2.8 exhaust centre box options

2.8 exhaust centre box options

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Discussion

Bercilac

Original Poster:

295 posts

76 months

Monday 1st June 2020
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I'm thinking about replacing the centre box on my 280s.

Much as I love the noises it makes it gets more than a little tiresome after 50 miles or so and a slightly more muted rumble would suit my driving style better I think.

Ideally I would like something that can be fitted by cutting the existing pipes and clamping on new box rather than fiddling about welding stainless.

What have others done? Should I perhaps look at getting the stainless one repacked? It was fitted in 1994, probably when the 1988 factory item rotted out.

WhatamIgettingmyselfinto

64 posts

91 months

Monday 1st June 2020
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I took my exhaust off to repair it recently. While I was there I had a look down the centre box, there didn't appear to be any packing in the front section, just perforated baffles, I'd assume the big box in the centre just has some baffle plates? Could be worth opening up the front section, packing it with exhaust wadding, then getting someone to weld it back up. I'm no exhaust expert though.

Bercilac

Original Poster:

295 posts

76 months

Monday 1st June 2020
quotequote all
Interesting - I only have the rectangular centre box. That could be why its a tad noisy. I wonder if I could replace it with a pair of repack-able silencers. Anyone done that?

O mage

229 posts

54 months

Monday 1st June 2020
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Bercilac said:
I'm thinking about replacing the centre box on my 280s.

Much as I love the noises it makes it gets more than a little tiresome after 50 miles or so and a slightly more muted rumble would suit my driving style better I think.

Ideally I would like something that can be fitted by cutting the existing pipes and clamping on new box rather than fiddling about welding stainless.

What have others done? Should I perhaps look at getting the stainless one repacked? It was fitted in 1994, probably when the 1988 factory item rotted out.
I would cut it open and see, it might only be half baffled and you can modify it.

ian-puzb9

18 posts

53 months

Monday 1st June 2020
quotequote all
Is it booming or is it rattling?
Stainless systems have a habit of detaching baffles - it isn't a Christopher Neil system is it?
The baffle in the Square section would have been packed with wadding originally but if you say it's been on there since 94 that is now long gone.
Whatever you do don't be be tempted to fit a 2.9 system, downpipes back, it won't work.

Bercilac

Original Poster:

295 posts

76 months

Monday 1st June 2020
quotequote all
No booming or rattling but just a general awareness that small children may burst into tears as I rumble past on tick over.

Interestingly the car's steering rack was replaced at Christopher Neil in 1994, but the exhaust (manifolds back) was custom made and fitted by JP Exhausts (Macclesfield) in 1992 for a grand total of £381.88.

I remember contacting them last year about having a pair of stainless manifolds made, nearly choked on my Cornflakes as it was almost as much as the whole car cost.

ian-puzb9

18 posts

53 months

Tuesday 2nd June 2020
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Problem is, if you have stainless steel manifolds made it will only make the system even louder.
I wouldn't bother doing that anyway since the Siamese ports on the head are biggest restriction for releasing more power.
I have seen Hayward and Scott exhaust systems (used on Subaru Impreza), heat wrapped which did take the edge off of the overall volume but not that much.
Am I right in thinking that your system has the down pipes and main section as one?

Bercilac

Original Poster:

295 posts

76 months

Saturday 6th June 2020
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Two sections Ian. The headers are standard TVR cast items (modified Taunus/Granada) with custom made stainless curved pipes that then join to custom made stainless long pipes and centre box.

Everything from the manifold back is JP Exhausts (was Macc, now Congleton I think) so I'm probably going to drop the long pipes and centre box back to them this winter to be cut open and modified.

Depending on their advice, I might go for two straight perforated pipes, or maybe a perforated X piece to give the same balance between cylinder banks (or an X piece outside the box), then fresh glass packing and welding back up.

v8s4me

7,264 posts

226 months

Saturday 6th June 2020
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Phillpot has a cherry bomb on his 2.9 and it sounds very nice.

Edited by v8s4me on Saturday 6th June 12:59

Bercilac

Original Poster:

295 posts

76 months

Saturday 6th June 2020
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That's an idea - I had one on my MG Midget as a single back box, very rorty (if not very fast!)

edsj

42 posts

102 months

Sunday 7th June 2020
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I opened my central box (top side) and found the baffles OK but hardly any damping material left. So I filled it with with steel wool first and glass wool on top (exhaust-purpose stuff) and had it welded shut. Also replaced the front box with dual piping. Worked great and still lovely sound without the "howling" at 3000 rpm that was deafening.

Bercilac

Original Poster:

295 posts

76 months

Monday 8th June 2020
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I suspect the same wadding removal process has been occurring in my car, given that the exhaust was fitted in 1994.