Decatted ??

[monaco]

I would be interested in hearing anyones views on decatting, Is this a common mod and how many people out there have done this ? I assume that you have to refit them for your m.o.t. and doesn't it void your insurance. Are the performance increases and better sound worth the trouble ?? I have a 94 4.0HC Chim any suggestions on mod's ?

[shak]

I've asked this question before though it was a while ago.The responses were generally negative. It's illegal,a pain for the MOT,and from what I've heard not a huge amount of performance gain. I personally wouldn't bother,though for track days it may be useful?? Zetec seem to do an easy remove cat/manifold set up-don't know if any users of this yet. Hope this is of help.

[graham]

The chimaera has three cats, one in each manifold and one further down. you can take the manifold cats out and the car will still pass emissions, a small increase in power but sounds much better The best bit about a complete de ct is the flame thrower effect on the overrun. get to close to a couple of the v8s's at mallory and you would have been BBQ'd Edited by graham on Wednesday 21st February 21:13

[Rich]

Peninsula do stainless steel manifolds and 'Y' piece decatted. Excellent sound. BHP gain is not massive however does make the car rev better ( less stifled) It is possible to get the emmissions low enough for the cars to pass an MOT without a cat The current test is that the co and hydrocarbons have to be below a level. This can be done by adjustment A well worthwhile mod in my opinion

[GreenV8S]

quote:The best bit about a complete de ct is the flame thrower effect on the overrun. get to close to a couple of the v8s's at mallory and you would have been BBQ'd

One of those V8Ss was mine, and it's still got the main cat in. I guess it may spit more flames more often if you take the cats out, but it seems you can get the 'flame thrower' effect even with the cats in! Peter Humphries (and a green V8S)

[monaco]

Chaps How would you go about removing the cat's in the manifolds ?? is it obvious that this has been done ? Would this not void your insurance if it was inspected after a smash.

[Kevin Secker]

I have a de-cat Chimp 500. This was produced at the factory and looking under the bonnet you can't tell the difference from a normal car(until you fire it up, that is!). The exhaust has exactly the same design as standard, just with bloody great voids where the cats usually go. I am sure with careful set up you will be able to get your car through the MOT emissions test. HOWEVER if you have a prang you will have given the insurance company the excuse they need to hang you out to dry. Lets face it, they are slippery enough bastards even a claim is cut and dried! In case your wondering, my car was delivered to Jersey, which is non EU, with no Cats fitted and then personally imported. This was totally legal at the time. Unfortunately now there is the SVA to get around. Kevin PS. I will be changing my exhaust for something a little spicier soon. If anyone would be interested in my "stealth" de-cat exhaust system, please let me know.

[craigw]

Kevin, is it too loud for long journeys? Been considering something like that for my griff. Don't want the girlfriends moaning to be lopuder than the exhaust though..oo er

[denley]

Any ideas as to how easy it is to remove the cats contained within the manifold, is it a case of unbolting the flanges & removing. Does it have on effect on the ECU & mapping of the engine system! Any practical advice would be great. Thanks Martin

[monaco]

I have been told that the cat's in the manifolds will just knock out, is this true and if so will it mess up the mapping and ecu ? I was told it will run just fine but would like to confirm this before I get the hammer out !!! 8-)

[graham]

if the manifold cats are buggered aparently you can knock them out in bits with a chisele, but if they are ok they are v difficult. i believe tower view and moore racing will modify by exchange a set of manifolds which envolves cutting out the cats and re welding a bit in place. they still look like standard manifolds though

[richb]

I have been told (but not actually tried it) that the pre-cats can be easily knocked out of the manifold header. Apparently some require a bit of help from a hammer. I guess a rolloing road tune-up would be appropriate after this. The engine wil be louder, and I am not sure what the bhp gains would be.

[Graham]

MY car looks totaly standard when you lift the bonnet.

but both the precats and the main cat have been cut out and replaced.

i've also had ecu mod and ecu balast resistor change. but i think you only really need the ballast resistor changing.


Results
1) better mpg !!!
2) nicer noise, not londer but deeper
3) more krackles and bangs plus flame is possible
4) much soother acceleration
5) feels faster but not been on the rollers to confirm

[philshort]

Mine was done by a dealer, using factory parts. Looks identical, but sounds a bit louder .

Not a cheap way to go, two manifolds plus Y piece comes to a four figure sum. I still have the originals though so could revert (though the engine was "chipped" and that would also have to be undone).

I suspect aftermarket manifolds might be a better way to go (weren't available when I decatted). Zertec do some I believe.

You could probably get more performance gains for your money elsewhere (like brakes and suspension for example!) but if you want the sound, or the flames, its your choice!

PS After de-catting my 500 is prone to cutting out at low revs, which means lots of throttle blipping in traffic. Since its not exactly quiet, you can get to feel a bit of a chump.


Edited by philshort on Friday 2nd November 21:20

[steveab]

All this talk of flames has me interested!! I wonder if Clive has any side exit exhausts (passenage side, obviously!) on the drawing board

[Graham]

quote:

PS After de-catting my 500 is prone to cutting out at low revs, which means lots of throttle blipping in traffic. Since its not exactly quiet, you can get to feel a bit of a chump.

my 'Baby' 4ltr runs much better, maybe its the chip you've got or a dirty stepper motor?

[ChimeraWolf]

Yeah! Flames do sound good and are very tempting. I saw a big yellow beast of a car driving up the A406 shooting fire out the back... no idea what it was but it was on the other side of the road so I couldn't see it properly!

I can just imagine trying to half de-cat my car and watching it fall apart as I turn the engine on.

Knowing nothing about engines, and not being able to what a cat looked like if it hit me in the face, how easy is it to do this type of thing yourself?

How much can go wrong and how bad would it be?

- ChimaeraWolf
- P56 SAH - Black Chimaera 4.0

[Greenv8s]

quote: The best bit about a complete de ct is the flame thrower effect on the overrun.

get to close to a couple of the v8s's at mallory and you would have been BBQ'd

Edited by graham on Wednesday 21st February 21:13

Would one of those V8S's been my green one? That has still got the main cat in! But I must admit the rest of the engine is far from standard and it is set up fairly rich!

Cheers,
Peter Humphries (and a green V8S)

[Greenv8s]

quote:
Have removed both manifolds today (not a fun job!) with the idea of removing pre-cats.Problem is they are like new and f**kin solid!.
Tommorow, may try again to remove them
but am also thinking of replacing them
altogether.
So,can anybody answer the following (urgent) questions.
1)Who can supply de-catted manifolds?
2)Where can i get Stainless/performance
manifolds?
3)Any tips on removing existing pre cats?

Notes;1)I intend to leave the main cat assembley in place.
2)any replacement manifolds will need to fit exactly like original.

Sorry to go on, but Im stuck and would like to get mobile asap!

Regards.

Yesterday Tower View had a set of decat manifolds delivered by mistake. Problem is the pre-cat exhaust is completely different all the way from the headers to the down pipe, and it needs an ECU upgrade too. Better bet is knock the pre-cats out of the headers and keep the ironmongery standard, very slight change to the noise, very slight improvement in top-end breathing, no need to re-map it or make any other mods. Mine came out on their own because they had fallen to bits, if yours are still intact they may need a little 'gentle pursuasion' but hopefully not brute force, they should come out intact.

Hope this helps,
Peter Humphries (and a green V8S with no pre-cats)

[zertec]

quote:
Thanks for reply Peter.
Can factory supply standard manifolds without pre-cats?

E-mail me and I can send you some leaflets on our manifolds.

Clive Reed
Zertec Limited
[e-mail]
www.zertec.co.uk