Tuning JTD exhaust pipe size

[Chris017]

hi all i need to know the exhaust size for my jtd
I am going to pull the centre cat off and weld a straight pipe instead. But not sure of the dimension of the pipe.

Not sure if it wold be easier just to pull the cat and the silencer off the same time and put a nice strait pipe instead of it.

I know you get better performance with ought the cat, but what difference do you get from pulling the silencer off?

What do you think?

Either way the cat is coming off.

The only reason for this is that the JTD doesnts need the centre cat. And im after more power.

I know iv done a thread on this before, but the time has come to do it now as I have time off to do it.

cheers guys

 

[Yellow Peril]

Strewth! A diesel with no silencer will be well noisy, and not a nice noise either..!

 

[Chris017]

rite ok. so i take it just the cat then.
i havent had a look underneath the car yet as it is really wet outside, but only going on picture on the net.

is the cat stuck on the pipe or is it bolted on?
i know that its bolted on the front of the cat but not sure behind it as the silencer is straight after the cat.

just makes life abit easier before i get it up in the air and start making a mess haha.

 

[Yellow Peril]

I think you won't know until you have a look under the car. According to ePER there are at least two very different arrangements, one with an integral cat and another where the cat is seperate and linked by a flange.

Tried to upload the pictures, but for some reason ePER won't play ball today, so you'll have to look for yourself...

 

[sussexa]

I'm guessing this is as bad as it would get, no precat, no main cat very small straight through silencer just before tailpipe and 2 1/5 inch from where precat was.
http://m.youtube.com/index?desktop_uri=/&gl=GB#/profile?user=sussexa&v=-AAdfsMnmh0&view=videos
Don't find it much noisier in day to day driving, even motorway quiet , only under load do it get louder.

 

[Chris017]

the link didnt work.
well can buy one of here
http://www.gazzellaracing.com/product.php?productid=18300&cat=3249&page=1

but i am not going to.
plus i can get it done in a custom exhaust place in swansea called Longlife. they want £69 welded or £99 bolted.

but as my mate has loads of exhaust lying around in his garage. im just gonna get one that is the same size pipe as mine and just cut the cat out and weld a strait pipe in.

unless anyone knows of a good cheap website to get the correct size pipe from?

cant get bloody hold of him now to go and see what he has got. bloody pain when you cant get hold of someone.

 

[sussexa]

Try here
http://www.js-tuning.nl/alfa-romeo-c-32.html?osCsid=umgob9kpsicjq725npq223aro3

 

[rattystilo]

i got that pipe in my garage that i will be selling in the new year.

 

[GizmOwin]

I took the silencer off too and just replaced the whole mid section with just a straight stainless pipe. Not noticably louder on idle but has a nicer note under acceleration. I wouldn't say it was much louder though.


Owen.

 

[s130]

Warning:

New MOT testing requirements start on 1 Jan 2012

Regarding CAT removal, section 7.1 Item 3 clearly states:

Reason for Rejection/Fail: 3. A catalytic converter missing where one was fitted as standard

I'm pretty sure that if you car has 2 cats (e.g. Pre and Main) and you remove EITHER then you will fail the MOT REGARDLESS of emission levels.

 

[sussexa]

I've seen this on many forums now, we will have to wait and see how individual testers apply the rules?
One guy wrote to vosa here on page 2 midway down is a reply.
http://www.tdocuk.com/viewtopic.php?f=41&t=11017
If anyone is on computer and not phone ,please copy and paste there reply here.

 

[Chris017]

Cheers for that heads up guys, but I am going to stick to a bolt on de cat so can change it for the mot and then pull it back off after it.

 

[Muppet1]

Strewth! A diesel with no silencer will be well noisy, and not a nice noise either..!

You would be surprized how much a turbo quiets things down to be honest.

Why not just knock the middle out of the cats so they look stock but their not.

 

[Chris017]

That is what I have been told to do, but lucky I haven't as of this new rule.

 

[Halil]

I know this thread has been dead for a while, but can anyone give me some details as to where exactly the cats are on a jtd? Im looking to just knock the centres out of mine.

Thanks
HH

 

[Chris017]

Hi there, there is one cat on the down pipe coming off the manifold and another under the car that is about alf the length of the car.
I have been so busy with work that I haven't even de cat my car yet, but I am suggesting just smashing the inside of the cat out, but my problem is that I think you need it for the mot but I'm not sure.

I don't want to smash it out and then need it for the mot and then have to buy another one for a couple of 100 pounds.

So what would be the best solution?

 

[Halil]

There is only smoke test for diesels, so i believe emissions wouldn't be a problem. The problem arises when you have no catalytic converter where there should be one. Hence, just smash it out so it looks like its still there and passes MOT. Or if you are paranoid you can get a bolt-on bypass that u can swap for MOT.

HH

 

[Chris017]

Let me know after you have done this as I would like to know if it works and also if it will pass mot with out the inside of the cat missing.
I know that the mot guy won't have a clue but won't it fail on the emission and smoke test???

Plus are you planning on pulling the inside out of both the cats on the car or just the centre one???

 

[Chris017]

Plus will it actually make that much difference?

 

[GizmOwin]

I had mine decatted, and the difference in performance is probably as significant as any tuning box out there. It gives you a rather turbo-esc boot around 3000rpm.

As for the MOT, I put mine in at Kwik Fit in January, who I imagine are pretty strict on things seen as they failed me on the brightness of number plate lights, and they didnt say anything about the decat. I think Halil is right, they only go off smoke tests and decat has little or no effect on emissions.

I think this new supposed legislation is probably targetting cars completely decatted (we're safe because we still have one present on the system). I think also they'd probably have something to say if removal of a cat made the car too loud, but I can assure there is no noticable difference in sounds, just more of a whoosh noise on acceleration.

Owen.