Drag Racing: the perfect launch
Drag racing, a competition between two cars that starts from a complete stop over a 1/4 mile (1320 feet) distance, is highly dependent on the first 60 feet of the race or launch. The technique used for launching varies greatly depending on how the car is equipped. The type of transmission, the wheels being driven, the tires, the power, the suspension and the track preparation all play a key role in how to achieve the best possible launch of the car.
Improvements in the time it takes for the car to travel the first 60 feet on the track have significant implications for the final ET (estimated time). As a general rule of thumb, 60-foot time improvements are magnified 2x at their final ET. For example, a Dodge Viper GTS that runs 12.2 @ 120 MPH in 1/4 mile with a 60 foot time of 2.0 can make significant improvements to its 1/4 mile times by getting a better launch. If the Dodge Viper GTS is capable of cutting .2 (two-tenths) of a second, that’s a 60-foot time, covering the first 60 feet in 1.8 seconds, its final ET for the 1/4 mile would be around 11.8 @ 119 – 121MPH. More examples can be found by searching the thousands of 60-foot records in the endurance racing database http://www.dragtimes.com.
The best possible launch is obtained by obtaining the optimal balance of applying the most power to the ground with the least amount of wheel spin. If too much power is applied during the throw and the tires skid, the resulting 60-foot time will be poor. The same goes for not applying enough power, causing the car’s engine to stall and the car to slowly slip out of line.
When launching a car with an automatic transmission, a technique called power braking is used. After correctly positioning the car in the drag track parking lane, hold down the brake with one foot, while slowly applying the accelerator pedal with the other foot. The car’s engine RPM (revolutions per minute) should slowly increase to a point where the car begins to move or the tires begin to rotate. Hold down the brake and accelerator pedals just below the point where the car is starting to move or spinning the tires. When the Christmas tree lights hit the last amber light before the green light, lift the brake and slowly push the gas pedal all the way down. The correct RPM to launch will be different for each car depending on all the variables mentioned above. Start conservatively with the first pitch and keep increasing the RPM the car is thrown at during subsequent races. If the car starts spinning the tires after launch, lower the launch RPM and try again.
When starting a car with a manual transmission, come to a complete stop after the car is properly primed. Press the clutch all the way in with one foot while pressing the accelerator pedal down with the other foot, raising the engine RPM to a constant moderate level for the first launch. Raise the clutch pedal to the point where the car is about to start moving and keep both pedals still. When the Christmas tree lights reach the last amber before green, slowly release the clutch while quickly applying the gas pedal just enough to launch the car quickly, but not too much to induce a large amount of wheel spin. Start conservatively with the first pitch and keep increasing the RPM the car is thrown at during subsequent races. If the car starts to spin the tires too much after launch, lower the launch RPM and try again.
To get better launches and reduce 60 feet even further, the use of drag or flat radial tires can be used on more powerful cars that have trouble taking off at any RPM with normal street tires. Drag radials and full slicks generally require a burnout to warm up the tires and clear them of debris for optimal performance. A burnout is a rapid spin of the car’s tires while the car remains relatively still.
All-wheel drive (AWD) cars are generally the easiest to start because the engine’s power is distributed over 4 wheels instead of two. Rear-wheel drive (RWD) cars tend to start better than front-wheel drive (FWD) due to weight transfer to the rear tires during start-up, causing increased traction. If the car has aftermarket adjustable suspension, drag racing specific adjustments can be made to increase weight transfer to the drive wheels.
Track launch pad preparation also plays a role in how well and how hard cars can launch. The launch area is generally prepared with traction compounds to increase track grip. A well prepared track will definitely help cut down on 60 foot times and result in lower 1/4 mile times.
During breaks and cool-down periods between drag races, take detailed notes on how you launched on the back of each timesheet. These notes can help you diagnose launch issues, adjust subsequent releases, and show improvements in searching for The Perfect Launch.