• Exhausts expel exhaust gases, keeping internal combustion engines working.bike exhaust image by Dumitrescu Ciprian from Fotolia.com
  
  The exhaust system of an internal combustion engine consists of four, sometimes five, key components. These serve to remove the unwanted byproducts of combustion reactions in the engine, and to filter out both high-volume sounds and deadly gases. By removing the unwanted exhaust gases, the air in the engine stays clean and the combustion process is not hampered. However, without volume reduction, the pressure in the exhaust system would cause loud and violent shock waves that would make operating an engine near people difficult.
  
  

Exhaust Manifold

• The exhaust manifold connects directly to the exhaust ports on the engine. It is used to collect the exhaust gases emitted by each of the engine's cylinders, so the gases can be expelled and replaced with clean air and fuel. This allows further combustion to take place, keeping the engine running.
  
  

Exhaust Pipe

• The exhaust pipe connects the engine manifold to the exhaust system.Motorcycle Exhaust image by Billy Tait from Fotolia.com
  
  The exhaust pipe connects the exhaust manifold to the rest of the exhaust system. It comes in a variety of lengths and shapes, depending on its specific purpose. For example, an intermediate exhaust pipe is simply a long pipe connecting the manifold to the muffler.
  
  

Muffler

• The muffler is a series of chambers formed by partitions connected by a series of tubes inside a custom-designed container. The purpose of the muffler is to reduce the power of the sound waves emitted by the high-pressure exhaust fumes as they leave the engine and travel down the exhaust system. The precise design of the muffler will vary between engines.
  
  

Resonator

• Some vehicles are not large enough to contain a substantial muffler to finish the job of reducing engine noise. In such cases, a resonator is fitted to the exhaust pipe, to round off the volume caused by the exhaust gases leaving the engine. Smaller cars are often fitted with resonators, due to their size constraints.
  
  

Catalytic Converter

• The catalytic converter is a device for reducing the number of pollutants emitted by car exhausts. Converters work by oxidizing deadly carbon monoxide molecules into carbon dioxide, and turning unburned fuel into carbon dioxide and water. In this way, the exhaust fumes expelled from the engine are relatively clean and less toxic.