knock, engine (pre-ignition or pinking) Metallic noise produced in an internal combustion engine, caused by detonation of part of the compressed fuel-air mixture before a spark from the spark plug ignites the remainder. It lowers the efficiency of the engine but can be overcome by adding an anti-knocking agent to the fuel. The traditional additive is lead(IV) tetraethyl, but because this compound releases lead into the atmosphere and thereby contributes to pollution, its use declined with the introduction of unleaded petrol.
More From encyclopedia.com
Internal-combustion Engine , Internal-Combustion Engine The invention and development of the internal-combustion engine in the nineteenth century has had a profound impact on hum… Diesel Engine , diesel engine, type of internal-combustion engine invented by the German engineer Rudolf Diesel and patented by him in 1892. Although his engine was… Jet Engine , A jet engine is a heat engine that is propelled in a forward direction as the result of the escape of hot gases from the rear of the engine. In an ai… Jet Propulsion , jet propulsion, propulsion of a body by a force developed in reaction to the ejection of a high-speed jet of gas. Jet Propulsion Engines The four bas… Engine , engine Machine that produces useful energy of motion from some other form of energy. The term is usually restricted to combustion engines, which burn… Steam engine , Steam Engine History The workings of a steam engine Resources A steam engine is a machine that converts the heat energy of steam into mechanical ener…
About this article
Updated About encyclopedia.com content Print Article
You Might Also Like