BMW M3 / M4 Sound and Exhaust System: Deep Dive and Interview

[Savory]

Originally Posted by JAM3S

The car farts just like a Honda with a coffee can on the back of it.

Some of you drink the BMW Marketing diarrhea straight from the bottle it seems.

It sounds nearly like a raspy E46 M3. And some people, including myself, liked those exhaust characteristics

[spool twice]

Originally Posted by termigni

so you know more about the exhaust system of the new M3/M4 than these engineers at BMW AG in Germany? please specify what you studied, what you do for living and for how long. or are you just a street tuner?

I don't understand your question? I'm not challenging what BMW AG decided to use for the exhaust. I'm simply stating the obvious, and that's BMW choosing to use an H-pipe instead of an X-pipe. It's a given that X-pipes smooth/mellow out sounds over an H-pipe; doesn't take a PhD to figure that out. Get off your high horse

[spool twice]

Originally Posted by Year's_End

+1

It looks like an H-pipe to me. I don't know the ins and outs, but wouldn't an X-pipe configuration be more suitable, especially as they tend to aid top end gains?

Possibly, but there are benefits to an H-pipe as well. However, that H-pipe definately is contributing the overall sound quality for the better or for the worse since sound is subjective.

[Ashley Schaeffer BMW]

Originally Posted by Savory

It sounds nearly like a raspy E46 M3. And some people, including myself, liked those exhaust characteristics

That sounds nothing like an E46, my E46 also didnt fart on upshifts.

[Year's_End]

Originally Posted by spool twice

Possibly, but there are benefits to an H-pipe as well. However, that H-pipe definately is contributing the overall sound quality for the better or for the worse since sound is subjective.

Right, and I'm no engineer so I only have a shallow education in the matter. I guess the pulse flow and added back pressure and would aid the F/I setup and the aural characteristics.

Originally Posted by JAM3S

That sounds nothing like an E46, my E46 also didnt fart on upshifts.

I think that has more to do with fuel cutoff between upshifts than anything else.

[brianeck]

Originally Posted by JAM3S

That sounds nothing like an E46, my E46 also didnt fart on upshifts.

Agreed it doesn't sound like an E46. I liked some of the earlier vids, and now with the two drivebys I'm back into the ehhhhhhhhhh not so sure boat that I started in.

I don't really care either way, aftermarket will fix all. My 335 was like a friggin prius until and got the BMW PE put on, and then I LOVED it. I had compliments all the time, one from a guy with an 11' M3 coupe who thought mine sounded better then his stock exhaust (I agreed!).

[Savory]

Originally Posted by JAM3S

That sounds nothing like an E46, my E46 also didnt fart on upshifts.

Sure, near redline it sounds nothing like the E46. But under load near the low end of the RPM range, they sound quite similar. Especially when compared to the M4 with the M Perf Exhaust

[Jblack4083]

In the lower RPM ranges it sounds just like my E46. Its in the higher revs that the E46's induction noise seems to differentiate from this engine.

[V1.47fan]

Originally Posted by termigni

so you know more about the exhaust system of the new M3/M4 than these engineers at BMW AG in Germany? please specify what you studied, what you do for living and for how long. or are you just a street tuner?

I hope the guys in charge of this exhaust system are better than the BMW engineers that for decades cant figure out how to solve the rod bearings problems or give me a simple oil cap for the S65 engine that doesnt leak. Lol

[swamp2]

Wow, this is by far the most detailed of this series of articles. Thank to M4post.com and to Herr Drees. Having worked for many years in the field of vibro-acoustics, I'm really impressed that BMW M is willing to share so much detailed information. Unfortunately there is just no way around (pretty much as discussed) the fact that normally aspirated sound >> turbo sound.

This has also slightly altered my stance on their using electronics (stereo system) to pipe noise into the vehicle. Knowing exactly what the engine is doing (state of load and engine speed) through acoustics only is an important part of driver awareness and can directly impact driving decisions. If this is improved through this technique it makes the system a bit more purposeful and less "oh let's just supplement the poor turbo sound".

[swamp2]

Originally Posted by V1.47fan

I hope the guys in charge of this exhaust system are better than the BMW engineers that for decades cant figure out how to solve the rod bearings problems or give me a simple oil cap for the S65 engine that doesnt leak. Lol

Nice signature pic by the way, you need to add the new M4 though! Finally a reversal in the trend! Did you come up with and make that yourself?

[CanAutM3]

Originally Posted by chmura

Very awesome read.

By looking at the exhaust it seems one can do the OEM exhaust mod fairly easily as it was done to the e92/e90 M3. It actually looks easier you just have to cover up 2 proiferated pipes instead of 4 on the previous M3.

Even more simple. Just get the valve to stay open all the time

[CanAutM3]

Originally Posted by M6-Coupe

what is that arrow up with number 7 ? the forth video at 1:12.
which feature is it?

Optimum shift indicator for fuel economy. See here.

[CanAutM3]

Originally Posted by Year's_End

I think that has more to do with fuel cutoff between upshifts than anything else.

Or maybe the anti-lag trickery at work.

[Celesabc]

I like it but won't stop me getting the M Perf Exhaust!

[Year's_End]

Originally Posted by CanAutM3

Or maybe the anti-lag trickery at work.

Possibly. I've noticed that this "belching" noise isn't exclusive to the F8X's though, and it's becoming increasingly common amongst a variety of OEMs. Most ZF 8HP-equipped models, be it BMW or Jaguar, exhibit that exhaust rip on upshifts. As do many MBs, Audis, etc. Hell, even a ZL1 equipped with a 6MT and a supercharged LSA will do it, so it might not even be related to a turbo setup which the anti-lag feature would be appropriate.

[kgroschi]

Ricer

[half man half amazin]

still sounds nowhere near as sexy as the e92,3 etc. im just hoping it much better in person under load. The fart sounds are killing me though. id much rather hear the BOV.

[Ducfan]

Originally Posted by swamp2

Wow, this is by far the most detailed of this series of articles. Thank to M4post.com and to Herr Drees. Having worked for many years in the field of vibro-acoustics, I'm really impressed that BMW M is willing to share so much detailed information. Unfortunately there is just no way around (pretty much as discussed) the fact that normally aspirated sound >> turbo sound.

This has also slightly altered my stance on their using electronics (stereo system) to pipe noise into the vehicle. Knowing exactly what the engine is doing (state of load and engine speed) through acoustics only is an important part of driver awareness and can directly impact driving decisions. If this is improved through this technique it makes the system a bit more purposeful and less "oh let's just supplement the poor turbo sound".

I've changed my view as well. Reality is that I, and in my opinion most have been altering the sound of our vehicles for decades to make them sound more like what we want them to sould like. Many (not me) justify this to themselves that they are actually getting more power with that different exhaust because they want to project that they are above such superficial desires as sound alone. Listen to the new F1 engine....clearly the most dense power package available with today's technology does not meet our conditioned sense of what it should sound like.

Ok it is nice of BMW to give us this driver feedback explanation (which I can buy into some) and avoid telling us we're a bunch of superficial posers. I now think what BMW has done with the electronic system is cool. Allowed themselves the ability to create the most effective exhaust system without the need to compromise performance to achieve a sound.

Now let's talk about a real hard to swallow pill. Would you still change the exhaust system? IMO we know that most exhaust only swaps do not really improve performance...it's for sound. And it will clearly be possible to alter the sound in the cabin electronically (coding or whatever) so if you still say yes to a different physical exhaust are you not really saying that what you care about is what other people hear? Sounds vain to me.....

Please don't get all upset with me. These are just thoughts and odds are I will still change the exhaust on my car in spite of what I just wrote....old habits and beliefs die hard.

[jackmcclane]

An interessting article about the sound of the new M3/4 but did I miss the section of the synthetic part of the sound aka the "Active Sound Design"?

Oh I think I found it "However, the new BMW M3 and BMW M4 meanwhile use a more intelligent system. The technology employed here makes it possible to restore the sound that is actually produced, albeit damped by the turbo system, and render it audible in the passenger space. This can only be done systematically in those areas in which excessive damping takes place,..."

Find it kinda ridiculous when the "M engineer responsible for the acoustic characteristics of M automobile" mentions this "more intelligent system" only so little.

[LSM]

Great read!! As for the sound disappointed...As others have said sounds like its flatulating

[damnitBobby]

Originally Posted by swamp2

Unfortunately there is just no way around (pretty much as discussed) the fact that normally aspirated sound >> turbo sound.

this

9 times out of 10 a NA car will sound much more pure and raw compared to turbo motors

i'm not quite sure what to make of the exhaust sound, it doesn't sound bad but not all that impressed either.. probably because i'm spoiled from the sound of my Z