rlich8

Hello all,

I would like to know the best way to most closely replicate the original exhaust system for this car. It has the single pipe system. Right now, for off road purposes, I have tested a straight pipe, but I found it too loud. It's ridiculously loud - I can park it outside of my office in back and hear it through a couple of walls.

I can't seem to locate a good original primary muffler (all are rusted out). I'd like to cut the straight pipe and install something more tame. Of course, if I nail it, I'd like to be able to hear a little of that classic V8 rumble, but at idle it should be a tame beast.

Thank you in advance,
Royal

Mongo

The only way to truly replicate it as close as possible would be to purchase a used OEM one. In the case of the ROW type system, the factory installed a resonator where your straight pipe is in the midsection of the car; a second resonator may also be found on the driver side, pretty much under the driver seat, then leading into a large rear muffler (aka the 'pumpkin').

The system would look similar to the one on the right side of this picture:



Since the factory piping after the merge for the cat/resonator is metric, it's about 2.75" IIRC. 3" would be the closest diameter pipe to use. If you are looking to replace the straight pipe, you could use a straight through type muffler such as a magnaflow to take the bite out of the tone. As for the rear muffler, just replace it with better condition, but used pumpkin.

rlich8

OK, all of that sounds good. I think what I want to do is replace the straight pipe with a muffler. We used 3" pipe for the straight pipe. It had a catalytic converter that I removed and do not want to replace. I do not need a catalytic converter as this is only for off-road testing purposes.

The catalytic converter was rotten. The car sounded like it was farting (but more muffled than now (it sounds like a rusted out V8 Camaro now...totally tacky)) when it had the cat on there. I think we just want to take the bite out of the tone with a nice Magnaflow or something similar. I may try that and see what it sounds like.

My punkin is fine. No holes, not rotten. Replacing the straight pipe sounds good.

Mongo

I'm not affiliated with this site, but this seems like a pretty good deal and an 18" long 3" muffler will REALLY QUIET the car down. I don't know if it there is enough space underneath the car for it to fit though.



http://performance-curve.com/12249-3magnaflow.aspx

Jadz928

I'm confused. Isn't the original system for a RoW 'S' dual pipe?

If so, how are we talking about single pipes?

GlenL

That's what I was wondering. Your car may have had a dual exhaust.

Check the PET.

rlich8

I have checked PET, and my car. For the model year 1978 it appears as if they had dual. 1979 onward, not sure until when, the single pipe setup was used.

My car has the single pipe setup.

We made this and installed it. I am thinking of just splicing in a magnaflow.

Jadz928

^^^
78-79 had single.

80-onward EuroS had dual

80-84 US has single. (Edited)

This is from memory, but should be close.

For your single setup, how about a bullet resonator to cut the edge off it. They're good for 5-10 decibles.

James Bailey

The 1985 and early 1986 USA was two side by side pipes as was the Euro S.......your S NEEDS a two pipe exhaust ! Highly recommend you find one and fit a proper X pipe in front. What was on there was an early exhaust with cat....for federalization not function.

Landseer

System in Mongo's picture... right is 84 USA.

Left is a cobbled system to replace 84 USA.
It is an Eastern Cat for 85, then a pair of magnaflow same side offsets, then a magnaflow short dual.

James Bailey

there are different rear "pumpkin" mufflers and as noted the 84 shown above has two inlet pipes but is just one pipe back to and including the cat.

Landseer

One thing that is possible is taking the downpipes / cat from a 32V car and bolting it to your stock Euro 4.7 manifolds. The cat acts as a primary.

OR, you could put a set of 85/6 manifolds on first. Then with some slight mods fit the 32V downpipes and cat. You can then combine with a Y and run a big single out the back, with out without something else along the way. That's what I've done with Jadz's 4.7 Euro.

James Bailey

I had bolted an 85 dual side by side exhaust with dual cat on the 928 my wife drove for years....minor mods to the heat shields was all . It sounded GREAT

Hilton

If you car is definitely a "Euro" 928S with the M28.11 4.7L engine, it had a dual pipe exhaust from factory, and your car is probably being strangled with the exhaust from a US car.

It possibly happened as part of it being federalised - or a local replacement was bought for it by a shop who didn't know that Euro 928's have different parts than US 928's of the same year.

The front muffler is a big 2-pipe affair which has perforated straight pipes through it, and it bolts directly to the manifolds on either side of the bell housing.

Hilton

Here's a pic from PET, and a pic of one installed on one of my S4's

All twin-pipe non-cat exhausts use the same front muffler from 1980 through 1989 (and later in some countries where cats weren't required). Its part no 928 111 096 03, so I have a couple of these in the roof of my garage from my non-cat S4's.

This is probably the easiest thing to do - buy a complete exhaust from a US 85 and bolt it onto your manifolds. You get the benefit of the cats making a less smelly exhaust, plus the US 85's have the same dual-pipe rear muffler as your car had from factory (assuming its been replaced with a single-pipe one). Then if you really want stock, you can hunt for a euro front muffler at your leisure.