Exhaust manifold 10V design feature

[twoqu]

Can anybody explain why whoever Audi used for manufacturing the exhaust manifolds on the Works cars(Trans Am and Rally) appears to have extended the manifold pipe beyond the flange rather than finishing it flush.
Is it just a manufacturing legacy or would it have any theoretical performance advantages? It clearly would necessitate large than stock exhaust ports or even perhaps a much thicker gasket.
To see what i am on about see the pic of a what is supposedly a Lehmann manufactured Trans Am manifold. This is obviously a work of art, not only in construction but material by the look of it.

[twoqu]

Here is a pic of the manifold used in the A2 Rally Urq. Yep it really was that shape!
You can see that the pipework is further than the flange.

[Error404]

Can't answer your question mate but that A2 manifold is bizarre

[twoqu]

In fact looking at that A2 manifold the turbo flange has the same treatment.
The manifold flange is welded to the pipes so it does not move independently to provide clamping.

Perhaps to assist gasket sealing. Of course that type of feature is incorporated into even OE cast manifolds at least on the turbo connection.

[morgenlatte]

i think, they had no actual seals at the flanges.. with that extended pipes, they made the actual sealing.. as far as i know

[twoqu]

Yes that would make sense especially due to the inaccessability of the manifold in the field! Never seen a Works head so its difficult to say. Other than that if they did use gaskets it would prevent erosion from the inside out.

[pasbogdan]

Seams the heat is absorbed first by the pipe and transferred in smaller amount to the flange?Distortion problems,pipe to flange weld crack for classical approach?
Or smaller runners are used to accelerate the hot gases and they flow better if they are inserted into the head?

[twoqu]

Well its difficult to tell whether a gasket was used or not but it is clear the exhaust port was machined to accept the pipe! It does appear that this engine was rebuilt using gaskets.
One less Audi mystery for me to worry about!

[s2driveruk]

that A2 manifold...looks really overly complicated to an idiot like me, what were they thinking?!?!?!?

[JariP]

Can you find a picture of the manifold showing what the pipe entrance looks like? Is the transition from head to manifold made smooth without steps or stepped? Most times when looking at high level competition parts you must remember that those parts are purpose build to gain every advantage available within the rules or pushing the limits of the rules. That's why many competition things don't make any sense when applied to something like an unlimited street engine.

[twoqu]

Its difficult to find pictures od such rare parts that show the details you would like to examine in depth without owning the part yourself. This feature is applied to at least 4 different manifolds so there must be a good reason for it!
The pic below is of another variant that shows the flange detail from behind if thats of any use.