Bracket racing is a form of drag racing that allows for a handicap between predicted elapsed time of the two cars over a standard distance, usually 1/4 mile (402.336 m) or 1/8 mile (201.168 m).
The effect of the bracket racing rules is to place a premium on consistency of performance of the driver and car rather than on raw speed, which in turn makes victory much less dependent on large infusions of money, and more dependent on mechanical and driving skill, such as reaction times, shifting abilities, and ability to control the car. Therefore, bracket racing (using the aforementioned handicapping system) is popular with casual weekend racers. Many of these recreational racers will drive their vehicles to the track, race them, and then simply drive them home.
This format allows for a wide variety of cars racing against each other. While traditional drag racing separates cars into a wide variety of classes based on power and weight, bracket racing classes can be simpler, and can accommodate any vehicle with basic technical/safety inspection. Race events organized in this way are sometimes called "run-what-ya-brung".
Each car chooses a dial-in time before the race, predicting the elapsed time the driver estimates it will take his or her car to cross the finish line. This is usually displayed on one or more windows so the starter can adjust the "christmas tree" starting lights accordingly. The slower car in the race is given the green light before the faster car by a margin of the difference between their two dial-in times.
In principle, if both drivers have equal reaction times and their cars run exactly their posted dial-ins, both cars should cross the finish line at precisely the same time. In reality, this is an extremely rare occurrence. Measuring devices both at the start and at the end of the track post times down to 1/1000 of a second (0.001s precision), which makes tied races almost impossible.
Reaction time 
When a car leaves the starting line, a timer is started for that car. The difference between when the green light comes on and when the car actually moves is called the reaction time. In most events there's a minimum reaction time of 0.500 seconds. That is, if a driver manages to start moving his vehicle within 0.500 seconds from the green light, he is automatically red-lighted and disqualified for that round. In a drag race event when both drivers get red-lighted (both started early) the winner by default is the one who performed the lesser aggravation (0.498 wins over 0.410, for example). The sanctioning body of the event can also demand that both drivers start off again and can allot a cool-down time at their discretion.
Sometimes, people incorrectly refer "reaction time" the unrelated 60 foot takeoff time. The reaction time is merely an indication of how fast a driver reacted to the green light. The 60 foot takeoff time is an indicator of how fast the vehicle started moving at the beginning of the race, regardless of the driver’s reaction time. If the driver launched the car with too much power for the available traction, he will have wheelspin and correspondingly will have a longer time to cross the 60 foot barrier if he were to drive with more finesse.
Breaking out 
Breaking out is when a racer manages to cross the 1/4 mile in less time that the one he dialed-in beforehand.
- If a car "breaks out", it is disqualified and the other one wins by default (assuming the other car didn't break out);
- If both cars break out, the one who breaks out by the smallest margin of time wins.
|Race||Dial-in||Race Time||Reaction Time||Outcome||Reason|
|Driver A||16.0||15.8||0.586||Broke Out||Racer A broke out.|
|Driver B||15.6||15.9||0.719||WINS||Did not red light, nor broke out.|
|Driver C||16.1||16.0||0.780||Broke Out (WINS)||Racer C "broke out less" (0.1 seconds)|
|Driver D||15.5||15.2||0.505||Broke Out||Racer D broke out with a wider margin (0.3 seconds), so he loses.|
|Driver E||14.9||14.9||0.480||Red Light||Driver E earned a red light for a reaction time < 0.500 seconds.|
|Driver F||15.8||15.7||0.705||Broke Out (WINS)||Driver F did not red light, so he can break out and still wins.|
This eliminates any advantage from bending the rules by putting a slow dial-in time on the windshield to get a head start. However, some racers will purposely dial a slower time and then let off of the throttle or use their brakes near the end of the track in an attempt to trick the other driver into breaking out. This racing technique is called sandbagging and, although useful and technically legal (not always), is looked down upon at most amateur events as a form of cheating and un-sportsman like conduct. In some track clubs, a sign of obvious sandbagging (letting off the throttle near the finish line or applying the brakes to comply with the dial-in time) earns an immediate disqualification from the event.
Red Light and other fouls 
If a car leaves the starting line before the green light comes on, a foul is recorded (a red-light start), and that car is provisionally disqualified. If both cars red-light, the one that fouled first is shown the red light, and an automatic green light is shown in the other lane. Another form of foul is to cross the dividing line between the two lanes, or the line at the edge of the racing surface, both of which negates a red light foul. A foul is worse than a break out; one car can break out but if the other car fouls, the car that breaks out advances to the next round. If both cars foul, the lesser of the violations is the winner; a break-out is the least serious violation, then a red light, crossing the boundary line at the edge of the surface, crossing the dividing line between the lanes, and then leaving before the tree is started.