Stock Exhaust ‘85 to ‘83 928?
Race Director
Joined: Sep 2007
Posts: 12,162
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From: Johnson City, TN
85 or 86 cats to 16v 84 is bolt up to the existing early manifolds. Caveat, on a couple I've had to put torch to cat downpipes at cat to bend slightly to enhance fit.
If you swap to the 85 86 ss manifolds at same time, though, then you need to fab a spacer.
87 and later cats can also be used, but you need to get creative with transition pipes coming out of cats.
We had a crazy setup on jadz928 s euro 84, using SS manifolds, into 87 cats with a spacer, then a flow master Y, to a big single pipe. Had a spin tech resonator, single in single out also. Beast.
If you swap to the 85 86 ss manifolds at same time, though, then you need to fab a spacer.
87 and later cats can also be used, but you need to get creative with transition pipes coming out of cats.
We had a crazy setup on jadz928 s euro 84, using SS manifolds, into 87 cats with a spacer, then a flow master Y, to a big single pipe. Had a spin tech resonator, single in single out also. Beast.
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Joined: Jul 2014
Posts: 2,934
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From: Blacksburg, SC
Seth - Your Red Witch is an 86.5.
Doesn't it have the S4 exhaust?
Does it have the same manifolds as an 85?
I'm not super 'up to speed' on this, so I may be way off base, but looking in the PET, there seem to be different exhausts for the S2 (84 - 86 Euro - Duals that run together), the 83 - 85 (US - single pipe) and 86.5 (S4 dual exhausts that run separate).
Doesn't it have the S4 exhaust?
Does it have the same manifolds as an 85?
I'm not super 'up to speed' on this, so I may be way off base, but looking in the PET, there seem to be different exhausts for the S2 (84 - 86 Euro - Duals that run together), the 83 - 85 (US - single pipe) and 86.5 (S4 dual exhausts that run separate).
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The 2 valve heads the exhaust ports are not centered but the 4 valve they ARE so when 85-86 manifolds are fitted to the 2 valveheads they do NOT bolt up to the down pipes./ But the twin pipe "dual" exhaust of the Euro S; or 85-early 86 USA is a bolt up to the 2 valve cast manifolds. Worth noting that when Porsche made all the engine changes to get 300 HP they felt it NEEDED the twin pipe exhaust ! If nothing else the twin cat of the 85> has to flow better.
