Wikia

Tractor & Construction Plant Wiki

Petrol engine

Talk0
15,044pages on
this wiki
45px-Gnome-dev-camera.svg
This article is without an Image.

You can help Tractor & Construction Plant Wiki by adding a suitable Image to it.
This template will categorize any article that includes it in to Category:Image required.

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. The pre-mixing was formerly done in a carburettor but now (except in the smallest engines) it is done by electronically-controlled fuel 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 .

ApplicationsEdit

Petrol engines have many applications, including:

DesignEdit

Working cyclesEdit

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

Cylinder arrangementEdit

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.

CoolingEdit

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 ratioEdit

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.

IgnitionEdit

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 (ECU).

FutureEdit

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.

See alsoEdit

SourcesEdit

  • Wikipedia as basic explanation of term
  • Linked Tractor Wiki articles

External LinksEdit

Smallwikipedialogo This page uses some content from Wikipedia. The original article was at Petrol engine. The list of authors can be seen in the page history. As with Tractor & Construction Plant Wiki, the text of Wikipedia is available under the Creative Commons by Attribution License and/or GNU Free Documentation License. Please check page history for when the original article was copied to Wikia

Around Wikia's network

Random Wiki