Editing Drag racing (section)

== Basics of drag racing ==
[[File:Chevrolet Gasser Wheelie.jpg|thumb|A drag race [[wheelie]]]]

=== Starting ===
Push starts to get engines running were necessary until the [[National Hot Rod Association]] (NHRA) mandated self-starters in 1976.<ref name="NHRA.com">Burgess, Phil, ''National Dragster'' editor.  "Obsolete skills, part 1: On the track", at [https://www.nhra.com/news/2008/obsolete-skills-part-1-track  NHRA.com] (retrieved 22 September 2018)</ref> After [[Burnout (vehicle)|burnouts]], cars would be pushed back by crews; this persisted until NHRA required reversing systems in 1980.<ref name="NHRA.com" /> [[Don Garlits]] was the first to do burnouts across the starting line, which is now standard practice.<ref name="Drag Illustrated">Tocher, Ian. "'Big Daddy' Describes Birth of the Burnout", published 18  March 2018, at [https://dragillustrated.com/big-daddy-describes-birth-of-the-burnout/ ''Drag Illustrated''] (retrieved 23 September 2018)</ref> Each driver then backs up to and stages at the starting line.

=== Prerace preparations ===
Before each race (commonly known as a pass), each driver is allowed to perform a [[burnout (vehicle)|burnout]], which heats the driving tires and lays rubber down at the beginning of the track, improving traction. The cars run through a "water box" (formerly a "bleach box", before bleach was replaced{{when|date=March 2021}} by flammable traction compound, which produced spectacular, and dangerous, flame burnouts; the hazard led NHRA to mandate use of water in the 1970s<ref name="Drag Illustrated" />).

Modern races are started electronically by a system known as a ''[[Christmas tree (drag racing)|Christmas tree]]'', which consists of a column of lights for each driver/lane, and two light beam sensors per lane on the track at the starting line. Current NHRA trees, for example, feature one blue light (split into halves), then three amber, one green, and one red.<ref>{{cite web |url=http://www.nhra.com/story/2011/4/12/new-tree-implemented-for-visitmyrtlebeachcom-nhra-four-wide-nationals/ |title=Archived copy |access-date=6 May 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110420065503/http://www.nhra.com/story/2011/4/12/new-tree-implemented-for-visitmyrtlebeachcom-nhra-four-wide-nationals/ |archive-date=20 April 2011 }} New Tree implemented for NHRA VisitMyrtleBeach.com Four-Wide Nationals</ref> When the first light beam is broken by a vehicle's front tire(s), the vehicle is "pre-staged" (approximately {{convert|7|in|mm}} from the starting line), and the pre-stage indicator on the tree is lit. When the second light beam is broken, the vehicle is "staged", and the stage indicator on the tree is lit.<ref>[http://www.nhra.com/nhra101/basics.aspx NHRA.com] Basics of Drag Racing</ref> Vehicles may then leave the pre-stage beam, but must remain in the stage beam until the race starts.

=== Staging ===
Once one competitor is staged, their opponent has a set amount of time to stage or they will be instantly disqualified, indicated by a red light on the tree. Otherwise, once both drivers are staged, the system chooses a short delay at random (to prevent a driver being able to anticipate the start), then starts the race. The light sequence at this point varies slightly. For example, in NHRA Professional classes, three amber lights on the tree flash simultaneously, followed 0.4 seconds later by a green light (this is also known as a "pro tree"). In NHRA Sportsman classes, the amber lights illuminate in sequence from top to bottom, 0.5 seconds apart, followed 0.5 seconds later by the green light (this is also known as a "sportsman tree" or "full tree"). If a vehicle leaves the starting line before the green light illuminates, the red light for that lane illuminates instead, and the driver is disqualified (also known as ''red lighting''). In a handicap start, the green light automatically lights up for the first driver, and the red light is only lit in the proper lane after both cars have launched if one driver leaves early, or if both drivers left early, the driver whose reaction time is worse (if one lane has a -.015 and the other lane has a -.022, the lane of the driver who committed a 0.022 is given the red light after both cars have left), as a red light infraction is only assessed to the driver with the worse infraction, if both drivers leave early. Even if both drivers leave early, the green light is automatically lit for the driver that left last, and they still may win the pass (as in the 2014 NHRA Auto Club Pro Stock final, [[Erica Enders-Stevens]] and [[Jason Line]] both committed red light infractions; only Line was assessed with a red light, as he was -.011 versus Enders-Stevens' -.002).

=== Measurements ===
Several measurements are taken for each race: reaction time, elapsed time, and speed. Reaction time is the period from the green light illuminating to the vehicle leaving the staging beams or breaking the guard beam. Elapsed time is the period from the vehicle leaving the starting line to crossing the finish line. Speed is measured through a [[speed trap]] covering the final {{convert|66|ft|m}} to the finish line, indicating average speed of the vehicle in that distance.

Except where a breakout rule is in place, the winner is the first vehicle to cross the finish line, and therefore the driver with the lowest combined reaction time and elapsed time. Because these times are measured separately, a driver with a slower elapsed time can actually win if that driver's advantage in reaction time exceeds the elapsed time difference. In heads-up racing, this is known as a ''[[holeshot]] win''.<ref>{{cite web|url=http://www.nhra.com/glossary.aspx|title=NHRA Glossary|publisher=NHRA|access-date=11 August 2011|url-status=dead|archive-url=https://web.archive.org/web/20130903044153/http://www.nhra.com/glossary.aspx|archive-date=3 September 2013}}</ref> In categories where a breakout rule is in effect (for example, NHRA Junior Dragster, Super Comp, Super Gas, Super Stock, and Stock classes, as well as some dial-in classes), if a competitor is faster than his or her predetermined time (a "breakout"), that competitor loses. If both competitors are faster than their predetermined times, the competitor who breaks out by less time wins. Regardless, a red light foul is worse than a breakout, except in Junior Dragster where exceeding the absolute limit is a cause for disqualification.

=== Bracket system ===
Most race events use a traditional [[Bracket (tournament)|bracket]] system, where the losing car and driver are eliminated from the event while the winner advances to the next round, until a champion is crowned. Events can range from 16 to over 100 car brackets. Drivers are typically [[Seed (sports)|seeded]] by elapsed times in qualifying.  In bracket racing without a breakout (such as NHRA Competition Eliminator), pairings are based on times compared to their index (faster than index for class is better). In bracket racing with a breakout (Stock, Super Stock, but also the NHRA's Super classes), the closest to the index is favorable.

A popular alternative to the standard eliminations format is the Chicago Style format (also called the Three Round format in Australia), named for the US 30 Dragstrip near [[Merrillville, Indiana]] where a midweek meet featured this format.<ref>{{cite web|url=http://www.competitionplus.com/drag-racing/news/14381-chicago-once-a-funny-car-heaven|title=Encore Feature: Chicago Once a Funny Car Heaven|publisher=Competition Plus|access-date=21 March 2014|url-status=dead|archive-url=https://web.archive.org/web/20140506094925/http://www.competitionplus.com/drag-racing/news/14381-chicago-once-a-funny-car-heaven|archive-date=6 May 2014}}</ref> All entered cars participate in one qualifying round, and then are paired for the elimination round. The two fastest times among winners from this round participate in the championship round. Depending on the organization, the next two fastest times may play for third, then fifth, and so forth, in consolation rounds. Currently, the National Drag Racing Championship in Australia uses the format for major categories.<ref>{{cite web|url=https://nationaldragracing.com.au/wp-content/uploads/NDRC-Competitor-Regulations-and-Information-231018_v1.11-1.pdf|title=National Drag Racing Championship Competitor Regulations|publisher=National Drag Racing Championship (Australia)|access-date=29 January 2023}}</ref>

=== Distances ===
The standard distance of a drag race is 1,320 feet, 402&nbsp;m, or 1/4 mile (±0.2% FIA & NHRA rules). However, due to safety concerns, certain sanctioning bodies (notably the NHRA for its Top Fuel and Funny Car classes) have shortened races to 1,000 feet. Some drag strips are even shorter and run 660 feet, 201&nbsp;m, or 1/8 mile. The 1,000 foot distance is now also popular with bracket racing, especially in meets where there are 1/8 mile cars and 1/4 mile cars racing together, and is used by the revived American Drag Racing League for its primary classes (not Jr Dragster). Some organizations that deal with Pro Modified and "Mountain Motor" Pro Stock cars (Professional Drag Racers Association) use the 1/8 mile distance, even if the tracks are 1/4 mile tracks.

[[File:1958 Fuel Dragster.jpg|thumb|An early example, a 1958 [[Top Fuel|Fuel]] [[Dragster (car)|dragster]] (technically, a [[Hot rod#Rail|rail]]), on display at the California Automobile Museum]]
[[File:Showtime Nitro Funnycar - Flickr - exfordy.jpg|thumb|Funny Car with body up]]