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From the April 2020 issue of Car and Driver.
How does 900 horsepower strike you? Now imagine it’s stuffed into a car that weighs just 1400 pounds, including a driver. No, this isn’t Formula 1. This is the fire-breathing, dirt-chewing World of Outlaws Sprint Car Series. These tube-frame open-wheel racers are spartan by design: Anything that’s not needed to go fast on dirt is omitted. Modern sprint cars can reach nearly 150 mph and circle a half-mile oval in 13 seconds, most of which is spent searching for traction. In 2020, the series had been scheduled to line up more than 80 times in 24 states. The recent pandemic will determine how many races are completed this season. Here’s a primer so you’re ready for race day.
Illustrations by Moron EelCar and Driver
1. ALUMINUM COURAGE
The massive top wing can have an area of up to 25 square feet and be adjusted fore and aft using a lever in the cockpit so that a driver can balance the aero load to suit the ever-changing conditions of the dirt track. Tip plates along the sides keep high-pressure air moving over the wing. The left plate is positioned higher than the right to generate more downforce on the left half of the car. That’s imperative when so much of each lap is spent sideways.
2. HEARTBEAT OF AMERICA
Each car’s aluminum-block pushrod V-8 is limited to a maximum displacement of 410 cubic inches (6.7 liters) and can spin at an earthshaking 9000 rpm. Injector nozzles squirt methanol fuel, which offers performance and cost benefits over gasoline. Plus, methanol fires can be extinguished with water.
3. SPRUNG OUT
Most modern cars have coil springs, but sprint cars use torsion-bar springs in their suspension design. The bars can be quickly swapped to accommodate track conditions, with the effective spring rate determined by the outside diameter of the bar. Conventional dampers soak up the track’s imperfections.
4. STAGGERING GENIUS
World of Outlaws cars use a spool in place of a differential, so both rear tires spin at the same rotational speed. To compensate for the fact that the cars are almost constantly turning left, the inner-rear tire has a smaller diameter than the outer one [see above]. As tire temperatures increase, bleeder valves release air to maintain steady pressure.
5. THE ON-OFF SWITCH
With no conventional transmission, Outlaws send torque to the rear through a single reduction gear. That ratio can be changed between races to match the car’s speed to each track. Outlaws don’t have a starter, either. Sprint cars are push-started by engaging the direct drive once the car is rolling fast enough.
