The first "Phase I" LT5 engines were installed by Lotus in standard-bodied '86 coupes like
The letter "Z" attached to a Corvette has always denoted enhanced performance and exclusivity, and the '09 ZR-1 is no exception. As was the case with the ZR-1 model that hit the market nearly 20 years ago, this 638hp super-Vette commands huge sums over sticker for the privilege of ownership. But the original King of the Hill shares more with its successor than an ability to stoke the passions of collectors. Its advanced performance technology continues to influence current Corvettes and the hardware that motivates them. The real story of the '90-'95 ZR-1 is how this technology was developed.
It all began when Dave McLellan became Corvette's chief engineer in 1975. McLellan inherited a chassis that was introduced in 1963 and a body that was restyled in 1968. He knew the clock was ticking on the C3 design, so he immediately began work on the C4. McLellan and his team started with a clean sheet of paper. The car's aerodynamic drag was reduced, thanks to a raked windshield and a smaller front end. The chassis made extensive use of aluminum and other weight-saving materials. Electronics helped cut emissions and fuel consumption. When the car was introduced to the public in the spring of 1983, it received rave reviews for its handling but garnered considerable criticism for its lack of power. McLellan knew the car needed an engine producing well over 300 hp, and he pushed Director of Powertrain Engineering Russ Gee to come up with a solution.
(From left) Gordon Killebrew, Gib Hufstader, and Dave McLellan were all integral parts of
Gee developed a few turbocharged V-6 and V-8 prototype engines for testing, but concerns over cost and reliability ultimately ruled out the forced-induction approach. Gee then turned to engineer Tony Rudd from Lotus Engineering, a company GM owned at the time. In November 1984, during a visit to Detroit, Rudd described the DOHC 4.0L V-8 the British manufacturer was devel-oping. It produced 350 hp-close to what McLellan wanted to slip into the C4 chassis. Gee initially thought Lotus could build cylinder heads to add to the Corvette's existing 350 small-block, but it was soon discovered that this was not the case. The only option was to craft a completely new block to accept the Lotus DOHC heads. Approval to build the engine was granted, and the process began in August 1985. The goal was to have the first engine running by May the following year.
The first "Phase I" LT5 engine ran for 30 minutes on May 1, 1986. Track testing began at Lotus in the summer, when the company received a shipment of engineless component cars from GM. Twenty-five of these standard-bodied ZR-1 test cars were built and subsequently used by Lotus and GM for development purposes. As far as we know, only one remains: a yellow car currently in the hands of a British collector.
The early test engines were hand-built in England by Lotus techs, under the supervision of
Meanwhile, testing continued on the Phase I and, later, Phase II LT5 engines. During this time, considerable effort was devoted to packag-ing the accessories and solving the engine's persistent oiling problems. Since the LT5 would be built in limited numbers and installed strictly in the Corvette, GM selected an outside contrac-tor to construct it. In March 1986, Mercury Marine in Stillwater, Oklahoma, was approved as the sole builder of the LT5 powerplant.
ZR-1 chassis development was also well underway at the time. Since GM was already using the SCCA's showroom-stock racing series to validate the endurance of the standard C4, it was a relatively simple matter to secretly install LT5 engines in some of these cars for testing between races. Additionally, two showroom-stock Morrison Corvettes were fit-ted with modified, 500hp small-blocks and raced at Daytona and Sebring. These races provided GM engineers with valuable data on the car's chassis strength and durability.
When the testing program was completed, GM ordered Lotus to destroy all of its prototypes.
In the summer of 1987, the initial batch of pilot ZR-1s was built at the Bowling Green assembly plant. These were the first cars to be fitted with the wider body and 11-inch rear wheels that would come to characterize the production model. In June 1988, Chevrolet invited the press to Riverside Raceway to drive what was then slated to become the '89 ZR-1. The response was overwhelming, and the car was subsequently featured on the cover of most major car magazines. In March of the following year, a yellow ZR-1 and a cutaway chassis were displayed at the Geneva Autoshow. Twenty-five ZR-1s were also shipped to Europe to participate in a four-week ride-and-drive program for selected press members. Again, the response was very positive.
Production of the ZR-1 was well underway in 1989 when it was decided to halt the build process and introduce the car as a '90 model. The '89 ZR-1s already built could not be sold to the public, so they were either scrapped or used as test vehicles. One was sent to California and fitted with a V-12 racing engine built by Ryan Falconer. The longer powerplant required GM to stretch the car's front chassis to make room. This V-12 Vette-unofficially dubbed "Conan" in reference to its brutish power output-currently resides in GM's Heritage Museum.
In 1986, two Morrison Motorsports showroom-stock Corvettes were converted to ZR-1 chassis
Another '89 ZR-1 was used by Tommy Morrison to set a new 24-hour speed record. The car was already fitted with a rollcage and fire system, as it previously had been used by GM engineer Jim Minneker for powertrain-endurance testing. In March 1990, the Morrison team installed a production LT5 engine in the car and took it to a test track in Fort Stockton, Texas. The goal was to break the existing, 161.80-mph mark set back in 1940. The team covered 4,221.256 miles in 24 hours, averaging 175.885 mph in the process. This car is now on display in the National Corvette Museum.
A third '89 ZR-1 with a unique history is the "Snake Skinner," so named for its ability to outperform Dodge's then-new Viper. This was engineer and race driver John Heinricy's personal project car. Heinricy and his team of engineers removed the car's A/C, radio, and center console. They also replaced the large rear window with a Lexan unit and exchanged the fiberglass hood for a lightweight carbon-fiber duplicate. The stock flip-up headlights were converted to fixed units in the lower nose panel. Finally, carbon-fiber brakes were installed to help rein in the car's tweaked LT5 engine. In all, the modifications flensed a shocking 900 pounds from the car, resulting in a curb weight of just 2,700 pounds. We had a chance to drive the Snake Skinner with Andy Pilgrim, and it's still among the fastest street Corvettes we've ever experienced. If you happen to spy an innocuous-looking white ZR-1 on display at the NCM, take a closer look-it's probably the infamous Snake Skinner.
Collector Tyler Townsley owns this '88 prototype ZR-1 (No. EX5014). The car was built in B
In 1990 the ZR-1 retailed for $58,995, but many were sold for well over their sticker price. In total, 3,099 units were purchased that first year. In August 1989, a handful of prototype '90 ZR-1s were built with a complex active-suspension system operated via computer and hydraulic controls. The intent was to offer the system as a $39,000 option over the base price of the car. While the idea was soon dropped, the cars were used extensively for testing, yielding valuable data that helped give rise to the active-suspension systems found on current Corvettes. The GM Heritage Museum displayed one of these rare cars at the '07 Corvettes at Carlisle event.
The original ZR-1 Corvette was a performance icon of the '90s, with the high-tech muscle to back up its supercar reputation. Despite its low build volume-a total of 6,939 cars were produced between 1990 and 1995-this is the car that helped reestablish the Corvette as a legitimate world-class performance car. It's a distinction the Vette hasn't relinquished since.
The interior of the Snake Skinner was Spartan, to say the least. The car had no A/C, radio
Assistant Corvette Engineer John Heinricy modified this ZR-1 prototype into the legendary
This production-ready ZR-1 was featured at the '89 Geneva Auto Show. It now resides at the
This bare ZR-1 chassis was also unveiled at the '89 Geneva show. The display has since bee
Twenty-Five ZR-1s were shipped to Carcasonne, France, later that year, to allow a select g
In March 1990, this prototype '87 ZR-1 was fitted with a production LT5 engine and used to
This car, chassis No. 3, is the lowest-production-number '89 ZR-1 in existence. It's curre
When the ZR-1's '89 production run was canceled, the existing cars were scrapped or used f
In August 1989, a small number of '90 "Active Suspension ZR-1" prototypes were built at th
Here's what the Active Suspension cars looked like under the hood. How would you like to c
This GM display shows the complexity of system's left rear corner.
Four '90 ZR-1 convertibles were built to evaluate whether the topless chassis was strong e