Remap Query - To Cat Or Not?

[grey]

I'm considering getting my 110 HDi remapped using HDI-Tuning to boost it up to 130/140ish and was wondering if its worth going through the extra hassle and expense of replacing the cat with a straight through pipe and removing the EGR valve?

The simplest option would be just to leave everything as it is and upload the remap, would there be a major difference this way?

Cheers

[Welly]

The CAT is currently unnecessary for the MOT so yes it can go, it must be replaced with tubing of the same bore as the exhaust.

Driving-wise you should get 'on boost' quicker and maybe a sharper throttle response, the main benefit from de-catting is at higher revs which diesels don't really do....all in all if you can do it then do but if not it shouldn't matter too much.

Bailes on here has de-catted his Mondeo I think? he might be able to say how it feels now.

[grey]

Thanks for that, I was just thinking if its worth it overall in terms of the a) the extra expense and b) how much I'd actually gain from doing it.

I could apply the remap and EGR for about £110 and off I go, in order to get the exhaust taken out it will probably add another £75 to the job.

[jonny81191]

Decat definitely. It makes such a difference to the responsiveness and feel of the engine.

[davew]

i would decat it mines been done, just drop the front pipe off and smash the insides out and refit took me about 1.5 hours all in and cost zero.

[GingerMagic]

Hi, there are no sensors or lambdas or anything fitted to the exhaust after the cat on a Hdi, so smashing the guts out of it will not to any harm or set off any alarms, and keeping the cat shell fitted looks good when its MOT time.

[grey]

Interesting, how would one go about smashing up a cat in that way then?

[davew]

i removed mine from the car and used a crow bar and just rammed it into the cat and it will start to break it up ,any kind of metal bar will do something with a sharp end on it is best and use a hammer and just keep chipping away until you get it all out, and wear a mask i wouldn't want to be breathing the dust in.

[grey]

I found this thread:

http://306oc.co.uk/forum/thread-41.html

Whilst searching for decats and it seems to be quite a bit more complicated than just whacking a crowbar in order to get all the bits and pieces out.

Does anyone have any pointers on where to get a replacement bit of pipe that fits instead? Also, I read elsewhere that decatting and just leaving the old box there is no good for airflow/pressure or some other technical point and in the long run you are better off either a) just dropping in a straight pipe and ditching the cat or b) dropping in the straight pipe and wrapping the box of the cat around it to make it look standard.

Cheers

[Welly]

For normally-aspirated engines then the eggsauce diameter is crucial for eggsauce gas 'scavenging' as it helps evacuate the cylinders ready for the next cycle however the rules are a bit differed for forced induction systems where the eggsauce diameter is generally considered 'bigger the better' (within reason).

I must admit I wouldn't want an 'empty cavern' halfway along the system.

[Doggy]

I've had a comparatively massive 'cavern' part way along the zorst on both my 2.2's with no issues whatever. Took the cat out of the first one, but didn't bother with the current car as a CLEAN cat doesn't seem to make a blind bit of difference.

* takes cover *

[jonny81191]

That guide isn't what you want to do, I purchased the exact car that had that fitted and after a couple of months did the proper decat with a bit of straight pipe in to replace the cat. Saw good gains over just the empty cat. But bear in mind the car was running 165BHP at the time, so I'd have seen a greater gain.

[grey]

Fark.

Looks like the remap won't be happening, hit a roundabout today whilst driving around a darkened street trying to read directions off the back of a pack of Rizlas.

Seems there'll be another 406 for spares or repairs up on here...

[Doggy]

Bad luck. I had one of those roundabouts run out in front of me a few years back. I shortened the wife's 216 GTI twin cam a bit.
2003 I think it was, she hasn't reminded me about it for over a month now.

[GingerMagic]

The 216 twin cam was an awesome car....

Hope you can get the 406 sorted, lots of spares around for them and lots of help on-line too.. Good luck.