De-CAT

[jimmy]

Possibly one aimed at Dieselman.

Has anybody any experience of De-CATing a Mercedes? In particular a diesel?

As I understand it you do not need a CAT on diesel as long as it will pass the emmissions test. I have heard that De-CATting can release upto 15-20 horses. My front pipe and CAT is looking a bit tired and guess it will be another year before the brakets rust off, so I thought about gutting the CAT, obviously if it is no good I can get a replacement very cheap (well compared to MB anyway).

I have heard all sorts about back pressure etc, and simply gutting the CAT will cause turbulence and its better to use a bypass pipe. I would rather try gutting the CAT becuase to look at, it would still look like it had a CAT.

My main concern is noise, the CAT is right under the front seats and acts as a silencer, would removing the internals make it much noisier? A friend had to gut the CAT on his Berlingo van as it was damaged and was breaking up so could have blocked the silencer, it recently passed the MOT with no problems but sounds very tinny and raspy.

 

[Dieselman]

I wouldn't think the Cat would release much extra power as it's flow rate should have matched the engine gas flow. However you will definately have a quicker responding turbo and engine due to reduced back pressure.
You could check the before and after back pressure using a pressure guage screwed into the downpipe.

The exhaust may become a bit more tinny but overall noise won't change mutch.

As stated you don't need the Cat for an MOT on a diesel.

I would cut out the cat and slip a straight through pipe in, that way you can reinstall it if required.

Just for the day why not fit a full straight through, Your tuningbox, polish the turbo and up the boost as you already have extra fuel.

Alternatively a turbo the size of a dustbin and some oversized injectors just to finish the job off.

 

[jimmy]

I would cut out the cat and slip a straight through pipe in, that way you can reinstall it if required.

It's not that straight forward, the front pipe comes into the CAT at an angle and exits straight out the back, so it would need a angled piece of pipe, doable but not easy. Also by cutting out the CAT you can see that it has be done.

Just for the day why not fit a full straight through, Your tuningbox, polish the turbo and up the boost as you already have extra fuel.

I sold the tuning box and the Remus, but will polish the turbo if I get a spare afternoon.

Alternatively a turbo the size of a dustbin and some oversized injectors just to finish the job off.

Hey, youre getting silly now, I was just thinking of a dose of propane, nothing too mad.

 

[Shude]

I just found a mention in the catalogue for the oem "elimination of catalytic converter" option

 

[jimmy]

I just found a mention in the catalogue for the oem "elimination of catalytic converter" option

Tell me more, any mention of models, years or part numbers?

 

[Shude]

Tell me more, any mention of models, years or part numbers?

It said to read the microfiche! I will check it again though

 

[Ian B Walker]

What would be the implications of doing a De Cat on a petrol model?

 

[big x]

I gutted the cat on my c180 as the ceramic honeycomb was breaking up and put the box back on.
Noisewise a slightly gruffer sound but according to my measurements less than 1db louder.Slightly better performance according to my buttdyno but really a zero-sum game.
In 6 months time I'll put it through an MOT and compare the readout from last time. In theory it should be a borderline fail as this is a very clean engine emmission wise without cat.

adam

 

[andy_k]

Ian, there is a list of exempted cars but as a general rule, I think if your car is post 1992 then the only significant result will be an MoT failure

Andy

 

[crosbie2000]

Just had a fiull stainless handmade exhaust fitted on my E300TD.

For all you enthusiasts out there the CAT was ripped out together with the rustimg leaking back box and the whole system made from Powerflow components. 2 1/2 inch seamless tubing with a small box in the middle for sound damping and a bigger box at the back.
The design changed from the crap Mercedes in and out at the same end of the back box (restrictive) to a fully flowed through although this meant the pipe exits at the other side of the car.
Not loud as it wouldn't suit the car but the power has definitely increased as it's breathing more effectively, Economy is up by 5 MPG too, I'm over the moon

A work of art complete with polished welding and all de-blued too. I was so pleased with teh result I sent a letter to the guys who made it.
Excellent job and local too ( northern Ireland)

 

[230K]

Hi

Send me more details by PM if you like, the 5mpg increase impresses me.

230K