Yes....sorry, another cat question.

 

So, I'll be putting an exhaust on my car soon, and I know the MOT rules changed recently (Jan I think).

 

My engine (NA), is from a 92 car, in a 90 shell. Both are imports.

 

I read somewhere, that even if you don't need a cat, one has to be present at the mot!?

 

I found this -

 

Car that needs cats -

- 1992 for normal UK cars;

- 1992 for imported cars that were officially available in the UK; and

- 1995 for imported cars that were never officially available in the UK

 

However, I also found a flow chart that stated that if the car wasn't on the database (and I believe import Zeds arent?) then they are tested as 'no cat' by default.

 

I just don't want to put a non cat system on, to have to remove it again, to cat it.

 

Any help would be appreciated.

Technically your car, its shell is a 1990, the fact the engine is from a later car is neither here nor there. The cat is part of the exhaust not the engine. I cant see why it would cause you any issues what so ever.

Could have sworn it was after 93 that they had cats. But the zed just has to pass a basic emissions test. You'll be fine with a decat system.

Doesnt make a difference with an import as its not on the mot database and has to be tested as a pre cat, so carry on :thumbup1:

what about a uk car ?

A UK car is on the MOT check list ive seen on the garage wall, not sure if its on the database, but pre cat test will be done on a 92

mine is 1990 so can I run remove all cats

Yes mate you can :thumbup1:

Tip them thoroughly enjoy the replacement of your turbos lol.

the turbos are getting changed end of the year any how so if thay start smoking it not a prob

That's fine then mate. They do tend to have a tendency to leak, they are old and very basic turbos.

I can live with a bit of smoke if it happends till I get new turbos

Ime on my 5th zed and every single one i decatted with a bar of boost...never had one of them go tits up with smoking tubs and when i get the chance i drive em hard. Ironicly on 4 out the 5 i modified the PCV system which i firmly believe is the cause of at least 75% of smoke issues:)

You takes your chances. Mine failed almost instantly after decatting :( theoretically it shouldn't make any difference common issue though.

If your tubs were weak in the first place then decatting will only advance death quicker lol

Exactly that, the cat merely masks the symptom.

Cheers all, decat it is then! :)

Are you going to use the non turbo ones which means you don't have to change the pesky elbow section, or the full on divorced downpipes tt ones?

Ime on my 5th zed and every single one i decatted with a bar of boost...never had one of them go tits up with smoking tubs and when i get the chance i drive em hard. Ironicly on 4 out the 5 i modified the PCV system which i firmly believe is the cause of at least 75% of smoke issues:)

 

Totally agree with this!-backpressure has no effect on turbo seals whatsoever.

The problem with the seals is when fed too much oil and it can't drain quick enough,flooding the seal.

PCV system to blame 90% of the time IMHO...........

Sort of the full story sort of not.

Theoretically the rear oil seal is like a splash guard, it's not a seal as such. The turbo should be able to run without the "seal" and still not smoke. Where things get complicated is pressure. With neutral pressure inside and out the turbo oil will not leak. Sadly this doesn't occur. Over pressurisation causes a higher pressure in the turbo core than in the exhaust, the oil backs up and weaps out. This can be caused by multiple conditions, excessive blow by, inefficient scavenging of the engine oil galleries or blockages in the oil return line from the turbo.

Equally negative pressure can occur can occur in the exhaust due to design. This causes the oil to be sucked out the core.

 

The presence of the cat causes an increased pressure in the exhaust system, this effectively masks the worn seal, or other symptom be it Pcv or inefficient combustion that is raising crank case pressure. Obviously it helps to not create a vacuum situation as well.

 

The type of turbos fitted to out cars as stock have a very basic real seal, this changed in later incarnations if the t2 core. Also the jounaral bearing design uses far more oil to lubricate and effectively float the shaft. More oil in the core requiring to escape creates more issues. This is why modern BB based turbos are less prone to smoking. The thought that deleting the Pcv helps, is only half the story. A fully functional Pcv system actually lowers crank case pressure below 0 creating a negative pressure environment thereby helping contain the oil.

 

I have some reference to explain all this better and from one of Australia's leading turbo shops. Il try to dig it up for you guys tomorrow :)

Well worth a read.....

 

http://www.procharge.com.au/turbotorque/6-blog/blog/117-the-turbo-blues/

I'm in the market for a new tester for my mots, it's a 93 jdm, I guess I better ask around and find a tester that is sure it doesn't require a cat test?

mine is being de-catted any day , my mot tester sometimes classes it as a k reg primera , don't think he even used the exhaust probe thing last time

My previous tester mot'd it for the last 7 years and has never probed it. He's not a million miles away but is prefer to go to one of the many garages that are very close to me.

When I told my local tester that the car is an import and not on the data base he checked on the machine and after following some on screen instruction's agreed with me that a cat test was not needed, he also would not put it on the brake test machine because of the LSD.

I didn't know about the the brake test thing until a few days ago :no: