The winningest driver in NASCAR history, King Richard Petty, told a group of auto journalists before this year's Daytona 500 that the racing organization would like nothing better "than to see a pack of cars start the race and, 500 miles later, see that same pack racing toward the finish." Keeping everyone as competitive as possible is the name of the game. NASCAR regulations for the cars leave the maximum room for driver skill and racing excitement and minimal room for design engineers to maneuver.
"The formula is maddening for engineers," says Jim Wall, Hendrick Motorsports lead engineer. "They do everything to control technology and let the drivers and race teams at the track make the difference." The cars are based on full-bodied sedans rooted in production cars the public can (or at least could at one time) buy--rear-wheel-drive machines still using carburetors and no engine fuel management. Active suspension, as on purpose-built race cars, is out. Production parts, such as engine blocks and manifolds modified for greater strength and fatigue resistance, are the basis for some components. Materials are top grade, but aerospace-types such as composites are limited in application to some air ducting and facias. And while digital instrumentation and recording devices are permitted when testing cars, these are not allowed during a race--the ultimate test. Here, notes Wall, "The driver and track teams are again the key components for feedback to optimize the car" during pit-stop suspension and engine adjustments.
Wall says, "Innovation comes from working within the rules. The races are very exciting since 10 to 20 cars can be on the lead lap at the end, and the difference between a good car and an average one is a small amount of time." For the cars, the race teams are handed a baseline vehicle from a sponsoring auto maker as approved by NASCAR. "We take and optimize as much as NASCAR will allow for a given set of conditions and power trains as well," he adds. Such freedom includes adjusting the center-of-gravity downward and laterally by internal component placement. And while a powerful engine may lead the pack, a more efficient one will still have enough fuel in the tank to finish a race. And finishing is the key to amassing points--while there is not much difference in points for the top finishers in a race, consistently placing near the lead can bring the season crown. A strong winner of several races, but who breaks down in other events, may not get the title.
The organization will also handicap a given type of car if it perceives it as having an advantage over other types. For example, the Chevrolet Monte Carlo was seen having an advantage aerodynamically over the Thunderbirds previously used by Ford teams, thus Chevy's rear-spoiler height was cut to reduce downforce, making the T-Birds faster in the turns. But this year, an advantage to the Chevrolets in engine power somewhat offsets the slicker aerodynamics of the Ford Taurus.
Concluding, Wall likens working with NASCAR to dealing with the IRS, "If you find an advantage under the rules, you take it. We are like tax attorneys working within a given set of rules, being aggressive without stepping over the lines."