Catalytic converter required or not?

If your car was registered after 1st August 1992 you must have the Cat present and working for the MoT. Previously registered cars can have the Cat permanently removed

I think the cat requirement relates to the car rather than the engine, so if it didn't need one before the swap, it still won't need one.

Kit-car builders often use this loophole. They build the car with an old engine to get it SVAd and registered with no requirement for a cat, then immediately swap the engine to a more up-to-date one.

Cheers,

Colin.

Wrong, wrong, wrong, wrong and (wait for it) wrong.

Any car can have the car removed, no matter when it was built or registered. There is no onus on you to physically have a catalytic convertor on your car, the only thing that matters is that you pass the emissions test.

There is a requirement for manufacturers to build their cars with catalytic convertors on them to gain type approval. But once they are out of the factory, the customer can do what they want with them.

Test according to which is older, engine or vehicle. e.g. A 1995 car fitted with a 1991 engine (of whatever make), test to 1991 standards for emission purposes.

Note: The onus is on the vehicle presenter to prove engine age.

Incorrect.

The MOT does *not* require a Cat to be present on your car.

However, your chances of passing the emissions test with no Cat are slim-to-none (although it can be done !).

You never need a Cat - but the chances of passing the post-92 emissions-test without one, are minimal.

I'm pretty sure a 1991 car only needs testing to 1991 standards, no matter what engine is installed.

BUT - you have a full get-out clause anyway. The MOT tester can only apply the more-stringent post-92 test if he has an *exact* match for your make/model/year in his book. Now obviously he's not gonna have a match for your '91-car-with-'01-engine, so you'll get a pre-92 test.