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Offered from 1987 to 1991, the RPO-B2K upgrade was available from any Chevrolet dealer and also Callaway’s first major Corvette tuning program. Together, GM and Callaway made the upgrade package a Regular Production Order (RPO) which was the first time GM had outsourced such an option to a specialist manufacturer. It even had a factory back warranty. As the C4 updated, so did Callway’s program and by 1988, the B2K was pushing 382 bhp and 562 ft. lbs. of torque.
This Sledgehammer reached 254.76 mph at the Transportation Research Center (TRC) in Ohio and became the world’s fastest street-legal car for some time. It was built up by Reeves Callaway in Connecticut as an example of what was possible with the new ZR1 and and turbocharging its LT5 engine. The result was a 898 bhp coupe that still retained luxuries such as air conditioning and a radio. It got this power by using a NASCAR-spec block with Mahle pistons and a massive turbo.
While not exactly a "collector's edition" Corvette in its own right, it nonetheless has become a uniquely identifiable and collectible Corvette from the fourth-generation era. 1988 marked the 35th anniversary for Corvette, and so it was decided that Chevrolet should commemorate the milestone by introducing an anniversary-edition model. This anniversary car was the first of its kind in a decade, given that Chevrolet opted not to manufacture a Corvette in 1983.
1988 Corvette Challenge Car Series
The 1988 Corvette Challenge Series was created by John Powell of Powell Motorsports. Chevrolet built fifty-six identical Corvettes for the first year of the Corvette Challenge in 1988. Each was equipped exactly the same, with all standard equipment, the 245hp Cross-Fire fuel injection engine, Doug Nash 4+3 transmission, Z51 Handling Suspension package.
In 1989 Callaway introduced a Speedster which was the culmination of their styling, engineering and trimming talents. Their first example was a bright green ZR1, which had a severely chopped windscreen, no side mirrors, eighteen inch wheels and a vibrant blue leather interior stitched purposefully from Germany. Nothing about Callaway’s Speedster was reserved, and this is especially true when investigating the specification. The car had 450 horsepower.
The 1989 Corvette Challenge cars had a unique option code from the factory, it was "R7F". The documentation from GM clearly indicates that the cars were produced for the express purpose of racing in the SCCA Corvette Challenge Series. There is also documentation that identifies by serial number, all Corvettes produced with these option codes. Therefore, it is relatively easy to validate the authenticity of any Challenge car.
There were several successful attempts to build a convertible ZR-1, most of them by private people. The DR-1 was a GM prototype to test the structural integrity of the ZR-1 chassis when it would be topless. The car was built by American Sunroof Corporation (ASC) for Don Runkle, who was the vice-president of Advanced Engineering Staff, which explains the “DR-1” designation. It was a standard convertible transformed to ZR-1 specs.
In the late 80s, Chevy was developing what some dubbed a ‘Super Vette.’ But the 1989 debut of the Dodge Viper sent GM engineers on a new path to develop a ‘Viper-Killer.’ It started with a factory test mule and the experiment was to see how a ZR-1 would perform if given more power and less weight. It was so fast it was called "Snake Skinnner", for it's ability to beat the Viper and Cobra.
How do you beat a slew of Fox-Body 5.0 Mustangs that seemingly dominated the roads in the late '80s? You take a 454 cu.-in. big-block engine and stuff into a C4 Corvette and call it "Big Doggie". An experimental vehicle used to determine how to convert from a small block to a big block. Its 454 big block V8 along with its orange paint make this high horsepower engineering study a one-of-a-kind standout in Corvette history. The car had as much HP as the '90 ZR-1 did and it was named "ZR-2" or "Big Doggie". Old dog, new tricks joke?
ZR- World Record Endurance Run Corvette on display at NCM
On March 1-2 1990 a unique group of people using a Chevrolet Corvette ZR-1, reset The 24-hour World Speed Record. That achievement proved unequivocally that the car is indeed...King of the Hill. "The 24" had stood for 50 years. Last set at Bonneville in 1940 by AP Jenkins driving the "Mormon Meteor Ill", a purpose-built. single-seat race car with an aircraft engine. The objectives: set the 24 as well as 5000 kilometer and the 5000 mile marks with a ZR-1 while using an L98-powered Corvette to set the six-hour record and other shorter distance marks.
While it was understood that the Corvette Indy Concept would never be fully realized as a production vehicle, it paved the way for the creation of the twin-turbo CERV III. The CERV III (Chevrolet Engineering Research Vehicle No. 3) was introduced in January, 1990 at the International Auto Show in Detroit, Michigan. Like the latter iteration of the Corvette Indy Concept car, the CERV III was fitted with a 5.7 Liter, 32-valve, dual-overhead cam LT5 engine that featured twin turbochargers. It had 650 hp and 655 lb/ft of torque and top speed of 225 mph.
The 1990 Escort World Challenge Series Corvette R9G's were only available for one week. Only race teams were allowed to order this very rare Corvette through dealerships. The 1990 Corvette had its own code like the '88 & 89's did, it was dubbed the "R9G" Corvette. The cars were produced for the express purpose of racing in the SCCA World Challenge Series. In 1990, dealers could order cars destined for the World Challenge race series.
This vehicle pioneered the advantages of “Active Suspension” and had GTP Corvette race car technology. Built at the Bowling Green Plant, this vehicle was developed as a prototype for a limited edition run in the 1990 model year. Chevrolet ordered it to be built with a complex, high-tech active suspension that includes an Eaton hydraulic pump and Moog actuators. This car and the technology inside of it led to the Active Handling system GM released in 1996.
1993 ZR-1 COrvette
The C4 ZR-1 Corvette, even some 30 years after its initial year of production, carries indisputable performance merit, the likes of which few can deny. In fact, the ZR-1 is often cited as the car which helped fend off threats, both foreign and domestic in origin, to the Corvette's elite performance car status. However, after only 6,939 ZR-1 Corvettes were built, and 6 years of production had passed, the program was terminated, falling victim to decisions regarding pricing.
The offspring of collaboration between Corvette performance guru Reeves Callaway and designer Paul Deutschman, the Super Speedster LM is an astonishing step up on the original Speedster, taking full advantage of the ZR1’s Lotus-engineered, all-aluminum DOHC engine and 6-speed manual transmission. One of only three twin turbocharged and intercooled LT5 engines built by Callaway, it delivers a pavement-shredding 766 HP.
Chevrolet Corvette ZR-1 Spyder prototype, 1991, by ASC. An experimental styling prototype ordered by Don Runkle, Chevrolet’s chief engineer, to see how far the ZR-1 might be pushed in convertible form. The windshield was chopped in half and the seats were mounted directly to the floorpan. The black example in the National Corvette Museum was originally painted Sebring Silver with a Neutrino Yellow interior.
For the fourth generation Corvette, legendary Corvette racer John Greenwood developed the G4R. It was essentially a radical bodykit that usually followed a high level of performance upgrades. Included was a ground effects package that had integrated lights on the front valance. Furthermore the a new engine scoop and rear wing were fitted.
Chevrolet's introduction of the LT1 in 1992 as the base engine in the Corvette phased out the L98 based Callaway Twin Turbo. Previously, Callaway Corvettes made their increased power through positive manifold pressure; now they made it through increased displacement and finesse. Initially called the CL1 or CR1, they designated the chassis they were built upon. They were based on the pushrod LT1 cars (CL1) or the 32 valve DOHC LT5 ZR-1 cars (CR1).
CERV IV was nothing more than a C4 with the all new powertrain and interior in it. Read the commentary of a car magazine reporter: "We suspect that the first, very early prototypes of the all-new, Gen III ran on the dynos at GM Powertrain sometime in the early spring of 1993. In-vehicle testing began at the GM Milford Proving Ground in the first week in May of 1993 with the "Chevrolet Engineering and Research Vehicle IV-A".
The Corvette Stingray Concept was developed as an internal design challenge to combine classic Corvette cues with surprisingly high-tech features, modern materials, and a striking new appearance. The car is well-appointed with a clamshell hood, scissor-style doors, ergonomic seats, rear-view camera with night vision enhancement, and a high performance hybrid drive. Interactive touch controls allow the driver to customize the power and efficiency of his or her ride.
The Corvette team decided to one-up the Viper with four extra cylinders, they decided on one of Ryan Falconer’s stunning, all aluminum, 600-cubic-inch, 683hp, 680 lb-ft V-12 racing engines. The biggest challenge was the fact that the all-aluminum V-12 engine was 8.8-inches longer than the production Corvette engine. So the front end of the ZR-1 would have to be stretched 8 inches. This test car was named Conan, after his raw, beastlike charisma.
When Chevrolet changed gears to the LT1 engine, Callaway revealed their new SuperNatural line and the CR1 based on the ZR1’s LT5. Options for the CR1 included the radical Aerobody, German upholstery and special wheels, brakes and exhausts. The CR1 used a larger displacement to produce either 475 or 490 bhp.
1993 Corvette C4 40th Anniversary ZR-1 parked on street
In 1993 just 448 ZR-1 Corvettes were produced and only 240 of them were 40th Anniversary Edition cars. The 40th Anniversary Package consists of a deep and glossy Ruby Red exterior finish over a matching Ruby Red interior with leather adjustable sport seats. A Corvette with both of these highly desirable packages is rare and special. At the heart of the ZR-1 is the 405-horsepower LT5 V8 engine mated to a 6-speed manual transmission.
Reeves Callaway has always had a dream of competing a Corvette of his own at the 24 Hours of Le Mans, France. The idea begin with the body work for a street version, but one thing led to another, and a full race version was completed as well. The street version is almost identical to the race version because the hood, tail, rocker panels, and lower door halves, are all made of carbon fiber, just like the race version.
As the story goes, when the Corvette ZR-1 came out in 1990, Dick Guldstrand saw an opportunity to create his vision of the perfect Grand Sport ride, instead of his name just getting slapped onto another Chevrolet product. He asked GM for fifteen ZR-1’s and some money. He got one car and permission to do whatever he wanted to do with it. And that’s exactly what he did. Called the "GS90", Dick's car would prove to be the most elaborate and expensive specialty Corvette ever built.
This car was created by Doug Rippie. His claim to fame was the Corvette Challenge Series. Rippie loved racing Corvettes in the US, but, his life-long dream was to take on the world-class marques at Le Mans. So, when Chevy introduced the C4 ZR1 the opportunity was opened up. Via his collaboration with MerCruiser and Lotus Engineering, all with Chevy’s blessing, the "Black Widow" program created special street and race versions of the LT5 engine. This engine made 525hp.
The actual Corvette Pace Car that served at the 79th running of the Indianapolis 500 was a near-stock LT1 Corvette Convertible, except for the mandatory safety features that were required by the Indianapolis Motor Speedway.  The Official Pace Car cam equipped with strobe lights, a special roll-bar, five-point safety harnesses for the driver and passenger and an on-board fire suppression system. Chevrolet built just three of the actual pace cars.
Chevrolet knows their clientele, and with the 1996 Corvette Collector's Edition LT4, the automaker put together a special package that would entice hard-core 'Vette fans with a unique tribute to the outgoing C4 model. The $1250 option brought unique Sebring Silver Metallic paint, 5-spoke wheels, and, of course, special badges and embroidery. It also received the upgraded LT4 powerplant available in the Grand Sport, and with 330 horsepower on tap.
Priced at an additional $3250  for the coupe or an additional $2880 for the convertible, the Grand Sport package included exclusive Admiral Blue paint and featured a single white stripe that ran the length of the body as well as two red accent stripes (also known as “Sebring Stripes”) on the driver side front fender.  This unique paint scheme was deliberately developed by GM to pay homage to the classic Corvette Grand Sport Racer of the 1960’s.
To understand why the Guldstrand GS-90 coupe and convertible differ so much, keep in mind that during the course of the C4 development cycle, no ZR-1 convertibles were planned, so the base C4 convertible had to be used in building a GS-90 Nassau Roadster, as it was called. The coupe, however, had the advantage of using the ZR-1 platform right from the get-go.