[NathObeaN]

Hi all,

Coming from a 2018 M2 LCI, there were various effects the engine modes had on exhaust output:

Comfort = Quiet
Sport = open valves, louder, "pop" on upshift
Sport + = same as sport, but less of a "pop" on upshift
MDM = open valves, more burbles (Easter egg mode)

That said, what are the results for the M2C? From initial testing so far it simply appears that:

Comfort = Quiet
Sport and Sport+ = open valves, louder (same loudness in both modes?)
MDM = no effect

Is this right? Am I missing anything?

Thanks,

[hlm2c]

Pretty much for the M2C. Sports and sports+ has a difference though. More pops and crackles on sports+. I believe the braaaaap noise is only on sports+ too. Sport sounds like gurgling overrun instead. Stock there might not be a big difference, but once you go aftermarket exhaust, you'll hear the difference.

[NathObeaN]

Originally Posted by hlm2c

Pretty much for the M2C. Sports and sports+ has a difference though. More pops and crackles on sports+. I believe the braaaaap noise is only on sports+ too. Sport sounds like gurgling overrun instead. Stock there might not be a big difference, but once you go aftermarket exhaust, you'll hear the difference.

Thanks, what do you mean by the 'braaap' noise though?

[xxyion]

Originally Posted by NathObeaN

Thanks, what do you mean by the 'braaap' noise though?

the sound you get when you upshift on heavy throttle.

But yeah for the most part M2C doesnt change much sound wise. You can even get pops in Effecient mode. The only real difference i've found is you need to push the car a bit harder in Sport Mode to get pops compared to Sport + where it happens all the time.

[pz619]

You can actually get the noise on all modes with heavy throttle/boost.

[VisualEcho]

You forgot that in both Sport and Sport+ modes on throttle lift you get a long fart sound. Worst thing they ever did to both exhausts.

[Moflow]

My theory is that the fart sound is basically our version of a blow off valve. It only happens during heavy boost when suddenly letting off the throttle. I get it in all three exhaust modes.

I think bmws valvetronic design/lack of throttle body makes a BOV impractical. I believe (and someone correct me if you know better) that bmw just takes the pressure wave and rather than vent it to atmosphere, they just open all the valves and blow the air right through the cylinders. That’s the farting sound because it’s air passing through each cylinder without being mixed with fuel and ignited. The cool part about such a system is that the pressure wave can then hit the exhaust side of the turbos which keeps them spooling, a bit like an anti lag system. Only with air instead of explosions.

[pz619]

Originally Posted by Moflow

My theory is that the fart sound is basically our version of a blow off valve. It only happens during heavy boost when suddenly letting off the throttle. I get it in all three exhaust modes.

I think bmws valvetronic design/lack of throttle body makes a BOV impractical. I believe (and someone correct me if you know better) that bmw just takes the pressure wave and rather than vent it to atmosphere, they just open all the valves and blow the air right through the cylinders. That’s the farting sound because it’s air passing through each cylinder without being mixed with fuel and ignited. The cool part about such a system is that the pressure wave can then hit the exhaust side of the turbos which keeps them spooling, a bit like an anti lag system. Only with air instead of explosions.

Exactly this, by blowing the pressure out through the exhaust valves it’s keeping the turbos spinning at a high rate of speed. It’s functional for sure. As you pointed out, the S55 (also S58) doesn’t have blow off valves or bypass valves. In the end, it’s a very clever feature.

[BigKutta]

Originally Posted by hlm2c

Pretty much for the M2C. Sports and sports+ has a difference though. More pops and crackles on sports+. I believe the braaaaap noise is only on sports+ too. Sport sounds like gurgling overrun instead. Stock there might not be a big difference, but once you go aftermarket exhaust, you'll hear the difference.

I get the braaaaap even in S mode, when going between gear 1-2-3. I find the conditions need to be perfect for loud braaaaps! The car should be warm, but not too warm/hot.

[Rockfresh15]

Originally Posted by pz619

Exactly this, by blowing the pressure out through the exhaust valves it’s keeping the turbos spinning at a high rate of speed. It’s functional for sure. As you pointed out, the S55 (also S58) doesn’t have blow off valves or bypass valves. In the end, it’s a very clever feature.

Hmm, now I'll admit, I'm not the most mechanically savvy, so correct me if I'm wrong, but isn't this the exact burbling sound everyone in this thread is disabling?

https://f87.bimmerpost.com/forums/sh....php?t=1744237

And if so, wouldn't that mean they're forgoing the benefit of keeping the turbos spooling with air?

Sorry if this is a dumb question, just trying to get a better understanding.

Thanks!

[pz619]

Originally Posted by Rockfresh15

Hmm, now I'll admit, I'm not the most mechanically savvy, so correct me if I'm wrong, but isn't this the exact burbling sound everyone in this thread is disabling?

https://f87.bimmerpost.com/forums/sh....php?t=1744237

And if so, wouldn't that mean they're forgoing the benefit of keeping the turbos spooling with air?

Sorry if this is a dumb question, just trying to get a better understanding.

Thanks!

Not a dumb question. The burbles are something else. You get those when you lift off the throttle even in light application. Those are created by injecting some fuel in the cylinders and delaying the ignition. It’s that pop, pop, pop sound you get along with some “burbling”. That can be disabled by a tune that simply doesn’t inject the extra fuel. The brrraaapp noise is when you come off of heavy throttle or boost, which is the excess turbo pressure being released through the wastegate/exhaust. I don’t think that can be disabled without mechanical changes.

[Rockfresh15]

Ohh I see, got it! Thank you!

[boss2k]

I did a cold start in my garage today for the 1st time and i didnt get the pop sound in sports plus mode when i revved till 4k rpm , it happens everytime when i drive the car , any idea why? Could hear the valves open

[VisualEcho]

Originally Posted by Moflow

My theory is that the fart sound is basically our version of a blow off valve.

Well that's terrible news for those of us that hate it. I don't even drive in Sport or Sport + so I don't have to hear it. I never get it in Comfort or Traction modes.

[pz619]

Originally Posted by boss2k

I did a cold start in my garage today for the 1st time and i didnt get the pop sound in sports plus mode when i revved till 4k rpm , it happens everytime when i drive the car , any idea why? Could hear the valves open

Should be normal. I don't get the pops until the car begins to warm up. Maybe give it a try again when the car is warm. I suspect it'll work.

[VisualEcho]

Originally Posted by pz619

Should be normal. I don't get the pops until the car begins to warm up. Maybe give it a try again when the car is warm. I suspect it'll work.

Same. There is a bit of a growl present when the car is cold that is gone when it warms up (pity), but when it warms up is when I get the pops/burbles.

[pizza240]

Sport is my fave but I wish it had some of the "whooshing" sounds you get in Sport+. Not a big fan of all the pops/crackles of Sport+.

Efficient = quiet until 4500RPM, some overrun at higher RPMs.
Sport = louder, couple of burbles off throttle, nice overrun sound.
Sport+ = loudest, lots of crackles/pops, nice overrun sound, whooshing interior noise.

Sport is juicy, like a ripe peach; but Sport+ is a carbonated crispier version of it... Definitely GMO.

[Sarg33]

Originally Posted by VisualEcho

Same. There is a bit of a growl present when the car is cold that is gone when it warms up (pity), but when it warms up is when I get the pops/burbles.

I agree with this part, I like the exhaust sound when the car is cold, but then it goes away when it warms up.

But as far as the BRAAAP or Fart sound between shifts I really like that!

[TrentMeister]

I’m addicted to the braaap

The addiction has only become more boyracer/douchy after the aa mid...

I am currently at peace with my problem

[Pottah]

Originally Posted by LBbluem2

I’m addicted to the braaap

The addiction has only become more boyracer/douchy after the aa mid...

I am currently at peace with my problem

It's funny I thought I would hate it before I got the car but now I kinda like it. I do wish maintained that deep exhaust sound though.

[nearwater4me]

Originally Posted by LBbluem2

I’m addicted to the braaap

The addiction has only become more boyracer/douchy after the aa mid...

I am currently at peace with my problem

I love that fart too.
I give a lot more gas when accelerating just to hear that braaap. Lol