How Billy Bob became the Corvette Z06

It was an outcast in polite company, like bringing Lady Gaga to a Presbyterian Tea. Rough and raucous, the fifth-generation Corvette Z06 was a tire-smoking badass.

With 385 horsepower—and later, 405 hp—pouring out of its LS6 V-8, the car ripped. But the Z06, introduced in the 2001 model year, was no mere hot rod. There was plenty of racing sophistication under its skin. The result was a machine that had a great power-to-weight ratio of only 8.12 pounds-per-hp, a figure that beat other cars of its time, including the 2000 Porsche 911 Turbo and Boxster, as well as the Ferrari 360 Modena and BMW Z8.

Although that was great company to be in, the Z06’s origins were hardly noble. Its original nickname was the “Billy Bob Corvette,” initially meant to be an entry-level model using fixed-roof or hardtop architecture, the third body style created for the C5.

The original concept was supposed to feature lower-cost cloth seats and manual windows, but Chevy research would soon discover that the public had higher expectations of what a Corvette should be. So the entry-level model was scrapped in favor of a slightly lower-priced performance coupe with leather seats and a manual-only transmission option.

The hardtop included the 345-hp LS1 engine and Z51 performance-handling package. Only five exterior colors were available.

Because of its fixed roof, it was 12-percent stiffer than the Corvette coupe and some 80 pounds lighter, which gave it a natural performance advantage over the other models. Price wise, the hardtop was about $2,000 less than the standard Corvette coupe.

Only 4,041 were built in 1999 and another 2,090 in 2000. These were disappointing numbers, so Dave Hill and his engineers decided to use the fixed-roof coupe for an entirely different purpose. And that purpose became the reincarnation of the Z06 nameplate. The original Z06, of course, was the moniker for a performance Sting Ray in 1963 that racers could order to do battle with Cobras and other sports cars in SCCA competition.

Hill’s team started under the hood with a new variation of the small block known as the LS6, which put out 385 hp at 6000 rpm versus 345 hp for the stock LS1. Torque was 375 lb.-ft. at 4400 rpm, an increase of 15 lb.-ft. over the LS1.

The LS6 was a deeper-breathing engine than the LS1, with air fed directly to the engine through front fascia openings as opposed to feeding from the bottom. Once air entered the engine, it encountered fewer restrictions, thanks to a new mass airflow sensor and a new freer-flowing intake manifold.

The cylinder heads incorporated new D-shaped ports, improving the flow of combustion gases by 10 percent. The compression ratio was increased to 10.5:1 from the LS1’s 10.1:1. A revised camshaft increased valve lift by five percent. Fuel injector capacity was increased as well. All told, the LS6 could comfortably rev to 6500 rpm versus 6000 for the standard LS1. This higher revving capability also necessitated new, stronger valve springs.

The Z06 also got a beefier suspension, with a large, hollow front stabilizer bar, stiffer rear springs and revised front and rear camber settings. Tires were Goodyear Eagle F1 Supercar units that did not have extended mobility capability and therefore necessitated the addition of a tire inflator system.

The wheels were one inch wider than the stock Corvette size and came in a unique matrixed design, which helped showcase the car’s bright red brake calipers. Z06s were also distinguished by a rear brake-cooling duct just behind each door and a special mesh grille up front, plus a Z06 badge flanking each front quarter panel.

Weight was also considered. The exhaust system was made of titanium, the first such use in a mass-produced automobile, and was 19 pounds lighter than the stock Corvette exhaust system. Also contributing to the mass savings were a thinner windshield and lighter insulating material. All told, 58 pounds were shaved from a standard C5 coupe with its Targa-style removable roof panel.

While the Z06 is one of the sweetest performance Corvettes ever built, it’s a car with a harder personality—more exhaust noise, tire noise and road vibration, and diminished all-weather capability. In making the Z06 go faster, the engineers by necessity reduced the refined feeling of the Corvette coupe or convertible.

But for hard-core purists, the changes were worth it. The Z06 was now fully capable of zero-to-60 times in the sub four-second range and could turn the quarter-mile in less than 12.5 seconds. “This is the sport bike of the family,” powertrain engineer Bill Nichols said in a 2001 Corvette Quarterly article. “It’s for the person who likes to get up Saturday morning and wax the car, who would reserve Sunday afternoon for a gymkhana.”

For the final year of C5 production, Chevrolet rolled out a beautiful Commemorative Edition Z06 with Le Mans Blue paint and a silver racing stripe outlined in red. The car featured aluminum-spun wheels and a carbon-fiber hood. The Commemorative Edition is considered the crown jewel of the C5 Z06 line—hardly the type of machine once nicknamed “Billy Bob.”

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