Turbocharger

A turbocharger, or turbo (colloquialism), from the Latin "turbō, turbin-" ("a spinning thing") is a forced induction device used to allow more power to be produced by an engine of a given size. A turbocharged engine can be more powerful and efficient than a naturally aspirated engine because the turbine forces more air, and proportionately more fuel, into the combustion chamber than atmospheric pressure alone.

Turbochargers were originally known as turbosuperchargers when all forced induction devices were classified as superchargers; nowadays the term "supercharger" is usually applied to only mechanically driven forced induction devices. The key difference between a turbocharger and a conventional supercharger is that the latter is mechanically driven from the engine, often from a belt connected to the crankshaft, whereas a turbocharger is powered by a turbine that is driven by the engine's exhaust gas. Compared to a mechanically-driven supercharger, turbochargers tend to be more efficient but less responsive. Twincharger refers to an engine which has both a supercharger and a turbocharger.

Turbos are commonly used on truck, car, train, aircraft, and construction equipment engines. Turbos are popularly used with Otto cycle and Diesel cycle internal combustion engines. They have also been found useful in automotive fuel cells.

Forced induction dates from the late 19th century, when Gottlieb Daimler patented the technique of using a gear-driven pump to force air into an internal combustion engine in 1885. The turbocharger was invented by Swiss engineer Alfred Büchi (1879-1959), the head of diesel engine research at Gebruder Sulzer engine manufacturing company in Winterhur, who received a patent in 1905 for using a compressor driven by exhaust gasses to force air into an internal combustion engine to increase power output but it took another 20 years for the idea to come to fruition. During World War I French engineer Auguste Rateau fitted turbochargers to Renault engines powering various French fighters with some success. In 1918, General Electric engineer Sanford Alexander Moss attached a turbo to a V12 Liberty aircraft engine. The engine was tested at Pikes Peak in Colorado at 14,000 ft (4,300 m) to demonstrate that it could eliminate the power loss usually experienced in internal combustion engines as a result of reduced air pressure and density at high altitude. General Electric called the system turbosupercharging. At the time, all forced induction devices were known as superchargers, however more recently the term "supercharger" is usually applied to only mechanically-driven forced induction devices.

Turbochargers were first used in production aircraft engines such as the Napier Lioness in the 1920s, although they were less common than engine-driven centrifugal superchargers. Ships and locomotives equipped with turbocharged Diesel engines began appearing in the 1920s. Turbochargers were also used in aviation, most widely used by the United States, which led the world in the technology due to General Electric's early start. During World War II, notable examples of US aircraft with turbochargers include the B-17 Flying Fortress, B-24 Liberator, P-38 Lightning, and P-47 Thunderbolt. The technology was also used in experimental fittings by a number of other manufacturers, notably a variety of Focke-Wulf Fw 190 models, but the need for advanced high-temperature metals in the turbine kept them out of widespread use.