8V N/A Exhaust manifolds

[JM1962]

My 85 car car is fitted with a cast exhaust manifold, I am sure I read somewhere that the later 8V cars had a sheet metal or tubular manifold that was 3kg lighter. Can anybody shed some light.

Thanks.

 

[JamesO]

I have a late (89) manifold in the shed, I can weigh it if you want. It doesn't look cast.

 

[JM1962]

Thanks, a picture would be good rather than the weight.

 

[JamesO]

Will take a pic tomrrow.

 

[zcacogp]

Sounds like you are trying to lose 3kg ... but I'd have thought that the manifold is an odd place to start trying. Unless you have a car that is very stripped, and you are chasing every last few grams ...


Oli.

 

[JM1962]

Oli

I am nearing the end of a 2 year restoration, the last job, more or less, is a cylinder head overhaul and repair of a blowing exhaust somewhere between the manifold and the front box. Since these things can be picked up for next to nothing I will replace the manifold if I can get one. I have aquired, via a misunderstanding ( I was told they were off an 8V engine) what looks like the tubular manifold, downpipes and front box for an S2, no big problem as they were cheap (£35) I can sell them on easy enough or use the front exhaust section on the Lux and keep the manifold as a spare for my 968.

My understanding was that later 8V engines had a sheet metal rather than cast manifold, if this is true (the pet shows only one set of part numbers) I will try to get one. As for the weight, as I have rebuilt the car after its respray I have tried to lose a bit of weight here and there, but as the car is a road not a track car its really just a side issue.

 

[Jonny944CS]

Jim

See the attached for a picture of a 8v NA tubular manifold

~ 3.5kg lighter than the cast iron (pre '85.5) unit, but more more prone to warping at the flanges IMO. I fitted one to my car with a thermal barrier coating and have enountered some sealing issues. Be sure to use the later style manifold -> head gaskets (I will try to post a pic if I can find one).

Hope this helps

Jonny

 

[JM1962]

Aha, thanks Jonny, I knew I had seen one somewhere. So, is this the standard fitment to all 8V's after 85.5 ? If so should be easy to get hold of one.

 

[Jonny944CS]

I believe so, though I'm not 100% sure.

Attached is a picture of the different gaskets.

Run some sand paper over the flanges before you bolt them up. With a set square on the land between the fixings, the gap should be ≤ A4 paper thickness.

 

[JM1962]

Here's a bad pic of what I've got, doesn't look that different apart from the 3 fixing lugs instead of 2. Perhaps could even be made to fit with a little judicious use of the angle grinder. I have a spare head in the garage, I will see how they match up.

 

[JamesO]

Ah that saved me some effort. Mine are the same but are brown!
With regards to using the 16 valve manifolds, the flanges to the down pipe are reversed but if you use the 16 valve down pipe/centre section, it should bolt up to the 8v back box. Assuming you get it bolted to the head in the first place, no idea if they could be made to fit or if its worth the effort.

 

[JM1962]

Right, the manifold could be made to fit, the pitch of the exhaust ports mates exactly, but the orientation of the flanges welded to the manifold is slightly out and to much effort to get right, so I won't be modifying it.

So still looking for the proper manifold.

 

[JamesO]

I would let you have my 8v manifolds, but they are to be re-used. I'm sure a set will turn up.

 

[mr brightside]

My '86 924s has the tubular manifold, might be another avenue of possiblities....