No CAT...

Townlea

Townlea

Townlea

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Joined
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Preston, UK
I was wondering, What kind of performance gains can you get with not having a CAT?

Do they really constrict the bhp a lot?
 
Townlea said:
I was wondering, What kind of performance gains can you get with not having a CAT?

Do they really constrict the bhp a lot?
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depends, because most sports cars have a sports cat, which is less restrictive. On a ST170 for example I think the gain is around 8-10 bhp, not worth it
 
i wouldent say its not worth it, it depeds if you happen to have a decat pipe in the shed and can get i fitted for a tenner, i think you will struggle with most cars to get ~8hp for less. but i wouldent like to spend 60 quid on it unless it was really holding me back, a freind had this on his punto turbo and we noticed a verry big gain from it, he was happy with the money he spent anyway. also think about MOT time:)

Dan
 
Bear in mind that also in general it will fail the MOT if you don't put it back on. I'm not sure what the deal is if you ever get stopped by the police, and I think you'd have to tell the insurance too.
 
Freefaller said:
Bear in mind that also in general it will fail the MOT if you don't put it back on. I'm not sure what the deal is if you ever get stopped by the police, and I think you'd have to tell the insurance too.
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Insurance is invalid as, technically, the car wouldn't pass an MOT without it and is hence unroadworthy, as I understand it.

However there is some discussion about whether, if a car that is supposed to have a cat can pass the MOT without it, and nobody notices its missing at test time, the car may be deemed roadworthy...

I don't have one in the Lotus, it makes it pop and bang more ;)
 
Nozzer said:
However there is some discussion about whether, if a car that is supposed to have a cat can pass the MOT without it, and nobody notices its missing at test time, the car may be deemed roadworthy...
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unless the engine is super clean in the first place i think its going to struggle getting past the macheine, i know a tester verry well and he doesent care if that cats there he cares that the mechine shows green numbers, cat or no cat.
 
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The car hasn't had a cat on for over a year now :)

I am running on LPG so it passed the Emmision test easy :)

Also on my MOT cerificate... it sais LPG no-cat :)

So MOT isn't a problem


The reason why I have no CAT is because my one blew so cheapest option was a straight through pipe :D
 
minidan said:
unless the engine is super clean in the first place i think its going to struggle getting past the macheine, i know a tester verry well and he doesent care if that cats there he cares that the mechine shows green numbers, cat or no cat.
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The K-Series in the S1 Elise is quite happy passing MOT emissions tests without a catalytic convertor, assuming it's well looked after.
 
Mondeos seem to do well without the main cat. The V6's have a precat for each bank so that does some of the work(usually enough to see it through an MOT without main cat)
 
Nozzer said:
Insurance is invalid as, technically, the car wouldn't pass an MOT without it and is hence unroadworthy, as I understand it.

However there is some discussion about whether, if a car that is supposed to have a cat can pass the MOT without it, and nobody notices its missing at test time, the car may be deemed roadworthy...

I don't have one in the Lotus, it makes it pop and bang more ;)
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Nope, not at all. Roadworthy and passing an MOT are 2 totally different things.
 
Muncher said:
Nope, not at all. Roadworthy and passing an MOT are 2 totally different things.
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So you're telling me that if I write my car off and it's found to be missing the catalytic convertor which was fitted when it passed its last MOT, my insurance will pay out?

I can't see it, myself.
 
Muncher said:
Of course they would. In any case it is not a material cause, but that's another issue entirely.
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Well said. If this wasn't the case you could have invalid insurance in an accident claim for something as minor as a number plate bulb being out.
 
pinkaardvark said:
Well said. If this wasn't the case you could have invalid insurance in an accident claim for something as minor as a number plate bulb being out.
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I'm not convinced.

I'm quite prepared to be proven wrong... Preferably without having to crash the car though.
 
I've informed my insurers of my decat (in an around about way).

The exhaust is non standard, and with no cat it's performance enhancing - so I disclosed it.
 
Hmm Officer told me you do not need a cat as long it passes the emisions they cannot make you need one.

sounds perfectly reasonable to me..but thats not how our government wok :p
 
All cars work better without a CAT, that's not even an debate. Just how much better is the issue and that all depends on the car

In my experience removing the cat and fitting a freeflowing exhaust to the Pulsar transformed the car from being asthmatic from 5500k rpm to allowing it to freely rev to the limiter at 8200rpm.

This freed up around 150bhp and 30lbs torque and thats a pretty standard return on Pulsar's

Of course it being a new exhaust system also helped, simply removing the cat on it's own would not have had that kind of benefit. I do believe some cars have a few CATs nowadays and not just the one which seems total overkill.
 
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