AL-Shark

I have read several posts about using early 32 valve exhaust manifolds as sort of a "shorty header" on the 4.7 liter US engine.

I have some questions for those of you who have attempted our completed this process.

1) Do the 85/86 manifolds bolt up to the original 16v exhaust or is the mounting points changed to the point of needing a new exhaust for fit?

2) Will an x-pipe fit either the 85/86 manifold or the 4.7 liter manifold (assuming you change from the xpipe back)?

3) Would an exhaust set-up with 86 manifolds through an x pipe through an 86 cat-back fit in the stock locations on an 83 US auto?

I may have a line on some cheap exhaust parts from an 86 and I want to see what options I would have using them in conjunction with a few new parts on my 83 US exhaust.
Thanks for any feedback.

Scott M.

1) Not a direct bolt up... pass. side of exhaust needs lengthened to fit the 85/86 manifolds.

2) An x-pipe will fit the 85/6 manifolds.

3) Yes. But early cars are single pipes, later cars were true duals. I have an 86.5 exhaust on my 84 but had to add an extra hanger on the pass side for the middle can to hang from, otherwise there is no problem even around the battery box.

Imo000

I’ve heard that some of the flange holes need to be slightly elongated to maket he manifold fit. Other than that and the extension of the X/Y pipe on the passenger side it as close to a bolt on as it comes.

SharkSkin

I've been thinking of going this route, but having my brother fabricate a flange to mount the EGR valve out of stainless and weld it to the 85/6 manifold, with the objective being to make it look like it belongs there. I'm assuming that the smog techs will have no clue what it's actually supposed to look like, and will accept it as unmodified. Anyone know what alloy the 85/6 manifolds are made of?

BTW this is one reason I don't care to go with headers -- installing once is bad enough, but in & out every 2 years, plus having them in the way of clutch work? I don't think so.

checkmate1996

I have headers and totally agree with Dave. PITA!.

I have realized though for clutch work I can get away with just loosening the passenger side header to get the bell housing off...then you are good to go from there..

Imo000

I don't know the alloy ( I think they are some grade of stainless steel) of these maniflds but do know that they are double walled. So welding an EGR tube can be a bit tricky.

AL-Shark

Thanks for the great responses and the guidance.

trialattorney

I installed the 85/6 stock porsche headers on my 84 supercharged car with no difficulty (except having to lengthen passenger side outlet); also used 85/6 "dual" exhause in place of the "y" pipe, "racing" cat - breathes a lot better. Car not only passes CA smog (emissions) but it is so low that tech had to double check to make sure he had the tailpipe sensor in correctly. Visually, no way the tech could tell; this, by the way, was without a smog pump or EGR hookup. If I get a chance, I'll put the car on the rack and take a picture of the underside. It makes a significant difference in the running of the car (not to mention the weight savings of the headers over the cast 84 headers).

BarryW

How do you pass the visual inspection with the supercharger in CA?

Big AL in VA

I used this set up on my engine (84 4.7). I purchased the 85 exhaust manifolds that look like headers. They bolt right up to the block. Then I ordered the X-pipe and adapter from Dave Lomas at 928 Motorsport in Utah. You need the adapter on one side of the engine. This adapter by the way is a big PIA to put on.
And man is this set-up loud. It will wake the dead. It sounds like open headers slightly muffled. I thought I had a leak at first. I am just waiting for the police to pull me over.
The thread titled how do i remove 16 valve heads shows the pictures of these short headers and I think a bottom view of the x-pipe and hi flo cats.

Big AL from Virginia
84 928S EURO twin distributor monster with large valve cut outs in the pistons

Big AL in VA

Here is a pic of the headers and 16 valve head.

BIG AL from Virginia
84 928S Euro twin distributor monster with large valve cut outs in the pistons.