![]() ![]() The German Luftwaffe also had supplies of a similar fuel. Military use of high-octane fuels began in early 1940 when 100-octane fuel was delivered to the British Royal Air Force fighting in World War II. The development of 100-octane aviation fuel, pioneered in the USA in the 1930s, enabled the use of higher boost pressures to be used on high-performance aviation engines and was used to vastly increase the power output for several speed record airplanes. As a result, the amount of boost supplied by the superchargers could be increased, resulting in an increase in engine output. Electric superchargers use an electric motor rather than a mechanical power source.įuels with a higher octane rating are better able to resist auto ignition and detonation.Variable speed ratio, variable ratio centrifugal.Belt (V-belt, synchronous belt, flat belt).Other supercharger manufacturers have produced blowers rated up to 16–71.ĭynamic compressors rely on accelerating the air to high speed and then exchanging that velocity for pressure by diffusing or slowing it down.Ĭommon methods of driving a supercharger include: However, because 6–71 is the engine's designation rather than that of the blower, the actual displacement of the blower is less for example, a 6–71 blower pumps 339 cu in (5.6 L) per revolution. The 6–71 blower, for example, is designed to scavenge six cylinders of 71 cu in (1.2 L) each, resulting in an engine with a total displacement of 426 cu in (7.0 L)). The GMC rating is based on how many two-stroke cylinders - and the size of those cylinders - that it is designed to scavenge, with GMC's model range including 2–71, 3–71, 4–71 and 6–71 blowers. In the case of the Roots blower, the GMC rating pattern is typical. The rating system for positive-displacement superchargers is usually based on their capacity per revolution. Other types include the rotary-screw, sliding vane and scroll-type superchargers. The most common type of positive-displacement superchargers is the Roots-type supercharger. Positive displacement pumps deliver a nearly fixed volume of air per revolution of the compressor (except for leakage, which typically has a reduced effect at higher engine speeds). Internals of a rotary-screw (Lysholm) supercharger Lysholm-style blowers (a rotary-screw design) can be nearly as efficient as dynamic superchargers over a narrow range of load/speed/boost, for which the system must be specifically designed. Roots blowers (a positive displacement design) tend to be only 40–50% efficient at high boost levels, compared with 70-85% for dynamic superchargers. Another family of supercharger, albeit rarely used, is the pressure wave supercharger. Positive displacement superchargers deliver an almost constant level of boost pressure increase at all engine speeds (RPM), while dynamic superchargers cause the boost pressure to rise exponentially with RPM (above a certain RPM threshold). There are two main families of superchargers defined according to the method of gas transfer: positive displacement and dynamic superchargers. Supercharging is less commonly used in the 21st century, as manufacturers have shifted to turbochargers to reduce fuel consumption and increase power outputs. In piston engines used by aircraft, supercharging was often used to compensate for the lower air density at high altitudes. ![]() The first supercharged engine was built in 1878, with usage in aircraft engines beginning in the 1910s and usage in car engines beginning in the 1920s. However, up until the mid-20th century, a turbocharger was called a "turbosupercharger" and was considered a type of supercharger. The current categorisation is that a supercharger is a form of forced induction that is mechanically powered (usually by a belt from the engine's crankshaft), as opposed to a turbocharger, which is powered by the kinetic energy of the exhaust gasses. In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement. Roots-type supercharger (right) on a 2006 GM Ecotec LSJ four-cylinder engine ![]()
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