Original S1 exhaust construction. Help!!

[YeS1tis]

I'm constructing a new exhaust in stainless steel which will be as near original spec as I know how. Unfortunately my car was fitted with a horrible baffled silencer when I got it so I don't have the original system as a pattern. I do have some pictures. I know that the rear part has a sawtooth profile of perforated steel with the sound-deadening material above it and I understand that the front bit has an oval of perf. steel which goes around both downpipes where they enter the box (I realise there are sleeve joints just in front of the box). I presume that where the front bit joins the main silencer that the oval opens into the main silencer. What I am unsure of is whether there should be any sound-deadening material wrapped around the oval tube or whether the front part is purely an expansion chamber. I'm using E-glass for deadening, which I believe is quite durable. I once packed a silencer with glass fibre loft insulation and it was gone in a day! I'm also unsure as to the exact length of the front section. Any info would be appreciated. I'm aware that by the time people open up original silencers the stuffing has often long gone so does anyone know what was originally there?

[greymrj]

Hi there, I didnt want you to think that nobody on the forum would answer you. It is a difficult one though, I have been on the forum for a few years now and, while there are plenty of good engineers and DIY mechanics out there, I have never heard of anybody making their own exhaust. Quite a few with MIGs but not TIGs. Members will often work out how to do things and make parts but most,like me, would have to outsource stainless fabrication.
I am not sure if I can help you very much but the exhaust is lowered on my S1 at the moment until my fuel tank comes back from restoration. I could therefore get you pics and dimensions if that is of any help.

I presume you are aware that the box has to be a precise fit inside the chassis rails.

I had my silencer cut open by an exhaust specialist last year because a baffle had come loose and was making an irritiating sound. Unfortunately I didnt see it open but it definitely has a zig zag baffle pattern and the weld heat marks on the outside still show. No mention was made of any sound deadening material.

[tel595]

I had a go at repairing my original mild steel one on my S1 a few years ago. I cut the top off the silencer and noticed the corrugated, perforated steel baffle had broken apart and all the wadding had been blown out. I welded up what I could inside the silencer and re-packed with some glass-fibre. It worked really well until I went to Classic LeMans in her. It sort of disintegrated again inside the silencer and made more noise than a car without any exhaust I think.. I soon ditched it when I got back and bought a secondhand stainless item off a mate who has a S1.5. I'm sure they can be repaired, but I didn't have great success..

[Alan Whitaker]

Hi All
I made my own, 63mm - 2 1/2 all the way, 2 chrome cherry bombs in the middle out to a X pipe and out to 2 big DTM rear cans.

Alan

[YeS1tis]

[quote=greymrj]
I am not sure if I can help you very much but the exhaust is lowered on my S1 at the moment until my fuel tank comes back from restoration. I could therefore get you pics and dimensions if that is of any help.

I presume you are aware that the box has to be a precise fit inside the chassis rails.

Thanks greymrj,
I am aware of the precise dimensions of the back part of the silencer, it's just the front section I'm unsure of, so if you could give me the length of that I'd be grateful. I am anxious that the first part should start at the correct distance from the exhaust ports as the pressure wave should then be reflected correctly to give better low and middle range torque, always assuming TVR tuned it in the first place, so the distance from the front of the crossmember in front of the rear section to the front of the front section would be useful as check.