What's inside a catalytic converter?

1y 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

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!