Drilling out the cat converter

[POD]

I've read a few mentions on here of 'drilling out' the catalytic convertor on the Puma engine pipe. Can anyone explain in more detail what this involves? I have no knowledge of what the internals of the catalytic convertor look like, so would like to be armed with more knowledge before removing it to do this. Any pics would be great, but in particular, what does one drill? does it require a large drill to bore material away to the i.d. of the exhaust pipe? or is it as series of holes required to cut something away? I'm planning on wrapping the front pipe with heat shield material and would like to be prepared to get rid of the restriction whilst it's off.

[CraigE]

Not sure about drilling out, I know with some others it is a case of fitting a straight through pipe through the centre, however just be aware that whatever you do technically may be illegal if you get an inspector that knows what they are looking for. While I dont think the cat is a requirement in Australia modifying any part of a vehicle like this from standard can have implications. I would ensure first that this is a legal mod as I know on most petrol engine cars it is not.

[n plus one]

From memory, it's a big no-no on post 2007 vehicles.

Having said that, if I was inclined to modify it I'd pull out the entire section (need to pull the cross member and front prop to do this?) and drill out the honeycomb centre with a long bit. Alternatively, I'd fit a a bolt on de-cat pipe from one of the UK mobs.

Personally, I intend on fitting a full hi-flow system that includes a hi-flow cat.

[Naks]

My indie mechanic removed the cat and drilled out the innards.

Truck runs better - a bit more ooomph at low revs, reduced EGTs and also reduced heat by the driver's footwell.

You cannot do this if your Puma has a DPF, only a 'passive' cat.

[pannawonica]

From memory, it's a big no-no on post 2007 vehicles.

Having said that, if I was inclined to modify it I'd pull out the entire section (need to pull the cross member and front prop to do this?) and drill out the honeycomb centre with a long bit. Alternatively, I'd fit a a bolt on de-cat pipe from one of the UK mobs.

Personally, I intend on fitting a full hi-flow system that includes a hi-flow cat.

That's what I am about to do, I got a two piece from Gary at alive tuning? Being stainless steel with a bracket to mount the factory heat shield, you can chop the original and fit without removing the cross member and prop. Or do as I,m going to do remove whole and to preserve. It looks so good it could be factory! :D:BigThumb::

[Drover]

I removed my cat and centre muffler over 3 years ago.

Used stainless TF de-cat and centre pipe.

Definently better low end response and much cooler drivers floor, although I did wrap the de-cat with ceramic wrap.

[POD]

Yeah I'm aware that there are aftermarket front pipes available that replace the catalytic convertor, I was more interested in information about drilling the converter as I have seen mentioned on here several times.

[isuzurover]

The inside/matrix of a catalytic converter looks like this:
http://mkrd.info/uploads/images/audi_catalytic_converter_before_sm.jpg
https://www.aulro.com/afvb/images/imported/2014/01/700.jpg

It is a ceramic matrix with a "wash coat" of rare earth metals.

[Tank]

The inside/matrix of a catalytic converter looks like this:
http://mkrd.info/uploads/images/audi_catalytic_converter_before_sm.jpg
https://www.aulro.com/afvb/images/imported/2014/01/700.jpg

It is a ceramic matrix with a "wash coat" of rare earth metals.
.... and worth anywhere from $120 to $350 scrap price, Regards Frank.

[frantic]

Not sure of the legality but to be safe when I replaced my td5 exhaust with a straight through, I put the old cat and mid muffler in the garage as if I ever get pinged will be much cheaper to refit;)

[POD]

Not sure of the legality but to be safe when I replaced my td5 exhaust with a straight through, I put the old cat and mid muffler in the garage as if I ever get pinged will be much cheaper to refit;)

That's a thought I'll bear in mind, might want to sell the beast one day. Although I wouldn't think any roadworthiness inspector is likely to pick up on the convertor not having any guts inside?

[isuzurover]

That's a thought I'll bear in mind, might want to sell the beast one day. Although I wouldn't think any roadworthiness inspector is likely to pick up on the convertor not having any guts inside?

If you tap a cat converter housing it is easy to tell by the noise if it has been hollowed out or not.

[goingbush]

That's a thought I'll bear in mind, might want to sell the beast one day. Although I wouldn't think any roadworthiness inspector is likely to pick up on the convertor not having any guts inside?

Not a worry

I bought my Td5 Defender a few years ago with cat removed by previous owner, passed RWC back then no problems,

I just sold it the other day, But whilst I owned it I removed all the mufflers and it only has a 3" Hotdog , Passed RWC at an authorised ARB service centre last week, not like its a dodgy RWC at all. VIC RWC's are quite strict nowdays too. ( It has a mean exhaust note too)

[MD5]

In the past I replaced the stock exhaust and the central muffler of my Puma 110 with a straight empty tube from Terrafirma.

Since the noise was too loud and the smell of the exhaust gas was annoying for the cars behind mine, I replaced the stock ceramic cat with a 100 cells high flow stainless steel sport cat.

I very like this mod. Engine noise and smell are OK without gas flow restriction.

http://img703.imageshack.us/img703/4697/200celle.jpg

[Bigbjorn]

When our vehicles were first fitted with cat. convertors someone instantly started selling a gadget christened "Testube". Their ass-covering advertising said it was to "temporarily" replace the cat. to "test" if the cat. was blocked.

[skidrov]

I removed my cat and centre muffler over 3 years ago.

Used stainless TF de-cat and centre pipe.

Definently better low end response and much cooler drivers floor, although I did wrap the de-cat with ceramic wrap.

I have been reading your (and others) positive reports of fitting a de-cat pipe. Now, don't get me wrong, I believe you :) (and other posters), but has anyone ever actually seen dyno results of before/after, where the ONLY change was fitting a de-cat? Would really like to see some numbers...

Where I'm coming from is that on my wish list is a re-map AND the de-cat. I can find plenty of dyno reports on re-maps, but haven't found any dyno runs on ONLY a de-cat pipe. Happy to be pointed at one!

And, going "un-scientific"/subjective again, which change did people think gave bigger bang-for-buck - re-map or de-cat pipe?

[mools]

Regarding the question raised by the OP.

Drill, chisel, ram and smash they take some shifting but if in good condition the housing can take a fair beating. Don't be fooled by the honeycombed texture of the cats 'guts', they don't call them a brick for nothing! A sharpened star picket could be useful. Once you have broken through it's just a matter of clearing a good sized or orifice through the center. A surprisingly physical job. I don't know much about the toxicity of rare earth elements but I'd be we wearing a dust mask to do the job JIC.

Regarding the legality ?! Don't care other than to say that it is not particularly hard to identify a gutted cat if you know what to look for / can make a comparison; the smell is somewhat distinctive but an infrared thermometer will tell you for sure if the guts are in.

Regarding the performance gain, IME negligible. Nicer whistle from turbo perhaps slightly quicker spool up, no change to EGT. Like with most engine mods though its small incremental gains that sum together. Unlike other mods, very cheap to do.

Forgot to mention my experience is Td5 not Puma engine.

Ian.

[POD]

Thanks for the info so far, I'm now much more informed about what the heck is inside the thing. There've been a few mentions about the exhaust smell; mine emits a quite pungent exhaust odour, same as 2 other Puma-engined defenders that i have compared, but very different to the familiar diesel exhaust smell. Is this normal, or would it suggest that the catalytic converter is cactus?

[tuesdayfox]

Thanks for the info so far, I'm now much more informed about what the heck is inside the thing. There've been a few mentions about the exhaust smell; mine emits a quite pungent exhaust odour, same as 2 other Puma-engined defenders that i have compared, but very different to the familiar diesel exhaust smell. Is this normal, or would it suggest that the catalytic converter is cactus?

I sometimes smell that too!... wonder how to solve that.

Personally I would think twice about removing/ destroying the cat; as all puma defender are fitted with variable geometry turbo, i.e, no turbo lag (theoretically). so removing the cat might not help the lag but perhaps increase the boost?:confused:
secondly, Diesel exhaust is more than likely to be carcinogenic for humans (currently listed in IARC group 1...:(

Cheers
Martin