Corvette C4 Coupé (1983–1990)
|Class :||Sports car|
|Body versions :||Coupé , convertible|
Petrol engines :
|Wheelbase :||2440 mm|
|Empty weight :||1530 kg|
|Previous model||Corvette C3|
The Corvette C4 was built from spring 1983 to the end of 1996 as the fourth generation of the Corvette . A convertible of the C4 was introduced in early 1986.
This model with an even slimmer body than its predecessor Corvette C3 and an extremely flat windscreen inclined at 64 degrees as well as a completely new chassis set new standards in the sports car sector in terms of handling properties and performance. At that time, for example, no other series-production vehicle achieved higher lateral acceleration when cornering.
In the spring of 1983, after fifteen years of production, the C3 was presented with the C4, a revised model. However, the new Corvette did not reach dealers until the 1984 model year. The comparatively late start of series production in March 1983 meant that Chevrolet General Manager Robert C. Stempel decided to start the new generation with the 1984 model year.
In order to further improve handling and weight distribution, the C4 developers moved the engine further towards the center of the vehicle towards the bulkhead. The wider cardan tunnel gives the body more rigidity. ABS (from 1986) and traction control (from 1992) increased active safety . A new six-speed manual transmission from ZF (1989) reduces fuel consumption. After the cubic capacity and horsepower records of the previous generation, only V8 engines with a displacement of 5.7 liters were used in the C4. From 1985, the new L98 engine with modern fuel injection from Bosch including air mass measurement was installed. Despite the increase in output from 205 to 230 hp, this reduces consumption by 11 percent.
The lines were rather reserved and the engines were only moderately powerful by previous Corvette standards. Against strong Ferrari or Porsche , the Corvette ZR-1, which came on the market in early 1990, could only score again. Another record in the history of high-performance sports cars was set in 1992 with a white convertible (convertible): the one millionth Corvette rolled off the assembly line, matching the opening of the Corvette American Hall of Fame in Cooperstown, New York .
The Corvette C4 was built from March 1983 to the end of 1996 with a number of 358,180 units, including 74,651 convertibles. At the beginning of 1997, the successor Corvette C5 appeared after 13 years of construction.
Body and interior
For the first time, a conventional recessed engine hood was dispensed with. Instead, there was a so-called clamshell hood , which, together with the fenders, extended to the surrounding decorative strips on the sides and could therefore be opened as the entire front. Thus almost the entire engine compartment was released when the bonnet was opened.
The fourth edition of the sports car was given clear, functional lines by the designer Jerry Palmer in the style of the 80s. This straightforwardness proved itself particularly in the wind tunnel: the c w value of 0.34 is among the best aerodynamic results of that period, a merit even at 64 degrees standing very flat windshield. The dome-shaped rear window is the largest area of glass that an American car had until then.
Overall, the Corvette C4 was slightly smaller than its curvy predecessor C3: Compared to the last C3 version from 1982, the C4 shrank by 16 cm in length to 4.48 meters, but grew in width by 5 cm to 1.80 meters . With a height of only 1.19 meters, however, it crouches down on the street like none of its ancestors.
After a break of exactly ten years, a convertible was available again from the beginning of 1986. The hood was located under a flat flap. Although the open-top Corvette cost more than the coupé for the first time (around $ 5,000), in 1987, for example, every third buyer opted for the convertible. Like the C3, the C4 also had a removable Targa roof . Now, however, it consisted of a whole piece instead of two halves of the roof (T-top) as was the case with its predecessor. With the predecessor, a web remained in the middle of the roof after the two halves of the roof had been removed, while this central web was omitted for the first time on the C4.
The pointerless instruments in the interior were also completely new. Analog displays have been dispensed with in the cockpit; LCD displays have been used instead . The entire cockpit was designed in a rather futuristic and innovative way, which was not to everyone's taste.
Chassis / running gear
The suspension and chassis of the C3 were replaced, the Corvette C4 now got a modern system with independent suspension and five-link rear axle . The transverse leaf spring front and rear, albeit made of lightweight plastic, was rather unusual. The suspension was made of light metal.
The developers of the Corvette relied on consistent lightweight construction for the C4. Chassis components such as the upper and lower front wishbones, the bracket for the alternator and parts of the power steering and the air conditioning compressor are made of aluminum on the C4 models, and the drive shaft is also made of forged light metal. The bonnet is a sandwich composite part . The radiator has aluminum ribs and a plastic expansion tank. From 1985, plastic is also used for the brake booster housing. From 1986, aluminum was used in the cylinder heads.
We worked with Goodyear to develop the new generation of tires . The original idea of adding a “Corvette” lettering to the tires was rejected shortly before production started. In the course of this collaboration, the "Gatorback" tires were created which, in conjunction with the chassis designed for the highest speeds, enabled a lateral acceleration of 1.01 g (with a special “Z51” chassis setup, roadworthy only 0.90 g), which has not previously been achieved with any production car.
However, driving comfort suffered as a result of these measures. The 1984 model year Corvette obviously struggled to convince testers and critics of the qualities of its almost race-ready chassis. The driving comfort was only low, regardless of whether with the normal chassis or the “Z51” option, which brought even harder suspension, but made the car very manageable.
As early as 1985, the C4 received a revised chassis that solved the problems. The spring rate of the series Corvette has now been reduced to half that of the previous version. The same applied to the “Z51” option. From 1988, 17-inch wheels could be ordered with the options “Z51” and “Z52”, with which the C4 was able to compete with the European competition and, thanks to its better price-performance ratio, was able to prevail in many cases.
Also from 1985, the L83 engine with Crossfire injection system , taken over from the C3, was replaced by the new L98 engine with TPI ( Tuned Port Injection ) manifold injection . The new engine had more power and lower consumption. The power was last at 180 kW (245 hp) at 4000 min -1 and a maximum torque of 448 Nm at 3200 min -1 .
In 1992 the new LT1 engine replaced the L98, which had become outdated over the years. At constant consumption of more compact be built LT1 brought about 20% more power, maximum torque was indeed about the same as the L98, but was only 800 min -1 later. Thus, the performance of this engine were now at 225 kW (306 hp) at 5200 min -1 to a maximum torque of 451 Nm at 4000 min -1 . Only this LT1 engine helped the normal Corvette C4 achieve respectable performance compared to other sports cars.
In 1996, the last year of the C4, the output and rated speed were increased again with the LT4 engine. The LT4 has a higher densification than the LT1 and provides 243 kW (330 hp) at 5800 min -1 . However, the LT4 has not completely replaced the LT1, because the LT1 was still installed in all models with an automatic transmission, while the more powerful and higher-revving LT4 was used in all manual Corvettes, including the special Grand Sport model .
In 1990 the interior of the C4 was thoroughly renovated. There was a new driver-oriented cockpit. Speed, on-board voltage, temperatures and oil pressure were again displayed with analog instruments instead of LC displays. However, the speed, fuel level and the functions of the on-board computer were still displayed digitally.
For the 1991 model year, an external facelift followed in the summer of 1990, in which the front and rear were significantly changed. The nose of the vehicle became more rounded and the lamp units seemed to be drawn around the corners. The look of the new stern was based on the ZR-1, which appeared in 1989. The rear lights were no longer round, but strongly rounded squares.
In 1988, for the 35th anniversary of the Corvette, the C4 launched a “35th Anniversary” special model. This model was only available as a coupé with full equipment and in the color white with aluminum wheels also painted white. The roll bar, usually painted in the same color as the car, was painted black. The most striking features were the seats, which were completely upholstered in white leather, and the white two-spoke steering wheel. A total of 2050 pieces of this model were built, each with a numbered badge. 180 of these vehicles were equipped with a manual transmission.
Indianapolis 500 Pace Car Replica
In 1995 a Corvette was used as a pace car for the third time since 1911 at the prestigious Indianapolis 500 race . In the same year, Chevrolet launched a replica of this pace car as a special model. They were fully equipped convertibles with automatic transmission, two-tone paintwork in white and purple and a white hood. Each copy was accompanied by a striking sticker set, which was drawn around the front and over the entire sides of the vehicle. The interior was black with two-tone seats in black and purple. The logo of the 79th Indianapolis 500 was embroidered on the headrests . 527 Indianapolis 500 pace car replicas were produced.
As in 1982 when we said goodbye to the Corvette C3, there was also a non-limited special model called the Collector Edition last year . Perhaps the most striking feature was the silver-metallic paintwork, because this color was available for the first time since 1988 on a Corvette and exclusively for the Collector Edition . The Collector Edition models also had special emblems on the front, rear and wheel hub caps, silver-painted 17-inch 5-star aluminum wheels, black-painted brake calipers with Corvette lettering and gray sports seats with embroidered Collector Edition lettering. 5412 units were built, 1381 of which were convertibles.
In 1996, another Corvette legend was revived: the Z16 option was called Grand Sport and was only delivered in Admiral Blue with a white stripe in the middle across the entire vehicle and other smaller special details. The engine used was the LT-4, which had an output of 243 kW (330 hp) and was only delivered with a 6-speed manual transmission. The leather interior of the Grand Sport Corvette could only be ordered in black or a combination of red and black. The Grand Sport Corvette got its own VIN number series ( Vehicle Identification Number ) and the number of this vehicle series was limited to 1000 units, of which 810 coupes were produced and 190 convertibles.
In 1989, GM presented its own high-performance variant of the fourth Corvette generation to the public, which was sold as the ZR-1 from 1990 onwards. The ZR-1, quickly referred to by the press as the " King of the Hill ", was the top model of the Corvette at the time and with its completely redesigned DOHC V8 aluminum engine was to compete against the European sports car competition. The ZR-1 can be recognized by its tail that is 11 cm wider than the normal C4. The widening is required for the very wide tires on the 17-inch rims (315/35 ZR 17). For the first time in a Corvette, the "Selective Drive Control" chassis with adjustable damping from the interior was installed.
In 1990, the new LT5 engine appeared in the Corvette C4 ZR-1. The ZR-1 was propelled by a new development jointly developed by Lotus and Chevrolet. The LT5 engine was based on a design by Lotus (then part of the GM group). On the basis of this design, the LT5 was further developed at Chevrolet and, above all, adapted to the Corvette by increasing the displacement. The LT5 engine was produced in the United States by Mercury Marine of Stillwater. This machine with 32 valves was reserved exclusively for the ZR-1. The power was initially 280 kW (385 hp) at 6000 min -1 , the maximum torque was 502 Nm at 4800 min -1 . With the powerful LT5 engine, the ZR-1 reached a new top performance for Corvette models. From model year 1993, the performance is now 302 kW (411 hp) at 5800 min -1 and 522 Nm at 4800 min -1 increased.
For the conditions at the time, the performance was quite in the range of super sports cars . The acceleration from 0 to 100 km / h was specified by the factory as 4.4 seconds. The factory specification for the top speed was 290 km / h. In tests, the vehicle reached top speeds of over 300 km / h and was able to record several world speed records in 1990: for example, the FIA 24-hour record with an average speed of 283 km / h over a total distance of 6793 kilometers. Until the Corvette C5 Z06 appeared, the ZR-1 was the fastest and most powerful Corvette ever built.
In the last year of production of the C4 in 1996, the ZR-1 was no longer offered. It was produced until 1995 and a total of 6939 pieces were produced. The model was replaced by the limited “Grand Sport” version.
In 1987 a new option called "B2K" was offered. Reeves Callaway installed two turbochargers in the Corvette, which gave it a top speed of over 300 km / h. The earlier B2K models had an output of 257 kW (350 PS) and 610 Nm. Later versions developed 336 kW (457 hp) and 831 Nm. The B2K option could be ordered until 1991, but was initially only available in the USA. Callaway later offered the Corvette C4 B2K on the German market. This then developed 409 hp at 4500 min −1 and had a torque of 780 Nm at 3000 min −1 .
Callaway doesn't just tune the Corvette engines, but builds on a special version of the small-block V8, the crankshaft bearings of which are bolted with four instead of two bolts. There were also a forged crankshaft and the B2K version Cosworth pistons and two IHI - turbochargers with intercoolers , which the machine bar put pressure below 0.8. The biturbo Corvette did not need high revs to develop its power. Thanks to a differential lock, the car also got the power well on the road.
Callaway also built an 880 hp version of the Corvette in 1988 called the " Sledgehammer " (blacksmith hammer / sledge hammer) , which on October 19, 1989 - driven by John Lingenfelter - had a top speed of 254.76 mph (approx. 410 km / h ) reached. The test was conducted in Columbus , Ohio on the Technical Research Center (TRC) track with a modified '88 Callaway Sledgehammer (# 51).
The whole car was trimmed for speed and straight-line stability, but still offers comfort. Among the numerous changes to the engine and vehicle compared to a standard Corvette are two Turbonetics T04B turbochargers, which provide 1.5 bar boost pressure. The Sledgehammer's transmission is a Doug Nash design for NASCAR cars. The tires were made by Goodyear especially for this car and are mounted on Dynamag rims.
This Callaway Sledgehammer version was never an official GM option. It was officially announced that the Sledgehammer was a test vehicle for the tire industry, with which the possibilities of conventional road tires should be tested.
Until 2007, the Sledgehammer Corvette was the fastest road-legal land vehicle in the world with a top speed of 409.9 km / h. Not even the Bugatti Veyron , released in 2005, was faster. This record was only broken on September 17, 2007 by the SSC Ultimate Aero TT with 412 km / h. The Corvette Sledgehammer was only registered in the USA.