Drag Racing is a straight-line acceleration contest between two vehicles over a measured distance. General standard distances accepted worldwide are quarter-mile (1,320 feet) and eighth-mile (660 feet). The objective is for one vehicle to get to the finish line first.A drag racing event is comprised of a series of two-vehicle, tournament-style eliminations. Vehicles in competition are divided into a variety of classes. All classes have specific rules and guidelines that determine eligibility.A starting line device utilizing a set of lights, often referred to as a ‘Christmas Tree’, is used to initiate the race. In professional category racing, a .400-second flash of amber lights precedes the important green light, which signals the start of the race. If a driver leaves the starting line before the green light activates, a red light illuminates, signaling a foul start. The offending driver is disqualified.
A driver can win the race despite slower elapsed time and speed totals. In some rare instances, a winning driver can use a quicker reaction time to the green starting light, to overcome an opponent’s greater performance advantage on the track.Most sportsman categories operate on a handicap system, which allows slower vehicles the ability to compete on an even playing field with quicker and faster counterparts. During eliminations drivers make elapsed time performance predictions (called a "dial-in"). The slower vehicle will receive an advantage at the start, equal to the difference between the two vehicles’ performance predictions.In most cases, the vehicle that gets to the finish line first wins. However, if a vehicle goes quicker than their performance prediction, it is determined to ‘breakout’ and thus be disqualified. If both vehicles run under their projected elapsed time, a "double breakout" occurs, then the driver running closest to his or her dial-in is the winner. In other instances, such as a foul-start, crossing the center-line or making contact with an outside track boundary, drivers are automatically disqualified.
World Records for elapsed time and speed are maintained in all classes. IHRA rules require a record run to be backed up with another run within one percent of the record time or speed at the same event to be considered a record. Thus, drivers can have the quickest or fastest run in IHRA history in a certain class and not officially establish the World Record. For example, Paul Romine’s 4.709 second elapsed time at the 1997 Prolong Super Lubricants / Ohio Lottery World Nationals at Norwalk Raceway Park was considered one of the quickest IHRA Top Fuel ETs in history. However, he failed to back that run up within the required one percent at the World Nationals, and it is not the IHRA Top Fuel ET World Record.