Muffler

From Wikipedia, the free encyclopedia

This article is about the engine piece. For the piece of clothing, see Scarf. For a muffler/silencer as fitted to a gun, see Suppressor.

Muffler and exhaust pipe on a Ducati 695

A muffler (North America and Australia) or silencer (outside North America) is a device for reducing the amount of noise emitted by a machine such as an internal combustion engine or a gun. The first was invented by Hiram Percy Maxim to silence firearms. When used on internal combustion engines, the engine exhaust blows out through the muffler.

[edit] Description

Mufflers are typically installed along the exhaust pipe of the engine. They usually contain a series of baffles to absorb sound, although the majority of the noise reduction is not through absorption but through destructive interference in the muffler itself. The muffler accomplishes this with a resonating chamber, which is specifically designed such that opposite sound waves are likely to collide, canceling each other out. They are a common piece of equipment on automobiles, usually slung under the rear of a car, but many diesel-powered semi trucks have large mufflers mounted vertically behind the cab.

Catalytic converters also often have a muffling effect.

[edit] Advantages & Disadvantages

While the goal is to absorb energy that would otherwise be released as sound into the environment, mufflers do force engines to work somewhat harder pushing exhaust gas through them. Therefore, it is a common engine tuning practice to replace stock mufflers with versions that require less energy to force the gas through (usually described as lowering the "backpressure"). Such accessory mufflers can often increase a vehicle's power and fuel efficiency, but usually at the cost of less effective noise suppression.

Mufflers that reduce backpressure were invented in the late 20th century, and resulted in increased engine efficiency, performance, power output, and simultaneously decreased overall wear and tear on the engines' components, as well as sound to levels in compliance with the law.