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Pulling the Covers off of the 2015 Corvette Z06 and C7.R

The long-awaited day has finally arrived and Chevrolet has unveiled the 2015 Corvette Z06 and C7.R to a crowd of excited onlookers at the North American International Auto Show (NAIAS) in Detroit. Chevrolet is calling the Z06 “the most track-capable Corvette in the brand’s history,” with performance elevated to hold its own against stiff competition. Advanced aerodynamic downforce, an all-new supercharged engine producing “at least 625 horsepower and 635 lb-ft of torque,” and a totally new optional high-performance eight-speed automatic transmission make the Z06 a force to be reckoned with and an engineering masterpiece. Pricing and performance data has yet to be announced, but Chevrolet has said that the new Corvette Z06 will be available in early 2015, and pricing is not expected to be too far off from the price of the most recent Z06. Meanwhile, the new naturally aspirated 2015 Corvette C7.R race car will be powered by a 5.5L 336 cubic-inch powerplant, though horsepower ratings have yet to be determined.

“The new Z06 delivers levels of performance, technology, and design that rival the most exotic supercars in the world,” said Mark Reuss, president, General Motors North America. “And the Z06 leverages the engineering expertise of GM, offering the choice of two world-class transmissions, supercar performance without supercar fuel consumption, and technologies that make it easier to fully enjoy the incredible experience of driving it.”

Enthusiasts are excited to hear it straight from Chevrolet that the new 2015 Z06 will be the first of its kind to be built with a supercharger under-hood, feeding a LT4 6.2L V-8 engine. Built in Tonawanda, New York, and Bowling Green, Kentucky, at the new Performance Build Center, the LT4 features direct injection, Active Fuel Management (or cylinder deactivation), and continuously variable valve timing, which carries over from the LT1 Stingray. Fuel-efficient multi-speed transmissions, the aerodynamic design, and lightweight construction all make for surprising fuel-efficiency.

Mass and performance were two targets Chevrolet refused to miss the mark on, meaning the design of the powerplant was key. The LT4 features an efficient and compact next-generation 1.7L Eaton R1740 TVS supercharger which spins at up to 20,000rpm (that’s an incredible 5,000rpm more than the previous generation Corvette ZR1’s LS9 supercharger). Shorter rotors contribute to higher-RPM capabilities, which means they turn quicker and produce power-enhancing boost earlier in the powerband. A direct discharge port creates less turbulence, lower heat, and quicker airflow contributes to efficiency. To put it in perspective, in regards to the Stingray’s LT1, this LT4 produces 37-percent more horsepower and 40-percent more torque and only stands one inch taller, as the integrated supercharger/intercooler assembly is mounted in the valley between the cylinder heads.

With higher output and greater cylinder pressures created by forced induction comes the need for greater support, manifested through several unique features including stronger, more heat-tolerant Rotocast A356T6 aluminum cylinder heads, lightweight titanium intake valves and machined connecting rods for reduced reciprocating mass, a high 10.0:1 compression ratio to ensure enhanced performance and efficiency which is enabled by direct injection, forged aluminum pistons with a unique, stronger structure for strength under high cylinder pressures, lighter stainless steel exhaust headers and aluminum balancer, and a standard dry-sump oiling system featuring larger cooler capacity than the Z51, which is used with a dual-pressure-control oil pump.

“The supercharged LT4 engine delivers the greatest balance of performance and efficiency ever in the Corvette,” said John Rydzewski, assistant chief engineer for small-block engines. “It is one of the world’s only supercharged engines to incorporate cylinder deactivation technology, enabling it to cruise efficiently on the highway with reduced fuel consumption, but offer more than 600 horsepower whenever the driver calls up its tremendous power reserve.”

For those who wish to control their Z06 on an intimate basis, a standard seven-speed manual transmission with Active Rev Match is offered in addition to the 8L90 eight-speed automatic with paddle shifters for manual control (built at GM’s Toledo, Ohio transmission facility). The C7.R will put the power to the wheels via a 6-speed manual sequential built to racing specifications.

“Unlike most ultra-performance cars, the Corvette Z06 offers customers the choice between two transmissions to suit their driving styles,” said Juechter. “The seven-speed gives the driver the control of a true three-pedal manual transmission with perfect shifts enabled by Active Rev Matching. The new eight-speed automatic offers drivers the comfort and drivability of a true automatic transmission, as well as lightning-fast shifts and manual control for track driving.”

Rev-matching technology in manual cars, a driver-selectable feature, exists for upshifts and downshifts, but can easily be engaged or disengaged via paddles on the steering wheel. A new dual-mass flywheel and dual-disc clutch deliver greater shift quality and feel through lower inertia, while the eight-speed automatic has been designed for world-class shift-response times. The LT4 is kept comfortably within the sweet spot of the RPM band thanks to smaller steps between gears, and full manual control can be achieved through steering wheel paddles. Wide-open-throttle upshifts are capable of being executed up to eight-hundredths of a second faster than the Porsche 911’s dual-clutch transmission due to the 8L90’s execution of commands 160 times per second.

“There’s no trade-off in drivability with the new 8L90 eight-speed automatic transmission – it was designed to deliver performance on par with dual-clutch designs, but without sacrificing refinement,” said Bill Goodrich, assistant chief engineer for eight-speed automatic transmissions. “It is also the highest-capacity automatic transmission ever offered in a Chevrolet car."

GM engineers managed to package the four gear-sets and five clutches of the eight-speed automatic into the same space as the Stingray’s six-speed automatic, while weighing eight pounds less. Friction-reduction contributes to a five-percent greater efficiency over the six-speed automatic.

The Z07 Performance Package – a track-focused addition of components for true aerodynamic downforce – includes Michelin Pilot Super Sport Cup tires to enable enhanced gripping power, and Brembo carbon ceramic-matrix brake rotors to bring the Z06 to a halt. While the Z07 package is still undergoing development testing, it has already recorded some of the fastest lap times ever for a Corvette – even faster than the 2013 Corvette ZR1.

“The Corvette Z06 is a great example of the technology transfer between racing and production Corvettes,” said Tadge Juechter, Corvette chief engineer. “First, we took what we learned on the Corvette Racing C6.R and applied that to the all-new Corvette Stingray. Then, using the Stingray as a foundation, the Z06 and C7.R were developed to push the envelope of performance on the street and the track.”

A striking design to please enthusiasts was a must, but so were increased capabilities, so the design team was faced with fine guidelines to work within. Incredibly, tires were the first design change made, and larger Michelin Pilot Sport tires (Z06) and Sport Cup tires (Z07 package) mounted on lightweight, spin-cast aluminum wheels fit the bill. The front tires are 1.5-inches wider, while the rears are 2-inches wider than on the base Stingray.

“Virtually every exterior change served a functional purpose, as this beast needed more of everything,” said Tom Peters, Corvette design director, “The flared fenders accommodate larger, wider wheels and tires for more grip. The larger vents provide more cooling air to the engine, brakes, transmission, and differential for increased track capability. The more aggressive aerodynamic package generates true downforce for more cornering grip and high-speed stability.”

Two-piece steel rotors (14.6 x 1.3-inch front/14.4 x 1-inch rear) with aluminum six-piston and four-piston fixed calipers, respectively handle stopping duties on the Z06, while Z07 package-equipped Corvettes are graced with larger (15.5 x 1.4-inch front/15.3 x 1.3-inch rear) carbon ceramic-matrix brake rotors. A savings of 23 pounds is collectively achieved over the standard Z06 rotors. The brakes are kept cool by standard front and rear brake-cooling ducts, including Z06-signature rear ducts integrated in front of the rear fender openings. The C7.R will be fitted with steel rotors, six-piston monobloc front calipers and six-piston rear calipers.

Wider tire tread meant the Z06’s fenders had to be extended by 2.2-inches up front, and 3.15-inches at the rear. A wider, lower appearance further emphasized by a unique rear fascia was the direct result of these changes. Speaking of the rear fascia, while the taillamp assemblies have been carried over from the Stingray, Z06 taillamps have been pushed apart approximately three inches.

Three levels of aerodynamic downforce can be achieved through the consumer’s choice of package. A standard Z06 will feature a front splitter, spats around the front wheel openings, unique carbon-fiber hood with a larger vent, and the rear spoiler from the Stingray’s Z51 Performance Package. Further, a carbon-fiber aero package, available in black or with a visible carbon-fiber finish, adds a carbon fiber front splitter with aviation-style winglets, carbon fiber rocker panels, and a larger rear spoiler with a fixed wickerbill, which significantly contributes to downforce. Lastly, the available Z07 package adds larger winglets to the front splitter, and an adjustable see-through center section on the rear spoiler for track use. The Z07-equipped Z06 delivers the most amount of aerodynamic downforce of any production car that GM has tested.

Demands for cooler air come with the territory and the new supercharged Z06 needs all the air it can get. A mesh pattern on the front fascia was designed to deliver the greatest possible amount of airflow to the intercooler heat exchanger – so much so that the mesh grille directs more air into the bay than with the grille removed completely. The grille also is equipped with dedicated brake-cooling intakes and wider grille outlets on the bottom, which serve a purpose as air diffusers. A larger hood vent allows the escape of hot air from the engine compartment and contributes to downforce by creating a path for the air to escape upwards rather than being forced underneath, creating lift. Larger front fender vents, unique air blades over the inlets on the rear fenders, and larger rear-fascia openings all contribute to cooling and improved airflow as well.

The enhanced design continues into the cockpit with unique color schemes and a flat-bottomed steering wheel, which further distinguish the Z06 from the Stingray, however seat choice remains mostly the same. A GT seat for all-around comfort and a Competition Sport seat with more aggressive side bolstering, providing greater support on the track, are both offered, but both seats are made of magnesium for strength, rigidity, and weight-reduction. Also carried over from the Stingray is a steel-reinforced grab bar on the center console for the passenger and soft-touch materials on the edge of the console for driver comfort during high-load cornering. A fully-wrapped interior guarantees that every surface is covered with premium soft-touch materials including Napa leather, aluminum, carbon fiber, and micro-suede.

“Our mission with the seventh-generation Corvette was to make the performance levels more accessible, enabling drivers exploit every pound-foot of torque, every ‘g’ of grip and every pound of downforce,” said Juechter. “It’s a philosophy we introduced with the 460-horsepower Corvette Stingray – and one that’s even more relevant with an estimated 625 horsepower at your beck and call.”

For the first time ever, the Bowling Green, Kentucky, assembly plant will handle production of the Z06’s aluminum frame – the same robust, lightweight frame as the Stingray and the new C7.R. Because the aluminum frame is stiffer, a removable roof panel is to be offered for the first time and even with the roof panel removed, offers 20 percent more structural rigidity than the previous model did with a fixed roof, amounting to a 60-percent increase with the panel in-place.

The SLA-type all-around suspension of the Stingray is retained by the Z06, though it has been uniquely calibrated for higher performance capabilities. Third-generation Magnetic Selective Ride Control dampers come standard and can be adjusted for touring comfort or maximum track performance through the standard Driver Mode Selector, which continues to feature dozens of driver controls for the optimum driving experience, including: launch control, active handling (StabiliTrak stability control), traction control, Performance Traction Management, and Electronic Limited Slip Differential.

Which brings us to our last point: eLSD. It is standard on the Z06 to make the most of the torque split between the rear wheels. It features a hydraulically-actuated clutch, which can infinitely carry clutch engagement and respond from open to full engagement within tenths of a second. It also shifts torque-bias using a unique algorithm that takes into consideration vehicle speed, steering input, and throttle position in order to improve steering feel, traction, and handling balance. It is fully integrated with Electronic Stability Control and Performance Traction Management systems and performs in three modes based on the setting chosen. Mode 1 provides normal driving and vehicle stability, Mode 2 is engaged when electronic stability control is turned off in the Sport or Track modes, and enables more nimble turn-in and traction while accelerating out of a corner, and Mode 3 is automatically selected when Performance Traction Management is engaged and has the same function as Mode 2, however it is fine-tuned to work with Performance Traction Management.

We absolutely can’t wait to get our hands on a Z06 and put it to the test on the track, so stayed tuned to SuperChevy.com for more information as it becomes available. Check out the video below for Motor Trend's first look at the 2015 Corvette Z06!

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