Diesel De-Cat Information
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Information contained within this guide has been kindly provided by forum user Slim.
The following information applies to the XUD9TE turbo diesel engine, found in many Peugeot/Citroen/Rover cars. It may also apply to other marques/vehicles but you attempt this at your own risk.
Does my car have a cat/catalytic converter?
No, it has a diesel particle filter which removes some of the particulate exiting the exhaust system. It does indeed look like a cat from the outside though and you'll find it just downstream from the turbo.
Here is some additional information from saffil.com.
A Diesel Particulate Filter (DPF) reduces the particulate mass in the exhaust gas stream by capturing the ultra fine particles. DPF applications are different from catalytic converter systems as the gas stream passes through the porous walls of the substrate as opposed to flowing through the channels. Thus the backpressures on the system are much higher. DPF substrates are also heavier than catalytic converter substrates thus requiring different mat holding properties.
Can I remove the cat/particle filter?
Yes.
Are there any performance gains?
Yes. I, personally, observed a much better throttle response and the car seemed to rev more freely. Whether this did actually translate into any power or torque gain is debatable but I will propose it did.
Does this change the exhaust note?
Yes, the tone of the exhaust is slightly deeper and the noise of the turbo spooling is amplified, somewhat. Expect the typical diesel 'chug chug' to drown it out from the front, though.
MOT! Am I gonna fail my MOT?!
Not necessarily. Simply removing the particle filter does not mean you automatically fail the smoke test. If the smoke emissions are still measurably good (which they will be on a healthy DTurbo) then you should have no problem passing an MOT after this mod. I am yet to hear of someone who has failed their MOT as a direct result of removing the particle filter.
This is not to be confused with 'decat'ing a petrol vehicle where you almost certainly will fail the emissions test.
How much does it cost?
Entirely up to you. You could get a custom turbo back exhaust amounting to several hundred pounds or you could order a downpipe for a '94 model from your local motor factors (which natively had no particle filter) and fit that as a direct replacement, for the princely sum of, approximately, £30.
Could I do this on my HDi/some other diesel?
Who knows. Obviously, you will not be able to use a downpipe from a '94 DT because the exhaust is different on the HDi. General consensus is you can remove the particle filter on the HDi, although no 'cheap route' is known at this time.
Try it and let us know!
(Courtesy of Slim)
