• Cylinder head and exhaust manifold
• A turbocharger to increase engine power.
• A catalytic converter to reduce air pollution.
• A muffler (North America) / silencer (Europe), to reduce noise.

Design criteria

An exhaust pipe must be carefully designed to carry toxic and/or noxious gases away from the users of the machine. Indoor generators and furnaces can quickly fill an enclosed space with carbon monoxide or other poisonous exhaust gases if they are not properly vented to the outdoors. Also, the gases from most types of machine are very hot; the pipe must be heat-resistant, and it must not pass through or near anything which can burn or can be damaged by heat. A chimney serves as an exhaust pipe in a stationary structure.

Motorcycles

In most motorcycles all or most of the exhaust system is visible and may be chrome plated as a display feature.

On a two-cylinder motorcycle, "siamese exhaust pipes" are where both cylinders blow into the same exhaust pipe or run parallel and connect with a crossover. This usage is derived from "Siamese twin".

Trucks

In many trucks / lorries all or most of the exhaust system is visible. Often in such trucks the silencer is surrounded by a perforated metal sheath to avoid people getting burnt touching the hot silencer. This sheath may be chrome plated as a display feature. Part of the pipe between the engine and the silencer is often flexible metal industrial ducting, as in the image in the "Terminology".

Two-stroke engines

In a two-stroke engine, such as that used on dirt bikes, a bulge in the exhaust pipe known as an expansion chamber uses the pressure of the exhaust to create a pump that squeezes more air and fuel into the cylinder during the intake stroke. This provides greater power and fuel efficiency. See Kadenacy effect.

Ship's or large boat's onboard engine

With a ship's or large boat's onboard below-decks diesel engine:-

• Lagging the exhaust pipe stops it from overheating the engine room where people must work to service the engine.
• Feeding water into the exhaust pipe cools the exhaust gas and thus lessens the back-pressure at the engine's cylinders' exhaust ports and thus helps the cylinders to empty quicker.

Outboard motors

In outboard motors the exhaust system is usually a vertical passage through the engine structure and to reduce out-of-water noise blows out underwater, sometimes through the middle of the propeller.

Terminology

Manifold or header