Drag racing is a competition in which vehicles compete to be the first to cross a set finish line, usually from a standing start, and in a straight line. First gaining popularity in the USA after World War II (1945), the sport steadily grew in popularity and spread across the globe. By 2009, there were hundreds of drag strips in operation, mainly in developed countries.
Most races begin a standing (stationary) start and are just 1/4 or 1/8 mile long. The races last between 5 and 15 seconds, and finishing speeds range from 100 to over 300 miles per hour (480 km/h), depending upon the type of vehicle.
Below the staging lights are three large amber lights, a green light, and a red light. When both drivers are staged, the tree is activated to start the race, which causes the three large amber lights to illuminate, followed by the green light. There are two standard light sequences: Either the three amber lights flash simultaneously, followed 0.4 seconds later by the green light (a "Pro" tree), or the amber lights light in sequence from top to bottom, 0.5 seconds apart, followed 0.5 seconds later by the green light (a "Sportsman" or full tree). If the driver leaves the starting line before the green light illuminates, the red light for that driver's lane illuminates instead, indicating disqualification should no further infractions occur.
Several measurements are taken for each race: reaction time, elapsed time, and speed. Reaction time is the time from the green light illuminating to the vehicle leaving the starting line. Elapsed time is the time from the vehicle leaving the starting line to crossing the finish line. Speed is measured through a speed trap near the finish line, indicating the approximate maximum speed of the vehicle during the run.
The winner is the first vehicle to cross the finish line (and therefore the driver with the lowest total reaction time + elapsed time). The elapsed time is a measure of performance only; it does not, per se, determine the winner. Because elapsed time does not include reaction time, a car with a faster elapsed time can actually lose the race if the driver does not react to the green light fast enough. In practice, it is advantageous for the driver to "jump the gun" by a fraction of a second, starting the car during the split-second interval between when the yellow light goes out and the green light goes on. However, if the car leaves the front light beam before the green light comes on, the driver has "red-lighted" (because the red light is lit on the Christmas Tree) and should no further fouls happen during the race, is disqualified. Once a driver commits a red-light foul, the other driver can also commit a foul start by leaving the line too early but would win because he or she would leave the line slower. A driver who gets a substantial lead at the start is said to have gotten a "holeshot". A win where a driver wins a race with a higher elapsed time but lower reaction time is known as a "holeshot win".
It is also possible for a driver to be disqualified for other infractions, depending on the rules of the race, including crossing the centerline between lanes, touching a wall, striking a track fixture, failing to stage, failing a tech inspection, or running faster than expected/allowed for the assigned class. In boundary line violations, if the offending driver have made a clean start, and the red-light driver does not commit the violation unless forced by the offending car for safety reasons, the driver who committed a red-light foul wins.
In the common Eliminator racing format, the losing vehicle and driver are removed from the contest, while the winner goes on to race other winners, until only one is left. In cases where a driver has no opponent for a round, the driver makes a solo pass or "bye run" (in order to at least partially eliminate the advantage that would otherwise come from the engine having one less run on it) to advance to the next round. In most Eliminator formats, the bye runs take place only in the first round. On bye runs, some drivers may choose to drive slowly so as not to stress the car unduly, though choice of lane in the each round is often determined by time in the previous round, making this strategy possibly detrimental.
During drag racing events, vehicles are classified 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. (not all of these can apply)
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.
When approaching the starting line (also known as the staging area), most racers will apply water (formerly thought to be bleach by spectators as it was dispensed from old bleach bottles) to the driven tires either by backing into a small puddle (the "bleach box" or "water box") or having it sprayed on. The car then exits the water and does a burnout to heat the tires, making them even stickier. Some cars have a mandatory "line-lock" which prevents the rear brakes from engaging when the brake pedal is depressed (which can be toggled on and off). This allows the car to remain stationary (with the brakes applied) without burning up the rear brake pads while doing a burnout. Cars in street classes (which must be street legal) are the only exception to this pre-race ritual, as the grooved tires tend to retain some of the water.
After the burnout comes "staging", where the cars pull up to the starting line. Each lane has its own string of lights on the "Christmas tree", with two small orange lights on top. These are the "pre-staged" and "staged" lights. The two cars will slowly creep forward until the first (pre-staged) orange light is lit. This means they are very close to the actual starting line (a mere 7 inches). Then the cars will nudge forward until the second (staged) light is lit. This indicates they are at the starting line, this is the point where the driver will apply the "line-lock" to prevent the car from rolling while he uses the clutch and gas pedals. When both cars have lit both bulbs, the starter will engage the Christmas tree. If the racer moves too far the top bulb will go out and the driver is said to have "deep staged". While some drivers prefer this technique, some tracks and classes prohibit it. An advantage can be had, by deepstaging, in gaining a quicker reaction time (RT) but at the expense of the elapsed time (ET) and MPH achieved at the top end of the track; there is also a higher risk of "red lighting". A loose etiquette is followed when staging. The driver to illuminate the first light will wait for the second car to light both bulbs before advancing to the staged light.
Once the competitors have both staged, the starter presses a button to start the race. There are two types of tree used. A sportsman tree, used for bracket and handicap racing, consists of each yellow lighting 0.5 seconds after the one above it. The green comes on 0.5 seconds after the last yellow is lit. If the race is a handicap race each side of the tree will have its own timing. A pro tree consists of all three yellows being illuminated at the same time, followed by the green 0.4 seconds later. This type of tree is used for professional and heads-up racing. It should be noted that some tracks run a Pro-style tree for bracket racing during special "Street Racing" bracket events.
Several things are important on the way down the track in drag racing. The first is not to cross into the opponent's lane, as this will result in disqualification. In case of a double disqualification in which one driver commits a foul start and the second driver crosses into his opponent's lane, the driver who committed the foul start wins. Another important consideration is when to shift gears. Most drag cars are shifted manually by the driver, and there are optimum times for shifting that vary with each car. Typically, power will increase as the engine RPMs (revolutions per minute) increase, but only up to a point before power begins to taper off. The ideal time to shift is when the descending power curve for the lower gear crosses the ascending power curve for the higher gear. Most drag racers use a tachometer to judge shift points. In Fuel classes especially, "pedalling" the car (adjusting the throttle) to prevent loss of traction is often important and one measure of how good a driver is.
Strategies for crossing the finish line usually only involve bracket racing (see above). If one car has a huge lead, it may slow down before crossing the finish line to prevent a breakout. Especially in bracket racing, it is not uncommon to see the leading vehicle's brake lights come on briefly before the finish line. The term "sandbagging" is used in races where the driver in a bracket race puts a slower "dial in" (the predicted E.T.) that he/she could run and then at the finish line tap the brakes lightly or lift of the gas pedal (also known as pedalling) to reduce the E.T. to run as close as possible to the dial in.
If both cars break out, the car closer to their dial-in wins. In Junior Dragster racing, however, there is a mimimum elapsed time, quicker than the official break out elapsed time; a car which posts a lower time is ejected from the event.
Rules require a radiator overflow tank. This type (using an old beer can) is illegal at many tracks where a factory-type stock overflow tank (usually plastic) is required.
* Beam—starting line electric eye controlling "pre-staged" and "staged" lights
* Blow—supercharge; wreck. Said of an engine.
* Blower—supercharger (occasionally turbocharger); in '90s, generally grouped as "power adder" with turbocharger and nitrous
* Blown—supercharged; wrecked. Said of an engine.
* Blowover—flipping of a car, due to air under car lifting front wheels. Commonly suffered by dragsters
* Breakout—running quicker than dial-in; also "breaking out". Grounds for disqualification if opponent does not commit a foul start or cross boundary lines.
* Christmas Tree (or tree) — The series of lights that signal the approach and start of a race in addition to showing starting violations
* Dial-in—when bracket racing, drivers must estimate or 'dial in' the time in which they expect to run. Therefore two unmatched cars in weight and power can compete, by a handicap system. If one runs a faster time than dialed in, it is a breakout.
* Digger—dragster (as distinct from a bodied car or flopper)
* Flopper—Funny Car, short for "fender flopper." Coined by dragster crews in the late 1960s to separate Funny Cars, which had fiberglass bodies with fenders, from dragsters. Erroneously attributed to flip-top bodies of Funny Cars.
* Fuel—mix of methanol and nitromethane ("pop", nitro); race class using it
* Fueler—any car running fuel or in Fuel class (most often, TFD or TF/FC)
* Grenade—wreck an engine (the engine "grenaded") due to internal failure. Distinct from "popping a blower".
* Heads-up Racing—where both drivers leave at the same time and is used in all professional ("pro") classes.
* Holeshot—getting a significant advantage off the starting line. The other driver gets "holeshotted" or "left at the tree". A "holeshot win" is any win in a heads-up class where a slower car beats a faster car because of better reaction time.
* Hook Up—Good traction between tires and track resulting in increased acceleration and reduced slipping or smoking of tires.
* Lit the tires—lost traction, causing smoke
* Nitro—nitromethane (sometimes incorrectly used to refer to nitrous oxide)
* Overdrive-The ratio between the revolutions of the supercharger to the revolutions of the engine, controlling amount of boost; see underdrive
* Oildown — When a car's engine or lubrication breaks during a run, leaving a streak of oil and other fluids on the track. This is punishable by fines, point penalties, and/or suspension.
* Pedalling—working the throttle to avoid lighting the tires, or as a way to sandbag; "pedalled" it, had to "pedal" it
* Pro tree—timing lights which flash all three yellow lights simultaneously, and after four tenths of a second, turn green.
* Put on the trailer—lost (got "put on the trailer") or won (put the other driver on the trailer). From the obvious, losing drivers trailer their cars home.
* Quick 8 (Q8) Quickest eight cars in a defined race. Rules appear to can differ per location/race. Search for "Quick 8 rules" for more.
* Rail—dragster (as distinct from bodied car or flopper). From the exposed frame rails of early cars.
* Redlight(ed) a.k.a. bulb(ed)—jump(ed) the start, left before tree turned green. This is a loss unless a more serious (opponent crossing the center boundary line) foul occurs.
* Scattershield — metal sheet protecting driver in case of transmission failure
* Slapper bar — traction bar
* Slicks—rear tires with no tread pattern and softer rubber compound, for increased traction
* Slingshot—early front-engined dragster, named for the driving position behind the rear wheels (erroneously attributed to launch speed)
* Standard tree—timing lights which flash in sequence five tenths of a second between each yellow light before turning green. Traditional form, before introduction of Pro tree.
* Throw a belt-losing the drive belt connecting the engine's crankshaft to the supercharger
* Top end—finish line of strip; high part of engine's rev band.
* Traction bars—rear struts fixed to rear axle to keep rear axle from twisting, causing wheel hop and loss of traction; also called slapper bars.
* Trap(s)—the 20 meter (66 ft) timing lights at top end of race track to measure speed & E.T.
* Wheel Hop—violent shaking of the car as the tires lose and regain traction in quick succession.
* Wheelie bars—rear struts fixed to rear axle, which protrude out to rear of car to help prevent car's front from raising too high or flipping over on launch.