At TRAX, besides meeting up with a great group of people, enjoying Bengie's super BBQ skills, Emily's extremely sweet doggie-Princess and enjoying the sight of a lot of scantily-clad young ladies, I also learnt quite a few things.

Jason in particular enlightened me on a few finer points on Diesel exhausts:

1- Diesels don't have a lambda sensor unlike petrols - no CEL light probs with a decat:)

2- Diesel engines are already quietened down by the turbo, noise only increases slightly even with a plain-jane straight pipe setup (couldn't hear much of a difference between Jasons straight pipe and Xav's Uber-cool miltek setup, but cost-wise major difference obviously)

3- Jason's mongrel (which is a truly AMAZING example of modding:thumbup: ) has passed two MOT's with that setup:confused:

I am thinking of taking out the cat and replacing it with a straight pipe section, possibly even removing the back box at a later date. FAR cheaper than getting a Miltek exhaust shipped out to the middle of nowhere....)

How much effect might there be on:

1.smoke output (car is chipped)

2.Power output (no further remap tweaking afterwards)

3.Torque

4.BHP

5.Turbo Spoolup time

6.Exhaust gas temps

7.Engine temps

8.Economy

And I left out noise because hearing the turbo whistle through the pipe is just great!

Sorry if this is a little complex, but I really want to be sure of my facts here:D

and I'd welcome any constructive input....

(Smart-a55 answers NOT welcome, thanks:rofl: )

Cheers:thumbup:

Bas

My Fabia is running with a Blueflame turbo back system, and due to a recent catastrophic turbo failure, the 100cel "race" cat was rendered useless. I simply had it de catted, with no ill effects at all. Maybe a little more smoke when pulling away and a little more noise in the cabin. The noise however is really pleasant, as I can hear the turbo whine and spool up. That alone makes it worthwhile. Couldnt say if there is any mpg difference. I havent noticed any drastic changes. I cant imagine that the exhaust temps would increase, as everything is getting away that little bit quicker. I personally feel a small bhp gain may have occured by decatting, but my bum dyno says around a 5-10 bhp gain tops.

Been considering this myself.

Diesels don't get "emmision tested" at MOT, it's just a particulate test so a cat isn't essential. Apparently there have been some problems with the actuator sticking open with the reduced back pressure but again I am not sure what the outcome generally is.

If you do have it decatted then I would have thought a remap would be needed to take advantage of the extra flow fully.

My 2c's

i think i depends where you take your car to have it mot'd, technically speaking the car should fail an mot test if there is no catlytic convertor fitted, but in reality most people never even bother to look!!

i dont think a diesel catalyst is a testable item on an MOT test ,i.e. if its missing it wont fail , all that is tested is the smoke coming from the exhaust after 3 WOT applications ,or if it fails 3 further WOT can be done .

Obviously it was a petrol car but i took the Cat of my 206gti and it still passed the MOT no problem, it also improved low down power and throttle response (such as it was).

It isn't a requirement that a car either petrol or diesel has a catalyst, but it must be able to pass the MOT emissions test relevant to the age of the vehicle. Unfortunately in the majority of cases the only way it can pass these tests is with a catalyst.

Are diesel catalysts being used these days?, I thought that they were using particulate filters.

Catalyst is used on the Fabia vRS for example, no particulate filter on that yet (although there may be some kinda filtering on the 06 and later IIRC, mine sure hasn't got it though)

anyone else run a diesel minus the cat? I'd like to know what your experiences are like, thanks.

Cheers

Bas

Glad you liked her, Bas.