Drag racing is a form of auto racing in which any two vehicles (most often two cars or motorcycles) attempt to complete a fairly short, straight and level course in the shortest amount of time, starting from a dead stop. Drag racing originated in the United States and is still the most popular there. The most common distance is one quarter mile (402 m / 1320 ft.), although one-eighth of a mile (201 m / 660 ft.) tracks are also popular. The dragstrip extends well beyond the finish line to allow cars to slow down and return to the pit area.
Drag racing usually involves two cars racing each other over a set distance. Usually 1/4 mile. Although distances range from two hundred meters to one kilometer, the four-hundred metre drag race is the most popular. Races of this nature test a vehicle in terms of acceleration and top speed, as well as the driver with regard to skill and concentration. Although the driver does not have any turns to negotiate or opponents to defend against, apart from the competitor in the other lane, he or she must be very accurate with gear shifting and throttle modulation.
During drag racing events, vehicles are classified into different divisions by various criteria that take into account the extent of modifications to the car. These criteria include engine capacity, configuration of cylinders, frame type, vehicle construction materials, wheelbase, horsepower to weight ratio, number of cylinders, whether or not power adding devices such as turbochargers, superchargers or nitrous oxide are employed, vehicle type (such as car, truck, et cetera), or even make and model for limited entry fields. The aforementioned divisions are in place to ensure that the cars are evenly matched during the race.
Drag racing vehicles are special in that they are modified to be lighter and more powerful than in their standard form. A lighter vehicle means that the power-to-weight ratio is increased and hence a greater acceleration will be achieved. Power increases vary depending on the extent of the modifications to the engine. The table below illustrates some common outputs for different induction configurations for a typical drag-racing vehicle. Please note that the numbers expressed are not by any means limits for power, but they're rather accurate indications of typical levels of power produced by daily driven drag racing vehicles.