Elementary question

[Chinski]

Forgive me asking such a simple question but I'm really confused (not difficult) could someone explain pre cat and de cat etc. I'm also not sure of any benefits either way.

[Doc Toad]

Chinski said:

Forgive me asking such a simple question but I'm really confused (not difficult) could someone explain pre cat and de cat etc. I'm also not sure of any benefits either way.

Precats were vehicles produced prior to the legislation changes that forced manufacturers to fit catalytic convertors. I think anything TVR produced after K reg (1992/93?) will have a cat fitted, although most major manufacturers began offering tham as options before this.

Decatted cars were originally fitted with cats that have subsequently been removed in the quest for more noise/performance (although more noise definitely does not always equal more performance IMHO)

As I understand it, if your vehicle was fitted with a catalytic convertor when first registered, then you may have problems at MoT time if its been decatted. That said, so long as the vehicle passes the appropriate emissions test then many garages seem to pass them.


All sorts of variations - loads of opinions on pros and cons of decatting as you wil shortly find out...

[Doc Toad]

...remember reading somewhere that TVR had a number of chassis stockpiled so that they could carry on selling cars without cats a bit longer so maybe some L reg ones around?

I assume they changed the Certificate of Conformity at some stage and thats when cat versions started rolling off the production line?

Edited by Doc Toad on Saturday 16th March 22:19

[RochdaleGT]

also we should keep in mind that those models have pre-cats and main cats.

so most owners remove the pre-cats, located in front of the engine, which interestingwise has not a real negative effect on the emissions.

[blitzracing]

The pre-cat are only there to heat up quickly before the main cat and reduce cold start emmisions- hence the no big difference when it comes to MOT time.