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Glossary

D

DAG
Champ Car World Series acronym for "Data Acquisition Geek," a computer expert who maintains a team's Data Acquisition system and analyzes the data. Teams use sophisticated sensors, transmitters, computers and software to provide information regarding the car and the driver actions, or inaction. Everything from engine stress to the driver's heartbeat can be monitored. The information is analyzed to improve handling, performance and even driver technique. Data can be acquired by connecting a computer to the car or by wireless telemetry.
DEEP STAGE
To roll a few inches farther into the beams after NHRA-race staging, which causes the pre-stage lights to go out. In that position, a driver is closer to the finish line but dangerously close to a foul start.
DIALING IN
This refers to the driver and crew making setup adjustments to achieve the car's optimum handling characteristics.
DIAPER
An absorbent blanket made from ballistic material, often Kevlar that surrounds the oil pan to contain oil and parts in case of an engine explosion; required for Funny Car and Champ Car World Series cars.
DIFFUSER
The bodywork at the rear underside of the car that controls underbody airflow as it leaves the back of the car. A good diffuser generates significant downforce.
DIRTY AIR
The turbulence created in the wake of other race cars. At high speeds, following closely behind another car can disrupt downforce. A car following closely often will suffer understeer as a result.
DITCH-HOOKING
World Rally driving style which places the inside front wheel over the road-side ditch.
DNF
Did not finish.
DNQ
Did not qualify.
DNS
Did not start.
DOWNFORCE
The downward force generated as air flows around a moving object. Champ Car World Series series vehicles use wings, while NASCAR vehicles use rear-end spoilers to create downforce. The ground-effects tunnels underneath the car also provide downforce, creating a vacuum that sucks the car to the track. Increased downforce also results in increased drag, which slows a car down.
DRAFT
Airflow creates a low-pressure air pocket (or draft) behind moving objects. Most notably in NASCAR, drivers try to follow opponents closely enough to enter their draft and produce a "towing" effect known as "being in the slipstream." That's right, the car creating the draft actually pulls the pursuing driver, who can ease off the throttle and save gas.
DRIVERS' CHAMPIONSHIP
Points are awarded at each race based on finishing position. The driver accumulating the most points by the end of the season wins the drivers' championship. A similar award system is used by most major series for a manufacturers' championship.
DROP LIMITER
Electronic device that controls suspension travel, assuring conformity to mandated limits.
DROP THE HAMMER
Means a driver puts the pedal to the metal.
DROPPED CYLINDER
When an NHRA vehicle's cylinder runs too rich (too much fuel in the air/fuel mixture) and prevents the spark plug(s) from firing.
DRY LINE
Because of more frequent driver use after rain, this clear line develops on NASCAR and Champ Car World Series tracks.
DRY WEIGHT
A car's weight without any liquids, such as gas and oil.
DYNO
A contraction of "Dynamometer," an engine-testing device used in the shop that measures power and simulates the loads and environment of a NASCAR or Champ Car World Series racing engine.