We Toast the C5 Corvette's Final Year with a Test of the 2004 Corvette Z06 - Page 6 of 6

by Hib Halverson
text and images ©2004 Hib Halverson
No use without permission


Chevrolet Corvette Z06
General:  front-engine, rear-transmission, rear-drive, 2-passenger, 2-door coupe. EPA vehicle class: sports car. Manufacturing location: Bowling Green KY, USA.

Price as tested:  $56,720

Price information:  base Corvette Z06 $51858; Le Mans Commemorative Edition package, $4335, consisting of: polished wheels, special badging, special stripe package, lightweight hood, memory package and electrochromatic mirror package. Destination/freight charge, $800.

Significant Standard Equipment:  LS6 engine, manual trans., power steering, brakes, windows, mirrors and locks. Tilt wheel. Dual zone air conditioning. Head-up display. "Active Handling" stability control system. Traction control. Antilock braking system. Security system. Active keyless entry.

Entertainment:  Delco-Bose AM/FM stereo radio w. compact disc player. and 6 speakers.

Engine:  90° V-8, aluminum block and heads. Composite intake. Cast iron exhaust manifolds.

Bore x stroke:  3.90 x 3.62-in/99x92-mm

C5 Corvette Forum

Displacement:  346 cubic inches/5.66-liters

Compression ratio and recommended fuel:  10.5:1, 93-octane (R+M/2)

Valve gear:  roller hydraulic cam, pushrods, roller rocker arms, 2.00-in intake, 1.55-in exhaust valves with potassium/sodium-filled stems.

Ignition:  Distributorless, inductive, crank-triggered, individual coils.

Engine and emissions controls:  General Motors Powertrain/Delphi sequential electronic port fuel injection with electronic throttle control, feedback spark and air/fuel ratio control, dual 3-way catalysts, EGR and air injection upon start-up and OBD2 emissions controls diagnostics.

Mfg. rated SAE net power:  405hp@6000rpm

Mfg. rated SAE net torque:  400lbs/ft@4800rpm

Rev limit:  6600 rpm.

Single-plate dry clutch, flexible prop. shaft inside rigid torque tube. Rear-mounted, Tremec T-56, six-speed, transmission, aluminum case, steel internals w. computer-controlled 1-4 "skip-shift" feature.
Transmission ratios:  2.97, 2.07, 1.43, 1.00, 0.84, 0.56 and 3.28 reverse.
Chassis-mounted rear axle assy. w. clutch-type, limited-slip differential.
Final drive ratio:  3.42:1.

Structure:  steel perimeter frame, closed structural tunnel, steel/aluminum/magnesium cockpit structure and halo bar.
Exterior:  Sheet molded compound with carbon fiber hood.

Ft: aluminum short/long arm, aluminum knuckle, transverse composite spring and steel antiroll bar.
Rr: aluminum short long arm, aluminum knuckle, toe control link, transverse composite monoleaf spring and steel antiroll bar. Monotube, fixed-valve hyd. shocks. Hyd. power-assisted, speed-sensitive variable effort, rack-and-pinion steering.

Type:  four-wheel disc with vacuum power assist and antilock system.
Ft:  12.6x1.26-in rotors, 263-sqin. swept area.
Rr:  11.8x1.0-in. rotors, 158-sqin.Swept area.

Type:  Spun/cast aluminum/Goodyear Eagle F1 Supercar, steel-belted, asymmetrical, ultra-performance, street radial.
Ft:  17x8.5-in./P265/40ZR17
Rr:  18x9.5-in./P295/35ZR18.

Interior: SAE volume:  52 cuft. Cargo volume: 13.3 cuft. Bucket seats, driver 6-way power adjustable, passenger 2-way manual adjustable. 3-point, manual, shoulder/lap belts. Dual air bags.

Weights and measures
Wheelbase:  104.5-in.
Length:  179.7-in.
Width:  73.6-in.
Height:  47.7-in.
Ft. track:  62.4-in.
Rr. track:  62.6-in.
Ground clearance:  3.9-in.
Frontal area:  21.3 sqft.
Curb weight:  3118 lbs. (published) 3108 lbs (as tested)
Ft/rr. weight distribution:  53/47%

Crankcase:  6.5-qt.
Cooling system:  11.8-qt.
Fuel:  18-gal.

Calculated Data:
Engine Hp/cuin:  1.17
Vehicle Power/weight ratio:  7.67:1
Vehicle Weight/displacement ratio:  8.98:1

Performance (conditions: sea level, cool, damp, typical road surface)
0-60:  3.96-sec. (observed avg.)
0-100:  n/a
Standing 1/4-mi:  12.57-sec./114.8-mph. (observed avg.)
Braking from 60/80 mph:  n/a
Top speed: 168mph (estimated) (rev. limited)

Fuel Economy
EPA ratings:  19 city, 28 highway, 23 combined
Observed fuel economy:  22.3.

Analysis: Vette v. Viper

Some in the car hobby see the Chevy Corvette versus Dodge Viper contest as pretty one-sided with image and brutality combining with acceleration and speed to make the Viper a landslide winner.

No question, Viper cuts a more dramatic profile, offers its driver a more frenzied driving experience and can accelerate faster than Gray Davis' limo leaving the California Governor's Mansion-and that's quick! While the Vette and Viper are comparable up to 60 mph, past that, the Viper's 8.3-liter, V10 behemoth (525lbs/ft torque and 500hp) has it getting to the drag strip finish line about four tenths sooner. We've seen published accounts of 12.1 quarters and we bet under perfect conditions, the car might go high-11s. The Dodge is also the unquestioned winner in the top speed contest with 190 mph to the Z06's rev limited, 168 mph.

But let's widen our focus. Let's consider efficiency, ride and handling, refinement and cost. Efficiency? Even though the Dodge weighs 300 pounds more than the Z06, it beats the Corvette on power-to-weight ratio, 6.82 to 7.67. That's where the better acceleration numbers come from. It's engine displaces 506 cubic inches but generates only 500hp. On a horsepower per cubic inch basis, the Dodge V10 is 0.988 compared to the LS6's 1.157. Clearly, there's an efficiency gap in the engine department.

A Viper has somewhat better brakes and, yes, it's better on a skid pad by a couple tenths of a g., but otherwise, the Z06 seems to have the edge in handling. When Vipers and Corvettes face-off with each other on road racing tracks in SCCA T1, the Z06 is often the winner. A Viper rides hard, so hard in fact, that the media which have road tested even the improved '03-'04 models say things like, "...rides like a Nathan's Hot Dog cart." and "...bangs and crashes as if jumping curbs."

Other road tests tell of problems with squeaks and rattles, uncomfortable incidences of excessive cockpit temperature, particularly the footwells, and high levels of interior noise. One of these publications said about value in its '03 Viper test, "But, the truth is the Corvette Z06, some $33K less costly, is more effective because it's half (their italics) as difficult to drive." Though we've not tested the current generation Viper, we'll take our colleagues' words for it.

Not only does the Viper sell for more than half again as much as a Z06, then costs its buyer a $1300 luxury tax surcharge; it, also, earns its owner a whopping $3000 Federal "Guzzler Tax" hit because of its powerful, but inefficient engine.

Is the Viper the landslide winner some say it is? It's sure quick in a straight line but, otherwise, we're not so sure.

So, what does a Corvette Z06 need to completely de-fang those Vipers? A bigger motor with, say...500 hp and a little less curb weight.

Trust me, you've got about two years to wait. In the meantime, the Dodge Boys better stock-up on Depends.