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2001 - 2004 Chevrolet Corvette Z06 (C5)


History

A successor to the ZR-1 made its debut in 2001 as the Z06, a nod to the high performance Z06 version of the C2 Corvette of the 1960s. The z06 models replace the hardtop (1999-2000) models as the highest performance C5 corvette. Instead of a heavy double-overhead cam engine like the ZR-1, the Z06 used a high-output (LS6), a tuned version of the standard Corvette’s (LS1) producing 385 hp (287 kW). Although the Z06’s total output was less than that of the last ZR-1’s, the Z06 was much lighter and faster than the ZR-1 in every category except for top speed. The 2001 z06 by GM’s claims would run 4.1 to 60 and 12.6 in the quarter mile at 113 mph. At 171 mph the z06 runs out of 5th gear due to it’s shorter M16 transmission. 6th gear was too tall for anything other than fuel economy.

Like with the ZR-1, Chevrolet found that added power output did the Z06 little good without platform modifications to bring the rest of the car up to par. A hardtop body, uprated suspension, larger wheels and tires, a new six-speed manual transmission along with improved gearing, and functional brake cooling ducts all became part of the total package. The Z06 is 38 lb (17.3 kg)lighter than the standard hardtop C5 thanks to a titanium exhaust (from the catalytic converter back), thinner glass, lighter wheels, and a lighter battery. From 2002 onward, the Z06 produced 405 hp (302 kW) thanks to minor engine modifications including a more aggressive camshaft profile, lightweight sodium filled exhaust valves, stiffer valve springs, and deletion of the precats. The 2002 z06 also received revised rear shock valving, and steel links to replace plastic ones of the 2001 model. Electron blue color to replace Speedway white. The HUD became standard, and the previous forged wheels were replaced by lighter spun cast ones. The fender z06 badges bear "405hp" on them. The 2003 models received special silver 50th anniversary badges, and revised headliner. Later 2003 models received a more durable steel shift fork instead of aluminum.

GM claimed that 405 hp versions of the Z06 could make the 0-60 run in 3.9 seconds and 12.4 through the quarter mile at 116mph, although 4.0 seconds was the best that magazine test drivers could produce. Amateur racers have gotten the C5 Z06 down the quarter mile in an incredible 11.7 seconds whereas the magazine drivers could only get a best of 12.2. The Z06 is capable of matching or beating the 0-60 times of some of the world’s premier sports cars, including the Ferrari 360 and the Porsche 911 911. The C5 Corvette Z06 is one of the best performance bargains under $100,000.

The 2004 Z06 Commemorative Edition came with a carbon fiber hood which saved some weight, canceled out by heavier chromed wheels. It also received Nurburgring tested shock damping to improve handling, along with an exclusive Lemans blue color.


Overview

The Corvette Z06 provides so much more of the same that it is in a completely different category from all previous Corvettes.

There’s more power: 35 HP added to the stable to bring the honest net power rating up to 385 horsepower at 6000 rpm, and that power is put to the ground through more rubber (295/35ZR-18 Goodyears on lightweight, 18 x 10.5-inch alloy wheels at the back) via a revised six-speed gearbox that gets you off the line harder and faster than before with its 2.97:1 first gear. The other five gears are better spaced, all but the direct 1:1 fourth being lower than before. And, let it be noted, the all-new LS6 engine is so clean that the car qualifies as a low-emissions vehicle. Oh, yes, and it gets 19 mpg in town and 28 on the highway, EPA-certified. And it gets to 60 mph in four—four point zero—seconds.

Generation Five Corvette styling has been controversial from the outset. The car has just a few too many Japanese-looking styling cues, and the wide, tall posterior, for all that it sports the traditional four taillights, is more than a bit gawky. On the Z06, two changes from the mainstream Corvettes help the look quite a bit: the addition of truly functional air scoops at the lower rear edge of the doors for the rear brakes and under the daytime running lights in front, and the close-coupled top, a reversion to the classic Corvette notchback look that preceded a series of Italianate fastback coupe shapes from the ’63 "split window" C2 onward.

The Z06 is available in a restricted range of colors: black, white, red, silver, and the bright yellow that Chevrolet is pushing in its press fleets, perhaps because the C5-R factory racers are painted in yellow and white. The overall design is at its best in black.

The Corvette C5-Rs that ran at Le Mans last year—and that are sure to be back this June—and the program that brought them into being were certainly Viper-inspired. If the Corvettes have only beaten their crosstown rivals occasionally this year, they have only one season behind them, and the Z06 tends to prove that Corvette engineers now know what they’re doing and have the ear of management willing to let them achieve the necessary results.

That the engine is so powerful, flexible, and clean is to their credit, but where they have really shown their innovative spirit is in the Active Handling system, which, of course, includes traction control (which, of course, can be switched off if you like) but also has a skid control function.

Sensing control inputs, speed, loads on all four wheels, and rotational discrepancies, Active Handling reduces engine power when necessary and applies the brakes individually to hold the car in line. The system’s switch has three modes: traction and stability control off; traction and stability control on (Active Handling); and Competitive Mode, which eliminates traction control but will keep the car from spinning, thanks to the electronic stability program. Okay, you don’t need all this magic because you’re such a great driver, but, believe us, most people do and will benefit from this work accordingly.

The wheels themselves are bespoke for the Z06, claimed to be lightweight, and definitely both light and strong in appearance, with plenty of open area to let you admire the bright red calipers and the big vented brake discs. There are a lot of differences between the first Corvettes of 1953, every one of them white with red interior, and the 2001 Z06 model, but perhaps nothing marks the maturity of the Z06 as much as its wonderful brakes. Conceptually and dimensionally, the original Corvette was closely based on the contemporary Jaguar XK1 K1 20: same wheelbase, same bad seating position on top of the same type of thick ladder chassis frame, same engine type and configuration (in-line six), same steel disc wheels bolted to inadequate drum brakes that were prone to overheating and severe fade when used in anger. Not that there was much performance potential in the Corvette’s three-carburetor Blue Flame Six, hooked up as it was to a two-speed automatic, the only gearbox available until 1956.


Impressions from the drive tests

Designed specifically for competition-minded Corvette owners, the Z06 package included upgraded brakes (finned drum brakes with sintered-metallic linings), thicker antiroll bars, stiffer springs, stronger shocks, a 36.5-gallon fiberglass fuel tank fitted to the luggage area and special cast-aluminum wheels. The 360-horsepower L84 V8 engine was the only engine offered. A total of 199 Z06 Vettes were ordered, but they didn’t come cheap. The package added $1,818 to the Sting Ray’s $4,257 base price, as well as requiring $661 of forced content in the form of fuel injection, a four-speed manual transmission and a Positraction rear axle.

About a dozen changes can be found on the Z06’s engine when compared to the regular Corvette’s powerplant. Called the "LS6" (regular Corvette engines are labeled "LS1"), it looks very similar to the regular Vette V8 except for the red engine covers. Looks are deceiving though; this engine delivers almost 12 percent more power than the 2000 Corvette, totaling 385 horsepower at 6,000 rpm and 385 foot-pounds of torque at 4,800 rpm. Both the horsepower and torque peaks are 400 rpm higher than the LS1’s, but as the preceding chart shows, there is enough firepower here to take on any high-performance car and leave nearly all of them choking on the Vette’s exhaust fumes.

Internally, the LS6 features a modified engine block, high-strength pistons, a revised camshaft, stronger valve springs, larger fuel injectors and new cylinder heads. The cylinder heads have altered intake and exhaust ports to improve flow, as well as smaller pent-roof combustion chambers that increase the compression ratio from 10.1:1 to 10.5:1. A new composite intake manifold is used to deliver larger amounts of air to the combustion chambers with less turbulence. The previous stainless steel exhaust manifolds have been replaced with new thin-wall cast-iron exhaust manifolds to improve durability in sustained high-speed situations. Those manifolds then dump gasses to a new exhaust system constructed out of titanium that weighs 50 percent less than a regular Corvette exhaust.

The Z06 interior follows typical Corvette design architecture, which means well thought-out ergonomics and build quality a cut above other GM products. It is not a model of refinement, however, as panel tolerances would be almost laughable if they were located in a Honda or Toyota. It could also use more storage space, as there’s only a glove box, an anorexic center storage bin and a cupholder designed exclusively for small Dixie cups. The Z06’s hardtop format also drops cargo capacity from a generous 24.8 cubic feet found in the coupe to 13.3 cubic feet. Some optional equipment items aren’t available on the Z06, such as the head-up display, the power tilt/telescope steering wheel, the power-adjustable passenger seat and the 12-disc CD changer.

The Z06’s mechanical modifications are instantly apparent as the car moves off into traffic. The shorter gearing offsets the LS6’s higher power peaks and makes the transmission much more of a true six-speed rather than the coupe’s tranny which often feels like a four-speed with two ridiculously tall overdrive gears. Some of our staff hoped the Z06 would go without the first-to-fourth gearshift fuel-saving feature, but alas, it’s still quite alive. Chevrolet Chevrolet did remove the rubber bushings out of the Z06’s shifter, improving shifter feel and accuracy. There doesn’t seem to be any extra vibration coming through the stick, though the shifting effort is noticeably higher.

Around town, it’s fun to drive the Z06 just like you would your average Chevy Cavalier, giving the car about two-fifths throttle as you pull away from a stoplight and then short shifting at around 4,000 in each gear. In the Cavalier, the result would be, well, normal acceleration. In the Z06, acceleration is thoroughly abnormal - and you’re not even trying. Your fellow commuters back at the stoplight are now tiny dots in the Vette’s rearview mirror, and the speedo shows that you are easily capable of getting a speeding ticket. Like a 12-year-old boy holding an M-80 firecracker, you can feel the power in your hands; you just need to find a devious way of exploiting it.

Freeway entrance ramps seem to be the first thing more to the Z06’s liking. Stomp on the throttle and you are the kid with the M-80. Blam! The Corvette snaps ferocious, hits warp nine, and slingshots up the ramp. The acceleration gives you tunnel vision, and it is all you can do to just point the wheels straight, let ’er rip and hope you don’t run up into the back of a transit bus. Doing this for your first couple times numbs your brain like Novocain, and the only words that manage to tumble out of your mouth are monosyllable expressions like, "wow" or "woah."

Once on the freeway and in top gear, the Z06 relaxes. The ride quality is more agreeable here, and visibility is decent thanks to minimally sized B-pillars, wide side mirrors and the low hood. This could be a great cross-country sports car like the coupe or convertible, but the increased road rumble, exhaust boom and smaller trunk conspire against it. The Z06 is fitted with 18x10.5-inch wheels with Goodyear Eagle F1 SC 295/35ZR-18 tires in back and 17x9.5-inch wheels with 265/40ZR-17 tires in front. This new combination is wider, grippier and gives better feedback, but it lacks the run-flat capabilities of the EMT tires. Since C5 Corvettes weren’t designed to carry spare tires, the Z06 is fitted with a tire inflator kit.

Mid- to high-speed corners are the Vette’s favorite. Use the fade-free binders to haul the Z06 down from high speeds, let the car rail around the corner, and then nail the throttle to get a straight away shot towards the next bend. All the while, the LS6 V8 grunts and roars, feeding an endless supply of Herculean power to the rear wheels. Care must be taken with that power, however, as the stiffer rear leaf spring and shocks make the rear end feel greasy when mid-corner bumps are encountered.

Corvette has remained relevant because it continued to embrace new designs and technologies such as those featured on the current line: Magnetic Selective Ride Control, Goodyear EMT "run-flat" tires (coupe and convertible), active handling and a rear transaxle.

The C5 is beautifully balanced, surprisingly comfortable, and is built to a far higher standard than any Corvette in history. The C5 handles great on a road course, but still reminds us of a muscle car when cruising along or accelerating down a straight stretch. The Corvette is a beast.



3 comments:

I Still Like the Honda’s... They r safe and somewhat fast...which means they are fast enough...

is so cool the Z07 so cool

I belive that the 2002 and up Z06 is one of the most under rated cars of all time. I personly have a 2002 z06 and a 2006 viper. If your looking a fast car just for bombing around save the 65K and just buy a used Z06. The viper is a tiny bit quicker but it will be very close. Unless your a pro driver. The viper sounds a lot better and more heads turn when your driving it. But the same thing will happen in the vette if Chev will ever stop makeing 10 million of them a year.

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