Petrol engine

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Petrol engine

:Main article: Internal combustion engine
Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs in a combustion chamber inside and integral to the engine. In an internal combustion engine it is always the expansion of the high temperature and pressure gases that are produced by the combustion which apply force to the movable component of the engine, such as...

A Petrol engine or Gasoline engine is an internal combustion engine

Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs in a combustion chamber inside and integral to the engine. In an internal combustion engine it is always the expansion of the high temperature and pressure gases that are produced by the combustion which apply force to the movable component of the engine, such as...
with spark-ignition designed to run on petrol (gasoline

Gasoline

File:GasCan.jpgGasoline or petrol is a petroleum-derived liquid mixture, primarily used as fuel in internal combustion engines.It consists mostly of aliphatic hydrocarbons, enhanced with iso-octane or the aromatic hydrocarbons toluene and benzene to increase its octane rating....
) and similar volatile fuels. It differs from a diesel engine

Diesel engine

A diesel engine is an internal combustion engine which operates using the diesel cycle . Diesel engines have the highest thermal efficiency compared to any internal combustion or external combustion engine....
in the method of mixing the fuel and air, and in the fact that it uses spark plug

Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed Particulate gasoline by means of an electric spark....
s.

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Encyclopedia

Internal combustion engine

Gasoline

Diesel engine

Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed Particulate gasoline by means of an electric spark....
s. 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 usually pre-mixed before compression. The pre-mixing was formerly done in a carburetor

Carburetor

A carburetor or carburettor , is a device that blends Earth's atmosphere and fuel for an internal combustion engine. It was invented by Karl Benz before 1885 and patented in 1886....
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.

The first fast-running petrol engine was invented by the German automobile pioneer Gottlieb Daimler

Gottlieb Daimler

Gottlieb Wilhelm Daimler was an engineer, industrial designer and industrialist, born in Schorndorf , in what is now the Germany. He was a pioneer of internal-combustion engines and automobile development....
.

Applications

Petrol engines have many applications, including:

Motor cars
Automobile

An automobile or motor car is a wheeled motor vehicle for transportation passengers, which also carries its own car engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally f...
Motorcycle
Motorcycle

A motorcycle is a Single track, two-wheeled motor vehicle powered by an Motorcycle engine. Motorcycles vary considerably depending on the task for which they are designed, such as Touring motorcycle travel, navigating Naked bike, Cruiser , Motorcycle sport and Motorbike racing, or off-road conditions....
s
Aircraft
Aircraft

An aircraft is a vehicle which is able to flight by being supported by the air, or in general, the atmosphere, of a planet. Examples include balloons, airplanes and helicopters....
Motorboat
Motorboat

A motorboat is a Boat propelled by an internal combustion engine or electric motor driving a pump jet or a propeller. The International Regulations for Preventing Collisions at Sea defines a "power driven vessel" as any vessel propelled by machinery and even a sailboat while it has an engine running is technically a power driven ves...
s
Small machines, such as lawn mower
Lawn mower

A lawn mower or lawnmower is a machine that has one or more revolving blades to cut a lawn at an even length.Lawn mowers employing a blade that rotates about a vertical axis are known as rotary mowers, while those employing a blade assembly that rotates about a horizontal axis are known as cylinder or reel mowers....
s, chainsaw
Chainsaw

A chainsaw is a portable mechanical, motorized saw. It is used in logging activities such as felling, limbing, and Log bucking; by tree surgeons to fell trees and remove branches and foliage; to fell snags and assist in cutting firebreaks in wildland fire suppression, and to harvest Wood fuel#Firewood....
s and portable Engine-generator
Engine-generator

An engine-generator is the combination of an electrical generator and an engine mounted together to form a single piece of equipment. This combination is also called an engine-generator set or a gen-set....
s

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
Four-stroke cycle

Today, internal combustion engines in automobile, trucks, motorcycles, aircraft, construction machinery and many others, most commonly use a four-stroke cycle....
Two-stroke cycle
Two-stroke cycle

The two-stroke internal combustion engine differs from the more common four-stroke engine by completing the same cycle in only two strokes of the piston, rather than four....
Wankel engine
Wankel engine

The Wankel engine is a type of internal combustion engine which uses a rotary combustion engine to convert pressure into a rotating motion instead of using reciprocating piston engine....

Cylinder arrangement

Common cylinder arrangements are from 1 to 6 cylinders in-line

Straight engine

Usually found in 4- and 6-cylinder configurations, the straight engine is an internal-combustion engine with all cylinders aligned in one row, with no or only minimal offset....
or from 2 to 16 cylinders in V-formation

V engine

A V engine is a common engine configuration for an internal combustion engine. The Cylinder_%28engine%29 and pistons are aligned, in two separate planes, so that they appear to be in a "V" when viewed along the axis of the crankshaft....
. Alternatives include Rotary

Rotary engine

The 'rotary engine' was an early type of internal-combustion engine in which the crankshaft remained stationary and the entire cylinder block rotated around it....
and Radial Engines

Radial engine

The radial engine is a reciprocating engine internal combustion engine engine configuration in which the cylinder s point outward from a central crankshaft like the spokes on a wheel....
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

Air-cooled engine

Air-cooled engines rely on the circulation of air directly over hot parts of the engine to cool them....
, by fins on the cylinders, or liquid-cooled, by a water jacket

Water jacket

A water jacket is a water-filled void surrounding a device, typically a metal sheath having intake and outlet vents to allow water to be pumped through the void....
and radiator

Radiator (engine cooling)

Radiators are used for cooling internal combustion engines, chiefly in #Automobiles but also in #Aircraft, railway locomotives, motorcycles, stationary generating plant or any similar use of such an engine....
. The coolant

Antifreeze

Antifreeze is a cryoprotectant used in internal combustion engines, and for many other heat transfer applications, such as HVAC chillers and solar water heaters....
was formerly water but is now usually a mixture of water and ethylene glycol

Ethylene glycol

Ethylene glycol is an alcohol with two -OH groups , a chemical compound widely used as an automobile antifreeze. In its pure form, it is an odorless, colorless, syrupy, sweet tasting, toxic liquid....
. 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

Compression ratio

The compression ratio of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber; from its largest capacity to its smallest capacity....
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

Engine knocking

Knocking in spark-ignition internal combustion engines occurs when combustion of the air-fuel ratio in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front....
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 higher octane fuel.

Ignition

Main article: Ignition system
Ignition system

An ignition system is a system for igniting a fuel-air mixture. It is best known in the field of internal combustion engines but also has other applications, e.g....

Petrol engines use spark ignition and high voltage

High voltage

The term high voltage characterizes electrical circuits, in which the voltage used is the cause of particular safety concerns and insulation requirements....
current for the spark may be provided by a magneto

Magneto (electrical)

This article is about an electrical generator component used in engine and some old telephones. For other uses of the term, see Magneto . A magneto is a device used in the ignition system of gasoline-powered internal combustion engines to provide pulses of high voltage electrical power to the spark plugs....
or an ignition coil

Ignition coil

An ignition coil is an induction coil in an automobile's ignition system which transformer the Car battery 12 volts to the thousands of volts needed to spark the spark plugs....
. In modern car engines the ignition timing

Ignition timing

Ignition timing, in a spark ignition internal combustion engine, is the process of setting the time that a spark will occur in the combustion chamber relative to piston position and crankshaft angular velocity....
is managed by an electronic Engine Control Unit

Engine Control Unit

An engine control unit is an electronic control unit which controls various aspects of an internal combustion engine's operation. The simplest ECUs control only the quantity of fuel injected into each cylinder each engine cycle....
.