ryoung

Some of the X-pipe threads also discuss <a href="https://forums.audiworld.com/a8/msgs/72493.phtml">Firing Order</a> and exhaust note. With a 90 degree crank, the only other way to get an even firing exhaust is to cross over some of the primarary exhaust pipes to alternate collectors as seen in this GT40.

<img src="http://xtremeclassics.com/images/1stdrive12-640.jpg">

pkrasusky

...speculated no change in sound / power.

Regardless / undeterred - I've got to get some time again to redo some before vid's and AC-22 runs (lost my previous data in hard drive crash), then get the sucker installed and repeat.

Oy.

icsamerica

Interesting, thanks. I guess the jury is still out and I think BMW will go with the cross plane for smoothness. Those that say they'd accept the vibration for a bit more power clearly have never driven a flat plane V8. With a flat plane the vibration will come right through the gear shift on a manual car. The only way to fix that is with rubber bushings which would create very poor shift feel and I know BMW wont do that on a M car.

S8bell

Please record Temp and Barometer for each session ... oooh I like numbers!!!

pkrasusky

I'll see what I can come up with. Temp I could do (wets thumb / sticks in air), will *pass* on the barometer reading - unless you trust what my 2x knee surgeried knee tells me?

S8bell

<ul><li><a href="http://forecast.weather.gov/MapClick.php?CityName=Hartford&amp;state=CT&amp;si te=BOX">hartford weather</a></li></ul>

S8bell

I can't find this anywhere on the web. All the evidence, not much, points to the same firing order crank layout as all the other 4.2 litre Audi motors.

S8bell

Yes it is. Thank you. Looks like it's a dual plane crank.