The cat sits around a third of the way down the exhaust system
and resembles a small metal chamber that receives exhaust gasses
and changes the chemical nature of them to reduce
the volume of nasty emissions fresh from the exhaust manifold.
Within the cat housing is a ceramic-based honeycomb structure
,
with each metal having a specific job in emission-reduction.
There are three main emissions produce by car engines:
nitrogen gas (N2), carbon dioxide (CO2) and water vapour (H2O).
The converter unlimited however is mostly used to tackle the smaller,
more-harmful products that are produce due to the naturally-imperfect combustion process of the IC engine.
These are carbon monoxide, hydrocarbons and nitrogen oxides
converter unlimited due to the three main types of emission that they manage to tackle.
A ‘ converter unlimited’ is a substance that accelerates a chemical reaction, and within a catalytic converter,
there are two types of converter unlimited.
The first is a reduction catalyst which uses platinum and rhodium within the honeycomb to reduce NOx emissions.
NOx is produced
by nitrogen oxide and nitrogen dioxide within the exhaust gasses.
The nitrogen gasses come into contact with the converter unlimited metals which rip the nitrogen atoms out of the molecules
which in-turn releases cleaner oxygen to continue down the exhaust system.
The second converter unlimited type is an oxidisation catalyst which uses Platinum and Palladium to complete the job.
These Most converter unlimited on modern cars are located under the vehicle towards the exhaust which makes it easily accessible to thieves.
oxidise or burn the carbon monoxide and hydrocarbons lingering within the incoming gas, helping reduce the amount of smog produced
by evaporated, unburnt fuel.
The final stage of emission control comes in the shape of an O2 sensor found just upstream from the cat.
The sensor relays back to the ECU how much oxygen is found within the exhaust gasses,
with the on-board computer then able to adjust the air/fuel ratio to allowthe engine to run as close to the Stoichiometric point as possible.
This is the point at which – theoretically – all of the fuel entering the combustion chamber will use all of the oxygen provided to complete the combustion process.
Not only does this last stage help the engine’s overall efficiency,
it also allows the engine to provide the cat with enough oxygen to effectively
complete the oxidisation process with the second converter unlimited.