Unforgettable Corvette. The Fastest and the Most Beautiful Cars in the World
THE GENERAL’S SPECIAL FORCES FOR THE 1990S
In the 1960s, General Motors offered the widest selection of muscle cars, with every division except Cadillac producing at least one high-performance model. By the late 1970s, thanks to emissions and fuel economy concerns, most of these models had disappeared. Those that had soldiered on, including the Corvette, suffered from severe muscular atrophy.
By 1990, the GM muscle car ranks had dwindled to the Corvette, Camaro, and its Pontiac sibling, the Firebird. I he bright side was that computer technology, which enabled emissions and fuel economy friendly technology to coexist with power enhancements, had led to a resurgence of performance options. The Corvette led the way with development of the ZR-1, which was designed to establish the Corvette as a worthy equal to the world’s highest performing exotic sports cars.
While pushing forward with advanced technology, GM would also look to its past for inspiration in reviving limited-edition track-ready Corvette models such as the Grand Sport and Z06. On the Camaro side of the company, the Z28 name would also resume its lofty performance position. Another high-performance name of the past was revived with a 1990s attitude in the full-sized Impala SS. The Ram Air option made famous by the GTO was reintroduced with a vengeance as the Firebird Trans Am spread wings that had previously been clipped by emissions regulations.
Performance cars were not the only vehicles to capture GM’s attention at the beginning of the 1990s. The light-truck market was gaining momentum, and Chevrolet was gearing up for battle with Ford. If muscle cars were useiul sales tools during the 1960s, then high-performance versions of trucks could do the same in the 1990s. Some of the GM vehicles and names have disappeared or have had new faces since the 1960s. Pleading into the 1990s, GM was ready to start dealing out high-performance muscle cars again.
It’s good to be king. For Chevrolet performance addicts, the Corvette reigns over all. That’s why the Corvette special edition built in 1990 that took on the world’s performance leaders was affectionately dubbed “King of the Hill.” Corvette Chief Engineer Dave McLellan proclaimed that the “ZR-1 is a Corvette, only more so.” The ZR-1 Corvette option offered from 1990 to 1995 appeared in the Chevy catalog under the listing Special Performance Package. It was a rather understated description for a $27,016 (1990) to $31,258 (1994—1995) bundle of goodies that not only consisted of major mechanical changes to the regular-production Corvette, but a major philosophical shift in how those changes were developed. Adding to the heft of the ZR-1 package were the world-class performance hopes and aspirations of Corvette fans inside and outside of GM.
The ZR-1 was intended to be the world’s fastest production car. This vehicle was America’s answer to high-performance and higher-priced foreign competitors such as Porsche, Ferrari, and Lamborghini. The ZR-1 was not only significantly cheaper than its rivals, but it also easily met all existing emissions, noise, and safety laws and retained day-to-day drivability. It also burned regular unleaded fuel to avoid gas-guzzler taxes.
At the heart of this symbol of American high performance was a small-block 5.7-liter V-8. The red-white-and-blue DNA of the ZR-l’s engine was not in the form of stars and stripes, but the crossed bars of the Union Jack. The LT5 of the ZR-1 had an aluminum block and heads, four overhead camshafts, 32 valves, and was designed by Lotus in England. The engines, however, were made in the United States by Mercury Marine in Stillwater, Oklahoma. GM’s Lotus engineering group was chosen because of their experience with high performance and racing lourvalve overhead cam head engines. Chevy U.S. engineers consulted with Lotus during development. As for the manufacturing site, Mercury was chosen based on the company’s modern manufacturing facilities for building aluminum marine engines, and because only 18 LT5s would be turned out in a day versus the 1,000 or so a GM assembly plant was geared to do.
During the 1980s, Chevy had experimented internally with turbocharging in its quest for the “ultimate” Corvette. Fuel consumption, reliability, or emissions were usually not up to the standards set for a car that still had to be a capable daily driver. They even went outside GM in offering a 345-horsepower twinturbo package, installed by Callaway Engineering, as an option from 1987 to 1991. Eventually, computer technology such as direct-fire, distributorless ignition systems, electronic spark control with knock sensors, and electronic three-phase, twin-injector sequential fuel injection could carry out what Chevy engineers called vehicle could be a refined road car as well as a ferocious racecar based on driver input.
The LT5’s induction system consisted of a threevalve throttle body with a small primary valve for quick response and efficient low-speed running with two larger secondaries for full-power operation. The throttle valves work in conjunction with a 16-runner tuned-length intake manifold and a set of two electronically controlled fuel injectors per cylinder. Based on various sensors feeding into the engine’s electronic brain, at 3,500 rpm (half throttle) the secondary ports become wide open. In addition, the cams associated with the larger secondary throttle ports have greater timing than those of the primary ports. This provides variable valve timing to optimize airflow and fuel delivery. A secondary benefit of this system is that it allows a power switch, located on the car’s center console to “lock out” the secondary port throttle valves, to limit operation to the primary port system. This is a handy feature that denies access to all of the King’s horses to parking-lot attendants and other less qualified drivers. Other features of the LT5 include fast burn, center plug, cloverleaf-shaped combustion chambers, and advanced oiling and cooling systems.
Although Corvette engineers were shooting at a 400-horsepower target for the LT5, no one registered disappointment that the LT5 of 1990 to 1992 produced “only” 375 horsepower at 6,000 rpm and 370 foot-pounds of torque at 4,800 rpm. What proved disappointing were the valvetrain problems that delayed the ZR-1 from debuting as a 1989 model. ZR-1 production started in August 1989 with 84 cars built in 1989, but they were classified as 1990 models.
Call them whatever year you like, but call them fast. According to Chevy, the ZR-1 sprinted to 60 miles per hour in 4.9 seconds and hustled through the quarter-mile in 13.4 seconds. Top speed was around 180 miles per hour. Motor Trend tested the ZR-1 in April 1990 and achieved a 0-to-60 time of 4.4 seconds. Their quarter-mile test figures got down to 12.8 seconds. For comparison, a Motor Trend test of the previous “ultimate” Corvette—a 1967 427, 435-horsepower Sting Ray—turned up 0 to 60 in 5.5 seconds and the quarter-mile in 13.8 seconds.
Unlike musclecars of the past, the ZR-1 was more than just a “big-engine” option package. In addition to a six-speed manual transmission, leather sport seats with power adjustment, and a Delco-Bose stereo system, the ZR-1 included the optional (for other Corvettes) FX3 Selective Ride Control that consisted of three modes (Performance, Sport, and Touring) controlled by a console- mounted switch that varied shock dampening rates depending on vehicle speed.
Another Corvette option that was standard to the ZR-1 was the Z5 1 suspension with firmer springs and anti-roll bars. The ZR-l’s biggest handling advantage came from its huge rear tires that were the widest-ever Goodyear Eagle unidirectional radials. They measured a hearty P3 15/35 ZR17 and were speed-rated to 193 miles per hour. The front tires were P275/40 ZR17. A low-tire-pressure monitoring system came standard on the ZR-1.
1990 CORVETTE ZR-1 SPECIFICATIONS
Body/Chassis – Two-door coupe body on welded-steel uniframeю
Engine – 5.7-liter aluminum DOHC, 32-valve V-8 with sequential fuel injection; 11.0:1 compression ratio.
Power Ratings – 375 horsepower @ 6,000 rpm, 370 ft-lbs torque @ 4,800 rpm.
Transmission – Six-speed manual.
Suspension – Front: Independent aluminum short/long arm, transverse monoleaf spring, stabilizer bar, electronic dampers. Rear: Five-link independent, transverse monoleaf spring, stabilizer bar, electronic dampers.
Wheels/Tires – Front: 17×9. 5-inch aluminum alloy; P275/40 ZR17, Rear: 17xll-inch aluminum alloy; P315/35 ZR17.
Brakes – Four-wheel discs, front: 13×1. 1-inch rotors, rear: 12×1. 1-inch rotors.
Curb Weight – 3,465 pounds.
Wheelbase – 96.2 inches.
Length – 177.4 inches
The wide rear tires affected the ZR-l’s appearance as much as its handling. The rear bodywork of the 1990 ZR-1 was made about 3 inches wider to cover the big radials. The ZR-1 tail also had four rectangular taillights. In 1991, this tail treatment became standard on all Corvettes, although the ZR- 1 had wider door and rear body panels to cover its 11 -inch-wide rear wheels and huge tires. In 1993, improvements were made to the LT5 valvetrain and cylinder head that aided reliability and increased horsepower beyond the magic 400 mark to 405 horsepower, but it was too late to save the ZR-1. The last ZR-1 rolled off the assembly line in April 1995. Chevrolet produced 6,939 ZR-ls, but 3,049 were built in 1990 and 2,044 the following year. From 1993 to 1995, each year’s production was only 448 units. Chevrolet celebrated the Corvette’s 40th anniversary in 1993 by offering an optional Ruby Red color scheme with anniversary logos on all models. There were 245 ZR-ls painted in this color scheme.
A lack of distinctive styling, a high price (almost double that of a standard Corvette coupe), and early engine problems were all factors in the King’s demise, but the biggest factor was just how good the basic Corvette had become. Despite the aluminum block and heads, the complex valvetrain and other components made the LT5 engine 40 pounds heavier than an LTl small-block. In 1996, an aluminum-head LT4 version of the LTl with 330 horsepower became available. Combined with the optional Grand Sport suspension and trim package, it offered similar performance to the ZR-1 for about $25,000 less. The King was dead, but anyone who owned or drove one will chant, “Long live the King.’
Corvette Grand Sport
Chevrolet focused on the future when the 1990 ZR-1 “King of the Hill” was designed, but its successor to the Corvette performance throne had an eye on the 64 past. For 1996, Chevrolet introduced the Z16 Grand Sport option package that included a brand-new 330-horsepower version of the venerable small-block V-8. The Grand Sport name may only be familiar to hard-core Corvette enthusiasts. It was applied to what was to be a limited run of 100 lightweight 1963 Sting Rays built specifically to compete against the Shelby Cobra in SCCA and European road-racing events. Production Corvettes were too heavy to be competitive with the Ford racers, so Zora Arkus-Duntov came up with a competition car that resembled a Sting Ray, but weighed about 1,900 pounds. The first three were powered by an aluminum alloy version of the small-block V-8 punched out to 377 cubic inches (6.2 liters) that generated 480 horsepower. The cars, wearing the blue-and-white livery of the Mecom-Chevrolet racing team, made an impressive debut at the Nassau, Bahamas, Speed Week in 1963. Driven by Roger Penske and Augie Pabst, two of the Grand Sports came in third and fourth in the Governor’s Cup race. The only cars to beat them to the finish line were from the prototype class. In 1964, Penske returned to the Bahamas to win the Nassau Trophy race.
Unfortunately, only two more cars were built before the GM management ban on racing cut short the Grand Sport’s racing career. One of the final two cars has had Chevy race fans speculating what might have been as it was powered by a 427-ci engine. The modern Grand Sport pays homage to its forefathers with an Admiral Blue paint job bearing Arctic White stripes. The Mecom team used twin red hash marks on the left front fender to differentiate the two otherwise-identical racecars from each other.
Like its racing namesake, the 1996 Grand Sport also relies on a powerful small-block that uses aluminum in its makeup. The LT4 had special highcompression (10.8:1) aluminum heads. The base 1996 LT1 had a compression ratio of 10.4:1 and made 300 horsepower. In addition to the highercompression heads, the LT4 utilized Crane roller rockers, a recontoured camshaft, a performance crankshaft, and new fuel injectors to make 330 horsepower at 5,800 rpm. Fhe’redline was 6,300 rpm as opposed to the LTl’s 5,700-rpm redline, so an 8,000 rpm tachometer replaced the standard 6,000-rpm gauge. According to Chevy, this was good enough to go 0 to 60 in 4.7 seconds and travel a quarter-mile in 13.3 seconds.
Other pieces of the Grand Sport package, unlike the ZR-1, were available on convertibles as well as coupes, and included the five-spoke, 17-inch aluminum wheels (previously used on the ZR-1), which were painted black and had black brake calipers with silver “Corvette” lettering. Coupes received the ZR-1 front and rear tire combination of P275/40 ZR17, P31 5/35. ZR17 Goodyears but had rear fender flares in lieu of the wider rear panels used on the ZR-1. Convertibles eschewed the fender flares and rode on tires that measured P255/45 ZR17 up front and P285/40 ZR17 in the rear. Coupes also received 1 1-inch-wide rear wheels. Perforated-surface sport seats with power adjustment and “Grand Sport” lettering were also part of the Grand Sport option. Buyers could choose fromeither black or a red-and-black combination.
Corvettes with the Grand Sport option had a separate serial number sequence, 1G1YY2251T5600001 through 5601000. Of the 1,000 cars built, 810 were coupes and 190 were convertibles. The Grand Sport option (RPO Z16) added $3,250 to the $37,225 base price of a coupe, and added $2,880 to the $45,060 price tag of a convertible. Because of the added power of the LT4 engine, all Grand Sports were equipped with a six-speed manual transmission. Grand Sport handling was enhanced by the F45 Selective Real Time Damping package that replaced the FX3 Selective Ride control of the ZR-1. This new system relied on advanced wheel travel sensors that respond to changes in the road every 10 to 15 milliseconds and adjust each shock individually.
The Grand Sport emulated its historic counterpart in terms of lifespan as well. Chevrolet was cooking up an all-new fifth-generation Corvette for 1997 and the Grand Sport option was not on the C5 menu. (The 1996 Corvette Grand Sport Specifications, except for the engine, were the same as those presented for the ZR-1.)
«Modern American Muscle»
Patrick Paternie and Dan Lyons