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Bypass pipe

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bypass pipe
3K views 18 replies 12 participants last post by  Andy Bowles 
#1 ·
Is thre anywhere else that does a cat bypass pipe apart from Abbot,I mean how can they justify £175 each for a piece of s/pipe?
 
#2 ·
This is what I have recently done;

I paid a visit to a local engineering firm, and bought a piece of quality pipe which cost a few quid.

Took it to a local welder, he took CAT off, and I told him to take a deep breath and cut off the CAT flanges, weld them on to the straight pipe once he had cut it to size. Again a few quid.

total cost maybe 30 quid tops.

Ok, I have now got a CAT with no flanges (ooer), but MOT only comes round once a year, and I have got 12 months to get a couple of flanges welded back onto the cat, and then a simple on/off/on job next year.

take the plunge....go on go on go on

Cheers,
Andy
2.3 FPT 1994 (de-catted)
 
#4 ·
i was wondering if the non-cat equipped cars have the same size section where the cat is on cat equipped cars-if they do order one from eurocarparts at £30 or whatever it is. ok its not stainless, and it doesn't last, its maybe a little rough, but if you do, and it works - tell me.
and if you made sense of that message you did well.
 
#5 ·
Ok, I have now got a CAT with no flanges (ooer), but MOT only comes round once a year, and I have got 12 months to get a couple of flanges welded back onto the cat, and then a simple on/off/on job next year.  [/b]
Before doing that... get an emissions test done omn it first, should only cost a drink at your friendly mot garage.... worth a go..
Or if your ever round my way I'll do it for you...
 
#6 ·
Paul's suggestion might be feasible. I have one 9000 with each type of exhaust. If I can, I'll try to do some measurements in the next couple of days to see if the basic dimensions are right. You would need to support the new pipe from the cat hangers as it's flexible and designed to fit on the end of a downpipe that's rigid and that is bolted to the back of the engine.

It would be really great if they would fit on ramps. Paul, did your Carly fit on your mate's ramps?
 
#7 ·
There are numerous custom exhaust places that will make up a pipe for you. I spoke to one in Sheffield and they will do a custom back box with a 4" outlet for about £150, just got to book an appointment. On that basis, I can see a cat bypass being very cheap. I'll dig out the number which I think was in a classic car mag.

Ant
 
#8 ·
Leon/.

Thankyou for offer..

I have always been under impression that post 1992(or whenever it was) cars HAD to have a cat on by law to pass MOT. In other words , they would still fail an mot even if they had similar emmissions to an older non-catted car.
I thought that there was a completely new ( and stricter ) set of rules drawn up around 1992, so that cars any newer couldnt pass without a CAT.
Am I wrong, it would be useful to know if the Cat itself is essential, or just the emissions level..

Cheers, Andy
1994 2.3 FPT

Ps: you coming down to Southern meet on the 11th (closer to Burley than me...)??
 
#9 ·
AFAIK, no MOT tester will actually specfically look to see whether or not you have a cat, although a straight pipe is a dead giveaway... I just spent half an hour under my MY93 9000 last night dropping the cat back in (so now exhaust is purrring rather than grrowling ) cos she's off for MOT tomorrow.

That said, the key thing is the measured CO and HC emissions. If you can find a way to get these down, then AFAIK you car will pass the test. I did read somewhere that somebody had managed to achieve this by fitting an Ecotek. I tried myself- hooked up the car to the garage exhausst gas analyser, spent 45 minutes or so frigging about with the damn thing, standard/Abbott ECU's and the only thing I managed was an INCREASE in emissions. And I've never achieved a fuel saving but I think that's down to my turbo set up. I gather it does work on conventionally aspirated cars.

Mark
 
#11 ·
Just a thought... I don't suppose you could achieve a cat bypass by taking a dead cat
and smashing ten bells of u kno wot out of its innards with a long chisel ... or is it going to release some truly noxious palladium-rhodium or whatever compound that guarantees a long, slow lingering death?

And no, I don't know where you get dead cats from

Mark
 
#13 ·
Why not rev the nuts off the engine until something flies out through the bottom and hits the cat with an almighty whack. If it's dark, you'll be able to see the bits coming out the back because they glow with an attractive bright orange colour.

That's what I did with my Aero, anyway.

(The earlier cats are harder to gut like this as the cat isn't under the sump and in the line of fire.)
 
#15 ·
Well as long as you don't use a chisel, ylee won't report you, although I'm not sure where he stands on cruelty to roadrunners ...

Alternatively, and this IS a serious suggestion. If you park on a gravel drive why not try sprinkling some of the cat repellant that's intended for flower beds in a perimeter around your normal parking spot....

Mark
 
#16 ·
aeropilot,think yourself lucky you only have cats to contend with,I have a couple of fox cubs who spend the nightjumping unto the boot,across the roof,then slide on their bellies down the screen and bonnet,setting the alarm off in the process,then wait for alarm to stop and repeat as above.This has been going on for weeks only spotted the ba****ds purely by chance,am now experimenting with razor blades on edge mounted on bonnet.
 
#17 ·
Originally posted by MikeH:
[qb]aeropilot,think yourself lucky you only have cats to contend with,I have a couple of fox cubs who spend the nightjumping unto the boot,across the roof,then slide on their bellies down the screen and bonnet,setting the alarm off in the process,then wait for alarm to stop and repeat as above.This has been going on for weeks only spotted the ba****ds purely by chance,am now experimenting with razor blades on edge mounted on bonnet.               [/qb][/b]
We want the video/photgraphic proof of this please Mike - cause it sounds quite amusing from this side.

Aeropilot - Why not have a new paint job on Saab to include cat paw prints - lucky its not a St. Bernard really
 
#18 ·
I have always been under impression that post 1992(or whenever it was) cars HAD to have a cat on by law to pass MOT. In other words , they would still fail an mot even if they had similar emmissions to an older non-catted car.
I thought that there was a completely new ( and stricter ) set of rules drawn up around 1992, so that cars any newer couldnt pass without a CAT.
Am I wrong, it would be useful to know if the Cat itself is essential, or just the emissions level..
 [/b]
Car's from Aug '92 get a cat test, but if they fail the machine resorts to an ordinary gas test. This is the case up to Aug '95, so pre 'N' reg cars should be able to get away without a cat. '92 to '95 was classed as the change over time and a car in this period cannot be failed on the cat test if it passes an ordinary gas test.

HTH

Neil
 
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