Petrol engine


Petrol engine

A Petrol engine or Gasoline engine is an internal combustion engine with spark-ignition designed to run on petrol (gasoline) and similar volatile fuels. It differs from a diesel engine in the method of mixing the fuel and air, and in the fact that it uses spark plugs. In a diesel engine, merely the air is compressed, and the fuel is injected at the end of the compression stroke. In a petrol engine, the fuel and air are pre-mixed before compression injection. Pre-mixing of fuel and air allows a petrol engine to run at a much higher speed than a diesel, but severely limits their compression, and thus efficiency .

Applications

Petrol engines have many applications, including:

* Motor cars
* Motorcycles
* Aircraft
* Motorboats
* Small machines, such as lawn mowers, chainsaws and portable Engine-generators

Design

Working cycles

Petrol engines may run on the four-stroke cycle or the two-stroke cycle. For details of working cycles see:

* Four-stroke cycle
* Two-stroke cycle
* Wankel engine

Cylinder arrangement

Common cylinder arrangements are from 1 to 6 cylinders in-line or from 2 to 16 cylinders in V-formation. Alternatives include Rotary and Radial Engines the latter typically have 7 or 9 cylinders in a single ring, or 10 or 14 cylinders in two rings.

Cooling

Petrol engines may be air-cooled, by fins on the cylinders, or liquid-cooled, by a water jacket and radiator. The coolant was formerly water but is now usually a mixture of water and ethylene glycol. This mixture has a lower freezing-point and a higher boiling-point than pure water. In addition, the cooling system is usually slightly pressurized to minimise evaporation of coolant.

Compression ratio

The compression ratio is the ratio between the cylinder volumes at the beginning and end of the compression stroke. Broadly speaking, the higher the compression ratio, the higher the efficiency of the engine. However, compression ratio has to be limited to avoid pre-ignition of the fuel-air mixture which would cause engine knocking and damage to the engine. Modern motor-car engine generally have compression ratios of between 9:1 and 10:1, but this can go up to 11 or 12:1 for high-performance engines that run on, say, 98 R0N (93 AKI, US Premium- or European Super-grade) petrol. In the 1950s, with low-octane fuel and less well-designed cylinder heads, compression ratios were between 6.5:1 and 7:1. Old tractor engines running on tractor vaporising oil might have compression ratios as low as 4.5:1 but modern tractors have diesel engines.

Ignition

:"main article Ignition system"Petrol engines use spark ignition and high voltage current for the spark may be provided by a magneto or an ignition coil. In modern car engines the ignition timing is managed by an electronic Engine Control Unit.

Future

Concerns about global warming and air pollution have put a question mark over the future of the petrol engine. Much has been done to improve its fuel efficiency and reduce emissions and this has bought it more time.

ources

* Linked Wikipedia articles

External Links

* [http://www.kenneyjacob.com/2008/08/27/petrol-or-diesel-how-to-decide-when-you-buy-a-car/ Petrol or Diesel - How to decide when you buy a car]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • petrol engine — Gasoline engine Gas o*line en gine, or Gasolene engine Gas o*lene en gine . (Mach.) A kind of internal combustion engine; in British countries called usually {petrol engine}. [Webster 1913 Suppl.] …   The Collaborative International Dictionary of English

  • petrol engine — noun an internal combustion engine that burns gasoline; most automobiles are driven by gasoline engines • Syn: ↑gasoline engine • Hypernyms: ↑internal combustion engine, ↑ICE • Hyponyms: ↑put put • …   Useful english dictionary

  • petrol engine — gasoline engine, engine fueled by petroleum …   English contemporary dictionary

  • petrol- — a combining form of petrol meaning driven by electric motors powered by current from a generator which is driven by a petrol engine, as in petrol lamp …   Australian English dictionary

  • Engine braking — is where the retarding forces within an engine are used to slow a vehicle down, as opposed to using an external braking mechanism, for example friction brakes or magnetic brakes. The term is often confused with several other types of braking,… …   Wikipedia

  • Engine — This article is about a machine to convert energy into useful mechanical motion. For other uses of engine, see Engine (disambiguation). For other uses of motor, see Motor (disambiguation). A V6 internal combustion engine from a Mercedes car An… …   Wikipedia

  • engine — n. motor 1) to crank, start; operate, run; rev up an engine 2) to lubricate; repair; service; tune up an engine 3) to cut, kill, turn off; warm up an engine 4) an air cooled; aircraft; diesel; donkey; electric; internal combustion; jet; radial;… …   Combinatory dictionary

  • petrol — noun (BrE) ⇨ See also ↑gas, ↑gasoline ADJECTIVE ▪ lead free, ultra low sulphur, unleaded ▪ The price of a litre of unleaded petrol has risen. ▪ leaded, lead …   Collocations dictionary

  • Engine displacement — One complete cycle of a four cylinder, four stroke engine. The volume displaced is marked in orange. Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top… …   Wikipedia

  • Engine knocking — Pinging redirects here. For other uses, see Ping (disambiguation). Knocking (also called knock, detonation, spark knock, pinging or pinking) in spark ignition internal combustion engines occurs when combustion of the air/fuel mixture in the… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.