Extracting no less than 500 hp from its 7.0-liter (yes, 427 cid) V8, built as near to racing standards as one might wish for a road-going machine, the new model needed a large air intake in the nose. Designer Tom Peters may think the neatest part is that incorporating that scoop meant his studio got to draw a new front fascia with a slightly longer point in the nose. “I wanted to do that on the car originally, but we had to hold to the length of a Porsche 911, so I couldn’t pull it as far forward as I wanted,” Peters told us. “Now, you need it longer to fit the air intake.”
That’s what everyone will see, but it’s not there just to be seen. The scoop is required because the LS7 mill can use 100 cubic feet more air every minute than the base C6’s LS6. That’s 18 percent more airflow, a key reason the new Z06 is expected to run 0 to 60 mph in under 4.0 seconds and, given that it will go all the way to 100 km/h (62.1 mph) in first gear, perhaps quite a bit under that 4.0-second mark.
Dashing to 100 mph in seven seconds and past the quarter-mile pole in the 11s, the Z06 also needs more stopping power than an ordinary mortal. What is evident on the outside is the bigger air extractor behind the front-wheel opening, and a new intake scoop in front of the rear-wheel opening, to cool the bigger brakes (14-inch front, 13.4-inch rear rotors, the latter as big as the front rotors on a Z51-equipped 2005 Corvette). You’ll also spot the red-painted six-piston calipers up front, which use six individual pads to promote even wear. Rear calipers are more traditional four-pot/two-pad designs, also readily visible through the Z06’s 10-spoke wheels.
With top-speed performance of “over 180 mph” (we think the goal is 187 mph to hit the magic 300 km/h for European sales), the Z06 also needed some aerodynamic amendments. The fixed-roof fastback design (like a C6 coupe without the removable panel; we anticipate a convertible later) is the same configuration as that on the race car. It sports a new front splitter, rear diffuser and side “Gurney lips.” The wide front fender includes a deep curve behind the wheels, lined for protection from road debris. The shaping here is a near-direct borrowing from the racing program. Rather than employ the race car’s full wing, though, a taller wicker bill balances the downforce from the front splitter, without much drag penalty—the Cd is 0.31.
The final visual indicator of the new car’s prowess is the pair of large tailpipes carrying the exhaust from the LS7. Clearly the heart of this beast, each LS7 engine is hand-assembled by a single builder at GM’s new Performance Build Center in Wixom, Michigan, and heat-tested before it is shipped to the Corvette assembly plant in Bowling Green, Kentucky.
Chevy calls the LS7 a “small-block” V8, but it employs a different alloy block than the base Corvette’s LS2. This new casting allows the 4.125-inch bore and four-inch stroke that delivers the 427-cubic-inch displacement (an 8.0-liter version was tried, but wouldn’t fit in the car). Pressed-in cylinder liners permit the bigger bore in a casting you can still describe as a small-block
Racing influences? The 7.0-liter displacement matches that of the race car’s, and the C5-R’s engine was the first one the production team bench-tested to set its goals for the LS7, says GM Racing director Doug Duchardt. Start with the dry-sump lubrication system and move up through the new heads, and you’ll find the influence throughout. The LS7 employs six-bolt, doweled-in-place, CNC-machined forged-steel main bearing caps, a forged-steel crankshaft, titanium connecting rods, flat-top cast-aluminum pistons, CNC-ported aluminum cylinder heads with titanium intake valves and sodium-filled exhaust valves, and runs 11:1 compression. The valve angle is 12 degrees (vs. 15 in the LS2) and the cam provides 15 millimeters (0.591 inch) of lift.
The heads incorporate the entire combustion chamber, fed by straight tunnel-like intake runners akin to the race car’s leading into those 56-millimeter titanium intake valves. The valve seats are siamesed with those for the 41-millimeter exhausts. When those exhaust ports open up, the hot stuff escapes into a hydroformed tubular system, three inches in diameter. Overall, there is 43 percent more flow on the intake side, 27 percent more on the exhaust side, vs. the LS2. Exhaust backpressure is even managed, via an electronically controlled flap at the muffler, to maximize both low-rpm torque and high-rpm power output. The official figures are 500 hp at 6200 rpm and 475 lb-ft at 4800 rpm
All this premium hardware is coupled with the race-bred precision assembly techniques, including deck-plate boring and honing of the cylinders and crank-line boring of the block with the deck plates and side bolts installed. Dave Muscaro, assistant chief engineer of small-block V8 for passenger cars, says it’s the nearest thing to a race-quality engine program as can be found in a road car built in anything like Corvette volumes. The Wixom facility can produce 30 engines a day.
Impressive as the engine is, good aftermarket tuners are probably capable of squeezing 500 hp into your Corvette. Where the factory has an edge is in engineering and constructing a complete design to take full advantage of the power boost, and Hill’s team has left very little on the table. Start with the electronics, of course, fully integrating the ABS, traction control and stability control systems, all amended to suit the new hardware
Then there’s the weight-saving program. The chassis is now all-aluminum, replacing high-strength steels with the lighter metal in such key parts as the hydroformed frame rails. Other pieces that are fiberglass on the C6 use carbon fiber, such as the floor, which still has a balsa core but is now wrapped in carbon fiber. The engine cradle, aluminum on other Corvettes, is cast magnesium, and its lighter weight, along with the carbon fiber front fenders and wheel housings, helps to shift the balance of the car rearward. (Large-scale magnesium casting technology, by the way, is a direct derivative not of the racing program, but the Partnership for a New Generation Vehicle, the Clinton/Gore-era government supercar program.)
The Z06’s battery also moves to the back of the car, but that was mostly done to make room for the dry-sump oiling system under the hood—the weight shift is a bonus. Curb weight, says Hill, is “about 3130 pounds” vs. 3179 officially for the ’05 C6 coupe. The target was lower, but losing any weight at all is a real achievement while adding a dry-sump system, bigger wheels with grippy run-flat tires (275/35R-18s front and 320/30R-19s rear), an oil-to-oil cooler for the differential (using already cooled oil from the toughened transaxle to extract heat from the differential lubricant) and other features.
Even in the cabin, the team opted for the lower mass of manually controlled seats over the power-operated stock ones, and the two-tone seat itself, with larger side bolsters and Z06 logo embroidery, weighs less than the base seat. The steering wheel is 20 millimeters smaller in diameter, and about as small as you could go and still offer a clear view of the tachometer, redlined at 7000 rpm.
If that sounds a little spartan, fear not. Dual-mode climate control with cabin-air filtration, leather seating, HID lights with fog lights, and a HUD with g-meter and track mode are all standard. Speaking of track mode, Hill says occasional weekend competition use of your Z06 won’t void the warranty, unlike the case with some other manufacturers.
And when you’re not at the track, you may appreciate options like a Bose audio system, telescoping steering wheel, heated seats, side airbags, a navigation system with GPS, and XM satellite radio. |
