tips that are single walled typically deepen sounds. The actual tips of the regular cans are smaller in diameter, but have an outer cover (or "exhaust finisher" in chrome or black on the ZCP) tend to accentuate higher frequencies, exactly what is needed to highlight an equal-length design.

Here is another pic from a member that better shows what I did. He didn't have his painted black so visually its easier to see what was done. He uses an H-pipe though, where I used a Flowmaster "x-pipe" crossover:



I like how they angled his H-pipe design, it gives a better opportunity to merge sound waves. However if you do use an H-pipe, my recommendation would be to place it closer to the differential, because the pipes are closer together, which will maximize merging sound waves even more.

ive just been sat under my car twizzling my brain and it occured to me that where the 14" u bend is ,you would have to add the length of the cut out section to achieve the desired equal length.otherwise youve only added a portion of the required length to equalise.meaning you would have to add another 6 or 8 inches or whatever the cut out section was to the u pipe.

[spool twice]

Correct, the total amount should be around 14" of added "effective" length, accounting for the missing space.

In other words, my drivers side pipe from where it was cut and all the way to the inlet of the crossover is 40", where as my passenger side is now 54" of total pipe length.

[Flange]

Do you think equalising the pipes with the OPF’s still fitted would make it sound better / different / louder?

I have a Milltek race system fitted and was thinking of sending this thread to them and seeing if they could modify my system...

[ntg44]

Originally Posted by Flange

Do you think equalising the pipes with the OPF’s still fitted would make it sound better / different / louder?

I have a Milltek race system fitted and was thinking of sending this thread to them and seeing if they could modify my system...

Better? Yes
Different? Yes
Louder? Probably not

Nothing fancy going on here. Just need to find a fabricator who will take on the job. But if Milltek is in your neighborhood, why not?