2006 Chevrolet Corvette Z06

September 26, 2005
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Corvettes, God love 'em, have always been as American as Mom, apple pie, and the 32-ounce Big Gulp that Mom drinks to wash her pie down. Yet while these sporting Chevrolets have long amused speed-obsessed Europeans as prime icons of Yankee muscle and style, they've never really been at home in Europe, a land of puny roads, micro-machines, and fermented grape beverages served in small glasses. To European tastes, the heavy Chevys were not unlike that Big Gulp: too big, too plastic, too sugary and sloppy.
Being 4.7 inches shorter than its predecessor, the new C6 Corvette is within an inch of a Porsche 911, and Chevrolet thinks that means there might be some new business to be done in the Old World. Chevy believes that being just that useful little bit more compact and even faster than the C5, the C6 now presents a performance bargain so undeniable that even the Continent's cheese-eating surrender monkeys will be forced to show respect.
The Chevrolet folks are so confident that the C6 will successfully engage the European Union, they've boosted employment on the line at Bowling Green, Kentucky, to build as many as 3000 extra Corvettes a year, a 10 percent hike.
To make the point of its newfound Euro-friendly trimness, while highlighting new and mighty performance of the sort that plays everywhere, the Corvette's wranglers invited a contingent of American journalists to drive and experience the 2006 C6 lineup-most notably, the all-new and keenly anticipated Z06 version-on two of Europe's historic racecourses and some of the Continent's finer roads. Our mission, which we chose to accept:
Fly to Frankfurt, hop into Corvettes, and follow the Rhine. Head for the short track at the Nrburgring. Test metal and get mettle tested by well-known racing drivers such as Jan Magnusson. (Magnusson bagged a GT1 class win at Le Mans this year driving the Corvette C6R racer, to which the new Z06 is more than slightly related. This makes class wins for Corvette in four of the last five races at Le Mans, which ought to impress some Europeans.)
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Depart the 'Ring, blast through Luxembourg, and head to the almost equally legendary Belgian circuit at Spa-Francorchamps. Enjoy additional laps on the awesome course in the edifying company of pros. Grab further hang time with the chief engineer and architect of the last two Corvettes, Dave Hill, and his development team. Drive the base C6 coupe and convertible with the new six-speed automatic.
Eat heavy meals throughout, rich in heart-stupid cheese courses, custard desserts, and foie gras in its many and diverse preparations. Dodge magnums of red wine, unsuccessfully. Finish the trip with a triple-digit drive to Paris in the Z06, pitting along the way in Champagne country for a tour of a leading vintner's network of subterranean chalk tunnels and a (meager) taste of the bubbly. Fall into a catatonic stupor following an unusually large dinner at a superior Parisian Michelin two-star.
It sounded like an educational three days, and it was. My teeth turned purple, and I've begun to waddle. But I will never view Corvette performance the same way.
You may remember how we liked the Z06 of 2001 so much that we awarded it Automobile Magazine's coveted Automobile of the Year title. What could be better, we asked at the time, than a tricked-out version of the then radically new C5 Vette hardtop with 385 hp, straight from the factory?
The answer came in the form of the C6 Corvette, an evolutionary development of the C5 that would arrive four years later with an even steamier 400-hp, 400-lb-ft rendition of the classic Chevrolet small-block. That the Chevy small-block remains a huge player in America's arsenal of high-performance internal combustion is as remarkable as it is inarguable, what with the engine celebrating its fiftieth production anniversary this year. But longevity is no mystery when you consider the LS2-the direct descendant of Chevy engineer (later GM president) Ed Cole's 265-cubic-inch pushrod V-8 of 1955-in action. Always tractable, devastatingly fast, stone reliable. What could be better than that?
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At least, that's what we were asking just a short while ago. Obviously, we weren't thinking of the 2006 Corvette Z06 and the latest evolution of the fabled small-block that it comes with: the LS7. Bored, stroked, and totally stoked to deliver 428 inches of cubic capacity, the LS7 cranks out 505 cranium-melting hp and 470 lb-ft of torque, propelling the Z06 faster and quicker than any Corvette the factory has ever sold.
How does 0 to 60 mph in 4.1 seconds sound? A 12.0-second quarter-mile at 124 mph? Top speed of 198 mph? Redline at 7000 rpm? Not a shabby statistic in the bunch, especially for those of us old enough to remember the 1975 model year and Corvettes that reluctantly scaled the peaks of feebledom just long enough to deliver their pitiable maximum allotment of 165 hp at 3800 rpm. To those who would question the forward direction of man's technological progress, we point to the Z06 and rest our case. To those who would argue that pushrod, two-valve technology won't a sports car make, it is time to re-check the facts.
Actual top speed in the manufacturing validation examples of the Z06s we drove was not 198 mph but rather an electronically limited 191 mph, it pained us to learn. But as it turned out, we never had a chance to see the wild side of 160 mph, anyway. Out on the track, we were busy trying to learn the racer's line through strange corners. So consumed, we braked late, we braked early, and we generally clung to the inept journalist's line (also known as the loser's line) through the twisties, instead of worrying about going as fast as humanly possible down the straights. If we had been smarter, which is to say stupider, this would have been our chance.
That's because while certain stretches of German autobahn offered the occasional legal opportunity to throw the hammer down with complete abandon, road conditions made these windows more theoretical than practical. So did the long arm of the jambonerie in those places we'd pass through where the authorities continue to believe in speed limits. We regret to report that we didn't max out the Z06 in top gear, though we were able to make the acquaintance of all 505 of its horses in many lower gears, many times, and they are formidable in their unity and grunt. Praise must be sung. And in case you were wondering, the missing 7 mph of top speed will be restored in series production.
The myriad pleasures of immense thrust and 1.09 g's of grip aside, the Z06 experience is intensified by a twin-stage muffler that cuts in at around 3500 rpm, flicking a valve open to transform a low and muscular exhaust woofle instantly into a profound and psychotic wail, transporting driver and passenger from Main Street to front straight at the flick of a shoe. The sound of several Z06s gunning down the Nrburgring F1 course's front straight, exhaust valves cocked, is entirely recommended, except for those trying to sleep.
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The new Z06 costs $65,800, which undercuts all of its possible high-end competition at home. It can't hurt in Europe, where the current dollar/euro exchange rate ought to make American goods cheaper.
Still, back at home, the 2006 Z06 commands an almost $13,000 premium over the previous Z06, a nearly 25 percent fare hike, which surely will push the model out of some shoppers' price brackets. But make no mistake: an upgrade that buys 25 percent more ponies for a 400-hp car plus all the modifications and reinforcements necessary to cope with all that extra power, and one that does all that without adding weight, in fact while losing it, is an outstanding value at $13,000. The aftermarket would charge fearsome multiples more for less.
Dan Michaelson, chief engineer on the LS7 engine program, reckoned that a good deal of the extra money goes into making the Z06's wild engine wilder. "Squeezing out 100 extra horsepower is not cheap," he averred. But, on the evidence, it's worth it. What Michaelson called "the small-block's gift to our best and favorite customers," the LS7 is one fancy piece of good old American engineering mixed with some cutting-edge metallurgy. Compact and relatively light at 450 pounds, the all-aluminum LS7 shares architecture, but few components, with the LS2, which carries on in base Corvettes. Driving both the coupe and the convertible, with their greatly improved automatics (how could six paddle-shifted speeds not beat four with a lever?), we came to realize that the term base hardly does justice to these perfectly complete, wickedly fast cars. Indeed, we could make the case for skipping the Z06 package entirely.
But we won't.
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So let the makeover begin. More being more, the LS7 gets the party started by adding a full liter of displacement, making for 7.0 liters or 428 cubic inches (as against the LS2's once-impressive-sounding 364 cubes). It's a number, Chevy engineers say, that may well mark the upper limit on how much displacement the small-block can handle, although the overall pattern ought to be clear to all by now. Somehow, they will top the LS7 for the next Z06, with a trickle-down effect on the standard car. If the recent formula holds true, the base model will get the outgoing Z06's horsepower allowance, meaning the stock C7 ought to be good for at least 500 hp. "Where will it all end?" asked Tadge Juetchter, assistant chief engineer for the Corvette, over dinner one night. He was being ironic. I think.
Underneath all the computer and injection hardware beats a textbook lesson in old school, a pushrod engine with but one intake and one exhaust valve for each of its eight cylinders. However, the giant (2.2 inches) size of the intakes makes heavy breathing mandatory, and the eighteen-gallon fuel tank drains quickly if one honks an LS7 too hard. Yet the Z06 can also return more than 26 mpg on the highway, and, unusual for a supercar, its owners pay no gas-guzzler penalty on their purchase, an impossible luxury in a machine with this much performance.
High-capacity, dry-sump lubrication is a must when one considers the high g's the Z06 is capable of creating, as well as its likely exposure to hard and competition use. It's one costly line item on the LS7 build sheet. The quest for low reciprocating mass and maximum strength dictates several others. Connecting rods made of titanium weigh 30 percent less than the LS2's steel units. The intake valves are titanium, too; exhaust valves, made of steel, are sodium filled. The LS7 gets six-bolt, forged-steel main bearing caps, and a forged-steel crankshaft. As the final measure of its seriousness and exclusivity, each one is screwed together by hand at GM's Performance Build Center in Michigan and then signed by its builder.
Bigger brakes with six-piston calipers, heavy-duty cooling, the dry-sump system with its higher oil capacity and additional piping, a more robust rear axle, and larger three-inch dual exhausts with beefier quad pipes out the back all serve to complete the high-performance picture, but all contribute additional mass. Even moving the battery to the rear for better weight distribution adds pounds, because it necessitates running a cable to the front of the car.
Yet all of these vital weight-adding technologies make the best sense possible in the Z06 thanks to an aluminum frame. With some of the same hydroform dies used for the base car, the frame rails simply become thicker (four millimeters of aluminum as against two millimeters of steel) to retain stiffness while shedding weight. So revolutionary is this use of hydroform dies, Hill told us, that engineers from Boeing have visited to check it out. Better yet, it removes 136 pounds of mass from a Z06.
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A lightweight-materials showroom to start with, the 505-hp car accordingly ends up weighing slightly less than the humble 400-hp car with which Chevy began. Fiberglass-the stuff of all Corvettes from time immemorial-is light compared with steel, but the Z06 gets carbon-fiber front fenders, which weigh one-third of the base car fender's weight and one-fifth of what a similarly shaped steel fender might weigh. The costly carbon fiber appears in wheelhouses and in the floor (once again wrapped around a balsa core). Hood, doors, roof, and hatch are shared with the base car.
There are many subtle and not so subtle visual aerodynamic addenda-ducts, fairings, splitters, and spoilers-which serve two useful functions: keeping the car earthbound and helping the committed Z06 spotter. For everyone else, there's a Z06 badge at the rear. Collectively, the aero handiwork raises the car's coefficient of drag to 0.34 from 0.28, but in a 198-mph car, you'd want it no other way. And, of course, 505 hp is another telling clue to the Z06's identity. You won't need to ask twice which Vette that was when one goes sailing past you.
The key to it all, said Corvette leader Hill, is the power-to-weight ratio, "the most important metric in ranking supercar performance." With the car weighing 3147 pounds, each Z06 horsepower must accommodate 6.2 pounds, and you know how little 6.2 pounds troubles a horse.
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We met those horses, and we abused them in four countries and on two racetracks in three days, and they were clearly built to take it. You can head straight to the autocross with your Z06 and not live in fear of imminent equipment failure. (Speaking of fear, on the track, we found the intermediate Competition mode of the traction control system, which allows some wheel spin but abhors spinouts, to have potentially life-preserving properties.)
The Z06 is not without fault. Interior plastics have come a long way but still have several thousand miles to go. The combination of a cavernous cargo space behind the seats with nineteen-inch Goodyear run-flats almost a foot wide is always going to be sonically punishing in a plastic car. Tire noise is seriously for keeps. Then there is the Z06's Tremec six-speed manual transmission. Its heavy innards are placed just ahead of the rear axle for better weight distribution. It is clearly a more pleasant unit than Corvette gearboxes of the past, boasting shorter throws than C4s and C5s and a less obtrusive first-to-fourth econo-shift. It remains, however, despite the action of a lighter clutch, very much the manly shifting device. Not so much a joy to use but torture no more.
The driveline now emerges as the key irritant, making a nasty noise whenever the LS7 is being lugged. The engine itself is completely amenable to low rpm. But try them, and then up comes the sound of a UFO, an unidentified frying object, a.k.a. drive-line "sizzle." It's reminiscent of the sound of the worn rock-crusher transmissions that are found in old muscle cars and heavy-duty trucks. The Corvette engineers knew what we were talking about when we mentioned it, and they told us that it afflicts only Z06 manual transmissions. They said they were working on it.
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Still, you don't have to hit the Rhine wine to see that the Z06-and the standard Corvette with its new six-speed automatic-could do some business in Europe. It's not just Americana, it's an amazing performance achievement.


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