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Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as a loose indicator of the power an engine might be capable of producing and the amount of fuel it should be expected to consume. For this reason displacement is one of the measures often used in advertising, as well as regulating, motor vehicles.
It is usually expressed using the metric units of cubic centimetres (cc or cm3, equivalent to millilitres) or litres (l or L), or –particularly in the United States –cubic inches (CID, cu in, or in3).
The overall displacement for a typical reciprocating piston engine is calculated by multiplying together three values; the distance travelled by the piston (the stroke length ), the circular area of the cylinder (the bore ), and the number of cylinders that comprise the whole engine.
The formula is:
Using this formula for non-typical types of engine, such as the Wankel design and the oval-piston type used in Honda NR motorcycles, can sometimes yield misleading results when attempting to compare engines. Manufacturers and regulators may develop and use specialised formulae to determine a comparative nominal displacement for variant engine types.
In several countries fees and taxes levied on road vehicles by transport authorities are scaled in proportion to engine displacement. In countries where this is practised, vehicle manufacturers often seek to increase power output through higher-revving engines or turbocharging, instead of increasing the displacement.
Examples of countries where the road taxes are based upon engine displacement:
Wankel engines are able to produce higher power levels for a given displacement. Therefore, they are generally taxed as 1.5 times[ citation needed ] their stated physical displacement (1.3 litres becomes effectively 2.0, 2.0 becomes effectively 3.0), although actual power outputs can be higher than suggested by this conversion factor.
Historically, many car model names have included their engine displacement. Examples include the 1923–1930 Cadillac Series 353 (powered by a 353 Cubic inch/5.8-litre engine), and the 1963–1968 BMW 1800 (a 1.8-litre engine) and Lexus LS 400 with a 3,968 cc engine. This was especially common in US Muscle Cars, like the Ford Mustang Boss 302 and 429, and later GT 5.0L, The Plymouth Roadrunner 440, and the Chevrolet Chevelle SS 396 and 454.
However, trends towards turbocharging and hybrid/electric drivetrains since 2010 have resulted in far fewer model names being based on the engine displacement.
A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types. The main types are: the internal combustion engine, used extensively in motor vehicles; the steam engine, the mainstay of the Industrial Revolution; and the niche application Stirling engine. Internal combustion engines are further classified in two ways: either a spark-ignition (SI) engine, where the spark plug initiates the combustion; or a compression-ignition (CI) engine, where the air within the cylinder is compressed, thus heating it, so that the heated air ignites fuel that is injected then or earlier.
A straight-four engine is a four-cylinder piston engine where cylinders are arranged in a line along a common crankshaft.
The straight-six engine is an internal combustion engine, with six cylinders mounted in a straight line along the crankcase with all the pistons driving a common crankshaft.
The tax horsepower or taxable horsepower was an early system by which taxation rates for automobiles were reckoned in some European countries such as Britain, Belgium, Germany, France and Italy; some US states like Illinois charged license plate purchase and renewal fees for passenger automobiles based on taxable horsepower. The tax horsepower rating was computed not from actual engine power but by a mathematical formula based on cylinder dimensions. At the beginning of the twentieth century, tax power was reasonably close to real power; as the internal combustion engine developed, real power became larger than nominal taxable power by a factor of ten or more.
The Rover V8 engine is a compact V8 internal combustion engine with aluminium cylinder heads and cylinder block, originally designed by General Motors and later re-designed and produced by Rover in the United Kingdom. It has been used in a wide range of vehicles from Rover and other manufacturers since its British debut in 1967.
After an early flirtation with V-twin engines, Mazda's small cars of the 1960s were powered by OHV straight-2 and straight-4 engines. This family lasted from 1961 until the mid-1970s. Today, Mazda's keicars use Suzuki engines. It was produced at the Hiroshima Plant in Hiroshima, Japan.
The Mazda Wankel engines are a family of Wankel rotary combustion car engines produced by Mazda.
The Offenhauser Racing Engine, or Offy, is a racing engine design that dominated American open wheel racing for more than 50 years and is still popular among vintage sprint and midget car racers.
The Lamborghini V8 is a ninety degree (90°) V8 petrol engine designed by Lamborghini in the 1970s for their less-expensive vehicles. It was only the second internal combustion engine ever developed by the company, and first saw production for the 1971 Lamborghini Urraco. It was designed by Gian Paolo Dallara. The all-aluminium alloy engine was introduced as a 2.5-litre variant, displacing 2,463 cc (150.3 cu in), but was expanded, by increasing the piston stroke to a 3.0-litre variant for 1975 - now displacing 2,997 cc (182.9 cu in).
The Lamborghini V12 refers to the flagship V12 engine used by Lamborghini. Lamborghini has had two generations of V12 engines through their history, both of which were developed in-house. The first-generation Lamborghini V12 was a sixty degree (60°) V12 petrol engine designed by Lamborghini, and was the first internal combustion engine ever produced by the firm.
The J-series is Honda's fourth production V6 engine family introduced in 1996, after the C-series, which consisted of three dissimilar versions. The J-series engine was designed in the United States by Honda engineers. It is built at Honda's Anna, Ohio, and Lincoln, Alabama, engine plants.
Italian automobile company Lancia was the first to manufacture cars with V4 and V6 engines in series-production. This started with a number of V4-engine families, that were produced from the 1920s through 1970s.
The Lancia Flat-4 engine is an aluminum, pushrod flat-four (boxer) engine made by Lancia for the Flavia from 1960 through 1984. Though it was a pushrod engine, it was advanced for the time. The pushrod version of the Lancia boxer was only ever used in the Flavia, and its derivatives including the Lancia 2000. In 1976, a new overhead cam engine based on a similar layout was designed and brought into production in 2 and 2.5-litre displacements for the Gamma.
A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are typically two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankels and electric motors, have been used.
In a reciprocating piston engine, the stroke ratio, defined by either bore/stroke ratio or stroke/bore ratio, is a term to describe the ratio between cylinder bore diameter and piston stroke length. This can be used for either an internal combustion engine, where the fuel is burned within the cylinders of the engine, or external combustion engine, such as a steam engine, where the combustion of the fuel takes place outside the working cylinders of the engine.
The Volkswagen air-cooled engine is an air-cooled boxer engine with four horizontally opposed cast-iron cylinders, cast aluminum alloy cylinder heads and pistons, magnesium-alloy crankcase, and forged steel crankshaft and connecting rods.
British Salmson aero-engines refers to a series of small French designed, air-cooled radial aero engine that were produced by British Salmson, under license from Société des Moteurs Salmson, in Great Britain during the late 1920s and 1930s.
Austro Engine is an Austrian manufacturer of aircraft engines based at Wiener Neustadt in Lower Austria.
The Gnome 7 Lambda was a French designed, seven-cylinder, air-cooled rotary aero engine that was produced under license in Britain and Germany. Powering several World War I-era aircraft types it was claimed to produce 80 horsepower (60 kW) from its capacity of 12 litres although recorded figures are lower.