exhausts...

having just been reading the MOT tester's manual...

it doesn't say anything about cats on compression ignition engines - the vehicle has to pass the appropriate smoke test, is all.

new system put on the 300 TDi - both boxes are "straight-through" and as such don't restrict flow.

Put a non-cat front pipe on, mainly 'cos it's about 250 quid cheaper... I think it makes slightly more black smoke on fire-up, but overall, it's running better and smoking less, if anything, than before. It's definitely responding better, especially at low-medium revs. Next time it gets MOTed, I'll see if I've got leeway to turn the pump up a bit more :-)

Someone mentioned a bit back that on a turbo engine, the silencer is almost redundant, so in a spirit of scientific enquiry, after fitting the front pipe but no silencers (and of course no cat) I fired the engine up and revved it a bit. It *is* noisier than normal, but not much. Certainly nowhere near as noisy as a normal CI engine with no silencer on it.

so I reckon if you wanted, you could just run a pipe out the side or back. However, since the silencers supplied for the disco are non-restrictive (or the ones I got are) there's not a lot of point.

Reply to
Austin Shackles
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Austin Shackles came up with the following;:

Our local MOT centre (well, the one I use) is a large Goods Vehicle test centre too, and if you bung them a fiver they'll check the emissions etc for you. Money well-spent as a diagnostics I think.

Indeed. When our rear box 'fell-off' the only way we knew it was gone was when we got out and saw it hanging down. When the centre box went it was noisier, as you say, but only enough to make me think there was a problem, maybe a hole, not that there was no silencer at all. ;)

My next change wil be for a non-cat front bit.

Reply to
Paul - xxx

I toyed with making a straight through exhaust for my car (also a turbo), but I spoke to somebody else who did the same thing and he has put a silencer back in as the car didnt sound as nice without anything. This is a petrol though so may differ slightly from a diesel. I've just gone for one silencer rather than the stock 2 for the moment and am on the lookout for a less restrictive silencer to use as my only one.

Reply to
Tom Woods

You need to change the down pipe & middle box/tail pipe as one, but still a hell of a lot cheaper than a cat.

Richard

Reply to
beamendsltd

beamendsltd came up with the following;:

Yes, if using LR original parts. Our local Kwik Fit did me a great job with pattern parts, just replacing bits rather than a full exhaust.

Reply to
Paul - xxx

On or around Thu, 12 Jan 2006 11:18:38 +0000 (UTC), beamendsltd enlightened us thusly:

looks like the "300 TDI non-cat" front pipe would be a direct replacement using an existing centre box and rear pipe. It's also possible to fit it without removing either half the suspension or the gearbox crossmember, which looked like it would be the case with a cat one. I decided it was easier to hacksaw through the old one to get it off. Judging by how difficult fitting the non-cat pipe was, there's no way the cat one would have gone on without removing something. This one has a front anti-roll bar, should be said.

In this case the whole back half of the system was shot - the rear box fell off some time ago and the pipe was rotten all the way through. The centre box is actually OK but the pipe had detached itself from the back end of it. But provided you eschew the cat the whole system is not expensive enough to be worth putting half a new one on it.

Reply to
Austin Shackles

As I understood it, there is a requirement for a cat on vehicles on / after a K plate. I had a J-plate Audi and was told by a specialist exhaust manufacturer that if it had been a K-plate I wouldn't have been able to remove the cat legally, but as it was I could, and I did! I'm not sure about requirements for diesel vehicles though.

Only thing you need to be careful about when removing the cat is that it can cause vibration problems/noise within the exhaust at certain RPM unless it is replaced with a silencer box, but that's all down the the particular vehicle.

Matt.

Reply to
Matthew Maddock

No requirement on diesels as long as emissions are met. Binned the one on our defender (P reg) years ago. Middle box went next. Back box will follow. Coupled with the full width intercooler it flies!

Reply to
Graham G

On or around Thu, 12 Jan 2006 16:29:40 +0000 (UTC), Matthew Maddock enlightened us thusly:

It's not in the MOT regulations. The exhaust has only to be secure, not too loud and not leak. If the vehicle can pass the appropriate emissions test (which a good engine with a good LPG system can, if you're lucky) then the cat doesn't have to work. Not sure if it's an offence under C&U to remove the cat, if the emissions are OK without it.

Reply to
Austin Shackles

My plastic rocket is too old to need a cat, but owners of later models sometimes bash the cat innards out as the engine is clean enough to pass the emissions standards without it. They're hoping that if they get caught they can claim that they didn't know, although whether that'll stand up or not is another matter. Their understanding is that a cat is required whether it's needed or not, however given the confusion amongst MOT testers I think they're assuming that on the basis that the MOT tester will fail them anyhow even if it's not required.

Reply to
Ian Rawlings

Think it must be a date related thing. No cat on my k-plate 110 - ever, so far as I cat tell.

FWIW: we also have l-plate box that does have a cat and the restrictor/reducer in the fuel filler pipe.

Reply to
William Tasso

Pre-1993 IIRC, no cat on my '89 petrol-engined car.

Reply to
Ian Rawlings

Ooops, I mean there was a cat, but no requirement for it on the MOT, so I took it off as it was screwed, no problems at MOT time.

Reply to
Ian Rawlings

On or around Thu, 12 Jan 2006 19:03:02 +0000, Ian Rawlings enlightened us thusly:

but not required to test for cat function. The test is for emissions, and if your engine can pass with a cat with a hole through the middle, you can disclaim all knowledge of the hole. Nor will you get pulled up on it; if it fails the emissions test it'll be put down to a defective cat and it'll get replaced.

there's nothing in the test manual says the cat has to work, only that it has to pass the test. I'll have a look in C&U sometime.

Reply to
Austin Shackles

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