Gainesville, Georgia — The supercharged V-8 motivating the brand-new, bad-to-the-bone 2015 Chevrolet Corvette Z06 makes 650 howling horsepower, and Tommy Milner is letting every last pony run free as he keeps the throttle on the floor while cresting the hill on the back straight at Road Atlanta.
From my vantage point in the right seat, I see 154 mph flashing on the speedometer as Turn 10A approaches, and a trip into the gravel trap looming ahead of us appears to be inevitable. At the 150-foot marker, Milner buries the pedal for the carbon-ceramic brakes, and the ’Vette bleeds off speed like a fighter jet after making a carrier landing. “I think this thing brakes better than the race car,” he murmurs.
But there’s no time to marvel at the stopping power of the 2015 Chevrolet Corvette Z06. With its rear end dancing, Milner snakes the car through the tight left- and right-handers before the bridge then hurtles down the steep hill toward the scary-fast sweeper leading onto the front straight. I’m expecting him to breathe the throttle to get the Z06’s front end to bite. Instead, he keeps his foot in it and, much to my amazement, I feel the extra speed generating aerodynamic downforce that squashes the car to the pavement. “It’s unbelievable the amount of grip this car develops,” Milner says as he flashes past the start-finish line.
“It’s unbelievable the amount of grip this car develops”
Mind you, Milner isn’t a Corvette fanboy contributing annoying comments to an online track-day forum. He’s a factory driver for Corvette Racing, the factory-supported team fielded by Pratt & Miller Engineering that ran cars built directly on the Z06 platform in the 2014 Tudor United SportsCar Championship. Three days ago, Milner finished fourth in the GTLM class in the 10-hour Petit Le Mans here at Road Atlanta while racing against other factory-supported teams for the BMW Z4, Dodge Viper, Ferrari 458, and Porsche 911.
Corvette Racing’s Tommy Milner drove the Z06 at Road Atlanta two days after racing the C7.R at the same track.
There are stretches of Road Atlanta, in fact, where the 2015 Chevrolet Corvette Z06 is virtually as quick as the redoubtable C7.R race car that’s been campaigned not only here at this track but everywhere from Daytona to Le Mans. “In a fast corner, it’s easy to ask too much of a car and oversaturate the tires, and you get understeer or oversteer,” Milner says as we finally roll slowly into the pits after a cooldown lap. “But with the Z06, the downforce gives you so much grip that you’re starting to blur the distinction between a street car and a race car. Honestly, I’ve driven race cars that aren’t as impressive as this thing.”
Corvettes have gone through good times and bad over the past six decades. Some models have been enshrined as legends while others are best forgotten. But ever since it was introduced as a high-performance RPO (regular production option) code for the 1963 Chevrolet Corvette Sting Ray, the Z06 has been the purest expression of America’s sports car.
The 2015 Z06 arrives as the Corvette brand is on an impressive roll. The seventh-generation C7 Chevrolet Corvette Stingray debuted last year to almost universal acclaim for its dramatic exterior styling, its world-class interior (finally), and performance that makes the builders of exotic, more expensive sports cars drool with envy. The 2015 Chevrolet Corvette Z06 has been developed not as an afterthought but as a companion to both the standard C7 and the Pratt & Miller C7.R race car.
“That’s very unusual,” says Corvette chief engineer Tadge Juechter, who’s been working exclusively on Corvettes since 1993. “For most race cars, a company just hires a race team and hands them a check. With us, Pratt & Miller is an integral part of the development team.” The result is a street car and a race car that seem less like distant cousins than fraternal twins.
What sets the Z06 defiantly apart from its Corvette brethren is its awe-inspiring LT4 engine.
Every contemporary Corvette, including the C7.R, shares the same structurally rigid foundation—an aluminum frame with a backbone so stiff that the Z06 is offered as either a coupe (with a removable roof) or as a convertible, and no additional support is required for the open car. The Z06 also incorporates the same suspension layout as the conventional C7, with double-wishbone control arms and a transverse leaf spring both front and rear.
What sets the 2015 Chevrolet Corvette Z06 defiantly apart from its Corvette brethren is its awe-inspiring LT4 engine. The pushrod 6.2-liter V-8 is the same displacement as the LT1 found in the standard C7 Stingray, but it’s fitted with a racing-style dry-sump lubrication system, a host of upgraded components for the cylinder heads and valvetrain, and most important, a supercharger that boosts output from 460 hp to 650 hp.
Juechter insists he had no preconceived notions about which technology would give the Z06’s V-8 the amount of power the engineering team was hoping to achieve. But he knew that a naturally aspirated, larger-displacement engine would be a disaster on the emissions front. A turbocharged engine could have produced the requisite power numbers, but the intake plumbing would have forced the team to reposition the front shock towers, thereby compromising handling.
Corvette engineers already have plenty of experience with a supercharger in the LS9 engine of the Corvette ZR1, which had been the stop-me-I-must-be-dreaming version of the C6 Corvette. Better still, a blower and intercooler could be slotted into the vee between the cylinder banks at the front of the block, meaning that the engine would be only an inch taller than the naturally aspirated LTI in the C7 Stingray. Best of all, Juechter says, “A supercharger gives you instant and very well-modulated throttle control.”
Engine geeks will be happy to learn that the 1.7-liter Eaton R1740 TVS supercharger spins up to 20,150 rpm, enabling the Z06 to make not only 650 horsepower at the 6,400-rpm redline but also 650 lb-ft of torque at 3,600 rpm. This translates into 0-60 in 3.0 seconds when mated to the eight-speed automatic. “To be honest, we didn’t think this was achievable,” Corvette product and marketing manager Harlan Charles says. “Same with the 1.2 g of lateral grip. We exceeded our expectations.
Corvette chief engineer Tadge Juechter says that the Z06 and C7.R were developed concurrently. The larger, supercharged engine in the street car makes significantly more power than the C7.R’s naturally aspirated motor.
Ah, yes, 1.2 g—not just a momentary peak in cornering load but achieved in steadystate cornering around a skidpad. Reaching this race-car level of mechanical grip has required a bunch of engineering magic. To begin with, the 2015 Chevrolet Corvette Z06 has larger wheels, 19-by-10 inches at the front and 20-by-12 inches at the rear, a measure that requires flaring the front fenders by 2.2 inches and the rear fenders by 3.2 inches to clear the bigger tires. The Z06 gets P285/30ZR-19 front and P335/25ZR-20 rear Michelin Pilot Super Sport run-fl at tires. If you throw down the money for the track-ready Z07 package, you get Michelin Pilot Sport Cup 2 tires, which are about as aggressive as you can go, short of racing slicks.
The Z07 track package also comes with what the Corvette guys call Stage 3 aerodynamics. This includes aviation-style winglets that frame the stock front aero splitter and removable wicker bills attached to a higher-than-normal rear spoiler, plus an adjustable see-through center section that fi ts between the wickers. Oh, and to whoa the car down, the Z07 package also features 15.5-inch front and 15.3-inch rear carbon-ceramic brake rotors that produce gobs of stopping power while trimming 23 pounds of unsprung weight from the smaller two-piece steel discs found on the stock Z06.
Before climbing into this 2015 Chevrolet Corvette Z06 with the track-ready Z07 package, I got a few familiarization laps around Road Atlanta in a C7 Stingray Z51. Road Atlanta is one of the premier road courses in North America, with an invigorating (speedy and scary) mix of high-speed sweepers and slow technical sections on a natural-terrain circuit with plenty of elevation changes and several blind stretches. The Stingray was supremely competent and surprisingly quick around the racetrack. Which worried me.
I already felt like I was hauling ass in the Stingray, and now I was going to be driving a car with roughly half again as much horsepower and torque. What’s wrong with this picture? I fl ashed back to my brief experience behind the wheel of a Corvette ZR1, a brute that always seemed to be a quarter-inch of throttle travel away from terminal oversteer. Then I conjured up an image of the gravel trap that Tommy Milner had avoided just beyond Turn 10A, not to mention the concrete barrier waiting to collect poorly driven cars as they sped onto the front straight.
With its wide-track stance, oversized wheels and tires, and body scoops galore to cool the engine, the brakes, the transmission, and the differential, this Z06 with the Z07 option package looks appropriately nasty. I settle into a supportive suede-trimmed competition seat and get my bearings in the fighter jet-style cockpit. The Z06 isn’t cheap—it starts at $78,995 and approaches $90,000 with the Z07 package and required carbon-fiber ground-effects kit —but the interior finally looks and feels worthy of the elevated price tag. I’m also down with the racing-style suede-trimmed steering wheel.
After I crank the engine with the starter button, job one is selecting the correct driving mode. Thanks in part to an electronic differential that can go almost instantaneously from fully open to fully locked, the 2015 Chevrolet Corvette Z06 accommodates a wide range of stability and traction control settings. Using a rotary dial in the center console, I cycle through Weather, Eco, Tour, Sport, and Track modes. Double-clicking on Track puts me into the Performance Traction Management menu. Here, I dial up the midrange Sport 1 setting to warm up the tires. Welcome to the electronics of the modern high-speed automobile.
When I reach pit-out and get onto the track and lay into the throttle, my first surprise is the sound of the engine: minimal supercharger whine but seriously loud and much sharper than the C7 Stingray. (Sweeter, too, than the C7.R race car, which emits a deeper, truck-like note.) Acceleration is fierce but not brutal, and I’m seeing 150 mph on the head-up display in no time. Then comes Revelation No. 2. The initial hit of the Z07-spec ceramic brakes sends me hard against my suddenly taut shoulder harness, and more pedal pressure slows the car even more dramatically through the brake zone. This is great.
When I sink my foot into the throttle, I feel the electronic nannies working a bit too fussily for my taste, so I switch to Sport 2 mode, which maintains the same traction-control target as Sport 1 but deletes stability control. With the Z07 aero package, the car makes so much downforce that I never test the limits in the fast corners or riding the curbs through the esses. I’m able to take a few liberties in the slower sections, but even here, this Corvette feels so well-planted that I have no reservations about switching to Race mode, which minimizes electronic intrusions.
Now, I experience my third and most memorable epiphany. Unlike the ZR1, the 2015 Chevrolet Corvette Z06 isn’t a car that intimidates drivers. On the contrary, it’s a car that inspires confidence. This is the Corvette of more—more power, more grip, more brakes, more downforce. Sure, you have to be a Tommy Milner to unlock all of its potential. But even leaving a substantial margin for error, the car is capable enough to allow the rest of us to feel like heroes.
Corvette engineers insist that the Z06’s eight-speed automatic—no dual-clutch wizardry here, just a conventional torque converter—produces the fastest lap times, even without working the shift paddles on the steering wheel. I have more fun rowing the seven-speed manual in this Z07-spec car, although I reluctantly find myself using the automatic rev-matching feature because it’s so foolproof that it seems pigheaded not to.
The performance data recorder allows Z06 owners to analyze what they’re doing on the racetrack or on challenging roads such as Tail of the Dragon.
Another sweet touch is the very cool performance data recorder, which incorporates a tiny camera mounted above the rearview mirror to record high-definition video while a GPS unit generates a track map. Using software developed by Cosworth, 20 streams of data—everything from vehicle speed to brake pressure—can be synced to the video. This is the kind of stuff pros use to fi nd tenths of a second in lap time on a racetrack, and it ought to be a huge hit within the Corvette community as both instruction and entertainment. “I think people are going to do things with it that we never thought of,” says Corvette project manager Harlan Charles, who came up with the idea for the system after playing the “Gran Turismo” video game.
On the speed-limited roads of the real world, the 2015 Chevrolet Corvette Z06 trades beast-like performance for a more subdued, domesticated persona. Just loping along, it feels almost indistinguishable from the C7 Stingray, and it will happily deactivate four cylinders for a bump in fuel economy. But it doesn’t take much to go from Clark Kent to Superman—a secluded stretch of open road, a sign alerting you to twisties ahead, whatever. Suddenly, your foot is deep in the throttle, and your speed is climbing so rapidly that the digital readout can’t keep up. Now, all you’ve got to do is dial up Race mode to let your inner Tommy Milner loose.
Click here to learn how Zora Arkus-Duntov helped create the original Z06.
2015 Chevrolet Corvette Z06 with Z07 Option Specifications
- Base Price: $78,995
- Price as Tested: $89,985
- Engine: 6.2-liter, supercharged OHV 16-valve V-8/650 hp @ 6,400 rpm, 650 lb-ft @ 3,600 rpm
- Transmission: 7-speed manual
- 2-door, 2-passenger, front-engine, RWD coupe
- EPA Mileage (city/ highway): 15/25 mpg (est)
- Suspension F/R: Control arms, leaf spring/control arms, leaf spring
- Brakes: Carbon-ceramic vented discs, carbon ceramic rotors
- Tires F/R: P285/30ZR-19/P335/25ZR-20 Michelin Pilot Sport Cup 2
- L x W x H: 176.9 x 77.1 x 48.6 in
- Wheelbase: 106.7 in
- Weight Dist. F/R: 50/50%
- 0-60 mph: 3.0 sec (mfr est)
- 10.95 sec
- @ 127 mph (mfr est)
Technically, Zora Arkus-Duntov wasn’t the father of the Corvette, but he did more than any other man to put the “sport” in America’s sports car.
As a sometime racer at the 24 Hours of Le Mans before joining General Motors, Duntov became the chief engineer for the Corvette and was the driving force behind
the creation of the stunning Corvette SS that raced at Sebring in 1956. When the new Corvette Sting Ray was about to debut in late 1962, he persuaded Chevrolet to
off er a special RPO—the Z06—created specifically for road racing.
The Z06 came with a 327-cubic-inch fuelie V-8, four-speed manual transmission, Positraction rear axle, upgraded drum brakes, stiff er front anti-roll bar, stiff er
springs and dampers, and a 36.5-gallon fiberglass fuel tank that made the car perfect for the big SCCA three-hour enduro at Riverside International Raceway in Southern California, where Duntov planned to unveil the new racing-spec Corvette.
The first four Z06s to come off the assembly line were earmarked for top Corvette racers. One was shipped to SoCal speed king Mickey Thompson, a drag racer
and Indy car builder, while road-racing drivers Bob Bondurant, Jerry Grant, and Dave MacDonald fl ew to the Corvette assembly plant in St. Louis to pick up the cars they would race at Riverside.
Duntov’s brainchild scored a win in its inaugural race at Riverside in 1962.
They engaged in some informal racing during the drive west and had no trouble with the police, until Bondurant got nailed by a motorcycle cop on Sunset Boulevard
in Los Angeles.
The Corvette drivers were encouraged when they got their Z06s on the track. “It was quicker than the old Corvette because of the aerodynamics,” Bondurant recalls. “It also cornered really well, but it was a little weak in the brakes.”
Although the Corvettes ran out of brakes during the race, the real problem turned out to be the competition. Also making its debut at Riverside was Carroll Shelby’s
Cobra, which instantly rendered the Corvette Z06 an also-ran in its SCCA class.
As it happened, the lone Cobra broke, and Doug Hooper won in Mickey Thompson’s Corvette. But, as Bondurant recalls, “The handwriting was on the wall. We thought, ‘Holy crap, we’ve got our work cut out for us.’”