The Cat

[marlinturbo]

Hi builders,

This one concerns me. I havn't discussed this with Mark at Marlin yet....but does the Module III include a position for the Cat within the exhaust system.

I believe to pass the MOT with the identity of the donor you will need the Cat!

IMO, the best solution SHOULD be that the donor cat should fit on flanges provided on the exhaust system supplied...that way you can fit a standard rover de-cat pipe straight after it's registered...is this the case?

If not, what is the solution???

John
MarlinTurbo

[tomboysexi]

John,

The pipe is in 2 parts yo allow a cat, Marlin supply the straight through pipe but not the flanges to put the cat in.

There is a census of opinion that the cat only needs to be fitted if the donor is K reg (92) or newer.

I intend pleading pleading the insanity claus, but people tell me there is no such person as (Sanity Claus)

You will have noticed my current set up from the last set of photos.

Regards Trev

[marlinturbo]

Trev,

is the exhaust stainless or mild steel?
it looks like there is a removable "straight" section...

that means i'll have to source another cat to get thru the MOT...grrrr...

or weld in flanges to take my donor cat...luckily I have drawings for these flanges, but it is yet another "extra"...

sanity claus...what r u like mate! :-)

John
MarlinTurbo

[tomboysexi]

John,

It's a stainless exaust, but how about this, I think if you cut the flanges off the cat and use a little gentle persuation on whats left, you may find that it slips in as a replacement for the straight length.

Check the bore sizes first though.

See even more dosh saved by good ol

Trev
(and Craig the photographer / plumber / mechanic)

[Ex-Biker]

I think you might find the bore of the new exhaust is larger than the donor and the donor cat is a little too long. If a turbo donor cat fits pleaselet me know.

Would be nice if Marlin (or the club?) had a cat you could 'borrow' for the SVA and future MOT's so that everyone could use it. Then just swap back the straight connecting pipe!

One question.
If the donor has a cat, and therefore a Lambda sensor, how does not having a cat in the system effect the ECU?

[marlinturbo]

The O2 (lambda) sensor is situated pre-cat...so AFAIK the ECU doesn't know about the cat...certainly on earlier cars.

has anyone fitted an aftermarket cat to their exhaust system yet? if so, make and model please?

thanks,

john
marlinturbo

[marlinturbo]

Trev,

I'll investigate you're suggestion of "modifying" the rover cat to see if it could fit...late march I reckon...

Thanks mate.

john
marlinturbo

[holgate86]

I have been trying to find out the exact rules about catalyst requirement and it's a little vague. I know that most production cars from k reg onwards require a cat test but only if they are listed in the database. If you can't find the vehicle in the database you revert to non cat test.
If you have a kit car pre sva you certainly will not require a cat test, but there are another set of rules post sva and an mot tester will require the mac certificate which will have the necessary limits. I have seen conflicting information regarding requirement for cat test, some say 1992 and others have said 1995. I your donor is pre 92 no cat required (engine numbers and proof of age required). If it is pre 95 it may not require cat but i'm not sure of that, i'm just hoping thats the case.

The 02 sensor is a closed loop sensor and does not require cat for correct operation more the other way round. If you remove cat you still require 02 sensor in system or you will have excessively rich mixture.

A universal cat is available in the aftermarket and I think marlin supply the correct one for the job.

Brian :eusa_angel: