406oc.co.uk

hi
can anyone help please,im going to start rebuilding my 2.0i turbo 406 soon but i know it needs a new cat does anyone know if i can do away with it and put a cat replacement pipe on ? its on a R.reg,

2 options:- 1. Either gut the cat (remove it and drill out internals then refit) or 2. replace it with a 100 cell sports cat. You will need the appearence of a cat or a sports cat for 2012's mot purposes.

Will it not be impossible to pass the emissions test without a functioning cat on any post 1992 petrol engined car?

If it's a petrol-engined car it is very unlikely to pass the MOT without a CAT being fitted.

Sports cat would be good here, shouldn't be difficult to fit - I don't think D8s had any pre-cat/post-cat sensors. When I was in getting the Powerflow exhaust fitted to my Coupe I asked the guy about sports cats; he said for a naturally-aspirated car there's not a whole lot of point, but they'd be most concerned about the sensor(s) that is/are present around the factory-fitted cat.

With a D8 turbo petrol, not only would it be easy for an exhaust place to fit one, you might notice it being an improvement as a sports cat will be freer-flowing.

That said, I reckon you'd be best getting an original cat for this car; take one from a scrappy. It's an R-reg petrol-engined French saloon car with a lazy 8-valve engine with a low-pressure turbo fitted to it; a new cat (OEM or after-market sports cat) will cost you just as much as (if not more than) the car is actually worth.

If you do want to go ahead with a major (expensive) overhaul of your car, then I would recommend replacing the entire exhaust system from manifold to exhaust tip with a custom-designed Powerflow system. It will cost you a fair chunk of money (my cat-back system was £360 all-inclusive) but it will allow that engine to ditch its exhaust gas much more quickly, and it will never rust.

What make of exhaust was that again?

I think that's the bottom line, any car manufactured after August 1992 (which is all 406s) will need some form of cat. The diesels should hopefully get past with a hollow tube but I really don't think it'll wash on a petrol.

Powerflow!*

The reason diesels get away without a cat is down to the way the emissions test for diesels is performed in the UK (or possibly more accurately, the way that it isn't).

Petrol-engined cars have to pass a fairly stringent test, whereas the diesels basically don't have to worry about it (and some get away with murder, really, the amount of crap I see coming out of some diesel-powered cars). It won't be long before that changes, I reckon.




* other exhaust brands are available

I tried the downpipe / cat on project xsara 8VT and realised I had to cut it up to get it to fit, in the end I just cut the flange off and made my own decat pipe. Though I will have to fork out a couple of hundred for a sports cat come MOT time next July. At the moment the exhaust is a mix match of all sorts while I get it running.
I'll make a proper system up when I have more time.

thanks for all the comments, ive found a new after market cat on ebay for £93.00 (item number 180549763420) so i think i will just go for this as the rest of the system is brand new and standard.

A cheaper option than a 'sports cat' would be an ordinary one, from a bigger-engined car. [/2p worth]

It is possible that some cars can pass an mot with a gutted cat.

406loon wrote:It is possible that some cars can pass an mot with a gutted cat.

I did wonder about that, as my old 24V Carlton almost met the emissions limits for a post '92 car after removing the cat. (It was a '91 so didn't have to comply).

I wonder though if you fit a bigger CAT from a bigger car then it would take too long (or won't) heat up properly and still fail the MOT? [/2.4p inc vat]

Welly wrote:I wonder though if you fit a bigger CAT from a bigger car then it would take too long (or won't) heat up properly and still fail the MOT? [/2.4p inc vat]

The 406's V6 engine won't even pass its MOT using the standard cat unless the car's been idling for aaaaages. Damn things fail on it first time every bloody year