2006 Chevrolet Corvette Z06

Alex P

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.

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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