Yes, I love the new Z06



With the introduction of the second-generation Chevrolet Corvette in 1963, Zora Arkus-Duntov felt he had a contender that could compete with the world's best in production sports-car racing. To fully realize this potential, Zora put together a customer racing package that was identified by one of the regular production option codes also new for that year. If you ordered the RPO Z06 special-performance equipment, your new Sting Ray coupe would arrive from the factory as race-ready as Chevrolet could make it. This package was not for the casual buyer; it added $1818 to a base price of $4252 Even with a slightly decontented version available on convertibles later in the year going for $1294, only 199 examples were sold. 1963 was the only year this equipment package was available; today these cars are legendary and sought-after by collectors.

In 2001, the fifth-generation Corvette hardtop (introduced in 1999 as an unprecedented third body style) became an equally unprecedented high-performance model named for these cars. Even the 4-cam ZR-1 was technically a regular production option, not a separate model, and the hardtop with its fixed roof and notchback rear window was stiffer as well as lighter than the coupe or convertible, making it the ideal starting point. As a Z06 it became lighter still and was just as racetrack-ready as Zora's original version, but went even further with special wheels, tires, added engine power and more. With the 2002 Z06's 405 bhp propelling 3125 lb., its power-to-weight ratio was 7.7 lb/bhp compared to 9.2 for an equivalent base coupe. The C5 Z06 remains the best-handling, fastest-accelerating Corvette to date. And costing a little less than a fully optioned convertible, it has accounted for about 20 percent of Corvette sales through 2004.

While writing my article for Road & Track on the sixth-generation Corvette, I asked Chief Engineer Dave Hill what the new Z06 would be like. All he would say was that "it would distance itself further from the base Corvette." Well, he wasn't kidding! The 2006 Z06 moves to the highest level of the performance food chain with a bumper-to-bumper makeover of the base coupe. Powered by a 7.0-liter 505-bhp V-8 and weighing only 10 lb. more than the C5 version, its power-to-weight ratio is an impressive 6.2 lb/bhp.

0510_corvette_tech_engine.jpgThis relationship is the golden fleece of performance, and the achievement of Dave Hill's engineering groups can be put into context by comparing this super Corvette to the carbon-fiber exotics from Germany. It slots between the Porsche Carrera GT with 5.83 lb/bhp and the Mercedes-Benz SLR McLaren, which has 6.25 lb/bhp. Both of these cars cost over $400,000.

This is far more than a sixth-generation coupe with a big engine, but the first 427 to sit under the hood of a Corvette in 36 years has to be at the center of attention. Unlike the big blocks of old, this 427 is only 6 mm taller and no heavier — at 458 lb. — than the LS2 6.0-liter small block, making it truly a "big" small block. RPO LS7 is the latest addition to GM's growing family of high-performance aluminum pushrod V-8s based on the Gen III 5.7-liter LS1 dating from 1997, and the LS7s are assembled by individual technicians at a new high-performance build center in Wixom, Michigan. GM Powertrain chose high-tech simplicity to gain horsepower over supercharging or additional valves and camshafts. Instead of adding weight, increased external size and complexity, they opted for more cubic inches.

 

The starting point for all of this is the small-block Chevy V-8 of 1955 that displaced 4.3 liters. To maintain the compact size, GM has stayed with this engine's 4.40-in. cylinder-bore-center spacing for their small blocks to this day. The Gen I and II blocks were cast iron and from 1969 displaced 350 cu. in. (5.7 liters) in the Corvette. They had 4.00-in. bores with a 3.48-in. stroke and when the Gen III aluminum cylinder block came along, the bore diameter was reduced to 3.90 to make room for iron cylinder liners. Stroke was increased to 3.62 to compensate. But this conservative approach proved to be unnecessary so the bore went back to 4.00 in. on the 6.0-liter LS2. For the new Z06, lessons learned have allowed the bores to be safely enlarged to a whopping 4.125 in. that, combined with a 4.00-in. stroke, brings displacement up to 7.0 liters. Viewing these cylinder block decks (the cylinder head mating surface), this looks truly radical with very little remaining but holes ringed by cast-iron cylinder liners machined flat where they would otherwise overlap.

With multilayer steel head gaskets, the sealing between these cylinders is not a problem and the big-small-block approach has already been well proven. A limited number of specially cast big-bore cylinder blocks have been available from GM performance parts since 1998, and Katech has been using them in the C5-R endurance-racing Corvettes starting in 2000. What hasn't been available outside of the racing program are cylinder heads that can take full advantage of the extra liter of displacement.

The LS7 heads are a work of art with their valve angle reduced from 15 to 12 degrees, the same as the new C6-R's racing heads. The ports and combustion chambers are CNC machined, and it's no surprise that the valves get bigger with 2.20-in.-diameter titanium intake valves replacing 2.00-in. steel ones. As with the last Z06 engine, exhaust valves are still sodium-filled steel shells but they increase in size from 1.55 to 1.61 in. These valves are slightly larger than the ones in the racing heads because those engines have to breathe through rules-mandated air restrictors, while the LS7 inhales through a huge oval air filter that would look at home on one of GM's monster-displacement crate motors. This feeds an intake manifold made from the familiar black Nylon 6 plastic but with a more squared-off appearance filling all of the available space to increase its volume. There's a more aggressive camshaft than the one in the 2001 Z06 LS2 engine with a valvetrain that is unchanged except for the needle bearing steel rocker arms. The new cams are a little longer, have a different motion ratio, and are angled slightly to reach the relocated valves.

The compression ratio has been raised a bit from 10.9 to 11.0:1 and exhaust gases flow through hydroformed primary pipes into collectors welded directly to larger catalytic converters. The racy-looking short-skirt pistons are still flattops but have valve clearance notches for the first time in this family of engines. They are linked to the forged steel crankshaft by titanium connecting rods that are taken very close to the cam and block skirts by the long 4.00-in. stroke. The crank runs in six-bolt main bearing caps that are also forged steel, and its stroke is amplified by the 4.125-in. pistons' increasing windage in the compact crankcase to the point that a racing type dry-sump lubrication system is called for.

 

An engine oil tank takes the place of the battery against the firewall, and the LS7 gets a double oil pump with two "G" rotors in a common housing. The pressure rotor draws oil from the remote tank and lubricates the engine while the forward rotor scavenges returning oil from the collection pan and sends it back to the tank. There's a large oil cooler in front of the radiator. And while the engine still has a filler cap, oil is checked and filled through the 8-quart tank.

With a 7000-rpm redline, the engine's 505 bhp at 6300 rpm offers a 105-bhp advantage over the base 6.0-liter; it produces 470 lb.-ft. of torque at 4800; and thanks to the wonders of electronic engine management, fuel mileage is exceptional for an engine of this displacement and power output.

Electronics also plays a part in the exhaust system, allowing full-throttle backpressure to be kept to a minimum while still safely passing the drive-by noise test. The stainless-steel pipes' diameter has increased from 2 1/2 to 3 in. and they are welded to a pair of larger-volume mufflers. These mufflers each have the familiar pair of exhaust tips but the inboard ones are normally closed by vacuum-operated butterfly valves. They are allowed to open only when their electronic control system senses the throttle-plate angle and engine rpm have reached a predetermined point that is well beyond the range of normal driving.

For the most part the existing driveline is up to the job with the clutch requiring only stiffer damper springs. As with the previous Z06, only the Tremec 6-speed manual transmission is available and this gets a one-piece countershaft, which drives an oil-cooler pump like the Z51 version but has the base car's closer gear ratios. The 3.42:1 final drive ratio stays, but the ring and pinion set are larger in diameter, which means a new rear axle housing that also gets its own small oil cooler.

Starting with the C4, RPOZ51 has been the Corvette's performance handling suspension and for the sixth generation it becomes the far more comprehensive Z51 sport package largely taking the place of the last-generation Z06. Even so, the 2006 Z06 goes a step further with stiffer springs, a larger-diameter rear anti-roll bar and recalibrated Sachs shocks. Suspension geometry and the aluminum control arms remain unchanged except for the upper rear arms. Like the fronts, these now have aluminum bow-ties extending from their bushings so camber can be adjusted with shims, making them more racer-friendly. The larger cross-drilled brake rotors have 14.0- and 13.4-in. diameters, are thicker and are clamped by more powerful monolith 6-piston calipers at the front with four pistons used in the rear.

To get all of the additional power to the road and improve on the Z51's already considerable lateral grip, the Goodyear F1 supercar EMTs get wider; in fact, the rears are the widest tires to find their way onto a Corvette. Up front the 245/40s become 275/35ZR-18s and at the rear 285/35s are replaced by 325/30ZR-19s mounted on 5-spoke alloy wheels reminiscent of the last Z06. These wheels are manufactured with a thick ring on the back of their face, which is heated and stretched over a spinning mandrel to form 9 1/2-in. front and 12-in.-wide rear rims.

 

This is the first Z06 to have distinctive bodywork but it's nothing theatrical, just a pleasing reflection of its increased capabilities. The fenders are flared to accommodate the wider tires, increasing the body's overall width by 3.0 in. in front and almost 4 across the back. New wheel-well liners have Gurney lips ahead of the front tires, and small flaps extend from their rear edges. The recontoured front fenders have more prominent side ducts that display the Z06 badge, and there's a splitter at the bottom of the new front fascia to aid high-speed underside aerodynamics. Most of the 7.0-liter engine's increased cooling flow comes through a slightly larger opening that gets an eggcrate grille.

There's a small scoop in front of the hood, and there are rear-brake cooling scoops on the sides of the fenders behind the doors. The splitter reduces underside airflow to the point that cooling air for the front brakes, like the engine, has to come through the front fascia. There are long slots in the narrow vertical band at the back of the splitter feeding 2-piece brake ducts that take the air inside the wheelhouses and direct it into the center of the brake rotors. Except for a larger CHMSL (center high-mounted stop light) spoiler for additional rear downforce, the rest of the body remains the same as the base coupe. This includes the glass hatch rear window and normally removable roof panel, which is fixed in place on the Z06.

The coefficient of drag is 0.34, the same as the last Z06 but with better lift numbers despite increased cooling flow and much wider tires. What's even more remarkable than holding the line on drag and mass is that with all of the added content the car is 116 lb. lighter than a current Z51 manual-transmission coupe.

This was accomplished by the strategic use of lighter materials with the biggest savings coming from making the main structure out of aluminum rather that steel. The aluminum uniframe looks almost identical after it's dipped in black anticorrosive paint, but it is 132 lb. lighter. The frame rails are hydroformed in the same tooling but from tubing with twice the wall thickness. They are joined at both ends by extruded bumper beams with castings replacing the steel weldment suspension mounts. A cast magnesium roof armature is bolted in place to complete the structure, which has a first torsional frequency 2 Hz higher than the steel frame with its removable roof.

The balsa-wood-core floor panels are skinned in carbon fiber, and to take weight off the front end, carbon fiber is also used for the front fenders and outer wheelhouses. The engine cradle is cast magnesium, and the battery moves to the back of the storage area behind the seats. This gives the car a slight rear weight bias which comes out 50/50 with a driver.

The interior is available only in ebony and the new-for-2006 3-spoke steering wheel gets a 0.40-in.-smaller-diameter rim than the base wheel. There are contrasting accents on the seats that have Z06 logo embroidery and while options are still limited, there's more to choose from with two equipment groups.

Performance numbers for the car are impressive: 0-60 in the low 4s, with quarter-mile times in the low 12s and 0.98g around the skidpad. Even so, the car is more civilized with its low mass resulting from lightweight major components instead of peripheral changes like the last Z06's thinner glass, a fixed mast antenna and the lack of run-flat tires. There's an adage that says, "Speed costs money; how fast do you want to go?" In this case that only applies up to a point. Base window sticker will be $65,000 with an $800 destination fee, upholding the Corvette tradition of delivering performance beyond its price.

 

Technology? Im sure when they have it right unlike Ford where you had the DOHCs and it made a whole 200 HP.... Kinda a disgrace for a V8 when a 4 cylinder Honda does the same It took Ford how long to make decent power using OHCs?

*just poking fun so lets not start a flame war *

 

Yea...SCOTT!