Cortina

I'm in the process of trial fitting - not sure what make - of tubular exhaust manifolds to 1981 model 928S : Can the manifolds be fittted with the engine in situ , or does the engine need to be lowered in with manifolds already in place ?. I have had a look and fitting either side,from either front or back (from underneath obviously) looks kind of "tight" to me !
Thanks Alan

Fabio421

The manifolds in 1981 were cast manifolds. I'm not sure I understand your question.

Cortina

I thought the "not sure what make" might have been a clue - this is NOT a standard cast manifold I am fitting ! - Hence the title : Tubular exhaust manifold fitting ..................

Landseer

I can speak to install on 84 USA 4.7 and also Euro twin dizzy.

Have not installed onto earlier 4.5. Cant remember if 81 euroS is 4.5 or 4.7 due to age forgetfulness.

85/6 SS tubular can be installed in situ.
It is tight. 1/4 inch drive pneumatic ratchet can help.

Might be best to first redrill holes in SS manifolds with a fractionally larger drill bit. They need a tiny bit more clearance to center up and fit. (At least that's what we've been calling tubular manifolds)

Also best to utilize the 85/6 studs and nuts, which are also stainless. I forget if the originals on early cars are SS or steel.

Cortina

OK - thanks . 81 is a 4.7 - single dizzy (makes no difference). I now have radiator out , along with alternator / ps pump and reservoir - so will try again tomorrow with a bit more space. Strikes me that studs are too long (easy solved) and this in itself will cause a problem. Can you remember if you went in from front or rear (if you will pardon the expression !) Cheers (PS maniolds are mild steel I think , and already holes are big (too big for my liking - ref centralising port and exhaust pipe I/D))

Landseer

What are tubular manifolds from? Not 85/6?

Cortina

Mild steel I guess , but that is not important - thay are 100% NOT Porsche from any year - have been specially made (suspect in USA ?) for a 928 . These will not be a 1 off item , I thought they were a common modification in USA for increased performance ?

Landseer

,,,

Landseer

Pic would be interesting.


in USA the popular modification has been transferring 32v pre-S4 pipes to 16v. These are tubular instead of cast. Have distinctive accordion expansion joints. They are SS but develop a patina that makes them seem mild.

S4 manifolds are similar but have larger bolt holes or slots...I dont think they are used, cant remember why.

Then there are MDS (or MSDS?) Headers or a knock off of them. I removed a set of those but had cross member out and engine hanging from wood beams spanning across fenders

Sorry I cant be more helpful.

Cortina

OK , Random picture of car attached to remind myself how to attach photos - will take a shot of manifold later ... and attach !



1981 S Rally Car

Petza914

He's trying to fit these stainless round tube manifolds like it did on my 79 (though this is on a 83 4.7 replacement motor I put back in after blowing the head gasket on the 4.5).

As you can see, I pre installed these using copper exhaust lock nuts.

I have another pair of them to install on my 81 Euro S 5-speed and plan to do that set with the engine in the car so following along with interest. That car currently has MSDS headers that prevent the lower bell housing from being removable to do clutch work which is one of the great designs of the 928 so that's a non-starter for me. Whenever that car needs clutch work, the headers are coming off and these others are going on with a catless X-pipe and true dual exhaust. The car sounds fantastic with the custom setup that I bought it with, but I need to be able to service the clutch without major surgery.



Stainless round tube manifolds from alter car on a 83 4.7 block powder coated in high temp Cerakote



From underneath



You're going to need the special spacer shown on the one side unless the Y or X pipe you're using is custom

Special spacer from Dave Lomas at Motorsports in Utah


If you look in the reflection of the black car you can see the complete exhaust setup on the 81 Euro white car above it.

Landseer

Those are great reference pictures Pete. I came to same conclusion about the MSDS headers, discarded mine on 84 euro and replaced with 85/6 as you show


I think we need to confirm with his upcoming picture exactly which pipes, unless maybe you already know that. Question originally...is it doable in situ?

Cortina

These are the two headers I plan to fit - one shown losely fitted to a spare engine. Reason for trial fit - 2 fold. a) Are the pipes made to suit LHD vs RHD cars ?? ie , will what I have clear my steering rack ? and b) I am reengineering my sumpguard mounting points - so need to know fairly exactly where the headers route , so "we" don't have a physical miss-match between these two things !!. It would be handly if I could trial fit without having to lift engine ... tried again this morning with less bits in the way , and it was VERY close to do-able (shorter studs MAY be the solution). These manifold flanges are thinner than the cast ones , and I think slightly thinner washers may be fit for the job (think **** weight saving !!)

Petza914

So, totally different than what I thought you were trying to do. I don't have any direct experience with those or answers to your LHD questions, but I would make sure your lower bell housing will clear those and be removeable for clutch work before installing them. They look very similar to the ones on my car that I plan to replace for that very reason.

Cortina

Not concerned about clutch work (no pain , no gain) - but would like them to fit without any serious modification. I am "easy" on a clutch - did about 30 rallies in the car with no trouble - so will be interesting to see what state plates are in when I remove them . Planning for a mild engine tune .... and to loose 100Kg , that should liven things up a bit !!! ta.