What Is the Function of the Exhaust System?

by Tom Streissguth
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auto, detailed, tailpipe image by Rina from Fotolia.com

An exhaust system carries waste gases and other combustion products away from an automobile engine. It allows the vehicle to operate with minimal noise, smoke and pollution transmitted to the environment. A properly maintained exhaust system is essential to the clean and efficient operation of the car.


For the internal combustion engine that drives trucks, cars and motorcycles, the exhaust system carries waste gases away from the engine and through a system of manifolds and pipes. The exhaust system is an essential part of a vehicle engine and must be kept in good working order, otherwise engine performance and mileage will suffer.

Exhaust Manifold

The exhaust manifold is the first component of the exhaust system. It comprises a stainless steel, aluminum or cast-iron unit that adjoins the engine's combustion cylinders and collects exhaust gases from the combustion process. Car enthusiasts have the option of detailing their engine with exhaust headers or extractors, which are a series of pipes that are individually linked to the cylinders. The exhaust is funneled into a collector that directs the exhaust to the secondary components of the exhaust system. This arrangement allows the engine to run more efficiently.


A system of exhaust pipes carries the exhaust gases through a muffler, which contains a series of baffles that damp the noise of the engine combustion and escaping gases. Without a muffler, the noise of combustion would escape directly from the exhaust pipe, creating a tremendous distraction for drivers and pedestrians. By law in all states, automobile mufflers must be in good working condition.

Catalytic Converter

A catalytic converter completes the ignition of gases that have been incompletely burned within the engine's combustion chamber. The catalytic converter prevents pollutants such as carbon monoxide and nitrogen oxides from escaping into the atmosphere. By law, the catalytic converter must be in good working condition, and many states require annual testing of this component to assure that the vehicle is emitting minimal pollutants into the atmosphere.


The engine exhaust finally reaches the tailpipe, which is made of stainless steel or steel tubing. The exhaust pipe vents the gases behind or above the vehicle. Modern exhaust systems have reduced automobile pollutants by a considerable amount in the past few decades and have helped to reduce smog and other pollution in most large cities.

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