Do I Need A Cat On A Gti6 Engine On Carbs?

[monkee87 2]

Just wondered if I'd need it still because of emissions? Had a debate with a friend of mine about it as bikes don't use CATs do they? Also, aren't CATs primarily for injection engines?

 

Let me know if I'm wrong!

Thinking of converting my gti6 to carbs and wondered if I'd need the CAT still basically.

Thanks.

[Anthony 1,003]

Induction system makes no odds - if both the car and engine were manufactured after the date when CAT's became mandatory, then you need a CAT. New car and old engine, or old car and new engine is fine, as it's done by the oldest of the two.

 

Bike emissions are done differently to cars.

[monkee87 2]

Induction system makes no odds - if both the car and engine were manufactured after the date when CAT's became mandatory, then you need a CAT. New car and old engine, or old car and new engine is fine, as it's done by the oldest of the two.

 

Bike emissions are done differently to cars.

 

So what if I put an MI16 in my car? Precat engine in a CAT car it would essentially be. Got a 1993 GTi which is a cat model.

[marksorrento205 80]

You need a cat or a friendly mot man

[James_m 0]

Would carbs not kill the cat though? Thought they require 14.7:1 AFR as much as possible to work, would have thought that would be pretty difficult with carbs...

[Ryan 99]

So what if I put an MI16 in my car? Precat engine in a CAT car it would essentially be. Got a 1993 GTi which is a cat model.

 

You don't need a cat. If either the car or the engine is built before the cut-off date then you don't need one. It's up to you to prove the age of the engine at MOT time though.

[Anthony 1,003]

So what if I put an MI16 in my car? Precat engine in a CAT car it would essentially be. Got a 1993 GTi which is a cat model.

In that situation, you would not need a CAT - although the onus would be on you to prove the age of the engine to the MOT tester.

[SurGie 54]

You could get your self a sport cat if you do need to have one for the car, it will help the TB's get more power.

[Baz 421]

You could get your self a sport cat if you do need to have one for the car, it will help the TB's get more power.

 

WTF?

 

For starters, what TB's, the OP talks about Carbs. Secondly, how does any Cat, labeled 'sport' or not, help at all!

Edited August 17, 2010 by Baz

[marksorrento205 80]

In that situation, you would not need a CAT - although the onus would be on you to prove the age of the engine to the MOT tester.

 

Well bugger me You learn something new everyday. I thought it was dependant on the year of car. Hence you can put a gti6 lump (lets say) in a pre cat shell and not need a cat?

[Anthony 1,003]

Well bugger me You learn something new everyday. I thought it was dependant on the year of car. Hence you can put a gti6 lump (lets say) in a pre cat shell and not need a cat?

It's done on the oldest out of the car and the engine - although for most people, that's an older car with a newer engine, rather than the other way around.

 

(for late registered 205's with CAT's, it's worth double-checking the manufactured date, as many of them don't actually need to pass a CAT test despite being registered after the cut-off date - again, most people aren't aware that it's based on manufactured rather than registered date, hence for example 309 Goodwood's on K and L plates without CATs)

[marksorrento205 80]

Nice one As you said before its getting an mot tester to agree. Just because mines on a K plate most think it needs a cat

[Alastairh 47]

I had that problem with my old 309. He was told to go look up his paper work. 10 minutes later, I had a green slip!

[Baz 421]

If it's a pre Aug '92 built car then it should come up as not needing a CAT-test in that situation anyway though - being all computerised these days, makes for lazy MOT-testers that get 'informed' of which way to do the test!

 

But, it is in the notes that tester's use/can all look up easily on their computer systems linked to VOSA, that it goes off whichever is older, so if the tester won't take much persuasion, that's all they need to check if unsure. I checked it again a while ago and looked at it with my tester. A couple of notable parts;

 

One important issue must be cleared up straight away. There is no requirement for a catalytic converter to be fitted to any vehicle, regardless of its age. It is however the most popular way of ensuring engines meet the emission legislation. The MOT test is testing the emissions from the tailpipe and if those emissions meet the standard then the vehicle passes. The term 'cat' test is inappropriate, the correct term is 'advanced emission test'. Its not the 'cat' that's being tested. There are a number of vehicles which are subject to the 'advanced emission test' but are capable of meeting the requirements without the use of a catalytic converter.

 

Modified engines must still meet the requirements.

 

An older engine fitted to a vehicle will be tested to the age of the engine (evidence needed). A newer engine fitted to an older car will be tested to the age of the car i.e whichever is the oldest.

[monkee87 2]

My car is an L reg. Like the last of the GTis. IIRC it's august 93.

 

So hypothetically, if I had a GTi6 on carbs, I'd need a catalytic converter on the car to pass emissions as it's a newer engine than the car and had a CAT to start off with.

And if I had an Mi16 from say a 1990 car on carbs, I don't need the CAT?

That's actually quite intriguing.

 

But my question was, can the CAT cope with like say twin webber carbs? Does anyone run a 306 with a CAT that's on carbs?

 

Thanks.

[SurGie 54]

HERE .

 

Here also..

 

The chance of you needing to have one seems quite high, so a sport CAT will help release more power from those carbs.

Edited August 17, 2010 by SurGie

[Alastairh 47]

Just bolt a cat on for the day rather than any poxy expensive 'sport' cats!

 

Al

[Daviewonder 533 3 Cars]

I'm sure that if the engine has a code that isn't listed as being fitted to that car being tested then it just needs to pass a basic emissions test.

[welshpug 1,676]

I'm sure that if the engine has a code that isn't listed as being fitted to that car being tested then it just needs to pass a basic emissions test.

 

 

Intriguing, my engine never made it into a ZX in a RHD shell, so wont be on the UK emissions listings...

[SurGie 54]

Just bolt a cat on for the day rather than any poxy expensive 'sport' cats!

 

Al

 

 

I was going to suggest that but im not keen on giving illegal advice on the forum that could get him a fine or similar.

 

I have known of cars that have no cat and passed perfectly.

Edited August 17, 2010 by SurGie

[monkee87 2]

I don't want to have to go through the hassle of having to swap an exhaust just for an MOT. I'd much rather my car be legal all year round. Might have a chat with the guy who MOTs my car, see what he says!

 

It's all been very helpful and quite insightful too! Could just dump an Mi in and be done with the CAT all together!

 

Thanks guys!

[Baz 421]

Carbs and a Cat are never going to go hand in hand. Over-fuelling engines kill the internals of Cats in no time! And Carbs are well known to be a little on the rich side!

 

There is a possibility you won't need a Cat to pass a cat-test, or that you'll even need to do much 'proving' that your engine 'could be' from an older car, or at worst you have to twaek the carbs at idle to pass the Emissions test, no big deal!

[Masekwm 2]

Had a debate with a friend of mine about it as bikes don't use CATs do they?

 

Bikes aren't tested for emissions, the bike mot is the silliest thing I've ever seen. 2 wheels, check, brakes work, check, lights, yup. MOT for you!

[CaptainK 11]

I've got a GTi6 on ITBs and have decided to have a sports cat on it purely to keep it 100% Police happy.

 

However, I believe cars don't NEED to have a CAT on them, even newer ones. Now you're looking at me as though I'm insane...... I believe the rules are that your car must be able to pass the required emissions test for its year and model - e.g. a precat test for pre-1993 or a CAT test for after 1993. BUT, if your post-93 car can pass the test without a CAT then thats acceptable too. The problem is though that passing a CAT test without a CAT is a very hard thing to do.

 

On a different note, mine is a 1993 GTi as well and even though its a CAT model the CO2 limit for it is the same as the non-cat models - i.e. 3.5%. Its all on my MOT sheets. So I shouldn't worry about yours being a CAT model too much.