On May 11, 1897, Reeves Pulley's Milton O. Reeves and Marshall T. Reeves of Columbus, Indiana, received the US patent "Engine Exhaust Muffler." U.S. Patent Office Application No. 582485 claims that they "invented some new and useful improvements to exhaust mufflers for engines."
Dual tailpipes attached to the muffler on a passenger car A CRX muffler detached from the car
The muffler is installed in the exhaust system of most internal combustion engines, although the muffler is not designed for any major exhaust function. The silencer is designed as an acoustic soundproofing device designed to reduce the sound pressure loudness produced by the engine by acoustic mute. Most of the sound pressure generated by the engine is emitted from the vehicle through the same pipes used by the silent exhaust gas. The emitted noise is reduced by a series of channels and chambers lined with roving fiberglass insulation and/or resonant cavities that are harmonically tuned to create destructive interference, with the opposite acoustic waves canceling each other out.
The inevitable side effect of muffler use is increased back pressure, which reduces engine efficiency. This is because the engine exhaust must share the same complex exit pathway built into the muffler as the muffler is designed to mitigate the sound pressure.
Some owners remove or install aftermarket mufflers during engine tuning to increase power output or reduce fuel consumption due to economic or environmental issues, recreational activities, etc.
Although the legality of altering a motor vehicle's OEM exhaust system varies by jurisdiction, in many developed parts of the world, modification of a vehicle's exhaust system is usually highly regulated if not strictly prohibited.
There are 2 main types of performance mufflers based on the installation type.
• Vehicle-specific. These mufflers are manufactured for specific vehicle applications and can be directly replaced with an inventory muffler. They will work on the vehicle in the right way and use the factory installation point of the inventory muffler.
• Dimension-specific or universal. To select the appropriate universal muffler for a particular vehicle application, the exhaust (inlet, outlet, muffler diameter) must be measured and then selected from the muffler that corresponds to these characteristics.
Aftermarket mufflers usually feature different pitch and may alter the way vehicle performs due to back pressure decrease.
A muffler on a large diesel-powered truck