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Superchargers create better fuel efficiency by increasing the amount of oxygen available to an engine's internal combustion chambers. Oxygen, a crucial ingredient to combustion, was a limiting factor in the power of engines before superconductors. By compressing it to pressures greater than the external atmosphere, supercharges force additional air into the combustion chamber, where it is mixed with gasoline for the explosive reaction that powers the engine.
Because superchargers increase the power of the engine by utilizing more oxygen, they do not require a larger engine and therefore also increase fuel efficiency by allowing cars to be lighter. They are particularly useful in planes, which can fly at higher altitudes where oxygen is less abundant because of the increased efficiency of superchargers. -
There are many types of superchargers, though they all operate on the same simple principles. All must compress air to produce the pressure differential that forces additional air into the engine. Proper combustion within an engine requires a precise air-to-fuel ratio of 14:1.
Thus, though more fuel could be pumped to the engine, it could not be utilized without much larger air supply to the combustion chambers. Rather than building a larger chamber to store all of this additional air, superchargers condense incoming air so the requisite mass fits in the relatively small volume of the engine.
Compression is usually achieved through a system of rotating gears or fans. If the gears are driven passively by exhaust gases, it is called a turbocharger. The term supercharger typically refers only to devices whose compression mechanics are driven by the engine's crankshaft. The rotation in the supercharger produces the high-pitched whine audible during acceleration. -
An additional feature that increases the efficiency of the supercharger is the presence of an intercooler, sometimes called a turbocooler, which lowers the temperature of the air as it enters the intake manifold of the engine. Because compressing air increases its temperature, potential energy for the combustion stroke is lost to heat. Like a radiator, a turbocooler uses cold air or water to reduce the temperature of the compressed air before it reaches the engine. This provides peak efficiency by increasing the difference between the air's temperature before and after combustion, resulting in greater power. Without the intercooler, the risk of heat damage, excessive wear or an uncontrolled explosion in the engine increases.
