target01

<center><img src="http://www.autozine.org/technical_school/engine/smooth_v8_crank.jpg"></center><p>THis is what I meant with cross-plane.<ul><li><a href="http://www.autozine.org/technical_school/engine/smooth4.htm">http://www.autozine.org/technical_school/engine/smooth4.htm</a</li></ul>

ryoung

I had referred to them as either flat or dual plane cranks. With the following motor layout,

1 .. 5
2 .. 6
3 .. 7
4 .. 8

The flat crank Ferrari V8 has a 1-8-3-6-4-5-7-2 firing order. With the cylinders taking turns firing in each bank, even if the exhaust system had no crossover at all, the pulses from each bank of headers would be evenly spaced :-)

ryoung

Why is half the exhaust system carbon and half stainless steel?

On an otherwise all aluminum car, why are the front and rear subframes steel?

I believe target01 is correct ... cost.

dimitristx

Doesn't sound that swapping an H- for an X-link by itself adds to cost.

target01

Just different names then. Still, does the D3 have X-pipes now?

ryoung

I'll ask in the D3 forum for a picture of the exhaust system.<ul><li><a href="https://forums.audiworld.com/a8d3/msgs/18625.phtml">Question in the D3 forum</a></li></ul>

target01

it's all very flat and aerodynamic.

I dont think the car had a H or X pipe, hence my curiosity.

ryoung

... on his S8 with a new custom exhaust. Quoting Sven,

<i>"Is this the same car? The sound is gorgeous, but LOUD, a lot louder than I expected. I ease her off the bridge and out of the workshop, and push the fun pedal a bit in the right direction... OMG again ... This somehow makes me feel like a kid doing something he's not supposed to. At the end of the driveway I turn onto the main road and I give her some more juice. The growl reacts immediately and climbs a bit. When she's warmed up I can't resist trying what happens at WOT. What can I say? The sound of the quick climbing revs, followed by the gear change at redline is music to the ears of every petrol-head. Releasing the accelerator produces an equally thrilling sound... This is brutal! Bye, bye stealth ...

Back at EPS I'm greeted with the collective grins of the crew waiting outside. Somehow they heard me coming, I wonder how come ... The boss advises me to try the system for a while, give it a chance to `run in' and then decide whether I'm satisfied or not. In case I find the exhaust too intrusive on cruising speed they'll make me some extra pipe-dampers, to make it a bit more modest. I'm not sure yet, the sound is awesome, but it's a major change from `whoosh' to VRRROOAAAP, and I could imagine it may become a bit much travelling to the south of France."</i>

Shortly afterwards, he installed the first X-pipe crossover on an A8/S8.

<i>"And now the result ... Much to my surprise the sound is softer. Didn't expect that really. It's also 'rounder', and more 'balanced', which was expected. It sounds more 'German' now, if that makes sense. Less low V8 rumble, more an aggresive rev-happy performance sound. Less noticable on cruising speeds, but as soon as you blip the throttle there's little doubt what this baby can do."</i><ul><li><a href="http://www.tyresmoke.net/ubbthreads/showflat.php?Cat=1,20,22,25,27,3&amp;Number=246410 &amp;page=1&amp;view=collapsed&amp;sb=5&amp;o=&amp ;fpart=1">Tyresmoke post: X-pipe install</a></li></ul>

target01

Audi should install a small flap that opens and closes an x-pipe. All the noise, less loss in performance.