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Also from Issue 81

  • 60th Anniversary Salute: C4
  • Buyer’s Guide: C4
  • Supercharged 2003 Convertible
  • 1973 COPO Coupe
  • GM Heritage Center
  • Guldstrand 1965 Restomod
  • Profile: Gib Hufstader
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The new Stingray’s coefficient of drag has yet to be released—small details are still being fine-tuned—but Bennion says it will be roughly comparable to the C6’s figure. If that seems like a disappointing result, consider the fact that the designers had much more on their plates. “It used to be we only concentrated on just getting a low Cd, a slippery shape,” says Bennion. “Now it’s gotta be a slippery shape, low lift and, by the way, you have to pull in enough air to cool the engine, cool the front brakes, cool the rear brakes and cool the trans and diff, all off the exterior surface. There’s a lot more responsibility put on the exterior design than what we’ve done in the past.”

One of those responsibilities was ensuring that enough air flowed through the rear fender-mounted inlets. The one on the driver’s side feeds the transmission cooler on automatic-equipped Stingrays, while the one on the passenger side directs air to the differential cooler on Z51 Performance Package-equipped cars. At the Corvette team’s weekly development meetings, Juechter would slip Bennion a subtle reminder: “If we don’t get enough airflow to that transmission, we don’t have a car.” After running computational flow analysis on 16 different iterations and testing the finalists in the wind tunnel, Bennion’s team hit its mark. Thanks in part to the ramped-up quarter lines along the Stingray’s sides, the small inlets flow an incredible 8 cubic meters of air per minute.

Though the protruding triangles at the leading edge of the car are primarily aimed at improving the Corvette’s pedestrian safety test results, Bennion and his team made sure that they were of aerodynamic benefit as well, both in terms of lowing the Cd and reducing lift. “Every element of the Corvette has to earn its way onto the car,” he says.

As far as aerodynamic lift is concerned, the C7 has made progress over the C6. With the Z51 package, which includes a full-width rear spoiler and an altered air dam, the Stingray generates less lift than a ZR1; a base car has less lift than a Z06. The 700+ hours of wind-tunnel time were put to good use. Still, given the number of lift-reducing elements in the design—especially the vented hood—we were surprised to learn that the Stingray doesn’t actually generate downforce. “It’s not that we didn’t want a downforce car,” explains Bennion. “We could have put more downforce in the car, but that would have raised the Cd. We’re trying to achieve that optimal balance. We felt that if we’re better than a ZR1 for the Corvette Stingray’s starting point, that’s awfully good. A zero-lift, downforce car—that’s something we want to get to.”

Material

The Stingray’s body panels are fabricated using a new Sheet Molded Compound material that is both lighter and constructed to tighter tolerances. One of the drivers for this change was the C7’s carbon-fiber top and hood. Because carbon fiber has less thermal expansion than traditional fiberglass, it maintains its shape better and yields tighter tolerances. Essentially, the decision to use carbon fiber on the base car—a Corvette first—raised the bar on the rest of the body structure, forcing Chevy to come up with improved SMC. As a result, the Stingray’s body is 37 pounds lighter than its predecessor’s—despite the fact that the car is one inch wider and 2.4 inches longer—and will be assembled with body gaps of 3 mm or less, making for much-improved fit and finish.

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