World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0000618731
Reproduction Date:

Title: Muffler  
Author: World Heritage Encyclopedia
Language: English
Subject: Glasspack, Articles for deletion/Glasspacks, Bōsōzoku, Baling wire, Marvin Heemeyer
Collection: 1897 Introductions, Exhaust Systems, Noise Reduction, Vehicle Parts
Publisher: World Heritage Encyclopedia


Muffler (silver) and exhaust pipe on a Ducati 695 motorcycle

A muffler (silencer in English) is a device for reducing the amount of noise emitted by the exhaust of an internal combustion engine.


  • History 1
  • Description 2
  • Trade-off between power increase and noise reduction 3
  • References 4
  • External links 5


The US Patent for an ‘Exhaust muffler for engines’ was awarded to Milton O. Reeves and Marshall T. Reeves of Columbus, Indiana of the Reeves Pulley Company on 11 May 1897. US Patent Office application № 582485 states that they “have invented certain new and useful Improvements in Exhaust-Mufflers for engines”.[1]


Dual tailpipes attached to the muffler on a passenger car

Mufflers are installed within the exhaust system of most internal combustion engines, although the muffler is not designed to serve any primary exhaust function. The muffler is engineered as an acoustic soundproofing device designed to reduce the loudness of the sound pressure created by the engine by way of acoustic quieting. The majority of the sound pressure produced by the engine is emanated out of the vehicle using the same piping used by the silent exhaust gases absorbed by a series of passages and chambers lined with roving fiberglass insulation and/or resonating chambers harmonically tuned to cause destructive interference wherein opposite sound waves cancel each other out. An unavoidable side effect of muffler use is an increase of back pressure which decreases engine efficiency. This is because the engine exhaust must share the same complex exit pathway built inside the muffler as the sound pressure that the muffler is designed to mitigate.

Some vehicle owners remove or install an aftermarket muffler when engine tuning in order to increase power output or reduce fuel consumption because of economic or environmental concerns, recreational pursuits such as motorsport and hypermiling and/or for personal aesthetic acoustical preferences. Although the legality of altering a motor vehicle's OEM exhaust system varies by jurisdiction, in most developed parts of the world, modification of a vehicle's exhaust system is usually highly regulated if not strictly prohibited.

A muffler on a large diesel-powered truck

Trade-off between power increase and noise reduction

When the flow of exhaust gases from the engine to the atmosphere is obstructed to any degree, back pressure arises and the engine's efficiency, and therefore power, is reduced. Performance-oriented mufflers and exhaust systems thus strive to minimize back pressure by employing numerous technologies and methods to attenuate the sound. For the majority of such systems, however, the general rule of “more power, more noise”[2] applies. Several such exhaust systems that utilize various designs and construction methods:

  • Vector muffler - for larger diesel trucks, uses many concentric cones, or for performance automotive applications, using angled baffles to cause exhaust impulses to cancel each other out.
  • Spiral baffle muffler - for regular cars, uses a spiral-shaped baffle system[3]
  • Aero turbine muffler - creates partial vacuums at carefully spaced out time intervals to create negative back pressure, effectively ‘sucking’ the exhaust out of the combustion cylinders[4]


  1. ^ "Exhaust Muffler For Engines Muffler Patent". Google. Retrieved 22 June 2014. 
  2. ^ "Exhaust Theory". NSX Prime. Retrieved 22 June 2014. 
  3. ^ "Spiral Turbo Specialties:". Spiral Turbo Specialties. Retrieved 22 June 2014. 
  4. ^ "Aero Turbine Series Performance Exhaust Mufflers". Pickup Specialties. Retrieved 22 June 2014. 

External links

  • Howstuffworks: "How Mufflers Work"
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.