3.0 16v turbo Exhaust manifold

[RudidSA]

Hi All, I'm in the process of building a 3.0 16v turbo engine, I was planning on using the Exhaust manifold from the 8v Turbo that I took out of the car and discovered while mocking it up that it doesn't fit and the 16v manifold doesn't look like it will fit the cross over pipe to the turbo, I was wondering if anyone here has done this before and could provide any advice. I was planning on completing the mock-up today to see where the differences are exactly, but thought I might ask for some advice first.

[AudiSport]

Google, search old forums. Has been covered quite a bit. A bunch of people have done this. I hope you're doing you're homework. You'll need to build a custom exhaust. I don't believe anyone is making this as it's quite rare overall.

[Thom]

All you need to do is to replace the outlet flanges on the 16V manifolds with 8V flanges, which will allow a more or less perfect mating with the cross-over pipe.

[RudidSA]

Thanks Thom, that's exactly what I was looking for, I wasn't sure which manifold I would have to use but this clears it up, use the 16v manifold.

[Thom]

IIRC 8V manifolds are offset frontwards due to the outlet ports not being centered with the cylinders as is the case on the 16V manifolds. Since you may have to sacrifice a set of 8V manifolds to source the 2 outlet flanges you may as well also have the "bellow" section from the first runner cut and welded into the 16V manifold, to allow for additional expansion due to the increased heat. I am not done tuning my 16V engine yet but EGTs seem generally higher than on the previous 8V engine, FWIW at least as EGT depends on different factors - CR, cam timing, ignition curve, etc.

[RudidSA]

IIRC 8V manifolds are offset frontwards due to the outlet ports not being centered with the cylinders as is the case on the 16V manifolds. Since you may have to sacrifice a set of 8V manifolds to source the 2 outlet flanges you may as well also have the "bellow" section from the first runner cut and welded into the 16V manifold, to allow for additional expansion due to the increased heat. I am not done tuning my 16V engine yet but EGTs seem generally higher than on the previous 8V engine, FWIW at least as EGT depends on different factors - CR, cam timing, ignition curve, etc.

Are you running with the stock cam timing from the S2? I got my motor from a burned out 968 so I also have variocam to play with...

[Thom]

You will have to find what works best for your engine with different adjusments.