Do you know the difference between a muffler and an exhaust?

Well, the chances are that if you are reading this then you are one of the many people who don’t.


An exhaust or exhaust system is the series of pipes that carry gasses from the engine after internal combustion has taken place. These gases are known as “exhaust fumes” and mostly comprise of Carbon dioxide (CO2), Carbon monoxide (CO), Nitrogen oxide (NO), and Sulfur dioxide (SO2).

The exhaust system begins at the car’s cylinders where combustion takes place and usually extends to the rear of the vehicle where the emissions can be released safely.

There are several components to any vehicle’s exhaust system. To give you a better picture, let’s take a look at the average road car’s exhaust system.

Exhaust Manifold

Exhaust Manifold

The first component is the exhaust manifold.

During the engine’s piston cycles, exhaust gas is expelled from the engine due to the high pressure generated by the piston’s movement.

After it leaves the engine chamber, it enters the exhaust manifold. This is the part of the exhaust that comprises of 4 separate pipes that connect directly to the engine.

Once the gasses enter the exhaust manifold, they are channeled into a single pipe where they then travel under the car to the catalytic converter.

Catalytic Converter

Catalytic Converter

The purpose of a catalytic converter is to reduce air pollution. It removes harmful gasses by catalyzing reactions that convert toxic gases into less harmful ones. One of the main gasses that catalytic converters help to reduce is carbon monoxide (CO). They oxidize CO to turn it into less harmful CO2 or carbon dioxide.

After the car’s emissions exit the catalytic converter they continue their journey through the exhaust system until they reach the muffler.



A muffler (or silencer in British English) is the part of the exhaust system that allows the noise created by combustion within the engine to be reduced. Anyone who has ever heard a car with a broken muffler will know just how noisy a vehicle without one can be.

The confusion between the terms exhaust and muffler probably comes from the fact that the muffler is part of the overall exhaust system. It is the large cylinder ‘box’ that is found at the rear of the vehicle, located just before the tailpipe.

How A Muffler Works

In order to reduce the noise that traveling through the exhaust system a muffler must act in the same way that any soundproofing material/device does. Since the vast majority of the noise generated by an engine is transferred down through the exhaust system (just think of how noise travels down a tube), a muffler has to absorb a lot of noise.

The way it does this is through its design. A muffler is made up of several chambers that allows the exhaust fumes to travel in via one pipe and leave through another.

The first chamber has what is known as a resonator built into it.

Sound travels as waves or vibrations. A resonator is a device that helps interrupt these waves and therefore reduce noise levels. The chamber that houses the resonator in the muffler acts to cancel out a certain sound frequency as the gasses enter it.

As the gases are pushed through each separate chamber in the muffler, the air pressure resistance from within the muffler causes them to slow. When coupled with the internal design of the muffler, which includes 180 degree turns and perforations in the pipes, this helps reduce noise levels to legal levels.

Finally, after the gas has traveled through the muffler, it briefly reenters the exhaust system before being expelled through the tailpipe or outlet.

Key Differences Between An Exhaust And A Muffler

  • The exhaust is the system of pipes that take gasses from the engine to where they are safe to release.
  • A muffler is a device for reducing the noise levels of the sound waves traveling from the engine.
  • A muffler is included as part of the exhaust system.
  • Both the exhaust system and a muffler are required by law for any road going car.