Retired GM Engineer John Heinricy...
Retired GM Engineer John Heinricy trailered his #001 Grand Sport to Bowling Green for the weekend events. Heinricy, a longtime racer, won Saturday's autocross event with his cherry ride.
The fourth-generation Corvette had a huge impact on the marque's performance legacy. Many versions were produced from 1984 to 1996, but two standouts were the ZR-1 and the Grand Sport. ZR-1s were offered as coupes from 1990 through 1995, while Grand Sports were available in 1996 in coupe and convertible form.
The National Corvette Museum paid tribute to both this year at its annual C4 Gathering in Bowling Green, Kentucky. Many rare and unusual ZR-1s and Grand Sports were on display during the event, and many of the key people who were involved in the design of both models were also present. They provided behind-the-scenes stories about the development of these landmark Corvettes during their informative museum seminars.
The C4 was unveiled to the motoring press in the fall of 1983 and soon after was named the Motor Trend Car of the Year. The new design was a complete departure from the previous Corvette, and sales soared. The car relied on modern electronics, vastly improved aerodynamics, and high-tech suspension components to provide owners with exceptional handling and fuel mileage. However, its anemic, 205hp Cross Fire Injection engine was a disappointing artifact of a bygone era. Things improved in 1985 with the introduction of the 230hp Tuned Port Injection (TPI) L98. Over 200 production improvements were built into the '85 Corvette, and these mitigated many of the quality complaints that plagued the '84 models.
NCM Hall of Fame member Gordon...
NCM Hall of Fame member Gordon Killebrew (seated in the Corvette) conducted one of his popular "Drive Through Troubleshooting" schools at the museum. Killebrew's knowledge of the C4 Corvette is unsurpassed.
The '85 Corvette proved to be the car to beat in showroom-stock sports-car racing. The factory provided heavy support to several teams like Baker Racing and Morrison Motorsports. The results were astounding: Corvettes were unbeaten in every race they entered during the '85 season. However, the car still needed an engine capable of fully utilizing its excellent chassis and suspension.
Work secretly began on an ultra-high-performance variant-known internally as the "King of the Hill"-in late 1985. The Morrison and Baker teams were very involved in the development of this car, which would come to be known as the ZR-1. Many of the heavy-duty parts they used on their showroom-stock race cars were actually tested for the ZR-1 program.
Bowling Green began building prototypes in 1987, and these were used to help develop the new supercar. Production was scheduled for 1989, but a variety of technical issues moved the introduction back to the '90 model year. Eighty-four pre-production ZR1s were built and ended up being used as test cars. One of these prototypes, EX 5669, was used by Morrison Motorsports to break Ab Jenkins' 24-hour average-speed record of 161.180 mph set in 1940. The team handily exceeded the half-century-old mark in April of 1990 with a speed of 175.885. This car is on permanent display at the NCM, and many of the people involved with its record run were on hand at this year's C4 Gathering to celebrate the 20th anniversary of their achievement.
Some of the key team members...
Some of the key team members are shown here, including (from left) retired Chief Engineer Dave McLellan, team owner Tommy Morrison, GM marketing exec Ralph Cramer, and drivers John Heinricy and Jim Minneker. The group gave a "tour" of the car and held an hour-long Q&A session.
When development on the ZR-1 was completed, many of the prototypes were destroyed. However, some were tucked away by GM and were recently sold at auctions. A few have been located, salvaged, and restored, and now reside in the hands of Corvette collectors. Some of these special pieces of Corvette history were also on display at the gathering. They included two of Tommy Morrison's original Mobil 1 ZR-1 race cars, which were driven to numerous victories during the 1994 and 1995 racing seasons. They're currently owned by collector Robert Pfeffer. Former drivers John Heinricy and Jim Minneker, along with team owner Morrison, were also on hand and were obviously thrilled to see them displayed.
The other C4 to receive special recognition at the event was the '96 Grand Sport. Heinricy, who served as GM's director of High Performance Vehicle Operations for a number of years, provided some background on the car's development during a presentation at the Grand Sport Registry business meeting. Heinricy was serving as Corvette Assistant Chief Engineer in the mid-'90s, and his role was to finish production of the C4, while his boss, Chief Engineer Dave Hill, worked on introducing the new C5. Heinricy, who had been a diehard racer for years and enjoyed many victories behind the wheel of the C4, felt the best way to celebrate the car's 12-year model run was to pay tribute to its performance heritage. He received approval to build a limited-edition model called the Grand Sport, a name that honored the five special Grand Sport Corvettes Zora Arkus-Duntov built for competition in 1963.
This pre-production '89 ZR-1...
This pre-production '89 ZR-1 (EX5669) broke a 50-year-old 24-hour speed record on March 2, 1990. The Morrison Motorsports team averaged 175.885 mph to set a new mark that stood for 12 years.
Heinricy worked closely with the GM design studio, engineering team, and Bowling Green Assembly Plant to produce 1,000 specially serial-numbered Grand Sports. Total production was 190 convertibles and 810 coupes. Each car was fitted with special paint (Admiral Blue with a white stripe), along with the one-year-only, 330hp LT4 engine and a six-speed manual transmission. Heinricy also told the story of how he was able to purchase Grand Sport #001 from a Michigan dealer. He even brought this historic Corvette to the Gathering and autocrossed it on Saturday. (Not surprisingly, he won.)
The museum also hosted scenic tours, track events, and other fun-filled diversions throughout the weekend, much to the delight of the participants. If, like us, you have an abiding appreciation for the fourth-generation Corvette and its many contributions the marque's history, we heartily recommend attending next year's C4 Gathering.

Saturday's autocross was held...

Saturday's autocross was held at the nearby Trace Die Cast parking lot. This low-speed event was well attended and proved a real hit with the drivers who participated.

When the record became official,...

When the record became official, all of the team members signed the underside of the red ZR-1's hood. A second ZR-1 was built and used to tour the U.S., but only the NCM car bears the team signatures.

The legendary Tommy Morrison...

The legendary Tommy Morrison owned the team that actively raced Mobil 1 Corvettes through the '80s and '90s. Morrison was happy to be reunited with two of his old race cars, which are now owned by Robert Pfeffer.

This 345-mile ZR-1 pilot car...

This 345-mile ZR-1 pilot car was the fourth unit built in 1989. Notice the cloth interior, which wasn't available on production models. This car was used by GM's ad agency to promote the new supercar and was later donated to a school, where it sat unused for many years. GM recovered it, refurbished it, and sold it at a Barrett-Jackson auction.

The new owner of the car in...

The new owner of the car in the preceding photo left in place the original GM warning sticker. The company was serious about preventing non-production vehicles from being driven on public roads.

Former Lotus engineer Graham...

Former Lotus engineer Graham Behan (left) and retired GM Powertrain engineer Gib Hufstader shared their insights on the ZR-1's development during the "Heart of the Beast" seminar.

GM Powertrain Engineer Jim...

GM Powertrain Engineer Jim Minneker stands in front of one of his projects: the V-12, 660hp Falconer-powered ZR-1. The engine produced 782 lb-ft of torque and earned the car the nickname "Conan the Corvette." This ZR-1 was another of the early '89 pilot cars.

Many special C4 Corvettes...

Many special C4 Corvettes were on display in the main museum hall throughout the weekend, including this Doug Rippie-built "Black Widow" ZR-1.

This '86 Corvette was fitted...

This '86 Corvette was fitted with an early prototype ZR-1 engine and used for testing by Lotus in Europe. The car was found crushed in an English junkyard by Keith Beschi and brought back to life as an important part of the ZR-1's development history. Thanks, Keith!

Here's a look at the "Phase...

Here's a look at the "Phase 1" LT-5 engine in Beschi's prototype. Most of the parts on this engine were hand fabricated by Lotus engineers.