Chevrolet's ongoing American Revolution came to NHRA Pro Stock with the introduction of the Chevy Cobalt at Bristol Dragway on April 29, 2005. It didn't take long for the new Chevy to earn a place in the NHRA record book. On June 18, 2005, Kurt Johnson qualified his ACDelco Cobalt in the No. 1 spot at the K&N Filters Super Nationals in Englishtown, N.J. One week later, Johnson put his Cobalt in the winner's circle at the Sears Craftsman NHRA Nationals in Madison, Ill. In 2007, Chevy Cobalt drivers combined for seven victories in 12 final-round appearances, with Dave Connolly finishing third in the final Pro Stock standings and Johnson finishing fifth.
"Chevrolet's performance heritage promises cars that are dependable, capable and exciting to drive," said Ed Peper, Chevrolet general manager. "The Chevy Cobalt puts the fun back into driving by delivering an experience never before seen in the compact-car segment. Chevrolet races to win: Chevy has a strong heritage in drag racing and is one of America's most successful automotive brands. The NHRA Pro Stock Cobalt is designed, built and engineered to continue that winning tradition."
Work on the Pro Stock Cobalt started in November 2003 when GM Racing engineers began exploring concepts for a new Chevy Pro Stock race car. They took a pre-production model of the new Cobalt to Don Ness Racecraft, near Minneapolis, and, along with Ness and representatives from the NHRA – including National Technical Director Danny Gracia – the group began reviewing the styling features of the new car.
During this initial design phase, NHRA officials mandated more than 20 minimum dimensions for the construction of Pro Stock cars, including the new Cobalt. The new specifications covered such areas as the height and width of the car, the front and rear overhangs and other critical dimensions.
"The first thing we had to do was make sure the new Pro Stock Cobalt fit within the box," explained Dan Engel, GM Racing program manager for NHRA drag racing. "NHRA specified several key minimum dimensions, so the goal was to meet them without changing the basic body shape. NHRA was involved in the process from the very start, and like everyone at GM, it was interested in retaining the body lines and contours of the production Cobalt. Chevy is selling and racing Cobalts, so we want the race cars to look like Cobalts."
The production version of the Cobalt provided a solid foundation for GM Racing engineers to begin the planning and construction of the Pro Stock version. Extensive research was conducted in the GM wind tunnel in Warren, Mich., evaluating various greenhouse shapes, decks, roofs and fender flares to determine the most aerodynamically efficient design.
"The Cobalt was a great car to start with," explained Engel. "Obviously, it's a lot easier to start with a smaller car than a big car, but the biggest hurdle we had was making enough room under the hood to get that 500-ci DRCE engine in there. We were able to get the body to meet all the dimensions mandated by NHRA, fit the engine, the rear axle, the entire chassis, and still retain the shapes and contours of the production Cobalt."
GM Racing engineers had two objectives for the Cobalt program: The first was to create a one-piece body, or unibody, that would make it more efficient for chassis builders to mount and work with, and for the NHRA Technical Department to inspect. The second was to reduce the weight of the body while maintaining its stiffness, strength and structural integrity.
"Whenever we create a new race car, we try to accomplish more than just introducing a new model," Engel said. "We also want to apply everything we've learned since building the older design so that we can keep moving forward, whether it's in the area of aerodynamics, strength of the body, safety, etc. These were two areas where we felt we could make improvements."
The Cobalt's predecessor was the Chevy Cavalier. The Pro Stock Cavalier featured a one-piece nose, hood, quarter panels and front valance. However, the rear end of the Cavalier race car comprised many different components, including right and left quarter panels, the roof, rear deck, rear deck filler panel and bumper cover. Chassis builders had to align these various components correctly to make a perfect fit for the template. NHRA officials were in favor of the new unibody construction because it would make it easier to check the car when it's going through tech inspection at the race track.
"We had great input from the people at NHRA throughout the entire project," Engel noted. "They were even at the second wind tunnel test when we made some minor changes to the car, and we provided them with all the aero numbers. They've been tremendous to work with."
After the second wind tunnel test, Five Star began the process of creating the molds that were used to make the actual body panels. But before it could make the molds, it had to complete a lot of prep and finish work to ensure the body was perfectly smooth and symmetrical.
After the molds were completed, Five Star created a Cobalt body that was sent back to Ness Racecraft, where it was mounted on a chassis. NHRA inspectors again went through the process of checking dimensions, and at this point the templates were made.
"We built the first set of production templates at Don Ness' shop," said Engel. "We gave them to NHRA and they become their master set. Besides measuring the car, NHRA also checked out the templates to make sure they fit the car. Because these are the templates GM has built under the supervision of NHRA, these will be the templates now used at the race track."
Chevrolet drag racers liked what they saw when the new Cobalt body was introduced.
"It's a great looking car," said Johnson, driver of the ACDelco Cobalt. "It's sleek, narrow and better in the wind tunnel than the previous car. It's always positive any time a racer gets the improvements of a new race car, and the new Cobalt is definitely a great package."
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