de-cat

niz406 · Post by **niz406** » Tue Nov 07, 2006 6:57 pm

I've just got my car back from the garage.... had a new de-cat pipe done... and I can feel the difference straight away... oh yeah... now I just need to fix the intercooler etc.. and away we go ! !

So its all good ! ! ! !

As for the turbo question and the diesel in theory it works the same way so a more free flowing exhaust will reduce heat, back pressure and increase performance ( slightly ) another problem is that the way diesel works on high pressures as compared to the lesser turbo lump... correct me if I'm wrong anyone?

nipper76 · Post by **nipper76** » Tue Nov 07, 2006 9:08 pm

[qoute]As for the turbo question and the diesel in theory it works the same way so a more free flowing exhaust will reduce heat, back pressure and increase performance ( slightly ) another problem is that the way diesel works on high pressures as compared to the lesser turbo lump... correct me if I'm wrong anyone?[quote]

you lost me lol

will it be worth doing on my car?? you saying all about this pressure on diesel cars... dose that mean i need that extra pressure??
has anyone tried this on a TD??

and what about the toxic fumes... dont they make you ill??

niz406 · Post by **niz406** » Tue Nov 07, 2006 9:39 pm

What I mean is that in theory a de-cat should benefit your cars breathing..... however because of the high pressures that diesel engines run on, you may find that it shows little or no benefit, as the diesel requires some backpressure to run correctly... a friend of mine had a diesel 406 and he had a decat... not sure if it was a TD or just a D....

nipper76 · Post by **nipper76** » Wed Nov 08, 2006 2:46 pm

oh i get you... soz im prob a bit slow lol
well if any of you out there have a TD and have done a de-cat it would be nice to here if its worth it.
i was assuming that because because the turbos build up pressure any how, that the cat would be slowing it down... but trust me to have a awkward diesel :S

niz406 · Post by **niz406** » Wed Nov 08, 2006 3:41 pm

The CAT is a restrictor, causing back pressure which if high enough can cause the turbo to stall... not to mention the excess heat that is created could damage the turbo/engine ! This is something avoided on stock set up, adjustment to boost etc.. will increase this back pressure, as the cat has a specific flow/filter rate, exceeding this can cause damage..

pipe*n*slippers · Post by **pipe*n*slippers** » Wed Nov 08, 2006 6:06 pm

[quote="niz406"]I've just got my car back from the garage.... had a new de-cat pipe done... and I can feel the difference straight away

Now if im right (which is doubtfull) a cars exhaust system should work in the same way as a bikes. They are tuned for gas flow rate and back pressure. By removing the cat and increasing the exhaust flow rate (same idea as fitting a race exhaust to a bike) this changes the fueling of the engine causeing it to run LEAN giving a better burn and more power BUT if the fuel mapping is not corrected this can cause the valves and or pistons to burn out.

niz406 · Post by **niz406** » Wed Nov 08, 2006 6:20 pm

But its on a turbo'd motor.... which means free flowing and alot less back pressure... turbo spools quicker and doesn't stall!

The stock boost control and map sensor will adjust the fuelling accordingly, within its limitations of course... well the boost limit of the 406 turbo is just a few p.s.i short of a bar max... so in theory by passing the stock boost controller you can set a default of 12 / 13 p.s.i without any problems....

Peugeot's set up gives only between 4 - 6 p.s.i through first, second, and third gear, then upto 10 p.s.i in forth and fifth, or so I've noticed when using the stock controller.

Of course a good Idea would be to use a fuel cut defender.... this way you can set the boost limit to 2 p.s.i higher than you require to prevent spark / fuel cut unless a problem arises and the turbo spools higher boost levels !

dervpower · Post by **dervpower** » Thu Nov 09, 2006 5:31 pm

i had my hdi decatted no performance difference but does rev slightly better black smoke for abut 100yards after decat was awesome gives you indication of how restrictive they are

darko · Post by **darko** » Mon Jan 29, 2007 10:37 am

What about eng light after de-cat on 1.8 16v, anybody jumped this?In my country we don't need cat jet so if this works with lambda ignored..why not?