A supercharger (also known as a blower, a positive displacement pump or a centrifugal pumper) is a gas compressor used to pump air into the cylinders of an internal combustion engine. The additional mass of oxygen that is forced into the cylinders allows the engine to burn more fuel, which improves the volumetric efficiency of the engine and makes it more powerful. A supercharger is powered mechanically by belt- or chain-drive from the engine's crankshaft. It is similar in purpose to the closely related turbocharger, but a turbocharger is powered by the flow of the engine's exhaust gases driving a turbine. Superchargers may absorb as much as a third of the total crankshaft power of the engine, and in many applications are less efficient than turbochargers. In applications where a massive amount of power is more important than any other consideration, such as top-fuel dragsters and vehicles used in tractor pull competitions, superchargers are extremely common. A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. ... The word cylinder has several meanings. ... A colorized automobile engine An internal combustion engine is a sexy engine that is powered by the expansion of hot combustion products of fuel directly acting within an engine. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... For the workstation, see SGI Fuel. ... Volumetric efficiency in internal combustion engine design refers to the efficiency with which the engine can move the charge into and out of the cylinders. ... Turbocharger Cut-away A turbocharger is a compressor used in internal-combustion engines to increase the power output of the engine by increasing the mass of oxygen entering the engine. ... WWII era steam turbine used for ship propulsion. ... // Mechanical power In physics, power (symbol: P) is the amount of work W done per unit of time t. ... Clocked Speed = 506kph, Kwinana Race Track, W.A., 2005 Top-Fuel Racing refers to a class of drag racing in which the cars are run on 85% nitromethane and about 15% methanol also known as racing alcohol, instead of gasoline. ...

Automobiles

Hot Rod magazine cover, featuring Offenhauser engine with large Roots supercharger (on viewer's right)

1929 "Blower" Bentley from the Ralph Lauren collection. The large "blower" (supercharger) is located at the front, in front of the radiator, and gave the car its name.

In cars, the device is used to increase the "effective displacement" and volumetric efficiency of an engine, and is often referred to as a blower. By pushing the air into the cylinders, it is as if the engine had larger valves and cylinders, resulting in a "larger" engine that weighs less. Turbochargers are more commonly used in this role because they use otherwise "wasted" heat energy instead of using up power from the crank, but the supercharger reacts more quickly to power application and thus outaccelerates a car with the same amount of boost being provided by a turbo. Hot Rod magazine cover, showing supercharged Offy engine. ... Hot Rod magazine cover, showing supercharged Offy engine. ... Download high resolution version (1975x1368, 269 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1975x1368, 269 KB) Wikipedia does not have an article with this exact name. ... Bentleys winged B hood ornament For other uses of Bentley, see Bentley (disambiguation). ... Wikimedia Commons has more media related to: Ralph Lauren Ralph Lauren (born Ralph Lipschitz, October 14, 1939, Bronx, New York) is a world-famous fashion designer. ... Engine displacement is defined as the total volume of air/fuel mixture an engine can draw in during one complete engine cycle; it is normally stated in cubic inches, cubic centimeters, or litres. ... Volumetric efficiency in internal combustion engine design refers to the efficiency with which the engine can move the charge into and out of the cylinders. ...

In 1900 Gottlieb Daimler (of Daimler-Benz / Daimler-Chrysler fame) became the first person to patent a forced-induction system for internal combustion engines. His first superchargers were based on a twin-rotor air-pump design first patented by American Francis Roots in 1860. This design is the basis for the modern Roots type supercharger. 1900 is a common year starting on Monday. ... Gottlieb Daimler (who later teamed up with Karl Benz to form the Daimler-Benz Corporation) is credited with building the first motorcycle in 1885, one wheel in the front and one in the back, although it had a smaller spring-loaded outrigger wheel on each side. ... Daimler-Benz AG was founded on May 1, 1924 by the merger of Benz & Cie. ... DaimlerChrysler AG (Xetra: DCX) , (NYSE: DCX), with headquarters in Stuttgart, Germany and Auburn Hills, Michigan, is a prominent automobile and truck manufacturer, formed in 1998 by the buyout of the Chrysler Corporation (USA) by Daimler-Benz (Germany). ... 1860 is the leap year starting on Sunday. ... The Roots type supercharger is a positive displacement type device that operates by pulling air through a pair of meshing lobes not dissimilar to a set of stretched gears. ...

It wasn't long after its invention before the supercharger was applied to custom racing cars, with the first supercharged production vehicles being built by Mercedes and Bentley in the 1920s. Since then superchargers (as well as turbochargers) have been widely applied to racing and production cars, although their complexity and cost has largely relegated the supercharger to the world of pricey performance cars. This page is about the Mercedes-Benz brand of automobiles and trucks from the DaimlerChrysler automobile manufacturer. ... Bentleys winged B hood ornament For other uses of Bentley, see Bentley (disambiguation). ...

Boosting has made something of a comeback in recent years due largely to the increased quality of the alloys and machining of modern engines. Boosting used to be an effective way to dramatically shorten an engine's life but, today, there is considerable overdesign possible with modern materials and boosting is no longer a serious reliability concern. For this reason boosting is commonly used in smaller cars, where the added weight of the supercharger is smaller than the weight of a larger engine delivering the same amount of power. This also results in better gas mileage, as mileage is often a function of the overall weight of the car and that is based, to some degree, on the weight of the engine.

There are three commonly used types used in today's automotive world: Roots type supercharger, and Eaton or twin-screw type supercharger, and Centrifugal type supercharger. The Roots type supercharger is a positive displacement type device that operates by pulling air through a pair of meshing lobes not dissimilar to a set of stretched gears. ... The twin-screw type supercharger is a positive displacement type device that operates by pulling air through a pair of meshing lobes not dissimilar to a set of stretched gears. ... Cover of Hot Rod magazine showing Ford Flathead V8 engine with centrifugal supercharger (on top) The centrifugal type supercharger is practically identical in operation to a turbocharger, with the exception that instead of exhaust gases driving an impeller, there is only a compressor housing, and that is driven from the...

For example, GM cars use the Eaton-type supercharger in the Chevrolet Monte Carlo SS, Chevrolet Impala SS, Pontiac Bonneville SSEi, Pontiac Grand Prix GTP, and Buick Regal GS. These cars use the venerable GM Series II, or newer Series III 3.8 L V6. General Motors Corporation NYSE: GM, also known as GM, is a United States-based automobile maker with worldwide operations and brands including Buick, Cadillac, Chevrolet, Daewoo, GMC, Holden, Hummer, Opel, Pontiac, Saturn, Saab, and Vauxhall. ... The Chevrolet Monte Carlo is a large coupe version of a sedan model. ... 1968 Chevrolet Impala at the weekly Garden Grove, California car show on April 16, 2004. ... Bonneville has been one of Pontiacs most enduring names, appearing as a high-performance, fuel-injected luxury convertible late in the 1957 model year and lasting until 2005. ... The Grand Prix name has been used on large Pontiac automobiles since 1962. ... The Buick Regal was a mid-sized automobile produced by Buick in the United States between the 1973 and 2004 model years. ... The 3800 family is a large V6 engine used by General Motors. ... The 3800 family is a large V6 engine used by General Motors. ...

Aircraft

A more natural use of the supercharger is with aircraft engines. As an aircraft climbs to higher altitudes the pressure of the surrounding air quickly falls off—at 6000 m (18,000 ft) the air is at half the pressure of sea level. Since the charge in the cylinders is being pushed in by this air pressure it means that the engine will normally produce half-power at full throttle at this altitude. The term aircraft engine, for the purposes of this article, refers to aircraft reciprocating, or rotary, internal combustion engines as opposed to jet engines or turboprops. ... The metre, (symbol: m) is the SI base unit of length. ...

Altitude effects

A supercharger remedies this problem by compressing the air back to sea-level pressures, or even much higher. This can take some effort. On the single-stage single-speed supercharged Rolls Royce Merlin engine for instance, the supercharger uses up about 150 horsepower (100 kW). Yet the benefits are huge, for that 150 horsepower (100 kW) lost, the engine is delivering 1000 hp (750 kW) when it would otherwise deliver 750 hp (500 kW). And while the engine might be fooled into thinking it's at sea level, the airframe is quite aware of the halved air density and the plane thus has half the drag. For this reason supercharged planes fly much faster at higher altitudes. The Merlin is an aircraft engine built during World War II by Rolls-Royce. ... The horsepower (hp) is the name of several non-metric units of power. ... Power kilowatt (symbol: kW) is a unit for measuring power, equal to one thousand watts. ... In physics, the drag equation gives the drag experienced by an object moving through a fluid. ...

A supercharger is only able to supply so much pressure because the compression increases the air temperature and the engine is limited in maximum charge-air temperature before pre-ignition occurs. The boost is typically measured as the altitude at which the supercharger can still supply sea level pressure (100 kPa or 1ooo mbar) and is referred to as the critical altitude. Throughout WWII British superchargers generally had higher critical altitudes than their German counterparts and, when combined with higher octane fuels that the Americans supplied, that allowed for higher boost levels. British engines were generally able to outperform German ones. Knocking (also called pinking or pinging)—technically detonation—in internal combustion engines occurs when fuel in the cylinder is ignited by the firing of the spark plug and smooth burning proceeds but some of the unburned mixture in the combustion chamber explodes before the flame front can reach it, combusting... The pascal (symbol Pa) is the SI unit of pressure. ... A bar (symbol bar) is a unit of pressure. ... German soldiers at the Battle of Stalingrad World War II was the most extensive and costly armed conflict in the history of the world, involving the great majority of the worlds nations, being fought simultaneously in several major theatres, and costing tens of millions of lives. ... Octane is an alkane hydrocarbon with the chemical formula CH3(CH2)6CH3. ...

Altitude efficiency

Below the critical altitude the supercharger is capable of delivering too much boost and must therefore be restricted lest the engine be damaged. Unless other measures are taken, this means that at least some of the power driving the supercharger is wasted. Also, due to the denser air at lower altitudes, the supercharger is not operating at its best efficiency, and this can cause an additional load on the engine.

For the early years of the war this was simply how it was and this led to the seemingly odd fact that many early-war engines actually delivered less power at lower altitudes, because the supercharger was still using up power to compress air that was not delivering any power back. As the war progressed two-speed superchargers were introduced using better controllers and, notably, hydraulic clutches, that allowed the boost to be managed over a wide range of altitudes by operating at low rpm down low and at high rpm at higher altitudes. This generally "flattened out" the power below the critical altitude.

Improving octane rating

In 1940 a batch of 100 octane fuel was delivered from the USA to the RAF. This allowed the boost on Merlin engines to be increased to 48 inHg (160 kPa) and the power to rise by more than 10% (from 1030 to 1160 hp, or 770 to 870 kW). By mid-1940 another increased boost yielded 1310 hp (980 kW). Supercharging, by itself, could not have achieved these improvements, but married with fuel improvements the engine could respond to both. 1940 was a leap year starting on Monday (link will take you to calendar). ... Octane is an alkane hydrocarbon with the chemical formula CH3(CH2)6CH3. ... The Royal Air Force (often abbreviated to RAF) is the air force branch of the UK Armed Forces. ...

Multiple stages

In the 1930s two-speed drives were developed for superchargers. These provided more flexibility for the operation of the aircraft although they also entailed more complexity of manufacturing and maintenance. Ultimately it was found that for most engines (excepting those in high-performance fighters) a single-stage two-speed setup was most suitable.

A final improvement was the use of two compressors in series, which were introduced to solve the pre-ignition problem. Compressing a gas always causes its temperature to rise, and an overcompressed fuel-air mixture may therefore prematurely ignite. In order to avoid pre-ignition the "two stage" design was used. After being compressed "half-way" in the low pressure stage the air flowed through an intercooler radiator where it was partially cooled down before being compressed the rest of the way in the high pressure stage and then aftercooled in another air/air or coolant/air radiator (heat exchanger). At low altitudes one stage could be turned off completely. The two-stage Merlin was losing 400 hp (300 kW) to turn the supercharger but developing between 1500 and 1700 hp (1125 to 1275 kW) at the propeller shaft, depending on model. Knocking (also called pinking or pinging)—technically detonation— in internal combustion engines occurs when fuel in the cylinder is ignited by the firing of the spark plug but burns too quickly, combusting completely before the optimum moment during the compression phase of the four-stroke cycle. ... The gas laws are a set of laws that describe the relationship between absolute temperature (T), pressure (P) and volume (V) of gases. ... An intercooler is a device used on turbocharged and supercharged internal combustion engines to improve the volumetric efficiency and increase the amount of charge in the engine, thereby increasing power. ... A heat exchanger is a device for transferring heat from one fluid to another, where the fluids are separated by a solid wall so that they never mix. ...

It is interesting to compare all of this complexity to the same system implemented with a turbocharger. Since the turbo is driven off of the exhaust gases, simply dumping some of the exhaust pressure is sufficient to drive the compressor at almost any desired speed. In addition the power in the exhaust would otherwise be wasted (except to the extent that the exhaust itself provided thrust) whereas in the supercharger that power is being taken directly from the engine. Thus at low altitudes the turbo robs nothing and, as the altitude increases, it can use just as much power as it needs and no more. Better yet the amount of power in the gas is the difference between the exhaust pressure and air pressure, which increases with altitude, so turbochargers generally have much better altitude performance.

Yet the vast majority of WWII engines used superchargers, because they maintained three significant manufacturing advantages over turbochargers, which were larger, involved extra piping, and required exotic high-temperature materials in the turbine. The size of the piping alone is a serious issue; consider that the Vought F4U and Republic P-47 used the same engine but the huge barrel-like fuselage of the latter was, in part, needed to hold the piping to and from the turbocharger in the rear of the plane. Chance Vought F4U Corsair The Chance Vought F4U Corsair was a fighter aircraft that saw service in World War II and the Korean War. ... The Republic P-47 Thunderbolt, or Jug as it was known, was one of the main US Army Air Force (USAAF) fighters of World War II. The P-47 was a big, rugged, overbuilt aircraft that was effective in air combat but proved particularly useful as a fighter-bomber. ...

More cons of supercharging

Superchargers are often considered inferior to turbochargers for several reasons. Firstly, a turbocharger is more efficient than a supercharger whilst requiring only 50% of the supercharger's manufacturing cost. In addition, turbochargers are able to reach efficient operating speed much more quickly than a supercharger.

The physical space occupied by a turbocharger is significantly less than it's direct-drive counterpart. This gives the opportunity of fitting multiple turbochargers to a single engine, such as in a "sequential turbo", where one turbo is tuned to give increased performance at low engine speed and another turbo is tuned to increase the high-speed engine performance.

An alternative arrangement utilises two turbochargers of the same type, known as a "twin turbo". This gives a large power increase for a given engine speed at the cost of increasing the lag-time for the exhaust to heat up sufficiently to drive the turbochargers. This lag can be addressed by reducing the size of each individual unit such that the combined output is still as great as a single large turbocharger without having to suffer the lag-time required to reach operating speed.

A final benefit of the turbocharger over the supercharger is the operating speed; It is not unheard of for a turbocharger to reach 200,000 rpm. This is well beyond the operating specification of a supercharger.

See also

• Turbocharger
• Naturally aspirated engine

Turbocharger Cut-away A turbocharger is a compressor used in internal-combustion engines to increase the power output of the engine by increasing the mass of oxygen entering the engine. ... A naturally-aspirated engine (NA - aspiration meaning breathing) refers to an internal combustion engine (normally petrol or diesel powered) that is neither turbocharged nor supercharged. ...

References

• Allied Aircraft Piston Engines of World War II, Graham White 1995: Airlife Publishing Ltd, England & Society of Automotive Engineers, Inc., in the USA. ISBN 1 85310 734 4, http://www.howstuffworks.com