De Catted cars

[Andy Lynch]

I have seen quite a few advertisements for de catted TVR's.

Can anyone tell me how is it possible to remove the CAT and still get the car through an MOT? or is it not, and they have two exhaust systems,

What is the benefit in decatting a car?

Thanks

Andy

[RichB]

I expect most of the chat you have read is about Griffiths and Chimaeras with the RV8. This is because they have a main catalyst and 2 x pre-catalysts. Without going into details you can remove the pre-cats and still pass the test provided the engine is warmed up. I don't know if the S series TVRs had pre-cats, but I don't think so. I used to have an S3C so I should know more sorry. The catalysts are an obstruction in the exhaust system so removing them improves the flow along the pipe allowing for improved power.

[tvrgit]

If the car was built after 1993, and cats were fitted originally, it should have the cats fitted to pass the MOT.

You can remove the cats from pre-93 cars, as long as it still meets emission tests. I've had 10 MOTs with my decatted 1990 S3C, no problem.

[Andy Lynch]

Thanks for the info

Unfortunately mine is a 93 version and should have the cats, but I regularly see newer cars advertised as decatted, As I may soon need a new front exhaust section, I was interested to hear peoples views on if they are really needed to pass an MOT or not?

Thanks

Andy

[sarbec]

http://www.dft.gov.uk/vosa/repository/Special%20No...
New RfR where a catalytic converters are not fitted to vehicles subject to a full cat test.
RfR means reason for rejection if you go to the above link all the new items are on there

[Pop Pop]

My V8SC is a 94' and one of the last couple of dozen Chimera engine spec' cars. These had pre-cats and I have had mine removed.
Would recomend this as its all gain. Less underbonnet heat, better breathing and a much better sound. Some can be a bugger to get out.

[GreenV8S]

Andy Lynch said:

Thanks for the info

Unfortunately mine is a 93 version and should have the cats, but I regularly see newer cars advertised as decatted, As I may soon need a new front exhaust section, I was interested to hear peoples views on if they are really needed to pass an MOT or not?

Thanks

Andy

There is no absolute requirement to have cats fitted, but you need to pass an emissions test. If your car is registered from '93 onwards, the emissions test it needs to pass is so tight that it is all but impossible to pass without cats. (But if you manage it, you're legal without cats.) If it was registered in late 92, it only needs to pass a much easier pre-cat emissions test. Since the 'K' registration year spans 92/93, it is sometimes possible to accidentally confuse an early '93 car with a late '92 car. That would obviously work to your advantage.

[sarbec]

Be carefull as from Jan 2012 if the car was fitted from factory with a cat it needs to be on the car as a rule of thumb K REG onwards

[Andy Lynch]

Thanks for the info, Sarbec

I believe mine has the pre cats in the manifold sections as well as the main cat in the down pipe, from the info Sarbec supplied, does that mean removing the pre cats should cause the car to fail the MOT?

Thanks

Andy

[GreenV8S]

Andy Lynch said:

Thanks for the info, Sarbec

I believe mine has the pre cats in the manifold sections as well as the main cat in the down pipe, from the info Sarbec supplied, does that mean removing the pre cats should cause the car to fail the MOT?

Thanks

Andy

There is no requirement to keep the cats for any TVR. The rule Sarbec refers to would only apply to cars built this year, and sadly there aren't any TVRs in production now. So, there is no explicit requirement to keep the cats.

Early K reg cars only have to pass a pre-cat emissions test which can be passed by most healthy engines without needing cats. Late K reg cars have to pass a much more stringent test which you're unlikely to pass unless you have cats. If the precats are fitted and working, they would usually be enough for you to pass a cat emissions test. If the main cat is fitted and working, this would also be enough as long as it was good and hot - maybe not so easy to achieve since it's well down the exhaust pipe so not as hot as the precats.

[Andy Lynch]

Thanks Peter for clearing that up, I think that is exactly the info I was after.

I just need to source, and save up, for a new stainless exhaust now, probably with a full compliment of cats.

Thanks

Andy