M5 exhaust manifold question

[SveinnH]

Hi guys,

One of the things that bother me the most about the S63 motor is the 2x4cyl soundtrack. I aim to change this as an experiment.

People have thrown the earth and the moon money wise towards these things and in my personal opinion the sound only gets louder, and playing a bad song at volume 11 doesn't really make it any better.

The real reason why we don't get the V8 rumble like the N63 has (and any other hot-V out there) is that some genius at BMW-M decided to extract the very last milliseconds of spool from the motor by crossflowing the exhaust banks.

Cyl 1 & 4 cross over to 6 & 7 and 5-8 cross over to 2-3. This is the same for all S63s, TU and non TU, X5/6, M5/6/8/XM

What I want to do is to separate the two exhaust banks. I bought a second hand X5/6M manifold but cutting that one up is a PITA because of all the heat shielding.
I have acquired a set of M5 manifolds now and will be building a jig and then cutting stuff up. I will post the results later.

Regarding the Turbos I have two options, get a set of M5 turbos and do that mod, or run the X5 turbos I have now, the motor only has 40k miles on it so I don't see the need to change.

However this means the flanges on the M5 manifolds need to be shimmed down.

SO MY QUESTION: Does anyone have detailed info on how much the M5 manifolds need to be turned down on the lathe to make the X5/6 turbos fit the flange.

Remember I am not after more power, just a nicer V8 sound.

[JellyStyle]

lot of work for better sound..
the M5 manifolds i thought didn't need to be shimmed, BOld Cars did an X5M conversion with M5 manifolds and turbos, you could ask Andrej over there how he did it, if he will share. Do share what you come up with, i am in the process of building an E70 X5M with better everything, so that its a forever car for me, plus i like to keep them around, i still have my 01 E46 m3 with 50k miles in the garage ha (with 100k in parts on it).. wack job i know..

Let me know what you find out from Andrej

[SveinnH]

Originally Posted by JellyStyle

lot of work for better sound..
the M5 manifolds i thought didn't need to be shimmed, BOld Cars did an X5M conversion with M5 manifolds and turbos, you could ask Andrej over there how he did it, if he will share.

Apparently the Turbo-To-Manifold flange on the X5M turbos is different from the M5 turbos so the M5 manifold side needs to be turned down on a Lathe I would prefer not to change the turbos.

But in the end its only some cutting and welding, M5 manifolds can be had cheap. No other modifications would be needed except making the X5 turbos mate up to the M5 manifold, and that is the info I am seeking.

People have spent a lot more money and a lot more time trying to make the S63 sound better, but In My Personal Opinion it never works. It just makes it sound like two loud Hondas