Glossary of Motorsport Terms - D

D

Deep braking

Applying the brakes later than normal when entering a turn.

Delaware start

A style of restart where the race leader starts in the first row by himself and the other drivers start two-wide. Named after a start method for the state of Delaware in the United States.

Delta Time (also Pit-Stop Delta)

The entire time it generally takes a driver to enter the pit lane, make a full pit stop, and exit the pit area back to the track to resume racing at optimum pace. For example, a Delta Time of 25 seconds means the entire pitting process (entering, stopping and exiting) cost the driver 25 seconds not driving at full race speed even though the car may have been stationary in the pit box for only 5 seconds.

Density Altitude (often DA)

(drag racing) which often refers to the quality of air. Technically "quality of air" refers to the pressure drop as altitude above sea level increases. Atmospheric air pressure is lower at a race track higher above sea level. All non-turbocharged internal combustion engines produce less power as air pressure drops, as each intake stroke draws in less air per volume than normally. This may require the engine to be "tuned" to optimize the power, as it may still "think" it's at a lower altitude. Because a supercharged engine pressurizes intake air at a fixed mechanical ratio to the engines RPM's, it suffers a proportionate loss in power, but not as severe as a naturally aspirated engine will. A turbocharged engine is largely unaffected, as the lower density of the intake air is offset by the lower backpressure resisting the exhaust flow through the turbo.

Dial-in

(drag racing) 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.

Did Not Attend (often DNA)

Denotes a driver who was entered for a race but did not attend the circuit. Sometimes referred to as Did Not Arrive or simply a "no show."

Did Not Finish (often DNF)

A driver who did not finish the race. Some sanctioning bodies do not classify a driver in the final results if he did not finish completed a certain number of laps.

Did Not Qualify / Did Not Pre-qualify (often DNQ / DNPQ)

A failure to qualify or pre-qualify for a race. Most often because the driver was too slow to make it into a limited number of grid positions, or was slower than the 107% rule. Refer 107% rule.

Did Not Start (often DNS)

A driver did not attempt to compete in a race, even though he may have competed in practice sessions and / or qualifying. Not the same as the DNA already mentioned.

Digger

dragster (as distinct from a bodied car or flopper).

Dirty air

The air disrupted by a car when it moves at speed, which can cause aerodynamic difficulties for a car following closely behind. The opposite of clean air.

Disqualify (often DQ or DSQ)

Where a competitor is removed from the results, usually in penalty for a technical infringement. Sometimes, but not always, interchangeable with Excluded.

Dogleg

A gentle turn or kink on a racing circuit, usually associated with road courses, but also present on oval tracks. On road courses, a dogleg may be present on a long straightaway (e.g. Mid-Ohio), curving the straight slightly, but usually not enough to require drivers to slow down much for the turn. On an oval, a dogleg can be located on the frontstrech (e.g. Charlotte) or backstrech (e.g. Phoenix) creating an oblong shape, adding a challenge, increasing sightlines for fans, and again, usually not requiring drivers to slow down for the extra curve. A quad-oval is also referred to as a "double dogleg."

Doped (or Dope)

(drag racing) commonly used word in the southern states if the car is using nitrous or propane injection on diesels.

Door-slammer

Drag racing term used to group vehicles, usually sedan bodied, that still have functional doors for driver access to the vehicle, as opposed to Funny cars which have a single lightwight outer body draped over the racing chassis.

Downforce

Increased force holding the car onto the track. This is created by the aerodynamics or aerodynamic aids (F1 wings, etc.) of a vehicle which causes a "reverse lift" effect. That is, creating an area of low pressure (suction) under the car and/or under the wing(s) or other aids fixed to the car, the higher pressure above forcing the tires harder to the ground, effectively increasing the static friction. This allows it to travel faster through a corner, at the cost of having a reduced overall top speed, since drag is proportionate to lift and downforce is caused by lift.

Drafting

A technique where multiple vehicles align in a close group reducing the overall effect of drag due to exploiting the lead object's slipstream. Same as slipstreaming.

Drag Reduction System

A mechnically activated element of the rear wing of modern Formula One cars, where in a predetermined position on the circuit a wing element will open, moving from steeply inclined to flat, thus reducing the amount of drag generated by the rear wing, increasing its top speed on a straightaway. The mechanism artificially assists overtaking with additional benefit of overcoming Dirty Air issues while following cars closely.

Drifting

Drifting is a form of motorsport in which drivers intentionally provoke constant oversteering slides while preserving vehicle control and a high exit speed. In motor racing, drifting is a cornering technique (also called a four-wheel drift) where a car takes a high-speed corner held at an angle on the track without major steering inputs, balancing natural understeer with power oversteer.

Drive-through penalty

A penalty applied by race officials while the race is underway. A competitor is directed to drive into the pit lane and travel its length at much reduced speed (pit lanes are mostly speed-limited to protect the pitcrew and marshals) losing significant track position in the process. When the driver is serving his drive through penalty he is not allowed to stop anywhere in the pits. See also Stop-go penalty.

Drivers' meeting

A meeting where drivers and officials meet before a race to discuss the upcoming event. Also referred to as Drivers' briefing or Driver and Crew Chief meeting, as in some series, the driver and his crew chief must attend.

DRS

see Drag Reduction System

Dry line

On a drying circuit, the racing line that becomes dry first as the cars displace water from it.