De-catting

[Vitesse39]

I know alot of Tuscans and Griffiths get de-catted.
I have some questions about this....
Is it not a requirement of the MOT that there is a cat even if it still passes the emissions test?
Does the ECU need to be adusted to compensate for reduced back pressure?
Does the lamda sensor or anything else have to be re-sited?

Reason for asking is cat is possibly going on my BM 530i V8 and I don't want to have to fork out for a new one !

[R666 TUS]

I can help with the first bit. It is a requirement
in law that all NEW cars sold are fitted with a cat
but once sold you can remove the cat and your only
obligation in law ai that it will pass the emissions
test at mot time.

Col

[Vitesse39]

I like the sound of that, cheers mate

[scott672003]

the lamda sensor needs to be reconnected to whatever you replace the cat with, so the engine management can receive readings,

I have heard from guys in the porsche club that de-catting cars in general will result in loss in power unless the car is re-mapped... I would have thought the engine management would have taken care of this,, but seemingly on the rolling road, engines with cats removed had 10-20bhp loss until they were re-mapped...

as for passing mot,,,, that might present more of a problem unless you have a friendly mot'er'

just for info,,, one of the speeds 6 guys had just had a new engine,, £12k,,, as the cat went,, while on track,,, created enough back pressure to put a conrod through the block,,,,,,,,

I intend getting the cats off during winter while car is off the road,, my main concern is increase in noise,, car is loud enough as is,,, with carbon cans

cheers
scott...

[alans]

I de catted my RR, it was unbearably loud (and I had a decatted cerb with sports pipes before!)but it did leave a big hole in the torque curve (a V8S left me for dead ) so a remap is proberbly needed. I removed the decat pipes and replaced the cats.
On the other hand it did sould like a demented le mans car

[whitey]

Pardon ?

[powerlord]

alans said:

I de catted my RR, it was unbearably loud (and I had a decatted cerb with sports pipes before!)but it did leave a big hole in the torque curve (a V8S left me for dead ) so a remap is proberbly needed. I removed the decat pipes and replaced the cats. On the other hand it did sould like a demented le mans car

whose car are they on now alan ? I have visions of these decat pipes still passing from tuscan owner to tuscan owner....new installation every month.



stu

[R666 TUS]

The de-catt did not seem to harm performance
on mine as you can see in this months Sprint
when I had it on the dyno. Mine actually produced
the torque lower down the revs than the catted Tuscan
of the guy who runs the rolling road shop.
This could just be diiference in individual cars,
time since last rebuild etc etc

Col

[alans]

powerlord said:

alans said: I de catted my RR, it was unbearably loud (and I had a decatted cerb with sports pipes before!)but it did leave a big hole in the torque curve (a V8S left me for dead ) so a remap is proberbly needed. I removed the decat pipes and replaced the cats. On the other hand it did sould like a demented le mans car whose car are they on now alan ? I have visions of these decat pipes still passing from tuscan owner to tuscan owner....new installation every month. stu

Hi Stu
They are sat on a bench in my garage I'm looking at getting replacement pipes made up by Powwerflow, and removing that silly little box (where the weld breaks)

>> Edited by alans on Wednesday 6th July 16:41