Dynamics of a SUPERCHARGER

.....Superchargers are defined as an air pump that forces more air (oxygen) into the combustion chambers to increase the volumetric efficency of the engine. They are driven by an engines crankshaft via a belt, chain, direct drive, or gear drive. Typically air enters the air filter, moves through a metering device such as a mass air flow meter, and is drawn past the engines throttle plate, then passes into the supercharger where it is compressed, and forced into the combustion chambers.

.....There are mainly two types of superchargers which are positive displacement, and dynamic. First lets start with positive displacement pumps. These types of superchargers are based upon a fixed volume of air at all engine speeds (rpm). The pump forces air mechanically into the engine to increase it's overall output (hp, torque). The second type mentioned above is a dynamic, which is interputated as a device that accerlates air at high speed, and exchanges velocity for boost (pressure) by slowing down the mechanical charger. Below are different types of superchargers.

Positive displacement

1. Roots
2. G-lader (rare type)
3. Lysholm Dynamic

1. Centrifugal
2. Axial

.....Over the last century roots type charges have been the most popular. They work by a pair of three rotor vanes that mesh together, and compress air along the inner housing walls. You might recognize them if you have seen top fuel dragster's racing down the quarter mile at blistering speeds. The second most popular P.D. type charger is Lysholm or twin screw. It operates by pulling air through a set of "worm" gears which overlap each other though not completely. The small amount of space between the gears is where the air is compressed. Unlike the roots type charger, the twin-screw system exhibits internal compression, therefore making it more thermally efficiencent than the roots type. The Ford GT supercar is an example of lysholm type supercharger being used currently. G-lader type compressors (lader means compressor in German) or other-wise known as scroll-type is not used wide speard due to it's complexity and VW patent. The operation of these types of compressers is based upon two sets of scrolls. One scroll is in a fixed position (housing), and the other scroll rotates in a circlular motion to compress air towards the center of the device, and form there into the engines combustion chamber.

.....Moving on to centrifugal supercharges which have been popular with most of todays street cars are quite capable of developing big horsepower numbers and torque. These types of designs are almost identical to a turbocharger with the exception of not being driven by exhaust gases. These types of mechanical designs offer a lack of low rpm boost, but can easily grant higher airflow speeds proportionate to engine rpm. These types of superchargers are driven by the crankshaft via a belt, gear, or chain-drive. Most of todays tuners wanting to boost performance with a supercharger will incorperate a centrifugal type compressor due to their ease of installation, reliability, and most of all performance.

.....As with all devives that compress air, an intercooler is used to decrease air tempuature to reduce the likelyhood of engine knock. Also not discussed in this segment is the use of wastegates, and bypass valves. These components will be discussed on their own due to the importance of thier characteristics. Thankyou and

Happy Boostin
Court Shanken

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