Auto Industry News : 12/21/07
CHEVROLET ENTERS THE WORLD OF SUPERCARS
WITH 2009 CORVETTE ZR1
New, Supercharged LS9 V-8 is the Heart of the ZR1
DETROIT – Chevrolet officially announced the 2009 Corvette ZR1 – an American supercar that brings the technology and engineering refinement of carbon-fiber, ceramics
and electronics together in a distinctive design.
“Chevrolet’s goal with the new ZR1 is to show what an American supercar can deliver, at a price that trumps exotics that cost two, three or four times as much – and does so with exceptional driveability,” said Ed Peper, Chevrolet general manager.
The ZR1’s basic stats:
The specialized components of the new ZR1 work harmoniously to deliver the most powerful and fastest automobile ever produced by General Motors. Performance estimates will be announced closer to vehicle’s summer 2008 launch.
“Preliminary testing shows the ZR1 builds on the highly respected Corvette Z06
in every performance category, from acceleration and braking, to cornering grip and top speed,” said Peper. “It all boils down to the power-to-weight ratio and the ZR1’s is exceptional – better than the Porsche 911 GT2, the Ferrari 599 and even the Lamborghini LP640. In fact, the ZR1 is expected to be the first production Corvette to achieve a top speed of at least 200 mph.”
Supercharged LS9 engine
The new LS9 6.2L small-block engine is the power plant the supports the ZR1’s performance capability. The enabler of the LS9’s performance and refinement is a large, positive-displacement Roots-type supercharger with a new, four-lobe rotor design. It is augmented with an integrated charge cooling system that reduces inlet air temperature for maximum performance.
A sixth-generation supercharger developed by Eaton helps the LS9 make big power and torque at lower rpm and carries it in a wide arc to 6,600 rpm, as it pushes enough air to help the engine maintain power through the upper levels of the rpm band – the area where supercharged performance tends to diminish. Heavy-duty and lightweight reciprocating components enable the engine’s confident high-rpm performance.
The LS9 is hand-assembled at GM’s Performance Build Center, in Wixom, Mich., and incorporates specialty processes typically seen in racing engines to produce a highly refined and precise product. For example, cast iron cylinder liners are inserted in the aluminum block and are finish-bored and honed with a deck plate installed. The deck plate simulates the pressure and minute dimensional variances applied to the block when the cylinder heads are installed, ensuring a higher degree of accuracy that promotes maximum cylinder head sealing, piston ring fit and overall engine performance.
Transmission and axle
The LS9 engine is backed by a new, stronger six-speed manual transmission and a twin-disc clutch that provide exceptional clamping power, while maintaining an easy clutch effort. ZR1-specific gearing in the transmission provides a steep first-gear ratio that helps launch the car, and top speed is achieved in sixth gear – a change from the fifth-gear top-speed run-outs in the manual-transmission Corvette and Corvette Z06.
As the term implies, the twin-disc clutch system employs a pair of discs, which spreads out the engine’s torque load over a wider area. This enables tremendous clamping power when the clutch is engaged, while also helping to dissipate heat better and extend the life of the clutch.
The twin-disc clutch system also contributes to the ZR1’s exceptional driving quality, with smooth and easy shifting. The twin-disc system’s design enables a 25-percent reduction in inertia, thanks to smaller, 260-mm plates, corresponding to a pedal effort that is similar to the Corvette Z06’s 290-mm single-disc system.
The rear axle also is stronger in the ZR1 and features asymmetrical axle-shaft diameters that were developed after careful testing to provide optimal torque management. The axles are also mounted on a more horizontal plane that correlates with the wider width of the rear wheels and tires.
Ride and handling
The ZR1 is built on the same aluminum-intensive chassis as the Corvette Z06 and features similar independent SLA front and rear suspensions, with aluminum upper and lower control arms. Where the ZR1 differs is the suspension tuning, which was optimized for the car’s steamroller-wide front and rear tires.
Magnetic Selective Ride Control is standard and tuned specifically for the ZR1. The system’s ability to deliver a compliant ride with nearly instantaneous damping adjustments enabled engineers to develop a surprisingly supple ride quality in a supercar that still delivers cornering grip of more than 1g.
From a high-performance perspective, Magnetic Selective Ride Control helps the rear axle remain planted during launch for smooth, hop-free acceleration. It also helps suppress axle movement when cornering on broken or uneven pavement.
Brakes, wheels and tires
Commensurate with the ZR1’s engine output is the braking system, which is headlined by carbon-ceramic brake rotors. Found on only a few exotics and more expensive supercars, carbon-ceramic brake rotors are made of a carbon-fiber-reinforced ceramic silicon carbide material . Their advantage comes in low mass and resistance to wear and heat. In fact, the rotors should never show any corrosion or require replacement for the life of the vehicle, when used in normal driving.
The vented and cross-drilled rotors on the ZR1 measure 15.5 inches (394 mm) in diameter in the front and 15 inches (380 mm) in diameter in the rear – making them among the largest carbon-ceramic rotors available on any production vehicle.
Clamping down on the high-tech rotors are six-piston front calipers and four-piston rear calipers, each painted a ZR1-exclusive blue. The front pads are equivalent in size to the largest on any production car with a single-pad design – double that of the Corvette Z06’s 70-sq.-cm. front pads.
The brakes are visible through the ZR1’s exclusive wheels: 20-spoke alloy rims that measure 19 inches in diameter in the front and 20 inches in the rear. They come standard with a bright, Sterling Silver paint finish and chrome versions are optional. The wheels are wrapped in Michelin Pilot Sport 2 tires developed specifically for the ZR1, measuring P285/30ZR19 in front and P335/25ZR20 in the rear.
The ZR1 is instantly recognizable, with perhaps the most identifiable feature a raised, all-carbon-fiber hood that incorporates a clear, polycarbonate window. The window provides a view of the top of the engine’s intercooler, with the legend “LS9 SUPERCHARGED” embossed on the left and right sides, and an engine cover with the Corvette crossed flags logo debossed at the front.
The underside of the hood has an exposed carbon-fiber-weave.
Exposed carbon-fiber is used on the roof, roof bow, rocker molding and front splitter. These exterior components are protected by a specially developed glossy, UV-resistant clear coat that resists yellowing and wear.
Widened, carbon-fiber front fenders with specific, dual lower vents, and a full-width, body-color rear spoiler incorporating the center high-mounted stop lamp, are also unique to the ZR1. All of the exterior features of the car were developed to enhance high-speed stability and driver control.
The “base” ZR1 (RPO 1LZ) comes with accoutrements based on the Z06, including lightweight seats and lightweight content. The uplevel interior package includes unique, power-adjustable and leather-trimmed sport seats (embroidered with the ZR1 logo); custom, leather-wrapped interior available in four colors; navigation system, Bluetooth connectivity and more.
By the numbers
In addition to the exterior cues and powertrain, ZR1 models will be distinguished from other Corvette models by their VIN. Each will carry a unique, identifying VIN digit, as well as a sequential build number. This makes it easy to determine the build number of a specific car – information treasured by enthusiasts and collectors. For example, a ZR1 with a VIN ending in “0150” would indicate it is the 150 th ZR1 built for the model year.
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