(continued)
Internally, the LS7’s reciprocating components make use of racing-derived
lightweight technology, including titanium connecting rods and intake valves, to
help boost horsepower and rpm capability. The rpm fuel shut-off limit is 7000
rpm. The LS7’s details include:
- Dry-sump oiling system
- Unique cylinder block casting with large, 104.8-mm bores and pressed-in
cylinder liners
- Forged steel main bearing caps
- Forged steel crankshaft
- Titanium connecting rods with 101.6-mm stroke
- Cast aluminum flat-top pistons
- 11.0:1 compression
- High-lift camshaft
- Racing-derived CNC-ported aluminum cylinder heads with titanium intake
valves and sodium-filled exhaust valves
- Low-restriction air intake system
- Hydroformed exhaust headers with unique “quad flow” collector flanges.
One of the clearest examples of the LS7’s race-bred technology is its use of
titanium connecting rods. They weigh just 464 grams apiece, almost 30 percent
less than the rods in the LS2 V-8. Besides lightweight, which enhances high-rpm
performance and rpm range, titanium makes the rods extremely durable.
The LS7’s CNC-ported aluminum cylinder heads are all-new and designed to meet
the high airflow demands of the engine’s 7.0-liter displacement, as it ingests
approximately 100 cubic feet more air per minute than the Corvette’s 6.0-liter
LS2 V-8 – an 18-percent increase in airflow. Consequently, a hydraulic roller
camshaft with .591/.591-inch valve lift is used to allow plenty of air to
circulate in and out of the engine.
To ensure optimal, uninterrupted airflow, the LS7’s heads have straight,
tunnel-like intake runners. Very large by production-vehicle standards – even
racing standards – they are designed to maintain fast airflow velocity,
providing excellent torque at low rpm and exhilarating horsepower at high rpm.
The heads feature 70-cc combustion chambers that are fed by huge, 56-mm-diameter
titanium intake valves. The lightweight titanium valves weigh 21grams less than
the stainless steel valves used in the LS2, despite the valve head having 22
percent more area. They are complemented by 41-mm sodium-filled exhaust valves,
vs. 39.4-mm valves in the LS2. To accommodate the large valve face diameters,
the heads’ valve seats are siamesed; and, taken from experience with the engines
of C5-R racecars, the LS7’s valve angles are held at 12 degrees – vs. 15 degrees
for the LS2 – to enhance airflow through the ports.
The LS7 has a dry-sump oiling system designed to keep the engine fully
lubricated during the high cornering loads the Corvette Z06 is capable of
producing. An engine compartment-mounted 8-quart reservoir delivers oil at a
constant pressure to a conventional-style oil pump pick-up at the bottom of the
engine. The pressurized oil feed keeps the oil pick-up continually immersed in
oil at cornering loads exceeding 1 g.
Oil circulates through the engine and down to the oil pan, where it is sent back
to the reservoir via a scavenge pump. The large-capacity reservoir, combined
with a high efficiency air-to-oil cooler, provides necessary engine oil cooling
under the demands of the engine’s power output. With the dry-sump system, oil is
added to the engine via the reservoir tank – which includes the oil level
dipstick.
The LS7’s dry-sump system was developed and tested on racetracks in the United
States and Europe , including Germany ’s famed Nürburgring. And while common in
racing cars, the Corvette Z06 is one of just a handful of production vehicles –
and the only production Corvette – ever to incorporate such a high-performance
oiling system.
Z06 Drivetrain and Chassis
The Corvette Z06’s powertrain and drivetrain systems are matched to the LS7’s
performance capability. The light, four-into-one headers discharge in to new,
close-coupled catalytic converters and through to new “bi-modal” mufflers. The
mufflers each feature a vacuum-actuated outlet valve, which controls exhaust
noise during low-load operation but opens for maximum power.
At the rear of the LS7 engine, a single-mass flywheel and lightweight,
high-capacity clutch channel torque to the rear transaxle. The six-speed manual
transmission has been strengthened to handle the LS7’s increased torque load.
The transmission includes a pump that sends transmission fluid to the front
radiator for cooling. Upon its return, the fluid removes additional heat from
the differential lube before returning to the transmission. The six-speed
transmission connects to a limited-slip differential, with enlarged ring and
pinion gears. Stronger axle half-shafts with tougher universal joints transmit
power to the rear wheels.
The Z06 has a unique aluminum body structure for optimum stiffness and light
weight for the fixed-roof bodystyle. Perimeter rails are one-piece hydroformed
aluminum members featuring cast suspension nodes, which replace many welded
steel components on other Corvette models. Other castings, stampings and
extrusions are combined into the innovative structure with state-of-the-art
manufacturing technologies.
Advanced structural composites featuring carbon fiber are bonded to the aluminum
structure. The wider front wheelhouses, for example, are carbon composites and
the passenger compartment floors combine carbon-fiber skins with an
ultra-lightweight balsa wood core.
The Z06 has a new magnesium cradle that serves as the attachment point for the
engine and some front suspension components. Magnesium is lighter than aluminum
yet incredibly strong. The magnesium cradle helps improve the front-to-rear
weight distribution, as do carbon-fiber front fenders and wheelhouses. Engineers
also moved the battery from underhood to a position in the rear cargo area,
behind one of the rear wheels.
The mass reductions are offset by some added performance enablers, including
dry-sump lubrication, exhaust system with outlet valves, larger wheels and
tires, larger brakes and larger roll stabilizers.
Suspension and Brakes
The Z06 retains the 105.7-inch (2686-mm) wheelbase of other Corvette models, as
well as the short-long arm suspension and transverse leaf spring design, but it
rides on all-new wheels, tires, brakes, as well as its own rear spring and roll
stabilizer.
The firmer suspension works harmoniously with large 18 x 9.5-inch cast-spun
aluminum wheels and 275/35ZR18 tires in the front, and 19 x 12-inch cast-spun
aluminum wheels with 325/30ZR19 tires in the rear – the largest wheel-and-tire
combination ever offered on a Corvette. The tires use the latest
extended-mobility technology from Goodyear to provide a satisfactory ride, but
still allow the vehicle to achieve lateral acceleration of more than 1 g. The
extended-mobility tires eliminate the need – and weight – for a spare tire and
jack or inflator kit, while also reducing the chance of a sudden loss of
handling capability.
Complementing the suspension system and large rolling stock is an equally
capable four-wheel disc brake system, consisting of 14-inch (355-mm) vented and
cross-drilled front rotors and 13.4-inch (340-mm) vented and cross-drilled rear
rotors. For comparison, Corvette Coupe and Convertible models have 12.8-inch
(325-mm) front and 12-inch (305-mm) rear rotors, while the ’06 Corvette with the
Z51 sport package has 13.4-inch (340-mm) and 13-inch (330-mm) rotors.
The front rotors are acted upon by huge, red-painted six-piston calipers that
use six individual brake pads. Individual brake pads are used because they
deliver more equalized wear compared to what would otherwise be a pair of very
long single-piece pads. For the rear brakes, four-piston calipers with four
individual brake pads are used. A Delphi four-channel ABS system is standard, as
is a very competent active handling system – complete with a Competitive Driving
mode.
The large brakes bring an excellent level of stopping capability with the Z06,
and with their four-wheel brake cooling, they provide excellent fade resistance
and lining life during track duties.
Design Details
The new Z06 has an unmistakable and aggressive appearance, with design cues that
include:
- A wide front fascia with a large, forward-facing grille opening, a
splitter along the bottom and wheel opening extensions along the sides to
provide aerodynamic downforce
- A cold air scoop in front of the hood that integrates an air inlet system
for the engine
- The trailing edge of the front wheel opening is radiused to achieve
improved drag, but protects the body finish with a tough molding, and a large
air extractor is located behind the wheel
- A fixed-roof bodystyle optimizes body rigidity and mass
- Wider rear fenders with flares cover the massive rear tires and a brake
cooling scoop in front of the wheels visually balances the fender extractor
- A tall rear spoiler houses the CHMSL on the top of the rear fascia
- 10-spoke wheels (18-inch, front; 19-inch, rear)
- Four larger stainless steel exhaust outlets
- New-design Z06 badging on the carbon fiber front fenders
The aerodynamics of the Z06’s exterior were shaped by the experiences of the
Corvette racing program, where high-speed stability and cornering capability are
paramount. And while the racecars use large rear wings, the Z06’s elevated
spoiler provides sufficient downforce to balance the road-worthy front splitter
without adversely affecting aerodynamic drag. The Z06’s Cd is .31.
For all its race-inspired functionality, the Z06 is designed to be a daily
driveable high-performance vehicle. To that end, comfort and convenience are
held to a very high standard. High-Intensity Discharge llighting, fog lamps,
leather seating, dual-zone air conditioning, cabin air filtration and head-up
display (HUD) with track mode and g-meter are standard.
The Z06 also has a revised gauge cluster that displays the Z06 logo on the
7000-redline tachometer and has a new readout on the oil pressure gauge to
reflect the higher standard pressure of the dry-sump oiling system. And, like
other 2006 Corvettes, the Z06 has a new, smaller-diameter 370-mm three-spoke
steering wheel that provides a more agile, performance-oriented feel. The seats
feature two-tone leather surfaces, with Z06-logo embroidery and contrasting
stitching.
Z06 options include a Bose audio system with an in-dash six-CD changer, polished
wheels, a telescoping steering wheel, heated seats, side air bags, a navigation
system with GPS, universal home remote and XM Satellite Radio.
But for all its comfort, engineers did sacrifice a few components in the quest
for lower weight and higher performance. Seat side bolsters are fixed and more
supportive to better hold the driver when cornering and they weigh less. The
passenger seat features manual controls, saving the weight of a power-adjust
motor, and the Z06’s acoustic package is revised to reduce weight and allow more
aural feedback of the powertrain.
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