What does an air intake resonator do?

Written by jason prader Google
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What does an air intake resonator do?
Air intake resonators help an engine run quietly and efficiently. (Thinkstock/Comstock/Getty Images)

Many car enthusiasts believe that air intake resonators are simply there to muffle the loud noise made by the engines of many old cars. For this reason, many people simply discard resonators when they are trying to spruce up their old cars to retain the authentic sound of the old engine in action. Although resonators do dampen the engine sound to a degree, this is not their primary function. Resonators fulfil crucial functions within an engine’s intake system and can also significantly increase the amount of horsepower available.


An air intake resonator is an expansive chamber within a car’s intake pipe. There are two main types of air intake resonators: in-line resonators, which are open chambers fitted to the intake tube and side-branch resonators, which are linked to the tube through a channel or duct. Depending on the design and manufacturer, a resonator may come fitted with a plate or baffle.

Pressure harmonics

Pressure wave harmonics occur when the cylinder head intake port receives air through an open valve when a car is in motion. When this valve shuts, the rush of air collides with the cylinder head, causing the air to condense and bounce back. The wave of pressure continues to travel backwards towards the first cylinder. This process is known as the first harmonic. This harmonic process will repeat three or four more times, building air pressure in the process, before the valve opens again and releases the pressure. Intake resonators are acoustic devices designed to inhibit these pressure wave harmonics.


Air pressure that bounces back from a car’s engine into the intake tube does not travel in a single pulse motion as it would with single intake runners. With air intake resonators, there are multiple pistons present that emit pressure waves at set intervals. Some of these waves bounce back into the engine while others rebound outwards. This creates an area of high pressure in the intake tube that restricts the amount of airflow available through the RPM (revs per minute) spectrum.


The addition of a resonator expansion chamber causes air emerging from the engine to slow down. This inhibits much of the airflow’s force and reduces the pressure wave reversion significantly. The reduction in the pace of the air allows new air to move towards the engine without having to battle through reversion waves as it travels. This process allows the waves to use up most of their energy, resulting in a reduction of intake noise from the engine. The resonator thus makes the engine run more quietly and more efficiently.

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