Exhaust manifold is the „starting point” of the exhaust system as it is attached directly to the engine and, to be exact, the place where the exhaust gas exits the combustion chamber. It has inlets on one side in the number equal to that of the engine cylinders with a single pipe on the other side which is usually fixed directly inside the catalytic converter.
Until recently the catalytic converter was the most valuable part of an exhaust system. At a glance a catalytic converter looks like a silencer and resembles a can. Inside of that inconspicuous can you can find valuable noble metals such as rhodium, palladium or platinum. They are the reason why the price of a catalytic converter is so high. The interior of a converter has the form of channels arranged in a design resembling a honeycomb with wall coated with noble metals which enable chemical reaction of the exhaust gas of the engine. The final effect is the removal of the harmful chemicals. Many people do not realize that even a damaged catalytic converter is quite valuable and the best thing you can do about it is to sell it at a collection point.
Particulate filter is another component of an exhaust system which is responsible for cleaning the exhaust gas. Until recently particulate filters could be found in Diesel cars only but now they are also installed in petrol-engine vehicles. Particulate filter removes particulate matter from the exhaust gas of an engine and burns them off inside the filter. Such a regeneration process extends the filter life. Most of the defects are caused by interrupting the regeneration process or by doing no regeneration at all. When viewed from the outside the filter resembles a catalytic converter with a housing made of stainless steel. The core has the form of a ceramic body with channels closed on one side. With such a design the exhaust gas is forced to diffuse between the channels and gets cleaned as a result. Channel walls are made of silicon carbide coated with aluminium oxide and cerium oxide and, finally, particles of platinum which is the reason why the purchasing price of a particulate filter is so high.
Rear silencers are connected directly to the catalytic converter or the particulate filter using exhaust pipes. In most of the cases two rear silencers are used connected in series i.e. one downstream the other. One of the silencers attenuates high frequency noise while the other one absorbs low-frequency noise.
Lambda probe is a small sensor installed in an exhaust system which is usually located inside the exhaust manifold. The main purpose of a lambda sensor is to analyse the composition of exhaust gas of the engine. The air-fuel mix ratio is adjusted according to the readings of the sensor.
The most valuable components of an exhaust system are the catalytic converter and the particulate filter as both contain noble metals which increase the value of the individual components.