Why does M6 exhaust note suck

[Fcs1965]

I do have a 2018 M6 Competition with downpipes and Burger tune and I have to say 2019 Mercedes C63 stock sounds much better. Why does C63 sound so much better considering it is also a twinturbo v8.

[Flo1989]

Sound is subjective. To me, I’m not a fan of that MY c63 exhaust tone. The artificial burbles + vacuum like sound under throttle just doesn’t do it for me.

Now when you have a S63tu m5/m6 that’s catless paired with a full Meisterschaft or a titanium Akrapovic system and you’ll be HARD pressed to find a better sounding v8 from its competitors (Audi, MB, Porsche). And I’m talking about those cars having a full exhaust system, not stock. Again, all subjective but I’m speaking from personal experience.

[brad850csi]

I assume you're aware of why normal V8s have a bit of a lumpy note to them due to the firing order. Check out this picture

[Fcs1965]

Originally Posted by brad850csi

I assume you're aware of why normal V8s have a bit of a lumpy note to them due to the firing order. Check out this picture

Ok but both the BMW and Mercedes are a twin turbo V8 with a big difference in sound. So Normally aspirated V8 firing order doesnt apply. Just trying to understand why such a difference in sound

[Mr. M6]

Originally Posted by Fcs1965

Ok but both the BMW and Mercedes are a twin turbo V8 with a big difference in sound. So Normally aspirated V8 firing order doesnt apply. Just trying to understand why such a difference in sound

because BMW want more money from you to spend on titanium MPE/AKRA exhaust then the sound will be perfect.

i removed my competition exhaust and bought an Akra 100% worth it

[Luftpost]

Of course BMW does not make money on aftermarket exhausts, so there is no motivation on BMW's behalf. And why do we have to do all kinds of custom work to have a decent sounding exhaust (and smellier)? The E63 AMG, stock, no doubt sounds WAY better than any M6 (also stock). Mercedes appeals to a whole additional client with this. I would like to see the sales numbers between the two.

My son just bought an E55 AMG and has me rethinking everything BMW.

L

[brad850csi]

Originally Posted by Fcs1965

Ok but both the BMW and Mercedes are a twin turbo V8 with a big difference in sound. So Normally aspirated V8 firing order doesnt apply. Just trying to understand why such a difference in sound

Mercedes don't do it the same way. Their exhaust manifold is like the 650i manifold. If you track down a 650i with an aftermarket exhaust you'll find it sounds just like a normal V8

[Boss330]

The S63 sounds different than the N63 as well as other twin turbo V8 engines with a cross plane crankshaft.

The cross plane V8 «suffers» from a arythmic firing order where two cylinders on the same bank fires after each other.
L-R-L-L-R-L-R-R
Thats why a cross plane V8 has that distinctive burble sound in the exhaust. The exhaust manifold for each bank gets, one exhaust pulse, pause as the other side fires, then it has two exhaust pulses right after each other, then pause again as the other side fires etc. etc.

This sequence is less than ideal for exhaust scavenging and also leads to uneven flow in the collector (or to the turbine on the turbo).

One way to avoid this is a flat plane crank as a Ferrari, Ford Voodoo V8 and race engines use. However that layout has vibration issues and is not ideal for a regular engine.

So the preferred solution is a 180 degree header, probably best known used on the original Ford GT40. BMW adopts this concept on the S63. Two of the exhaust ports from each bank is routed to the opposite side of the manifold. In effect the left side collector (turbo exhaust flange) has two exhaust ports from the left hand cylinder bank and two exhaust ports from the right hand cylinder bank. By doing this each turbo has an even exhaust pulse constantly instead of an odd pulse.

This is why the S63 sounds a bit like two four cylinder engines with the stock exhaust but sounds like a race car with more open exhaust.

Photos show the difference between the S63 manifold vs the N63.