hi again all i am thinking of de catting my 1990 n/a as the exhaust is rotting and will need replacement i have been told that cars registered before 1992 does not need cats for the M.O.T. anybody have any idea on the legality of this ie if the car was built with cats do they have to remain on the car? thanks

the 300 isn't listed on the dvla's database so they don't need cats

No probs decatting an N/A either, you may see slight gains in BHP but no downsides to it really.

No probs decatting an N/A either, you may see slight gains in BHP but no downsides to it really.

 

Just get some ear plugs :D

"Just get some ear plugs"

 

As above, it will be a bit boomy at 2k revs inside the car, you are better off getting some decat pipes with small silencers on, as the cats act as a form of silencer.

:hyper: just had mine de-cated. what a diffrence. a lot more sound and can feel a bit of extra bhp too. glad i done it. :hyper:

the 300 isn't listed on the dvla's database so they don't need cats

 

is that all the 300's or just the pre 92 cars?

is that all the 300's or just the pre 92 cars?

 

It's only the Jap imports that are not explicitly listed and therefore have a non-Cat test for the MoT. It is of course illegal to remove the cats from any car that was built with them - but nobody cares about that !

I have a 96 Jap import and was thinking about going de-cated but after a search on these forums there was some talk of 96 plus models having to pass a basic emissions test that kinda required cats. Anyone have any experience about this?

 

Dave

decat pipes are a little more than i expected!

 

lets not forget that on the Z there are not only the 2 catalyc coverters,

 

but ALSO 2 pre-cats, coming from the turbo downpipe.

 

dont know how hard the pre cats are to get at/remove tho ?

decat pipes are a little more than i expected!

 

lets not forget that on the Z there are not only the 2 catalyc coverters,

 

but ALSO 2 pre-cats, coming from the turbo downpipe.

 

dont know how hard the pre cats are to get at/remove tho ?

 

Nothing is cheap with these things! Youve got a TT havnt you? Be warned about the decat!

Also worth remembering that if you have your car de-catted, watch what they do with the cats, most of them contain 3oz+ of platinum. Which at £1000 for 25 oz Platinum is not cheap. (£70ish for EACH cat minus recovery cost) and don't forget rhodium and palladium... Why do you think there's so many "recycling" companies springing up for mobiles/computers & cars...? :shock:

 

Noticed any scrapyard owners driving round in bad cars recently....??? try to keep the cat and if the garage is reticent ask them how much they get for it...!!!:cool:

decat pipes are a little more than i expected!

 

lets not forget that on the Z there are not only the 2 catalyc coverters,

 

but ALSO 2 pre-cats, coming from the turbo downpipe.

 

dont know how hard the pre cats are to get at/remove tho ?

 

 

I know znut removed his own cats with a bit of brut force and used the standard piopes that were left hollow. I think you can also poor engine oil into them to soften them up first iirc

decat pipes are a little more than i expected!

 

lets not forget that on the Z there are not only the 2 catalyc coverters,

 

but ALSO 2 pre-cats, coming from the turbo downpipe.

 

dont know how hard the pre cats are to get at/remove tho ?

 

Only Uk cars have pecats, and just the one. Jap Imports do not have precats.

 

The Decat pipes usually include the elbows and downpipes that replace precat and cats. Price is about £130 for the Megan items.

I have a 96 Jap import and was thinking about going de-cated but after a search on these forums there was some talk of 96 plus models having to pass a basic emissions test that kinda required cats. Anyone have any experience about this?

 

Dave

 

Yes, all cars from 1995 onwards are required to be tested as Catalytic equipped vehicles wether the Data is in the Database or not. You would have to swap them back for MOT.

I know znut removed his own cats with a bit of brut force and used the standard piopes that were left hollow. I think you can also poor engine oil into them to soften them up first iirc

 

Yep, thats works, I did that with my first TT. It made a noticable difference to turbo spoolup time.

 

Although its not as efficient as using replacment decat pipes and the divorced wastegate elbows that they come with.

Only Uk cars have pecats, and just the one. Jap Imports do not have precats.

 

The Decat pipes usually include the elbows and downpipes that replace precat and cats. Price is about £130 for the Megan items.

 

really! great, ive got a Import TT, so no pre-cats.

 

i would imagine they are difficult to undo from the turbo, as boolts seize etc.

 

thaught the de-cat would just replace the cat, not the downpipe etc.

 

Be warned about the decat!

 

what you mean? about the backpressure isit?

what you mean? about the backpressure isit?

 

Nah, these babies are very common to blow the turbo seals after decatting.

 

search on the forums and you will see it has happend A LOT before!

 

what you mean? about the backpressure isit?

 

Yep, just make sure you have the readies available to pull the engine out and rebuild or replace both turbos incase it ruins one. If youve got the cash and are happy to spend it then yeah go for it...

But if you havnt and you de-cat it your going to be left with a broken zed, and no one wants that!

Nah, these babies are very common to blow the turbo seals after decatting.

 

search on the forums and you will see it has happend A LOT before!

 

Just to clear that up, the reason for the turbo seals failing is the lack of back pressure...

As i understood it if the seal starts leaking you can put the old pipes back on and it stops agian?

As i understood it if the seal starts leaking you can put the old pipes back on and it stops agian?

 

I doubt it, i think once it starts big time there is no stopping it.

 

I get the impression the seal ends up dislodged allow oil to seep past.

 

Im looking at past experience and observations, Decat cars seem to need new turbos around the 60k mark, yet i know of cars with the cats in place that are coming up on the 105k or so mark.

 

Just making people aware of the consequences, especially if you've not got the money to rebuild it if it fails.

hmm...

 

thanks guys, a little put off now tho!

 

i removed the exhaust on my S13, replaced with a decat & a blitz nur spec.

 

as soon as i started it, it poured out with smoke! changed the turbo then it was ok (well its smoked on boost)

 

then again, i did it on my first car, and had no problems at all.

 

all depends on the condition of the turbo i guess?

PS another thing,

 

on the S13, you can put a ONE WAY VALVE on the air intake/breather system,

 

this does something with the pressure, in the sense that you dont smoke on idle.

 

not sure how would work on a Z, as iv only just got one.

hmm...

 

thanks guys, a little put off now tho!

 

i removed the exhaust on my S13, replaced with a decat & a blitz nur spec.

 

as soon as i started it, it poured out with smoke! changed the turbo then it was ok (well its smoked on boost)

 

then again, i did it on my first car, and had no problems at all.

 

all depends on the condition of the turbo i guess?

 

Precisly, there are cars on here with a decat on standard turbos and no problems. Steve 300zx especially, but that is a 1996 car, so some 5 years newer than most cars which of course helps.

 

Also, with the imports who knows what milage they have really done? I mean i find it funny how most imports always seem to have about 60k on them.... somewhere around Dubai i'm convinced alot of milage is "bled" from them shall we say hehe.

 

What makes the 300zx risky is that everything comes in pairs, (and its hard to work on) but say an S13, you can get a good turbo for one of those for £400 ish easy, well its double that for the zed and you cant really get to them very well without popping the motor out.

 

I would do some searches through the forum and look at everyone elses experiences, most of the time the decat accelerates the demise of the turbos.

shit isnt it :(