Drag Racing: The Perfect Launch
Drag racing, a contest between two cars starting from a complete stop over a distance of 1/4 mile (1,320 feet) relies heavily on the first 60 feet of the race or launch. The technique used for the launch varies greatly depending on how the car is equipped. The type of transmission, which wheels are driven, the tires, power, suspension and track preparation all play a key role in how to achieve the best possible launch from the car.
Improvements in the time it takes the car to travel the first 60 feet of the track have significant implications for the final ET. As a general rule of thumb, 60ft time buffs are multiplied by 2 on your final ET. For example, a Dodge Viper GTS running 12.2 @ 120 MPH in 1/4 mile with a 2.0 60ft time can significantly improve its 1/4 mile times by getting a better launch. If the Dodge Viper GTS can shave 0.2 (two-tenths) of a second, that’s a 60-foot time, by covering the first 60 feet in 1.8 seconds, your final ET for the 1/4 mile would be about 11.8 @ 119 – 121 MPH. More examples can be found by searching the thousands of 60 foot records in the drag racing database at http://www.dragtimes.com.
The best possible launch is obtained by striking the optimum balance of putting the most power to the ground with the least amount of wheel spin. If too much power is applied during launch and the tires spin, the resulting 60-foot time will be poor. The same goes for not applying enough power, which causes the car’s engine to stall and the car to slowly roll off the line.
When a car with an automatic transmission is launched, a technique called assisted braking is used. After correctly positioning the car in the parking lane of the racetrack, hold down firmly on 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 will either start to move or start to spin the tires. Hold down the brake and accelerator pedals just below the point where the car starts to move or spins the tires. When the Christmas tree lights reach the last amber light before green, release the brake and slowly push the accelerator pedal all the way down. The correct RPM for launch will be different for each car based on all of the variables mentioned above. Start conservatively with the first launch and keep increasing the RPM the car launches at during subsequent runs. If the car starts to spin the tires after launch, lower the launch RPM and try again.
When launching a car with a manual transmission, come to a complete stop after the car is properly primed. Push the clutch all the way in with one foot while pressing the accelerator pedal down with the other foot, raising engine RPM to a steady moderate level for first launch. Lift the clutch pedal up 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 accelerator 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 launch and keep increasing the RPM the car launches at during subsequent runs. 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 foot times even further, the use of drag radial or full bald tires can be used on more powerful cars that have trouble launching at any RPM with regular street tires. Drag radials and full slicks generally require a burnout to warm up the tires and clean them of debris for optimum performance. A wear is a quick spin of the car’s tires while the car is sitting relatively still.
All wheel drive (AWD) cars are usually the easiest to launch because the engine power is distributed to all 4 wheels instead of both. Rear wheel drive (RWD) cars generally launch better than front wheel drive (FWD) cars due to the transfer of weight to the rear tires during launch, causing an increase in 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 big part in how well and how hard the cars can take off. The launch area is usually prepared with traction compounds to increase track grip. A well groomed track will definitely help drop 60 foot times and result in lower 1/4 mile times.
During breaks and cool-down periods between endurance races, take detailed notes on how you launched yourself on the back of each schedule. These notes can help you diagnose launch issues, adjust subsequent launches, and show improvements in your quest for the perfect launch.