Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the imperial horsepower, which is about 745.7 watts, and the metric horsepower, which is approximately 735.5 watts.
A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high 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 Stirling engine for niche applications. 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.
The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. The concept was proven by German engineer Felix Wankel, followed by a commercially feasible engine designed by German engineer Hanns-Dieter Paschke. The Wankel engine's rotor, which creates the turning motion, is similar in shape to a Reuleaux triangle, with the sides having less curvature. The rotor spins inside a figure-eight-like epitrochoidal housing around a fixed-toothed gearing. The midpoint of the rotor moves in a circle around the output shaft, rotating the shaft via a cam.
A cubic centimetre is a commonly used unit of volume that corresponds to the volume of a cube that measures 1 cm × 1 cm × 1 cm. One cubic centimetre corresponds to a volume of one millilitre. The mass of one cubic centimetre of water at 3.98 °C is almost equal to one gram.
A straight-four engine is a four-cylinder piston engine where cylinders are arranged in a line along 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 Jaguar XK is an inline 6-cylinder dual overhead camshaft (DOHC) engine produced by Jaguar Cars between 1949 and 1992. Introduced as a 3.4-litre, it earned fame on both the road and track, being produced in five displacements between 2.4 and 4.2-litres for Jaguar passenger cars, with other sizes being made by Jaguar and privateers for racing. A de-rated version was also used in certain military vehicles built by Alvis and Daimler.
The Rover V8 engine is a compact OHV V8 internal combustion engine with aluminium cylinder block and cylinder heads, designed and produced by Rover in the United Kingdom, based on a General Motors engine. 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 Giampaolo 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 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.
The Chrysler Hemi engines, known by the trademark Hemi or HEMI, are a series of American V8 gasoline engines built by Chrysler with overhead valve hemispherical combustion chambers. Three different types of Hemi engines have been built by Chrysler for automobiles: the first from 1951 to 1958, the second from 1964 to 1971, and the third from 2003 to 2024. Although Chrysler is most identified with the use of "Hemi" as a marketing term, many other auto manufacturers have incorporated similar designs. The engine block and cylinder heads were cast and manufactured at Indianapolis Foundry.
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.
A motorized bicycle is a bicycle with an attached motor or engine and transmission used either to power the vehicle unassisted, or to assist with pedalling. Since it sometimes retains both pedals and a discrete connected drive for rider-powered propulsion, the motorized bicycle is in technical terms a true bicycle, albeit a power-assisted one. Typically they are incapable of speeds above 52 km/h (32 mph), however in recent years larger motors have been built, allowing bikes to reach speeds of upwards of 72 km/h.
Stroke ratio, today universally defined as bore/stroke ratio, is a term to describe the ratio between cylinder bore diameter and piston stroke length in a reciprocating piston engine. 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 Mercedes Benz M180 Engine was a 2.2 L; 134.0 cu in (2,196 cc) single overhead camshaft inline-6 cylinder engine introduced at the Frankfurt Motor Show in April 1951 to power the company's new 220 (W187). It was the first engine with a cylinder bore greater than its stroke that Mercedes had installed in a production car, while using a reverse-flow cylinder head.
Austro Engine is an Austrian manufacturer of aircraft engines based at Wiener Neustadt in Lower Austria.
