Quote:
Originally Posted by NickAlero2000
really?
how's the time get measured?
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Two light beams cross the starting-line area and connect to trackside photocells, which are wired to the Christmas Tree and electronic timers in the control tower. When the front tires of a vehicle break the first light beam, called the pre-stage beam, the pre-stage light on the Christmas Tree indicates that the racer is approximately seven inches from the starting line. When the racer rolls forward into the stage beam, the front tires are positioned exactly on the starting line and the stage bulb is lit on the Tree, which indicates that the vehicle is ready to race.
Once both drivers have staged their cars in the starting beams, the Starting ("Christmas") Tree is activated by a Starting Line Official. Upon leaving the starting line, each contestant's vehicle activates a timer that is, in turn, stopped when the same vehicle reaches the finish line. The start-to-finish clocking is the vehicle's E.T. (elapsed time), which serves to measure performance and often serves to determine handicaps during competition.
Reaction times are a separate measurement which denotes driver's reaction to the starting signal, but has no influence over ET's. Both lanes are timed independently of one another, and the ET clock does not start until the vehicle actually breaks the starting beam just past the 2nd set of Stage lights. Reaction Times indicate how soon after the Green Light comes on that the vehicle trips the starting beam.
A perfect reaction time is .000, and if a car breaks the starting beam before the green light comes on the time is indicated by a negative (i.e., -.033) and a red light comes on instead of the green, further indicating a "foul". If you "red light" during competition your opponent wins (unless he red lights first before you do in that race).
If both vehicles cover the quarter-mile in exactly their predetermined elapsed time ("Dial-In"), the win will go to the driver who reacts quickest to the starting signal.
Because of this, a vehicle may sometimes appear to have a mathematical advantage in comparative elapsed times but actually lose the race. This fact makes starting-line reflexes extremely important in drag racing.