Thread: Drilling out the cat converter

Originally Posted by POD

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.

Originally Posted by POD

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)

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.

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.

Originally Posted by 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.

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?

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.

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?