Chevrolet Corvette C6 ZR1

The Chevrolet Corvette C6 ZR1 is a high performance version of the Chevrolet Corvette C6. Both the C3 from 1969–1971 and C4 Corvettes from 1990-1995 also had ZR-1 models.

This is the extreme version of the already bonkers Corvette Z06. Though that one has a giant 7 liter, the ZR1 makes do with a 6.1 liter number. But make no mistake, this one is a supercharged unit. Designated the LS9, it produces a maximum of 638 bhp of power, making this model of the Corvette the most powerful ever in its entire history. 

It provides Ferrari F12 like straight line performance, for less than half its price. For its price, it competes with the Ferrari 458 Italia, McLaren MP4-12C, Lamborghini Gallardo, Audi R8 and the Dodge Viper.   

Components

Engine design

The Corvette ZR1 engine is a heavily modified version of the LS3 Corvette engine, designated the supercharged LS9 Corvette engine. Producing 638 hp (476 kW; 647 PS) and 604 lbf·ft (819 N·m) of torque, it is the most powerful production Corvette to date. The LS9 has a sixth-generation Eaton TVS R2300 roots 4-lobe supercharger with intercoolers from Behr, utilizing an air-to-water, dual-brick design. The supercharger's four-lobe design offers improved efficiency over three-lobe models. To avoid changes to the hood appearance, the supercharger's output was split into two halves. Each cylinder bank has an intercooler.

The cylinder walls of the LS3 are thicker than the Z06's LS7 since the LS3 has a smaller bore. Oil squirters under each piston help cool the pistons. Connecting rods and the inlet valve are made of titanium. Heads are made from a special heat resistant aluminum alloy. The camshaft lift was reduced from the LS7's to improve idle quality. With the addition of the supercharger to the 6.2 liter LS9, the higher lift camshaft was no longer necessary to achieve horsepower targets.

Lubrication is provided by an improved version of the LS7's dry sump system. The new system increases oil capacity from 8.0 to 10.5 quarts (9.94 liters). A new dual gerotor oil pump increases scavenge performance and oil pressure, enabling oil to be delivered under the most extreme conditions. The LS7 oilpan is used for the LS9 with the addition of an oil cooler which is mounted on the left side of the pan.

With the 2011 model, GM offers the optional "Corvette Engine Build Experience," where the customer visits the General Motors’ Performance Build Center to help assemble the LS9 for the ZR1 purchased. Factory technicians supervise the process and the normal warranty covers the engine built by the customer's hands.

Transmission

The ZR1 flywheel has been improved over the 2008 Z06. The flywheel was upgraded by going from six to a 9 bolt design and cutting off nearly 9.8 ounces (278 grams) for improved throttle response and acceleration.

The ZR1 has a 6-speed manual Tremec TR-6060 transmission with a MH3 gearset, while the 2008 Z06 featured the MM6 gearset.

Differential/drive

The differential is a limited slip with carbon and steel plates. The differential uses SAE 5W-80 Dexron LS lubricant.

The two half shafts have different diameters (33mm left, 40mm right), designed to prevent resonance during acceleration and reduce the chances of wheel hop.

Production

Production vehicles are hand assembled in Bowling Green, Kentucky. The ZR1 engines are built at the General Motor Performance Build Center in Wixom, Michigan.

Ride control

The name of the ride control system is Magnetic Selective Ride Control (MSRC). MSRC is provided by Delphi Automotive Systems from technology invented by the GM Research Laboratories. The system uses two modes of control: Tour and Sport.

The system offers standing start launch modifications. When launching the ZR1 from a standing start, the shocks are completely softened on launch and stiffened on rebound. The softened shocks on launch aid the ZR1 by allowing weight to transfer to the rear, aiding traction. The ride control standing launch modifications are designed to minimize bounce.

Suspension

The ZR1 features a double-wishbone suspension system and Magnetic Selective Ride Control—which adjusts shock-absorber damping in real time to either "Tour" or "Sport" mode.

The MSRC shocks are automatically adjusted based on driving conditions and vehicle dynamics (cornering, braking, etc) for optimal handling. The system is adjusted every millisecond to provide sharp handling during spirited driving, and a smooth ride while cruising.

The new high-end magnetic suspension system enables the ZR1 to deliver great handling and grip to achieve 1.10 g of average lateral acceleration.

Chassis/body

Right rear 3/4 view of Corvette ZR1

The chassis, similar to the 2008 Z06, is made of aluminum. To cut weight, many panels are made of carbon fiber. Panels made of carbon fiber are the fenders, hood, roof, splitter, and rocker extensions. To prevent the sun from damaging the binder in the exposed carbon fiber composite body panels, panels are protected with a clear coating.

The rear wheels are the largest ever mounted on a production Corvette with 335/25 Michelin Pilot Sport PS2 tires on 20 in (510 mm) wheels.

The ZR1 has a length of 176.2 inches (4,480 mm), width of 75.9 inches (1,930 mm), and height of 48.7 inches (1,240 mm). The ZR1 has a curb weight of 3,405 lb (1,544 kg).

Clutch

The 260 mm (10 in) ZF-Sachs twin-plate clutch supplants Z06's 290 mm (11 in) single-plate unit to reduce inertia for better shift feel. The lower clamping force reduces clutch-pedal effort. The clutch upgrade is considered a dramatic improvement over the unit employed within the Z06.

Brakes

The front brake rotors are similar to the carbon ceramic design employed in the Ferrari FXX track car, the difference being a diameter reduction from 15.75 in (400 mm) to 15.5 in (390 mm) for added wheel clearance. The front calipers are Brembo 6-piston units.

Rear calipers are Brembo 4-piston units. The rear brakes are 15 in (380 mm) carbon ceramic rotors, originally employed as the Enzo Ferrari's front rotors. Same as those used in the BMW M3 GTS.

Both front and rear pads have twice the contact area of the Z06's, as well as the addition of brake pad wear sensors. The brake master cylinder, booster, ABS unit and system controller are now obtained from Bosch instead of Delphi.

As a result, the ZR1 will stop from 60 mph (97 km/h) in a current production car record-breaking 96 feet (29.3 m).

Ignition

Coil packs are identical to those used on the LS3. The coil packs are mounted on the valve covers.

Fuel system

A unique fuel pressure regulator varies pressure between 36.3 and 87.0 psi (250 and 600 kPa) depending on rpm.

Identification

Hood window of ZR1

The ZR1 features blue badges, engine valve covers, and brake calipers. The hood contains a polycarbonate window which allows the intercooler to be viewable. Doors and rear body are from the 2008 Z06. A spoiler which is larger than those on the previous models spans the top rear bumper. Functional fender vents provide engine cooling. The lettering "LS9 Supercharged" can be viewed on top of the plastic supercharger cover through the hood window.

Specifications

Estimated

• Displacement: V8 6.162 L (376.0 cu in) w/ (Eaton) TVS Supercharger & Intercooler.
• Horsepower: 638 bhp (476 kW; 647 PS) at 6500 rpm 
• Torque: 604 lbf·ft (819 N·m) at 3800 rpm 
• Bore: 103.25 mm (4.065 in)
• Stroke: 92.0 mm (3.62 in)
• Compression: 9.1:1
• Supercharger maximum boost: 10.5 psi (0.7 bar)
• Redline: 6500 rpm 
• Clutch: 260 mm (10 in)
• Final Drive Ratio: 3.42:1
• 1st gear ratio: 2.29
• 1st gear top speed: 106 km/h (66 mph)
• 2nd gear top speed: 155 km/h (96 mph)
• 3rd gear top speed: 210 km/h (130 mph)
• 6th gear ratio: 0.67
• Wheel size front: 19 in (480 mm) diameter by 10 in (250 mm) width
• Wheel size rear: 20 in (510 mm) diameter by 12 in (300 mm) width
• Tire size front: 285/30R-19
• Tire size rear: 335/25R-20
• Brakes front: Brembo 15.5 in (390 mm)
• Brakes rear: Brembo 15.0 in (380 mm)
• Front/rear balance: 52/48
• Curb Weight: 3,324 lb (1,508 kg)
• 0-60 mph (97 km/h): 3.3
• Top speed: 205 mph (330 km/h)
• Quarter mile (~400 m) time: 11.2
• Quarter mile speed: est. 130 mph (210 km/h)
• Production: 2000 units per year (estimated)
• Price: US$111,525 to US$129,945
• Lateral acceleration: 1.10 g (average) 

Awards and recognition

• 2009 Performance Car of the Year, Top Gear
• Best New Cars of 2009, About.com Cars
• Automotive Journalist and Top Gear presenter Jeremy Clarkson's Car of the Year Award.
• Achieved a Nordschleife lap time of 7 minutes and 26.4 seconds making it one of the fastest production cars to lap the circuit. / Inc., Quarter Mile time of 10.89 Sec..
• The 2012 Chevrolet Corvette C6 ZR1 was tested at the Nurburgring by Jim Mero on June 9, 2011. It was a base specification car with optional super-slick DOT track competition tires (Michelin Pilot Sport Cup Zero Pressure) and non-stock safety equipment. It recorded a time of 7:19.63 (Video confirmed), the 5th-best time ever for a production vehicle.
• Achieved the fastest recorded speed for a production car on the Bonneville Salt Flats of 176.54 mph (284.11 km/h) driven by Jeremy Clarkson of the BBC TV Show Top Gear.

American Hot Rods

They're low, they're fast, they're classics- they're the Hot Rods. The American way of being free, one of the fastest ways to say your cool, when your in the driver's seat in a Hot Rod, a huge V8 engine in front of you with all its massive dollops of horsepower under the control of your right foot, you know your going to thoroughly enjoy what happens next. Open top or hard top, engine enclosed in a beautiful hood or open and out there for the whole world to admire, matte finish or classic flames, they come in various kinds. Built to leave all other cars in its smoke in a straight line, they're engines are taken to the end of they're lives developing horse power more than double then what they originally produced. They are the choppers of the Driving world.

Check out the Hot Rod urban slang here.

Hot rods are typically American cars with large engines modified for linear speed. The origin of the term "hot rod" is unclear. One explanation is that the term is a contraction of "hot roadster," meaning a roadster that was modified for speed. Another possible origin includes modifications to or replacement of the camshaft(s), sometimes known as a "stick" or "rod". A camshaft designed to produce more power is sometimes called a "hot stick" or a "hot rod". Roadsters were the cars of choice because they were light. The term became commonplace in the 1930s or 1940s as the name of a car that had been "hopped up" by modifying the engine in various ways to achieve higher performance.

In modern culture

Lifestyle

There is a contemporary movement of traditional hot rod builders, car clubs and artists who have returned to the roots of hot rodding as a lifestyle. This includes new breed of traditional hot rod builders, artists and styles, as well as classic style car clubs. Events like GreaseOrama feature traditional hot rods and the greaser lifestyle. Underground magazines like Ol' Skool Rodz, Gears and Gals, and Rat-Rods and Rust Queens cover events and people.

History

Late 1930s–1950s

The term seems first to have appeared in the late 1930s in southern California, where people would race their modified cars on the vast, empty dry lake beds northeast of Los Angeles under the rules of the Southern California Timing Association(SCTA). The activity increased in popularity after World War II, particularly in California because many returning soldiers had been given technical training in the service. Many were prepared by Bootleggers in response to Prohibition to enable them to avoid revenue agents ("Revenooers"); some police vehicles were also modified in response.

The first hot rods were old cars (most often Fords, typically Model Ts, 1928–31 Model As, or 1932-34 Model Bs), modified to reduce weight. Typical modifications were removal of convertible tops, hoods, bumpers, windshields, and/or fenders; channeling the body; and modifying the engine by tuning and/or replacing with a more powerful type. Speedster was a common name for the modified car. Wheels and tires were changed for improved traction and handling. "Hot rod" was sometimes a term used in the 1950s as a derogatory term for any car that did not fit into the mainstream. Hot rodders' modifications were considered to improve the appearance as well, leading to show cars in the 1960s replicating these same modifications along with a distinctive paint job.

Engine swaps often involved fitting the Ford flathead engine, or "flatty", in a different chassis; the "60 horse" in a Jeep was a popular choice in the '40s. After the appearance of the 255 cu in (4.2 l) V8, because of interchangeability, installing the longer-stroke Mercury crank in the 239 was a popular upgrade among hot rodders, much as the 400 cu in (6.6 l) crank insmall-blocks would become. In fact, in the 1950s, the flathead block was often fitted with crankshafts of up to 4.125 in (104.8 mm) stroke, sometimes more. In addition, rodders in the 1950s routinely bored them out by 0.1875 in (4.76 mm) (to 3.375 in (85.7 mm); due to the tendency of blocks to crack as a result of overheating, a perennial problem, this is no longer recommended. In the '50s and '60s, the flatty was supplanted by the early hemi. By the 1970s, the small-block Chevy was the most common option, and since the '80s, the 350 cu in (5.7 l) Chevy has been almost ubiquitous.

Post WWII origins of organized rodding

Ford Popular

Rodded prewar British Rover 10

After World War II there were many small military airports throughout the country that were either abandoned or very rarely used that allowed hot rodders across the country to race on marked courses. Originally drag racing had tracks as long as one mile (1.6 km) or more, and included up to four lanes of racing at the same time. As hot rodding became more popular in the 1950s, magazines and associations catering to hot rodders were started. As some hot rodders also raced on the street, a need arose for an organization to promote safety. Hot rodders including Wally Parks created the National Hot Rod Association (NHRA) to bring racing off the streets and onto the tracks. They created rules based on safety and entertainment, and allowed Hot Rodders of any caliber the ability to race. The annual California Hot Rod Reunion and National Hot Rod Reunion are held to honor pioneers in the sport. The Wally Parks NHRA Motorsports Museum houses the roots of hot rodding.

1960s rise of the street rod

As automobiles offered from the major automakers began increasing performance, the lure of Hot Rods began to wane. It was no longer necessary to put a Cadillac engine in a Ford roadster to be fast. It was now possible to buy a muscle car that outperformed just about any hot rod, with more passenger room, and without having to expend the effort of building and tuning the car oneself. After the 1973 Oil Crisis, the public called on automakers to offer safety and fuel efficiency over performance. The resulting decrease in an average car's performance led to a resurgence of Hot Rodding, although the focus was on driving Hot Rods over racing so the term 'Street Rod' was coined to denote a vehicle manufactured prior to 1949, often with a more reliable late model drivetrain. Street Rodding as it was now known was a different phenomenon than Hot Rodding, as Street Rodding was mainly family oriented. National events were hosted by the National Street Rod Association(NSRA), which also stressed safety as the NHRA did 20 years before, but this was safety for the street as opposed to on the race track. Each NSRA event has a 'Safety Inspection Team' that performs a 23 points inspection process that goes beyond what normal State Safety Inspections Require.

In the mid-1980s, as stock engine sizes fell, rodders discovered the all-aluminum 215 (Buick or Olds) could be stretched to as much as 305 cu in (5 l), using the Buick 300 crank, new cylinder sleeves, and an assortment of non-GM parts, including VW & Mopar lifters and Carter carb. It could also be fitted with high-compression cylinder heads from the Morgan +8. Using the 5 liter Rover block and crank, a maximum displacement of 317.8 cu in (5,208 cc) is theoretically possible.

Modern rodding

1936 Chevrolet street rod

There is still a vibrant hot rod culture worldwide, especially in Canada, the United States, the United Kingdom, Australia and Sweden. The hot rod community has now been subdivided into two main groups: street rodders and hot rodders. Hot rodders build their cars using a lot of original equipment parts, whether from wrecking yards or NOS (New Old Stock), and follow the styles that were popular from the 1940s through the 1960s. Street rodders build cars (or have them built for them) using primarily new parts.

A common factor among current owners of hot rods is to make them more noticeable. There are now many different sectors of hot rodding, some of which are:

• Street rod: a very popular branch of hot rodding. Contrary to the implications of the term hot rod, street rods are a mix of hot rods, custom cars, and modern Detroit cars. Emphasis is on high-quality custom paint jobs, comfortable interiors, and modern engines and running gear. As specified by the NSRA (National Street Rod Association), a street rod must have been manufactured prior to 1949.
• Pro-Street rod: a branch of street rodding featuring mildly customized sedan and coupe models not normally associated with hot rodding that have monster engines and huge rear tires inside the fender wells. They retain all the other luxury features of street rods.
• Billet rod: street rods featuring many items being machined from billet aluminum
• Traditional rod: built according to a particular point in time and stick to those build techniques and materials
• Rat rod: constructed to resemble an old time jalopies, although they may require more work than a show rod
• Show rods (created to compete in national car shows such as America's Most Beautiful Roadster (AMBR), and the Detroit Autorama).

There are hundreds of local car clubs supporting the hot rod/street rod community. The National Street Rod Association (NSRA) is the largest club in the world and sponsors many local events including the Street Rod Nationals which serve as a showplaces for the majority of the hot-rodding and street-rodding world to display their cars and to find nearly any part needed to complete them. Collectively they are all referred to as Hot Rods.