Perhaps one of the most taken for granted pieces of the drag track is something intangible, always fleeting, and something that drag racers try to keep to an absolute minimum: time. Time is the best friend and enemy of drag racers. A split second is almost an eternity, as races are often won and lost by just ten thousandths of a second.
Methods for generating lap times have evolved over the 60-year life of organized endurance racing. Perhaps the most revolutionary innovation in timing advancements came from endurance race organizer CJ Hart in 1950. Hart designed a timing system comprised of two photocells that would record a runner’s top speed. Long before the construction of elaborate and specially designed timing towers, Hart’s timing system was operated from a decommissioned hearse parked near the finish line. Right outside the hearse, Hart would post the top speeds of the match and the names of those fast drivers on a scoreboard. The introduction of this timing system actually preceded the formal establishment of quarter-mile races, as competitions at that time were generally held at approximately three-tenths of a mile.
Today, this technology results in the bright orange cubes that we see strategically placed between the two lanes over the quarter mile distance. These “timing cones” are actually photocells, similar to those introduced by CJ Hart in 1950. The timing system has become more sophisticated, now recording incremental times, total elapsed times, and average miles per hour. Times are now recorded at 60 ‘, 330’, 660 ‘(1/8 mile, half track), 1,000’ and 1,320 ‘(1/4 mile, finish line). Average mile per hour is also calculated at the 1/8 mile and ΒΌ mile marks on the skid trail.
A modern sophisticated timekeeping system is capable of measuring ET to an accuracy of one millionth (0.000001) of a second. However, all the ultra-stylish high-tech digital and fiber optic technology in the world is useless if the driver cannot understand the generated data. In addition to the elapsed times that determine the outcome of the race, the precise numbers found on your timesheet are very beneficial in helping to improve your driving skills.
There is no better place to start this discussion than at the starting line. A common misconception of newcomers is that the ET (elapsed time) clock starts when the green light bulb on the start line turns on. This is a false misunderstanding. In fact, there are two separate time records taken on the race track: reaction time and elapsed time. Reaction time is the time from the flash of the green light bulb to the movement of the vehicle when it completely leaves the beam from the starting line. If that seemed too much for you, let me jog your memory and explain further.
Remember, timing sensors are triggered by a photocell interruption. Lining up the drag strip in strategic locations are photocells that project an invisible beam that makes contact with a reflector (the orange cube) on the center line. The disturbed beam activates the timing system. The stage light (second set of yellow incandescent bulbs just above the first amber LED bulb) on the Christmas tree tells the beginner and competitor that you are ready and committed to running the race. The stage light is activated by the beam from the starting line. The time that passes between the illumination of the green bulb and the front tire of the race car coming out of the beam from the stage represents the reaction time of the driver. A perfect reaction in a typical five-tenths (0.500) of a full second tree (countdown of three amber bulbs sequentially in half (0.500) second intervals) is 0.500 seconds, or more simply converted today as 0.000 seconds.
The Christmas tree has had a series of facelifts during its nearly 50-year span as the standard method for starting competitive racing. Throughout the 1950s and early 1960s, a flagger between the two race cars signaled when the drivers should launch from the starting line. The obvious dangers and subjectivity of using a flagger contributed to the design and implementation of the Christmas tree. The Christmas tree made its formal debut at the 1963 NHRA Nationals. The Christmas tree originally consisted of five amber bulbs, but was reduced to its now standard three amber bulbs in the mid-1980s. 2003, NHRA introduced LED bulbs, replacing what were once the standard amber incandescent bulbs.
There are two basic Christmas tree designations: professional tree and full tree.
The professional tree is mainly used in the heads-up categories (Top Fuel, Funny Car, Pro Stock, Pro Modified, Pro Stock Bike, Top Alcohol Dragster and Funny Car, and Super Comp / Gas / Street). With the professional tree, the three amber lights instantly lit up.
The full axle is primarily used for bracket style dial racing, when a stepped axle is necessary to accommodate sometimes very different ET vehicles. Such categories that use a full tree include Competition Eliminator, Super Stock, Stock Eliminator, Super Pro, Pro, Sportsman, and Junior Dragster. With the full tree, each amber bulb lights up sequentially, typically 0.500 seconds.
Yes, there are exceptions to these general rules. For example, most professional tree races are held in a 0.400 second tree, where 0.400 seconds separate the yellow amber and green bulbs. The Super Street category (10.90 heads-up), however, is an exception, as they use a 0.500 second tree.
Regardless of the 0.400 or 0.500 second trees, the driver’s time slip will read perfect as a standardized 0.000 seconds. To prove it, what was once a perfect reaction time of 0.500 seconds would now be a perfect reaction time of 0.000 seconds. The same goes for perfect reaction times of 0.400 seconds. Therefore, any deviation from a perfect reaction time of 0.000 seconds will be recorded as – / + 0.000 seconds.
