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[capoMV6]

Hi. What are the effects of removing the CATS on a 3.0 v6 MV6? Mine is a gonner and replacing it is a bit pricey. Am thinking of replacing them with straight thru pipes. No issues about MOT since we dont have this here in the Philippines. Also what does it mean "blanking the EGR". What are the effects?Appreciate the comments. Thanks.

[sjc]

Removing the cats is likely to reduce engine performance unless you alter the fuelling - i.e. replace the "chip" in the ECU with a performance one or have it custom mapped.  Reason is that you will be significantly reducing the back-pressure in the exhaust and the standard chip is designed to work with the back-pressure that would normally be present.

At least, that's what would happen on a 3L straight six Carlton so I would expect the same to happen on pretty much any cat equipped car.

Blanking the EGR is simply a case of making a gasket from an old drinks can that blanks off the passageways in the original gasket.  The valve can't be removed or disconnected because it will throw up a fault code so "blanking" it off is the easiest way to stop it letting crud into the breather system.

[Andy H]

Removing the cats is likely to reduce engine performance unless you alter the fuelling - i.e. replace the "chip" in the ECU with a performance one or have it custom mapped.  Reason is that you will be significantly reducing the back-pressure in the exhaust and the standard chip is designed to work with the back-pressure that would normally be present.

At least, that's what would happen on a 3L straight six Carlton so I would expect the same to happen on pretty much any cat equipped car.

Blanking the EGR is simply a case of making a gasket from an old drinks can that blanks off the passageways in the original gasket.  The valve can't be removed or disconnected because it will throw up a fault code so "blanking" it off is the easiest way to stop it letting crud into the breather system.

Two stroke engines (and some highly tuned 4 stroke engines with lots of valve overlap) require back pressure to stop the fuel/air mix from disappearing down the exhaust port. The Omega engine is neither. Reducing back pressure will improve exhaust flow and allow more air to be sucked in to the engine. The ECU calculates the fuel required by measuring the air being sucked in through the mass flow meter so more air flow will increase power. The fuel map in the ECU can cope with quite a lot more air flow than standard IIRC so no need to remap it to cope with a small increase due to de-catting

[sjc]

Removing the cats is likely to reduce engine performance unless you alter the fuelling - i.e. replace the "chip" in the ECU with a performance one or have it custom mapped.  Reason is that you will be significantly reducing the back-pressure in the exhaust and the standard chip is designed to work with the back-pressure that would normally be present.

At least, that's what would happen on a 3L straight six Carlton so I would expect the same to happen on pretty much any cat equipped car.

Blanking the EGR is simply a case of making a gasket from an old drinks can that blanks off the passageways in the original gasket.  The valve can't be removed or disconnected because it will throw up a fault code so "blanking" it off is the easiest way to stop it letting crud into the breather system.

Two stroke engines (and some highly tuned 4 stroke engines with lots of valve overlap) require back pressure to stop the fuel/air mix from disappearing down the exhaust port. The Omega engine is neither. Reducing back pressure will improve exhaust flow and allow more air to be sucked in to the engine. The ECU calculates the fuel required by measuring the air being sucked in through the mass flow meter so more air flow will increase power. The fuel map in the ECU can cope with quite a lot more air flow than standard IIRC so no need to remap it to cope with a small increase due to de-catting

Ok, that's good to know - as I said, 3L straight six Carltons would suffer on a standard chip if de-catted but then they used an air flow meter rather than a MAF so maybe it was that or the WOT fuel maps in the standard chip.

Another thought though... does the 3L V6 ECU test for cat function like the 2.6 and 3.2 do?  I'm guessing not since they only have one O2 sensor in each exhaust.

[bellers]

i was thinking of decating my mv6 aswell. anyone in the uk done it? will it pass mot emissions?

[aaronjb]

i was thinking of decating my mv6 aswell. anyone in the uk done it? will it pass mot emissions?

Not a cat in hells chance..

[bellers]

i was thinking of decating my mv6 aswell. anyone in the uk done it? will it pass mot emissions?

Not a cat in hells chance..

short but sweet 

[aaronjb]

  I'm nothing if not to the point..