Chevrolet Corvette C5 Z06
The Chevrolet Corvette C5 Z06 is a high-performance version of the C5 Corvette sports car. Introduced by Chevrolet as their corporate and performance flagship, production began in 2001 and ended with the 2004 model year.
- 1 General
- 2 Performance
- 3 Z06 refinements
- 4 LS6 engine
- 5 Active Handling
- 6 Transmission
- 7 Suspension
- 8 Wheels
- 9 Tires
- 10 Titanium exhaust
- 11 24 Hours of Le Mans Commemorative Edition
- 12 History of the Z06 & LS6
- 13 See also
- 14 Notes and references
The successor to the ZR-1 made its debut in 2001 as the Z06, giving a nod to the high performance Z06 version of the C2 Corvette of the 1960s (See the history below). Instead of a heavy, double-overhead cam engine like the ZR-1, the Z06 used a high-output, tuned version of the standard LS1 Corvette engine (designated LS6), which initially produced 385 horsepower (287 kW). Although its total power output was less than that of the last ZR-1, the Z06 was much lighter, and could out-perform the ZR-1 in every category except top speed. It also cost substantially less money than the ZR-1.
Like with the ZR-1, Chevrolet found that increasing the power output did the C5 platform little good without additional modifications to bring the rest of the car up to par. Starting with the most structurally rigid body style offered, the hardtop or "fixed roof coupé" (FRC), an uprated FE4 suspension, larger wheel rims and tires, revised gearing ratios, and functional brake cooling ducts became part of the total package. The Z06 is 38 pounds lighter than a standard C5 hardtop thanks to weight-saving measures such as a titanium exhaust, thinner glass, lighter wheel rims, non-EMT tires, reduced sound proofing, fixed rear radio aerial, and a lighter battery. Starting with the 2002 model year, the LS6 engine was uprated to 405 horsepower (302 kW) by means of a larger volume air intake, stiffer valve springs, lighter sodium filled valves, more aggressive cam phasing and lift, revised pistons, and revised block. While Chevrolet officially claimed that the ultimate power output of the LS6 was 405 horsepower (302 kW), many dynamometer tests have shown that Chevrolet underrated the engine by 20 hp (15 kW), giving it an actual total of 425 horsepower (317 kW).
Factory performance figures for the 405 hp (302 kW) version of the Z06 give an acceleration time from 0-60 mph as 3.9 seconds. Owner-drivers have reportedly achieved quarter-mile times of 11.7 seconds. Car and Driver recorded 1/4 mile times of 12.4 seconds for the 405 hp (302 kW) Z06 and 12.7 seconds for the 385 hp (287 kW) Z06 In their December 2002 issue. Quarter mile drag times are made up of multiple factors. One such factor is "Driver Skill" and or "Driver Aggressiveness" (gear shift timing, reaction time, and optimum shift points); this accounts for various reported times, which can lead to controversy. The Z06 is capable of matching or besting the 0-60 acceleration times of some of the world's premier sports cars, including the BMW Z8, Ferrari 360, and Porsche 911 Turbo (Type 996).
|0-60 mph||3.9 sec|
|0-100 mph||9.2 sec|
|0-100-0 mph||13.56 sec|
|1/4 Mile||11.9 sec |
|Skid Pad||1.03 G|
|Top Speed||186 mph (299 km/h)|
|Nürburgring Nordschleife Lap Time *||7:56|
The Z06 received several other refinements in addition to its unique engine, suspension, wheels, and tires that either enhance functionality, differentiate its appearance from the base-model C5, or do both:
- Screened air inlets in the center of the front fascia that deliver additional cool air to the intake system.
- Air scoop inlets on the sides of the front fascia that funnel air to the front brakes for better cooling. These inlets replaced the fog lamp housings and/or associated trim panels of the base-model C5.
- Air scoops on the rear rocker panels that funnel air to the rear brakes for better cooling. Z06 rear brake temperatures are reduced by as much as 10% under competition conditions; brake fade and wear are also greatly reduced.
- Flat underside body panels that provide superior aerodynamics and help in achieving a 0.29 drag coefficient. ()
- Z06 badges on the front fenders (see the Z06 Emblem below).
- Different front and rear brakes pads than a normal C5 with distinctive red painted calipers (compared to black or bare calipers on the base-model C5).
The Z06 uses a high-output version of the LS1 small-block engine. The named was changed to LS6 after substantial modifications. The new engine powerplant expels about 12% more power than the LS1 and physically looks identical in external appearance save for the red engine covers. The LS6 produces 405 horsepower (302 kW) at 6000 rpm, and 400 lb·ft (542 N·m) at 4800 rpm. The engine redlines at 6500 rpm (versus the LS1's 6000 rpm redline).
The LS6 utilizes a block made of aluminum. It has been modified to allow greater bay-to-bay breathing. Typically the LS1 engine allows too much air in its crankcase developing into parasitic loss of power. The LS6 relieves this unwanted pressure translating into a removal of parasitic loss thus gaining more power.
- New Pistons
The LS6 utilizes modified versions of the LS1 pistons. The new pistons are made from M142 aluminum alloy which has proved to be stronger and more durable then the material used in the LS1. The pistons have been reshaped to have a slight barrel shape difficult to see for the normal onlooker. The new design also reduces internal mechanical noise because of its increased efficiency.
- Increased Compression
The LS6 cylinder heads have been cast with pent-roof combustion chambers. This modification of the LS1 has decreased the cylinder size thus promoting a greater Compression ratio; from 10.1:1 to 10.5:1. The LS6 ports have been cast using tighter tolerances which has resulted in increase power, thermal efficiency, and an increase in volumetric efficiency.
- High-Profile Camshaft
The LS6 utilizes a camshaft constructed from steelbillet materials. The timing of the camshaft has been altered by increasing the lift from those of the LS1 to provide quicker opening times. To accommodate higher lift and longer duration of the camshaft the valve springs have been manufactured to become stiffer. The springs are wound tighter then those in the LS1 which results in stronger springs able to handle the increase strain from the camshaft. These modifications result in more efficient air-flow into the combustion chambers and thus an increase in power.
- Fuel Injectors
The LS6 utilizes new and larger fuel injectors. The new injectors deliver 3.6 grams of fuel per second an increase of 10% above the LS1. The injectors were designed to deliver more fuel as a result of the increase in air flow from the increased compression and camshaft opening duration modifications. The fuel to air mixture ratio needs to remain proportional to achieve operational status.
- Internal PCV System
The LS6 utilizes a newly designed Positive Crankcase Ventilation valve. The new PCV valve now rests in the "V" of the engine. The "V" aluminum cover contains composite oil separating baffles with unique tubing. This results in less overall oil tubing thus reducing the potentiality of oil leak sources. The presence of the oil baffles also reduces oil consumption and increases the performance capabilities of the ventilation system during high performance maneuvers (greater then 1 lateral G) which the Z06 is capable of.
- Exhaust Manifolds
The LS6 utilizes newly designed exhaust manifolds. These manifolds are constructed of cast-iron material and have been designed to reduce weight by utilizing thin walls.
General Motors developed a system they called "Active Handling" in 1998. This system is a stability control feature that utilizes on-board sensors that measure a vehicles lateral acceleration, yaw rate, and steering wheel position. These sensors work in conjunction with the vehicle's Anti-lock braking system and Traction Control System which automatically assist a vehicle's driver in understeering and oversteering situations. The Z06 came standard with the second generation "Active Handling" system. The second generation system added the following substantial improvements to the original system:
- New Pressure Modulator
The second-generation Active Handling system utilizes the Bosch version 5.3 hydraulic pressure modulator. Bosch improved this version to become smaller, quieter and more efficient at lower temperatures. The new modulator can operate at -4°F (-20 °C) resulting in accelerated functioning capacity after cold startups. The pressure sensor originally located in the master cylinder was also integrated into the new pressure modulator.
- Dynamic Rear Proportioning
The second-generation Active Handling system utilizes a newly designed dynamic rear brake proportioning system. The new enhancement is a software driven improvement which balances the rear brake pressure electronically thus preventing rear brake bias also known as "Brake Lockup". The new system replaces the physically standard brake proportioning valve and its tubing components thus reducing weight and overall complexity.
- Sideslip Angle Rate Control
The second-generation Active Handling system received a major addition in the form of a sideslip angle rate control. This addition is software based and senses a driver's response time to changing vehicle movements during handling maneuvers. The system compensates for driver errors by utilizing the vehicles braking and traction control systems to maintain the stability of the vehicle based upon the parameters programmed by General Motors.
- Coefficient of Friction Estimation
The second-generation Active Handling system received another software upgrade in the form of improved calibration algorithms that estimate the friction coefficient of road surfaces. As traction on roads decreases (such as slippery road surfaces), a vehicle is biased towards slipping sideways. The new coefficient estimation takes this traction problem into account and factors it in with the rest of the Active Handling system inputs.
- Rear Brake Stability Control
The second-generation Active Handling system also added another software enhancement in the form of a rear brake stability control. This addition releases brake pressure on the inside rear wheel during high lateral acceleration maneuvers. This system assists drivers who do not estimate radius turns correctly during high speed and light braking. The system compensates for driver errors by utilizing the vehicle's braking system thus allowing for a more predictable maneuver while keeping the vehicle on its initial vector.
- Better Coordination
As has already been stated the Active Handling system works in conjunction with the Traction Control System. The second generation system continues this relationship but has been modified and refined to target specific rear brake pressures and control engine torque based upon the parameters programmed by General Motors. This modification results in improved acceleration and fewer engine sags.
- Competitive Mode
The second-generation Active Handling system incorporated into the Z06 has a unique featured labeled "Competitive Mode". When activated this feature turns the vehicle's Traction Control system off while still employing all the other components of the "Active Handling" system. To enable this feature a driver merely presses down on the Active Handling button for five seconds. This can be done even while the vehicle is in motion.
- Steering Angle Sensor: This digital sensor actively monitors the driver's steering inputs and communicates the applied steering wheel angle back to the system. It is accurate to within one degree of steering wheel angle change, and is located inside the steering wheel column.
- Yaw-Rate Sensor: This solid-state device utilizes a tiny pair of ceramic tuning forks to measure the actual rate at which the vehicle is pivoting (or yawing) about its center-of-gravity. This data is continuously fed into the Corvette's computer where the yaw rate is compared to the steering angle. Any variation beyond a pre-programmed set of values will result in activation of the appropriate assist feature(s) of the Active Handling System. The yaw-rate sensor on the Corvette is located inside the center console.
- Lateral Acceleration Sensor: The lateral accelerometer measures the centrifugal force created during a turn, and is located beneath the passenger seat. The data it provides is weighed against all of the other inputs and is used to calculate whether or not the performance limits of the vehicle are being exceeded under the current speed and traction conditions.
The Second-Generation Active Handling System provides better performance with less perceived intrusion, and is more adept than the original system in controlling the vehicle whenever necessary. The improved agility of the vehicle allows average drivers to perform better during spirited driving, and provides a greater safety margin in emergency situations.
Summary of Active Handling System Modes
- ON — Active Handling is automatically enabled when the vehicle is started. This is also true of the ABS and Traction Control systems.
- OFF — Like Traction Control, the Active Handling System may be manually disabled if the driver so desires. This is not true of the ABS, which is always enabled.
- COMPETITIVE DRIVING — In this mode, Active Handling and ABS are both enabled, but Traction Control is disabled.
The "OFF" and "COMPETITIVE DRIVING" modes are important features on a high-performance sports car, as skilled drivers may find that some wheelspin and oversteer can be beneficial to their lap times in competitive events. The Corvette's system allows them to operate the car in this fashion when appropriate, although Chevrolet recommends against selecting these modes for street use. 
The Z06 utilizes the specially-built M12 6-speed manual transmission. While outwardly similar to the base-model MM6 manual transmission, the M12 transmission is unique to the Z06, and is the only transmission available for that model; it is not available on Corvette coupés or convertibles. The M12 has more aggressive gearing to increase torque multiplication in most forward gears, allowing for more rapid acceleration and more usable torque at higher speeds. A transmission temperature sensor was added to protect the M12 from higher thermal stresses. The sensor warns the driver, via the Driver Information Center, with a "TRANS OVER TEMP" message if transmission temperatures approach their operating limits, and which could lead to damage if the transmission were not allowed to cool down. As with all C5 Corvettes, the transmission is located toward the rear of the vehicle, as a rear-mounted transaxle assembly. This allows a better overall weight distribution for the vehicle, as the weight of the transmission offsets some of the weight of the forward-sitting engine.
The M12 6-speed causes the Z06 model of C5 Corvette to have a lower top speed than a normal C5 despite having a higher RPM limit and more power, this is due to its gearing.
Gear ratio comparisons of MM6 (base-model C5) vs. M12 (Z06):
|Final Drive Ratio||varies||1.91:1|
A special suspension (the FE4) was developed exclusively for the Z06, and is not available on other Corvette models. It features unique shock calibrations, a larger front stabilizer bar, a stiffer rear leaf spring, and revised camber settings — all calibrated with a bias toward maximum control during high-speed operation. 
- Front stabilizer bar diameter (hollow): 30 mm with 4.5 mm thick walls
- Rear transverse composite spring leaf: 125 N/mm (versus 113 N/mm in the base-model's optional FE3 Sport Suspension)
- Camber, front and rear: -0.75° (compared to -0.25° on the base-model C5)
The greater negative wheel camber used on the Z06 helps to keep the tire flatter in relation to the road, and increases the tire contact patch for greater grip while cornering. When coupled with other special Z06 components, the combination provides exceptional racetrack performance. 
These suspension refinements came as a result of extensive testing and development, including several high-speed test sessions at Germany's famed Nürburgring circuit. The 2004 Corvette C5 Z06 is one of only a precious few cars to have broken the 8-minute barrier for lap times at the Nürburgring circuit  (see Nordschleife fastest lap times for complete list). However, the Corvette testing at Nürburgring wasn't just about raw speed: engineers learned important lessons about tuning the chassis to enhance the poise, confidence, and "smoothness of response;" attributes that become increasingly important when subjected to the severe demands of a 14-mile (23 km) course that has approximately 170 turns, and virtually constant elevation changes. "Nürburgring, at the extreme edge of the envelope, provides conditions that can't be easily duplicated anywhere else," said David Hill, vehicle line executive and Corvette chief engineer. "But, even for the Z06, we spend considerable time ensuring we don't make adjustments that compromise the normal daily driving character of the car." (Source: )
Also unique to the C5 Z06 are wider wheel rims and tires, which increase contact with the road and are essential to providing better grip. The design aesthetics of the new wheel rims are also one of the visual identifiers for the Z06, and are the most mass-efficient aluminum wheels ever produced for Corvette. They are painted a light gray metallic, and serve to show off the red brake calipers used on the Z06, especially when the car is in motion. The center cap of each rim also displays the red Corvette "crossed-flags" emblem for added identification at rest.
Wheel Size Comparison
|Front Wheels||17 in x 8.5 in||17 in x 9.5 in|
|Rear Wheels||18 in x 9.5 in||18 in x 10.5 in|
Goodyear specifically designed new wider, "grippier" tires for the Z06. Called Goodyear Eagle F1 SC (Supercar) tires, they allowed the Z06 to handle, brake, and perform better than any production Corvette yet tested. These same tires can be found other super-high-performance vehicles such as the Ford GT, and differ from the Goodyear Eagle F1 GS EMT tires provided as factory equipment on C5 coupés and convertibles as follows:
Tire Size Comparison
Eagle F1 GS
Eagle F1 SC
The 26-pound titanium muffler and tailpipe assembly of the Z06 replaced the 44-pound stainless steel system used in the base-model C5. This provided a 41% weight savings which directly translated into improved performance: faster acceleration, better handling, higher cornering speeds, shorter braking distances, and increased fuel economy. In addition, titanium's natural resistance to corrosion and durability give the exhaust system of the Z06 a virtually unlimited life span.
The Arvin design addressed the differences between titanium and stainless steel, including characteristics such as springback, vibration and resonance frequency. New muffler components were custom-developed for titanium fabrication, and a unique acoustic tone to meet GM sound requirements. To meet both performance and production rate demands, TIMET and Arvin collaborated to develop a new "exhaust grade" of commercially pure titanium. Special surface conditioning allows efficient fabrication to help meet the cost criteria set by GM for the use of titanium on a performance car. The titanium system is as strong as the equivalent steel system, but weighs substantially less.
Titanium has a natural oxide layer that provides immunity to external corrosion from road salts, as well as to internal corrosion from sulfur-rich engine exhaust. The system will experience no pitting or rusting, even at the welds. Corrosion immunity also means that the exhaust is designed with no trade-off to the weight savings; in a production vehicle, the system will far outlast anything made of stainless steel, resulting in fewer warranty claims and increased customer satisfaction. When titanium emerged as the solution to the GM performance challenges, the manufacturing technology to produce titanium mufflers in mass-market quantities didn't exist. Working with TIMET to optimize an exhaust grade of titanium, Arvin successfully adapted its stainless steel stamping, bending, cold forming and welding methods to accommodate the structural differences between stainless steel and titanium. New testing and computer models were also developed to ensure GM durability requirements were met. Titanium is environmentally sound. It is completely inert, non-toxic, 100% recyclable, and its production leaves no harmful by-products. Titanium does not degrade or release anything into the air, water, or ground.
To create the distinctive Z06 exhaust outlet scoop, Arvin developed new technology to cut the metal on an angle and curl it on a tight radius. Further showcasing the unique look, titanium's oxide film takes on shimmering tones of blues, purples, and golds as exhaust raises the temperature of the pipes. These colors evidence and enhance titanium's natural corrosion resistance. Finally, to produce the singular Corvette exhaust resonance, Arvin designed a new internal muffler configuration and used advanced acoustic techniques to tune the muffler.
Although common in 2008, titanium exhausts where virtually non existent in 2001. At the time GM introduced the concept of the usage of titanium in exhaust systems only the mclaren F1 supercar had such an exhaust.
24 Hours of Le Mans Commemorative Edition
For the 2004 model year, a 24 Hours of Le Mans Commemorative Edition of the Z06 (dubbed the Z16 after its RPO code) was offered in celebration of the C5-R "1-2" in-class finishes at Le Mans. The option package consisted of a special paint color ("Le Mans Blue Metallic"); wide, silver-and-red stripes optionally applied down the center of the car; a carbon fiber hood (saving an additional 10 pounds of weight); special commemorative badging and headrest embroidery; and brightly-polished wheel rims (a first on the Z06) with unique centercaps. Though not as outwardly apparent, the Z16 also received shock damping tuning for improved handling. The Z16 was the most produced Z06 in 2004 totaling 2025 units; of that number, 325 went overseas, leaving North America with approximately 1700.
History of the Z06 & LS6
In 1962, Zora Duntov Chief engineer at General Motors (GM) first brought forth the concept of the Z06 following a ban on factory-sponsored racing by the SCCA. Duntov knew customers would continue to race Corvettes even though the ban, which initially had full support from GM management, was in effect. During the planning of the Sting Ray project, Duntov suggested that it would be a good idea to continue with parts development in order to benefit racers, and as a way of surreptitiously circumventing the racing ban. Eventually, when GM management relented from their support of the ban, Duntov and his colleagues created "RPO Z06" as a special performance equipment package for the Corvette. The Regular Production Option (RPO) was a GM internal ordering code designation. The package was specifically designed for competition-minded buyers, so they could order a race-ready Corvette straight from the factory with just one check of an option box (whereas previously, the optional racing parts were literally hidden in the order form so that only the most knowledgeable and perceptive customers could find them). The RPO Z06 package was first offered on 1963 Corvette, and included: 
- Front antiroll bar with a 20% larger diameter
- Vacuum brake booster
- Dual master cylinder
- Sintered-metallic brake linings
- Power-assisted Al-Fin drums cooled by front air scoops and vented backing plates
- Larger diameter shocks and springs — nearly twice as stiff as those on the standard Corvette
These Corvettes came to be known as "Big Tanks" because the package initially included a 36.5-gallon gas tank (versus the standard 20-gallon) for races such as Sebring and Daytona. Initially, the package was available only on coupés, as the oversized tank would not fit in the convertible, although the rest of the Z06 option package was later made available on convertibles as well.
Thus, the 1963 Chevrolet Corvette was technically the first Corvette that could be designated as "Z06." The only engine option on the Z06 was the L84 327 cu in (5.4 L) engine using Rochester fuel injection. With factory exhaust manifolds, required to run the cars in the SCCA production classes, Chevrolet rated the engine at 360 horsepower (270 kW). The Z06 option cost an additional $1,818.45 over the base coupé price of $4,252. Chevrolet later lowered the package price and eliminated the larger gas tank from the Z06 package, though it remained available as an add-on option for any coupé. All told, Chevrolet produced 199 of these "original" Z06s.
In 1971, Zora Duntov's team created a special 425 brake horsepower (317 kW) big-block V8 for the Corvette, again with racing in mind. GM offered this as the "LS6" engine RPO for just one year: a 454 cu in (7.4 L), cast-iron engine with aluminum heads. In terms of both power and legend, these original LS6 engine were second only to the L88 full-blown racing engine offered from 1967 through 1969. The LS6 produced 425 brake horsepower (317 kW) and was the most powerful engine offered in 1971. Only 188 cars were produced with this powerplant — less than 1% of Corvette's production run of 21,801 vehicles for the model year. The LS6 option price was $1,221.00, or 22% of the $5,496.00 sticker price for the 1971 Corvette C3 coupé. When tested by a leading automotive magazine, an LS6-equipped C3 with a four-speed manual and a 3.36:1 limited-slip differential produced the following numbers:
- 0 to 60 mph (97 km/h): 5.3 seconds
- Quarter-mile: 13.8 seconds @ 105 mph (169 km/h)
- Fuel economy: 9-14 mpg
Also during that model year, a ZR2 RPO package was offered, priced at $1,747.00. The ZR2 package included the LS6 engine; a heavy-duty, close-ratio four-speed manual transmission; heavy-duty power brakes; transistorized ignition; lightweight aluminum radiator; special springs, shocks, and front and rear stabilizer bars. Twelve ZR2-equipped C3 Corvettes were produced, making them far more rare than the Z06-equipped C2 Corvettes.
The Z06 and LS6 name designations were resurrected in the fall of 2000 as a new performance package for the 2001 model year of the C5. Using the previously-introduced FRC body style, the Z06 option offered improved suspension components and, initially, a 385 hp (287 kW) engine designated as "LS6." The modern LS6 is an improved, high-output version of the base-model C5's 350 horsepower (260 kW) LS1 engine, but recalled the mighty 425 hp, 454 cubic inch big block of 1971. For the 2002 model year, the LS6 was further refined and rated at 405 horsepower (302 kW); this power increase was achieved through deletion of two of the catalytic converters in the exhaust system, improvements to the air induction system, and a more aggressive camshaft along with a lighter valvetrain. Correspondingly, Z06 Corvettes produced from 2002 until 2004 displayed unique "405 HP" badges on both front fenders as a testament of the vehicle's engine power.
Notes and references
- Definition from Reference.com
- Supercar Killer Chevy's '04 Z06 does 11s bone stock--and so much more
- Zimbio C5 Z06
- Super Car Site Ranks
- Car & Driver 2002 Z06 Performance Review 0-100-0
- "Ask Dave Hill, December Edition". crossedflags.com. http://www.crossedflags.com/modules.php?name=News&file=article&sid=70. Retrieved on 2008-01-04.
- The world’s fastest cars from 0-100-0 mph (in order)
-  2004 Corvette Z06 Coupe Specifications
- Staff, GM (2000). "2001 Specialist's Data Book Corvette". Michigan: Gail & Rice Productions, Inc.. pp. 48.
- 2004 Chevrolet Corvette: Commemorative Edition Celebrates Racing Success, and Improves the C5 Breed
Chevrolet Corvette timeline, 1953–present
|Performance||Fuel Injection||L84||Big Block||Big Block||ZR-1||LT4||Z06||Z06|
|Motorsports: Grand Sport • GTP • C5-R • C6.R|