Superchargers are the most common way for competitors to get the most horsepower possible out of their engines in drag racing. They are a major part of what separates race cars from everyday vehicles.

How Superchargers Work
Superchargers are used to get air into an engine at a more frequent rate than is mechanically possible under standard atmospheric conditions. The purpose of this is to increase the amount of oxygen per intake cycle to achieve maximum horsepower. This process can occur mechanically or chemically.

The Importance of Chemistry
It is critical for the success of a run to properly bring high pressure oxygen into the intake stream of a given car, allowing the chemical and oxygen to yield an increased oxygen content that is super-cooled.  The most prominent chemical for achieving this  is nitrous oxide.  According to Drag Racing Online Magazine, “After the oxygen atoms are broken from the nitrogen atom (via heat) the oxygen can be used as an ingredient in the combustion process.

The article continues, “Because of the increased oxygen, an increased fuel quantity is needed to produce the increased power and also to stop engine damage from an oxygen-rich condition called running lean.” Although nitrous oxide (NO2) is effective in the amount of strength it can increase the engine’s power, it is not reliable as a mechanical supercharger.

Mechanical Superchargers
Mechanical superchargers are built as either positive displacement or not.  The most capable mechanical supercharger is a screw type. The screw type supercharger is equipped with two rotors, only one of which displaces air. According to Drag Racing Online Magazine, “The screw has an inlet cavity that decreases in size as the rotors rotate.”  Screw type superchargers are very strong, and usually have around 200 horsepower over a roots supercharger.

Roots Superchargers
Roots superchargers are one of the earliest types of superchargers. They were widely used on the first trucks put out by GMC. In roots superchargers, both rotors displace air, allowing for a sizable displacement.

Central Figure Superchargers
Lastly, there is the central figure supercharger. Central figure superchargers utilize belt driven turbine wheels that compress air out from the middle by the number of rotations per minute. From Drag Racing Online Magazine, “The impeller in the (central figure) supercharger causes air to move from the center of the turbine (where it) is accelerated outward towards the turbine housing, and is then directed towards the outlet ducts.”

The supercharger in the Dixie Twister helped Huston Platt outrun his competition.