" Y " me ????

[old64er]

My Y piece has split on the nearside upper seam,

can anyone tell me if this has a cat in it or where the cat is located on the exhaust.
My idea is to weld it up but if it has a cat i will remove it.(friendly MOT centre !!)
Or is any one selling a good Y piece for a 5 litre griff?

[Ballistic Banana]

Yep, it has a Cat and two pre-cats.

BB

[old64er]

ballistic,

are these in the y piece only ?

The reading from the lambda sensor will be incorrect if there is one before that, so do you know if one of them is?

cheers m8

[derekg500]

The main cat is located in the widest part of the Y ,
this has to remain I'm afraid, to pass the M.O.T.
The 2 precats are located further up the exhaust in the manifolds. These can be removed and still pass an emmisions test providing that the engine is hot.
Good luck with the weld.

[RAW-SEWedge]

There is a main cat in the Y and pre-cats nxt to the collectors.



and no I didn't just cut mine open to show you. This is wixer's and his has just past MOT ok with out them.

[Ballistic Banana]

You can take the pre-cats out and still pass the MOT legally i have been told, take the main cat out and it will probably fail(could be wrong) and the ECU will have to re programmed.
Also with taking the pe-cats out they should be re-placed with cones to help with back pressure.

BB

[HarryW]

RAW thats a pic of a pre-cat from one of the headers. These can be taken out and a reversal cone fitted in its place and it should not fail the MOT as they help keep the emmisssions down during warm up. The MOT should be done on a fully warmed engine when the main cat will do enough for it to pass.
The Y piece houses the main cat after the two banks blend together in the large dustbin like section . You can also have this removed as well but you will fail the MOT.

Harry

[old64er]

got the y piece off tonight and the precats are looser than a strumpet and tattling around in both headers, what does the reverse cone do ?

i can just about lift the precats out of the headers without splitting them, so if i can do this will it just destroy the main cat? (i.e no reversal cone)

cheers everyone for a quick response

[HarryW]

Check with someone more experienced, but AFAIK the anti-reversal cones are put in to do exactly what it says on the tin, stop reverse pulses messing up the next cylinder cycle between left and right banks.

Harry

[RAW-SEWedge]

old64er said:

i can just about lift the precats out of the headers without splitting them, so if i can do this will it just destroy the main cat?

Should be safe to remove :

Check here

wixer has done it and I'm not aware of any problems.

Pre-Cat removal OK for MOT

[RAW-SEWedge]

HarryW said:

RAW thats a pic of a pre-cat from one of the headers.

I know

[HarryW]

RAW-SEWedge said:

HarryW said: RAW thats a pic of a pre-cat from one of the headers. I know

Glad we cleared that up then

H

[RAW-SEWedge]

Hey, it may be early in the morning but I know my exhaust Or should I say I know wixer’s exhaust – I’ll get my coat


>> Edited by RAW-SEWedge on Thursday 8th July 01:08

[Marlon]

HarryW said:

Check with someone more experienced, but AFAIK the anti-reversal cones are put in to do exactly what it says on the tin, stop reverse pulses messing up the next cylinder cycle between left and right banks. Harry

Hmmm. My pre-cats have been removed, but the garage didn't fit anti-reversal cones. Is that "dangerous"?

Cheers.

[wixer]

Marlon said:

HarryW said: Check with someone more experienced, but AFAIK the anti-reversal cones are put in to do exactly what it says on the tin, stop reverse pulses messing up the next cylinder cycle between left and right banks. Harry Hmmm. My pre-cats have been removed, but the garage didn't fit anti-reversal cones. Is that "dangerous"? Cheers.

I didn't fit them to mine either and haven't suffered any detremental side effects. I can't see the point of de-restricting them by removing the pre-cats and then welding in something else that resticts the exhaust gas flow again.

[old64er]

just removed the precats and welded the y piece up on the broken seam, just going to fit it back now (i live laying on the garage floor!!!)

does it sound any better with the pre cats out ??? or louder ??

[old64er]

all back together again!!, not a nice job on the floor, but cant hear any difference yet.

i will take it for a run tommorrow to see if it sounds any better but at least the y piece is sealed.

thanks everyone

[IPAddis]

Precat removal definately doesn't affect MOT (at least it hasn't in the last 3 years where my car got a 0.01% CO reading)

Anti-reversion cones are worth 5-10 bhp apparently. They don't restrict the flow although ideally, you would fit longer primaries on the manifolds (expensive).

You could get a spare non-cat y-piece and keep the original for the MOT. Mark Adams Tornado chip can store multiple maps for cat and non-cat tunes, selectable by the user replacing the resistor in the wiring loom. Of course this would be technically illegal and you risk running foul of roadside checks.

Ian A.

[HarryW]

Ummmmm.............whilst on a RR yesterday had the honour of seeing Tim Lamonts (ACT) prototype 'new' exhaust system put through its paces. Redesigned manifolds with log primaries, new blended Y piece with cat bypass sections in, so you can bolt in or unbolt sports cats for track days . Sounded very nice too . I beleive he's gonna get the the thing jig'd by JP and offer it up to the buying public very soon. All I can say is I saw excess of 10bhp and 25lb improvement . Apparently its been design to fit both Griffs and Chims. So if you are waiting to change the exhaust for what ever reason I suggest you wait to see what Tim wants for his 'improved' version.

Harry

[HarryW]

Forgot to add it looks the dogs danglies as well

Harry