What's inside a catalytic converter?

An emission-cleaning witch, I think

3y ago

Since the 1970s, it has been compulsory in most countries to have a catalytic converter somewhere downstream in a car's exhaust system. Despite resembling just a slightly larger diameter of pipe compared to the generic exhaust tubing, the catalytic converter is a vital component in cleaning up and reducing the emissions created by the internal combustion in your engine.

The catalytic converter is a metal chamber that manages to change the chemical composition of the exhaust gases, reducing the nastiness leaving the manifold. It does this using a compact honeycomb material made up of a ceramic-based composite that is lined with precious metals, each of them contributing towards the reduction of emissions.

Platinum, rhodium and palladium are the three catalysts that do the job, accelerating specific chemical processes to reduce NOx gases, carbon monoxide and hydrocarbons, all of which are harmful to the environment.

A honeycomb layout is used to maximise the surface area of the catalyst materials which in themselves are extremely expensive, making the theft of cats a lucrative business for automotive-minded criminals.

In this age of heightened emission control, it is a definite risk to decat your car, seeing as it will fail an MOT check as well as allowing more harmful emissions to dissipate into the surroundings. A tiny gain in power may be achieved by reducing the restriction within the exhaust system, but nothing that will be evident in everyday driving. All you'll do is wake up the neighbours every morning with your decatted cold starts.

Here you can see the positioning of the cat in relation to the rest of the exhaust system

Here you can see the positioning of the cat in relation to the rest of the exhaust system

With the progression of exhaust technology meaning you can now buy sports or high flow cats for many performance cars, you can now amp up the drama of your exhaust tone without contesting the law. These cats are reduced in diameter and have a smoother surface finish compared to a stock cat, allowing the gases to flow in a swift and laminar fashion, allowing your engine to breathe as freely as possible.

So before chopping out your stock cat and replacing your entire exhaust system with a dustbin, survey the perfectly legal options that could even welcome a couple of horses into the stable.

Have you ever decatted your car? Or do you think it's a pointless and antisocial practice? Comment with your thoughts below!

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Comments (43)

  • I once upon a time ago went to an exhaust shop, now sit down, I'm in Malaysia and misspelling of english words are usual... so I saw a section of mufflers, resonators, custom intercooler pipe kit, and there it is... the Catholic Convertor... that is the best misspelled phrase in an exhaust shop you can find.

      3 years ago
  • Free the cats. Decat all the way. F the neighbour's

      3 years ago
    • fuck the neighbours, buy a dragster πŸ˜‚πŸ˜‚

        3 years ago
    • Why would you write "neighbour's" as the plural of neighbour? No apostrophe needed.

        3 years ago
  • I've run both test pipes, high flow, and stock cats. Honestly, I felt guilty running a test pipe because I like clean environments. Call me old fashioned, but being able to talk to people in your car and being nice to neighboring ears is always a plus. Cats all the way for me.

      3 years ago
  • Not only did my Porsche see significant HP gains with a de-cat, I also went from getting 16 MPG to 26. bullshit article

      3 years ago
  • I used to work in a factory that made cats. I witnessed a lab tech drop a gallon of liquid platinum... yes he was fired

      3 years ago