GM-EFI’S Guide to the C4 Corvette

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Reviewing the History of the C4 Corvette 

Since its 1953 debut and subsequent generations, the launch of a new Corvette has always garnered high anticipation as GM’s showcase for new automotive innovations. That said, by 1982 the C3’s swoopy styling had been around since the 1965 “Mako Shark II” concept and it’s platform for almost as long- however resistant to change the Corvette nation might be, a change was definitely overdue.

For 1984 the long-awaited fourth iteration of America’s sports car appeared and was touted as a leap forward in style, technology, luxury and performance, lining the Corvette up against the worlds best in every category.

Moving forward with our chronicles of late-model GM performance machines, we take a closer look at the C4 Chevy Corvette 1984-’96, it’s features/options, performance stats, special versions, production totals and it’s place in the great monikers 60+ year history.

A LONG TIME COMING: C4 BUILD-UP

By the time the C3 bowed-out and parked itself in the hallowed halls of Corvette history, it’s run had spanned three decades, fifteen model years, and more units sold than both its predecessors combined.

By the time the ’82 Vette bowed, it was a rather dated and archaic design, tracing its production roots back to the 1968 model year. A Collector’s Edition example is shown.

Intended for a 1982 release, development on the C4 actually began way back in 1977. However, despite the best efforts of then Chief Corvette Engineer Dave McLellan, GM’s thumbs-up didn’t happen until April 1980, pushing the C4’s debut to 1983.

Also contributing to the C4’s long incubation was the switch from the St. Louis, Missouri plant to the new, larger, modern facility in Bowling Green, Kentucky for all Corvette production. This change and retooling, along with continuing R&D on the C4 suggested a 1983 1/2 model, but with Chevy General Manager Robert Stempel deciding to skip 1983 entirely, the C4 was slated as a 1984 model.

Although 43 Corvettes, comprising of ten prototypes and 33 pilot cars were built and serial-numbered for ‘83, none were sold to the public, but were used for testing and presentation to the automotive press. Supposedly setting the General back $500k each, all 1983 Vettes met with the crusher accept one that later surfaced at the National Corvette Museum in Bowling Green.

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With only a handful built for pre-production purposes, only one remains: the 1983 Corvette!

 

During the C4’s conceptual stage of development, the father of the Corvette, Zora Arkus-Duntov, once again proposed the idea of a mid-engine platform. Having pioneered the great car since its earliest days, insisting on the Vette being only V8-powered, Duntov’s mid-engine dream would remain just that, as GM execs refused and stayed the front-engine/rear-drive course. With the configuration decided, McLellan would make sure the new C4 was otherwise state of the art in every way, introducing many upcoming features on the outgoing C3.

Weight saving was a major priority for the C4 and starting in 1980, the outgoing C3 was equipped with aluminum pieces such as an upgraded rear diff housing and frame member mounts, which reduced paunch by 300-lbs. Also on the way and first appearing on the 1981 C3, were fiberglass mono-leaf springs for the suspension, replacing the heavy steel units.

Acting as a final farewell to the C3 was the 1982 Collector Edition Corvette. Equipped with many upcoming C4 features including the Corss-Fire injected engine, drivetrain and a Vette first, opening rear hatchback glass window, 6,759 Collector Edition coupes were built to end the line.

After first stunning the press at Riverside International Raceway in December 1982, production C4s began rolling off the Bowling Green assembly line on Jan 6, 1983, finding there way to dealerships nationwide by springtime. Following the old adage “good things come to those who wait” the C4 Corvette was finally cruising American streets and would be for quite some time.

SO FRESH AND SO CLEAN: 1984

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“Performance, luxury, comfort — the new Corvette is a paragon of all things which the only true American sports car has come to stand for,” declared Corvette Chief Engineer, Dave McLellan, on the eve of the C4’s public debut. Definitely a heady statement for any car, but then again, the Vette isn’t just any car.

The C4 was built via “uniframe” construction, with fiberglass and (SMC) sheet molded composite panels mounted onto a one-piece-welded steel skeleton, then to a perimeter frame, all lowered onto the drivetrain.

Lower and wider than it’s predecessor, the C4’s engine was placed further back, married to the transmission and connected to the rear end differential by an aluminum C-section beam creating a rigid “backbone” of structure. The transmission tunnel was widened to allow for exhaust routing and the front/rear wheel tracks were pushed out. The result was a lower center of gravity and a Corvette with vastly improved handling capabilities.

Depicting a wind-cutting wedge-shape, the C4’s windshield was raked to 64-degrees, the most in Detroit history, creating a slippery 0.34 drag coefficient.

1989-chevrolet-corvette-convertible-interior-photo-525985-s-1280x782Gone were T-top roof panels, with all ’84 Corvettes fitted with a removable glass Targa-style roof. The lift-up opening glass hatchback window first seen on the ’82 Collector Edition, at the time, the largest piece of compound glass fitted to an American car, was integral to the C4s design.

With the new Targa top lacking any structural tie-in to the windshield frame, the C4’s side frame rails were raised to provide increased chassis rigidity. This made for very tall doorsills creating a deep cockpit floor and requiring palates-like agility for entry/exit.

As the hatchback finally allowed exterior access to the rear storage space, rather than ruining your chiropractor’s work by contorting through the interior, the fresh design also featured a hinged “clamshell” hood that lifted perpendicular to the car for unfettered engine/front suspension access.

Born from the mind of John Cafaro, then a newcomer to the Chevy 3 Design Studio, the C4’s forward-thinking design featured a parting line running the full surround of the car, dividing all panels into upper/lower halves. Unique to the C4, this stylistic/functional gesture provided ease of construction and deleted the often-visible bonding seams on previous models. A special rubber molding fit like a glove, right into the separating line and also displayed engine description writing.

Power was carried-over from 1982 in the form of the L83 350ci V8 with “Cross Fire Injection” now making 205hp — up from ‘82’s 200hp rating. Although not true electronic fuel-injection, but two computer-controlled Rochester throttle-body fuel injectors mounted on an aluminum cross- ram intake manifold, “Cross Fire” worked in conjunction with the (ECM) electronic control module to regulate ignition timing, air/fuel mixture, idle speed etc., providing more instant throttle response.

Unlike 1982, when the L83 was mated only to the new Turbo Hydra-matic 700-R4 four-speed automatic transmission, ’84 Corvettes got an available Doug Nash four-speed manual as well. Designated the “4+3”, the top three gears employed computer-activated overdrive operation via console switch for better fuel efficiency. Also new was the C4’s radiator that utilized aluminum cooling fins, lightweight plastic reservoirs and was thermostatically activated only when needed under 35mph.

Still wanting in the horsepower department, the C4’s chassis/suspension was its strong point, providing a new level of Corvette handling prowess. Up front, the 3088-lb. Vette employed independent short/long arm (SLA) suspension, with a transverse fiberglass leaf spring, (in place of the C3’s coils springs), a stabilizer bar and tubular shocks.

In back was a five-link set-up (in place of the C3’s three-link), with upper/lower control arms, tie rods, half shafts, transverse fiberglass leaf spring, stabilizer bar and tubular shocks. The new fiberglass leaf springs in front and rear, acted as both a coil spring and anti-sway bar in one lightweight space-saving piece.

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A new rack-and-pinion steering system provided enhanced control, while a set of wide staggered-size wheels, (16×8.5-inches in front and 16×9.5-inches out back) made the C4 feel as agile as it looked. Bringing the modern sports car to a halt were 4-wheel power disc brakes with new lightweight aluminum calipers from Girlock of Australia.

Already acclaimed as the best handling car in America in base suspension, with Motor Trend Magazine calling it “World Class,” the C4 could be brought to an even higher level by ordering the (Z51) Performance Handling Package. For an additional $600 RPO Z51 included:

  • Heavy-duty front/rear springs
  • Special shock absorbers
  • Special stabilizer bar/stiffer bushings
  • Faster ratio steering
  • Engine oil cooler
  • Extra radiator fan (“pusher” for increased air flow)

It should be noted that early C4 plans called-for 15-inch wheels as standard equipment and the 16’s as part of the optional Z51 package. With the 16-inch wheels now standard, the Corvette’s base price increased and Z51’s cost decreased to reflect this. From 1984-’87, depending on vendor and stock availability, base C4’s could be fitted with 16×8.5-inch wheels in front or all around. However, only 1984 C4s had staggered fitment 16×8.5-front/16×9.5-rear. With 25,995 C4 owners opting for the Z51 package, it was obvious that performance was still primary.

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Modern technology continued inside, where a fully digital gauge cluster with liquid-crystal graphics illuminated the cockpit like that of an F-14 fighter plane. The C4’s luxury component included many standard features including, power windows/door locks, base cloth seats, AM/FM stereo and body-color removable Targa-top.

Options available were:

  • Leather base-style seats
  • Power drivers seat
  • Cloth sport-style seats with power-adjustable side bolsters and inflatable lumbar support
  • Transparent roof panel
  • AM/FM stereo/Cassette
  • Delco-Bose premium stereo system

First year C4 Vettes could be dipped in no less than 11 available colors and 3 two-tone choices including:

  • White
  • Bright Silver Metallic
  • Medium Gray Metallic
  • Black
  • Light Blue Metallic
  • Medium Blue Metallic
  • Yellow
  • Gold Metallic
  • Light Bronze Metallic
  • Dark Bronze Metallic
  • Bright Red
  • Silver/Medium Gray
  • Light Blue/Medium Blue
  • Light Bronze/Dark Bronze

Production Totals:

As a result of the long lead-in period and early 1983 release, the ’84 C4 Corvette enjoyed an extended model year production equating to 51,547 Corvette coupes built, second only to 1979’s sales record number of 53,807.

Off to a great start, the C4 was proving to be worth the wait, and with more power on the way, its long reign had only just begun.

FOLLOW-THROUGH: 1985

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After a long lead-up, the C4 Corvette’s first at bat was definitely a hit that loaded the bases, with more of the same on deck for year two. Despite a valiant attempt at increased technology, the “Crossfire” injection L83’s day was over, and the new 350ci L98 V8 had arrived. Now fueled by a true EFI system, the (TPI) tuned-port injected L98 was good for 230hp/330lb-ft, up from the L83’s 205hp/290lb-ft numbers.

The new TPI system included a front-mounted air-cleaner assembly feeding a throttle body with a mass airflow sensor into a large aluminum intake plenum, flowing down and into the heads via eight “tuned” tubular “elephant trunk” intake runners. Two high-pressure fuel rails running along each set of intake ports supplied gas to eight individual Bosch injectors. The L98 wasn’t just more powerful but provided an 11% increase in fuel-efficiency.L98

Both Car and Driver and Motor Trend Magazine were ecstatic with the L98-powered Vette and touted its 6.2-second 0-60mph time 14.5-second 1/4-mile and ability to reach 150mph for the first time in over a decade. The C4 also tied Porsche in cornering prowess, recording .84 Gs on the skidpad.

Although acclaimed for it’s excellent handling abilities, the C4’s new-tech suspension had Vette owners a little sore in the rump, as multiple complaints surfaced about the rough ride. To remedy this, the transverse leaf springs were loosened a bit, by 26% in front and 25% in back.

Intended to be aggressive, the Z51 package also received a kinder, gentler spring rate, slackened by 16% in front and 25% in back. To make up for the softer springs, the Z51 package added thicker heavy-duty stabilizer bars.

Other improvements and upgrades for 1985 included:

  • Upgraded brake master cylinder with larger bore, now made of plastic (the first in an American car), 30%-lighter and corrosion-resistant
  • Four-speed manual cars now get new heavy-duty 8.5-inch ring differential with 3.07:1 gears. Automatics came with 2.73’s or 3.07s when ordering RPO G92 Performance Axle Ratio
  • Overdrive console switch on manual cars now relocated to the gearshift knob
  • Wheel balance weights were changed from clip-on outer rim-style to inner wheel adhesive type. Mainly for aesthetics, Chevrolet claimed better balancing with the weights closer to the wheels depth of center.
  • A full-length oil pan reinforcement was added to provide for a better overall compression seal
  • Modification of distributor to prevent spark ignition of external fuel vapors
  • Electronic gauges were revised, with clearer graphics, less colorful speedometer/tachometer read-outs and larger liquid-crystal digits for the center display
  • Sport seat option RPO AQ9 now available in leather, (midyear)
  • Stronger sun screening for RPO CC3 transparent roof panel
  • Map strap added to driver’s sun shade
  • Z51 Delco-Bilstein shocks and heavy-duty cooling available as RPO FG3/VO8 without Z51 option
  • Z51-equipped Corvettes now got 16×9.5-inch wheels all around, instead of 16×8-inch in front

Depicting a normal build period, total production for 1985 was 39,729 units. The C4 Corvette was definitely off to a good start and with each year it would get better.

SKY’S THE LIMIT: 1986

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The leading front-page story for the 1986 Corvette was the return of a convertible model not seen since 1975. Adding 5-grand to the price of a coupe, the topless Vette now fetched $32k-dollars — big money for 1986. Convertibles came with a standard black soft top, with white or saddle available.

Chosen as the second Vette to pace the Indy 500, the yellow convertible driven by retired Air Force General/WWII fighter ace and the first man to break the sound barrier-Chuck Yeager, needed no mods to lead the field.

All 1986 Corvette convertibles, regardless of color, were designated as pace car replicas and came with console I.D.s and “70th Indianapolis 500” commemorative decals to be mounted/or not by the owner. Of the 7,315 convertibles built for ’86 732 were ordered in race day yellow.

Becoming standard equipment in ’86 were Bosch 4-wheel anti-lock brakes (ABS). The system included rotational sensors at each wheel-transferring info to an ECU. Brake line pressure was then automatically adjusted to provide stopping power devoid of lock up or steering pull.

Lightweight aluminum cylinder heads would arrive in ’86, but initial problematic casting issues, made for mid-model year applications only. Corresponding with midyear production, all convertibles got the new heads, as did an estimated 8,594 coupes. Aluminum head L98s got a 5-horse bump in power, now rated at 235hp.

For 1986, federal requirements mandated the installation of (CHMS) center high-mount stoplights. Mounting position for coupes was on the roof bar above the rear hatch glass and integrated into the rear fascia above the “Corvette” nameplate on drop tops.

Nineteen-eighty six would also see the introduction of a new vehicle anti-theft system (VATS) later known as PassKey I, with a special computer pellet-embedded ignition key. Measured electrical resistance within the ignition lock cylinder allowed the car to start. Early examples had 15 security variations, unfortunately not enough to hamper car thieves of the day.

Other 1986 notables include:

  • Wheel caster changed from 3.8-degrees to 6.0-degrees to improve centering and decrease wander
  • The angle of the electronic digital gauge cluster was revised to reduce glare, improving daytime visibility. A “low coolant” and “anti- lock” display were added.
  • Upshift indicator light added to both automatic/manual transmission models, intended to help increase fuel economy
  • Wheel center section now a non-painted natural finish, instead of black on 1984-’85 cars. Radial slots remained black-painted
  • Z51 Performance Handling Package (coupes only) now included RPO V01, heavy-duty radiator
  • RPO C2L Dual Removable Roof Panels, body color/tinted optional on coupes for $895

On the color chart, after a 1985 leave of absence, and then showcased on the Indy 500 pace car, Yellow was back as a 1986 color; with Medium Brown Metallic, Copper Metallic and three new two-tones joining the pallet, Gray/Black, White/Silver, Silver Beige/Medium Brown. The blues and Bronze two-tones were gone however.

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Image: Corvette Magazine

Malcolm Konner Commemorative Edition:

After passing-on in 1983, and following a suggestion from his son, Chevrolet built fifty special edition 1986 Corvettes honoring the founder of New Jersey based Malcolm Konner Chevy, one of the nations top Corvette dealers for decades.

Designated as (RPO) 4001ZA and costing $500, all Malcolm Konner C4s wore a special two-tone paint scheme, Silver Beige/Black known as code “spec”. All were coupe versions with Graphite leather, 20 being manuals and 30 automatics. Twenty of the special Vettes had the Z51 package, split evenly between the sticks/autos.

One is rumored to have been the first C4 Corvette to receive a Callaway twin-turbo conversion, not readily available until the following year. Super rare, the Malcolm Konner Vettes are highly sought as some of the most collectible C4s.

1986 Corvette Indy:

In 1985, prior to GM’s acquisition of British-based automaker Lotus the following year, Chevrolet’s advanced engineering team and Corvette division began joint development with the “James Bond” of automakers on a highly-advanced concept car. Showcasing new technologies and the engineering expertise of both teams, the first conceptual machine called the Corvette Indy was displayed at the Detroit Auto show in January 1986.

Purely a non-drivable show car, aptly nicknamed the “pushmobile”, the Corvette Indy took it’s name from the transversely-mounted 2.65-litre Ilmore twin-turbo Indy car engine, fitted behind it’s fighter plane-esque cockpit.

The Corvette Indy concept displayed high-tech features that were on the way, including drive-by-wire throttle control, all-wheel drive with traction control, four-wheel steering, anti-lock brakes, a Lotus-developed computer-controlled hydraulic active suspension system and a monocoque chassis with a Kevlar/carbon fiber backbone like that within the 1997 C5 Corvette.

Although many felt that Zora Arkus Duntov’s dream of a Ferrari-like mid-engine Corvette was finally on the horizon, this was not the case. The Corvette Indy did however give an advanced look at things to come, like it’s more finished sibling the 1990 CERV III and the soon to be anointed king of all Vettes, 1990 ZR1.

Total production for 1986 equaled 35,109 units of which a fifth (7,315) were convertibles.

The C4 continued to sell well while serving as a great ambassador for GM’s emerging technologies- and more was yet to come.

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REFINEMENT: 1987

Changes for 1987 were few but significant, offering more performance, better road manners and a Corvette first-factory-sponsored special-manufacturer high-performance RPO. Appearance-wise, the ’87 C4 was unchanged, save for the wheels, now with Argent Gray-painted center cap/radial slots, replacing the natural finish centers with black-painted slots on ’86 models.

As a pleasurable consequence of newly installed friction-reducing roller lifters, ’87 Corvettes got a 5-horse bump to 240hp, up from the aluminum head-equipped ’86 L98 engines 235hp-for 1987 all Corvettes had the new heads.

Now available on stick-shift Corvette coupes only, the already hard-core and hard-riding Z51 package got even more serious with the edition of a finned power-steering cooler and convertible-sourced structural reinforcing for the front of the car.

Playing on the popularity of the Z51 package and its back pain-inducing reputation, RPO Z52 Sport Handling Package was introduced for ’87, offering all of the Z51 goodies minus the stiff springs and retaining the base Corvette’s softer springs instead. The Z52 package was available for both coupes/convertibles with manual/automatic transmissions.

The real numbers show the result of the more comfortable ride combined with the performance components, with 12,662 Z52-equipped Corvettes ordered, as compared to 1,596 Z51 cars.

Making a brief appearance in 1987 was a low-tire-pressure indicator RPO UJ6. The new system suffered from false signaling problems, where UJ6-equipped Corvettes could trigger each other’s alarms when in close proximity. Although 46 were built for ’87, the RPO was discontinued and revamped for a 1989 return.

Other revisions and upgrades for 1987 include:

  • RPO C68 electronic AC control now available on convertibles models, (only on coupes for ’86)
  • The overdrive-engaged light was moved from the 1984-’86 center dash location to within the digital tachometer display
  • New convenience options included a drivers side illuminated vanity mirror (D74), passenger side power seat (AC1) and dual remote heated mirrors now available on convertibles (DL8), with rear window defogger (Z68) on coupes

Callaway Twin-Turbo:

With aspirations of becoming a professional race driver curtailed by the lack of necessary funds to get started, Reeves Callaway began his automotive career instructing at the famous Bob Bondurant racing school. By the mid-‘70s, the newly released BMW 3-series was the schools weapon of choice giving Reeves plenty of seat time to learn its strengths and weaknesses. After swiping one of the little “Kraut” mobiles and bringing it to his Old Lyme Connecticut shop for some power tuning, his first prototype turbocharger system was born.

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Callaway displayed the new system to Car and Driver journalist Don Sherman and allowed him a spirited drive as well. After a shinning write-up and suggestion to build turbo kits for the Bimmer guys, Callaway Cars, Inc was formed in 1977.

For the better part of the next decade, Callaway turbo kits were developed for Germany’s finest including Audi, BMW, Mercedes Benz, Porsche and Volkswagen.

From 1983-‘86 Italian carmaker Alpha Romeo sought the services of Callaway Cars to produce up-gunned versions of their 2.5-liter GTV-6 coupe. The result was a twin-turbocharged iteration with suspension upgrades and big brakes. The Alpha’s superior performance caught the eye of then Corvette Chief Engineer Dave McLellan, leading to what would become Callaway’s real claim to fame.

As a definite nod to Callaway’s high-end systems, the Callaway Twin-Turbo engine package became the first and only factory ordered non-GM performance upgrade in Corvette history.90-Callaway-B2K_Corvette-DV-11-GC_e09

By checking RPO B2K and coughing-up an additional $20-grand, your C4 Corvette would leave the Bowling Green assembly line and travel to Callaway’s Old Lyme Connecticut facility to receive it’s modifications, then back to the dealership for delivery.

For 1987, the Twin-Turbo’s performance numbers were 345hp/465lb-ft and capable of a hair under 178mph top speed- Well within range of Italy’s finest stallions and all covered by GM’s 12mos/12,000 mile standard warranty of the day. The first four Callaway Vettes had LF5 truck-sourced short blocks with the rest receiving re-worked production L98s.

Along with the twin turbochargers, improved pistons and fuel delivery system, most ’87 Callaway TTs had a distinctive hood with dual contoured air ”scoops.” For 1987, 188 Callaway Twin-Turbos were built comprising 123 coupes and 67 convertibles, all had manual transmissions.

With the C4 Still selling well, the coming model year would see more improvements and a special birthday edition. Total C4 production for ’87 was 30,632 with a third (10,625) being topless.

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TRIPLE WHITE AND EVERYTHING NICE: 1988

Celebrating thirty-five years at the helm as America’s sports car, Chevy rolled out 2050 35th-Anniversary Corvettes for 1988.

Designated as RPO Z01 and available only on coupes, the “Triple White” Vettes as they’re known, wore white exterior paint, had white leather interiors, (including steering wheel) and unique white-painted 17×9.5-inch 12-slot wheels with 275/40ZR17 tires. The rolling stock was the new standard wheel for the Z51/Z52 packages.

Not cheap at $4,795, the Z01 35th-Anniversary Special Edition Package also included:

  • Black-painted roof bar with Blue tinted removable roof panel
  • Z52 Sport Handling Package
  • Console-mounted anniversary plaque, unique commemorative embroidery on the headrests and exterior badges
  • Electronic AC controls, power drivers seat, rear window/side window defogger and illuminated drivers side vanity mirror

Although not the best car to come home from your construction job in, the Triple White cars are widely accepted as one of the most attractive Vettes ever.

That said 1988 35th-Anniversary Corvettes make the short list of most desired and collectible C4s. Following the C4s trend of more power and better handling, 1988 would see another 5-horsepower jump to 245hp, but only for those coupes equipped with the G92 Performance rear axle’s 3.07 gears.

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Non RPO G92 coupes/convertibles with 2.59 gearing did not receive the free-flowing mufflers responsible for the increased grunt, still rated at 240hp. This output would carry through the 1989 model year as well.

In an effort to eliminate steering wheel pull from brake torque and the Corvettes wide patch rubber on uneven roads, the front suspension was completely revised for ’88. This included revamped steering knuckles, upper/lower control arms, springs, shocks, stabilizer shaft/link assemblies and wheel bearings.

Stopping power was upgraded as well, with all ’88 Corvettes receiving new dual piston front brake calipers and a revised parking brake system that engaged the rear disc brake pads, rather than the separate parking drum brakes used on all previous Vettes.

As mentioned before, RPO Z51/Z52 got new 12-slot 17×9.5-inch wheels with 275/40ZR17 rubber and Z51 cars got even bigger brakes, with new front calipers and 12.9-inch front/11.9-inch rear rotors, Z51 remained exclusive to stick-shift coupes.

Additional refinements for 1988 included:

  • New six-slot aluminum wheels with 255/50ZR16 tires (standard without Z51/Z52)
  • Carpeted doorsills
  • Solution-dyed carpets
  • Improved ventilation for coupes
  • Lower rearward relocation of parking brake handle
  • Revised hood support rod
  • New more efficient AC compressor and gear-reduction starter motor, both manufactured by Nippondenso

As for the color chart, Silver Beige Metallic, Medium Beige Metallic, Gold Metallic and Copper Metallic were gone, Charcoal Metallic was new and the only two-tone available was White/Black.

At an option cost of $25,895, 125 second year RPO B2K Callaway Twin Turbo Corvettes were ordered, now making 382hp/562lb-ft and topping out at close to $60-grand. For an additional $6500, automatics were an option, (re-worked truck Hydramatic 400’s) and Z51/Z52 suspensions, bigger brakes and free-flowing mufflers came with the package.

For 1988, the price of a base C4 Corvette was listed at $29,489 and going topless added $5K to that, big money for 1988 and perhaps a factor in the almost 8-thousand unit drop form ’86, with total production coming-in at 22,789.

Regardless of annual cost increases, the C4 would soldier-on into the last year of the decade with even more goodies in store.

 

ZAHNRADFABRIK FRIEDRICHSHAFEN MEANS PERFORMANCE IN GERMAN: 1989

Refinements, upgrades and new options were par for the course in ’89, not the least of which was a new optional six-speed transmission.

Replacing the well intended but lacking Doug Nash four-speed, was a new no-cost optional six-speed gearbox jointly developed by Chevrolet and German company Zahnradfabrik Friedrichshafen (ZF). RPO MN6 still employed Computer-Aided Gear Selection or (CAGS), that electronically bypassed 2nd and 3rd gears and locked-out 5th and 6th when cruising at low RPMs under 19mph. Intended to improve fuel efficiency, the CAGS system still raised complaints from many of the 4,113 row your owns, who felt it held the L98 back from it’s true potential.

Experienced ZF-shifted C4 owners learned how to fool the computer and offset the CAGS feature with some aggressive throttle-teasing 1st-to-2nd gearshifts above 19mph.

Optional suspensions choices were bounced around for ’89, with the Z51 Performance Ride Handling package still a stick-shift coupe exclusive, now reduced to $575.

New for the C4 was the $1,695 RPO FX3 Selective Ride and Handling Package, that could only be ordered with Z51-equipped cars and offered three shock-damping levels, touring, sport or competition, all electronically-controlled from a console-mounted switch.

Gone from the C4’s option list in ’89 was RPO Z52, although Z51/FX3-equipped Corvettes had Z52 springs/stabilizer bars as part of their components. The exception to this, were the sixty Corvettes built for the SCCA Corvette Challenge race series, all retaining their stiffer Z51 springs/stabilizers.

After a one-year appearance, the 16×8.5-inch six-slot wheels standard in ’88 spun-off into the stat books and were replaced by the 17×9.5-inch 12-slot wheels from the 1988 Z51/Z52 package.

Back from 1987 and improved was RPO UJ6 Low Tire Pressure Warning Indicator. Sensors attached to each inner wheel, sent a radio signal to the instrument panel when any tire fell below a preset minimum level, 6,796 C4 owners opted for the $325 feature.

Available for the first time since 1975, was RPO CC2 removable hardtop, at a cost $1995, 1,573 owners opted for the premium hard cover. All manual soft tops got a revised, simpler to use mechanism for ’89.

Another convertible-only optional feature was the $340 RPO V56 Luggage Rack, with 140 ordered.

All ’89 Corvette seats were restyled with base cloth, base leather and sport leather still the available choices. Taking into account weight/fuel economy, RPO AQ9 Leather Sport Seats were only available on Z51-equipped cars.

Callaway Cars in Old Lyme Connecticut continued to churn-out RPO B2K Twin Turbo Corvettes, with the same power output as ’88, but now offering the “Aero” body kit made famous by the world speed record setting Callaway Sledgehammer Corvette. Only 67 B2Ks were built for ’89, still fetching $26-grand on top of the price of a C4.

On the color chart, Silver Metallic and Yellow were unavailable and although initially listed as an optional color, Gray Metallic was cancelled in November ’88, and two-tones were gone for good.

Special order color combinations including Yellow/Buckskin and ext color Arctic Pearl were recorded in the build numbers but not officially available.

Total production for 1989 was 26,412 units, with 9,749 of them convertibles. This was the last year the C4 Corvette would see production above the 25-thousand unit mark, staying in the low twenty thousands till the end of the platform in 1996.

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ALL HAIL THE KING: 1990

RPO ZR1 was first used to designate a Special Purpose engine package for the 1970-‘72 350ci LT-1 small block-powered Corvette. It’s second usage from 1990-‘95 would become an instant legend and still hold the title as one of the greatest Vettes ever produced.

As early as 1984, talks commenced between GMs top dogs and those from soon to be GM acquisition Lotus, with the goal of creating the worlds fastest production car based on the C4 Corvette.

In Late 1984, On a business “holiday” from England to Warren Michigan, Lotus Engineering Managing Director Tony Rudd informed his Chevrolet opposite number, Russ Gee, that Lotus was pulling 350hp out of a four-liter dual overhead cam (DOHC) V8. GM thought that placing Lotus’s 4-valve per cylinder heads on top of the C4s L98 block would be great idea, but soon discovered the excess width too much for the C4s engine bay.

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After going to then GM Vice President of the newly formed (CPC) Group, Chevrolet–Pontiac-Canada-who then gently coaxed GM Board Chairman Roger Smith, the decision was made to engage in a joint design/development venture between GM and Lotus to build a totally new high-tech, aluminum (DOHC) V8 Engine designated the LT5.

Not since the WWII-winning North American P51 fighter was fitted with a Rolls Royce Merlin 12-cylinder engine, would there be such a powerful and significant Anglo-American conglomeration.

Initially titled the “King of the Hill” by Chevrolet Chief Engineer Don Runkle, the soon “Knighted” ZR1 first appeared in June of ’88 at the Riverside Raceway in California, where it left a gaggle of American auto-poets with jaws agape after a 150+ mph drive-by.

Early the next year at the Geneva auto show, the ZR1 was officially unveiled, but with further engine/drivetrain development needed, an April announcement confirmed a 1990 debut.

Records do indicate however, that 84 1989 ZR1 Corvettes were built for test/tune and press coverage. None were supposed to be sold to the public, but a few have since turned-up in private hands, both in the U.S. and across the pond.

Production of the LT5 engine would have to be handled by an outside source, since GM had not the time, and Lotus not facilities available for the low volume but complicated project.

Mercury Marine in Stillwater Oklahoma was a big GM customer for years, mating their marine stern-drive systems with GM engines and thus selected to manufacture the ZR1 power plants then ship them to Bowling Green for installation and final assembly.

Finally available in early 1990 the ZR1 was fitted with the Lotus/Chevrolet designed, all aluminum, 5.7L 32-valve DOHC LT5 V8, rated at 375hp/370lb-ft. With forged internals and aluminum pistons, the LT5 had an 11.0:1 compression ratio.

Acting as an early cylinder deactivation, active fuel management or power on demand system, (take your pick), the ZR1 was equipped with an electronic two-phase port fuel-injection system, controlled via a key-activated console-mounted switch.

Nicknamed the “Valet key” for obvious reasons, there were two positions, “full” and “normal”. Turned to “full”, all 16 intake valves would flap to life regardless of RPM or worthless fuel mileage concerns-turned to “normal” and only half of the intake valves and injectors would generate power for more economic cruising.

All ZR1s through ’95 were ZF six-speed equipped with (CAGS) and all were coupes.

Helping transfer the grunt to the ground, the ZR1 was fitted with the heavy-duty Z51 suspension, although with softer springs and stabilizer bars unique to the ZR1 and differing from the RPO for normal C4s.

On the appearance side, ZR1s had very deliberate and necessary differences from normal C4s.

Designed to accommodate exclusive 315/35ZR17 rear Goodyear meats mounted on 11-inch wide rollers, the entire rear section of the car was widened 3-inches. This included the doors, rear- quarters, rockers, rear fascia and upper panel.

The ZR1s quintessential distinguishing feature for 1990 was it’s more rounded up-turned tail and the incorporation of four rounded-rectangular taillights in place of the C4s familiar circular quartet.

As not to obscure the view of the new-style rear lamps, all ZR1s till ’95 had roof-mounted third brake lights, not one integrated into the rear fascia above the “Corvette” labeling.

All 1990 ZR1s got specific quad tailpipes instead of the dual rectangular set-up on normal Vettes.

For the additional $27,000 cost of RPO ZR1, you got the LT5 along with a full list of optional features including:

  • RPO AC1, Power Passenger seat
  • RPO AC3, Power Driver seat
  • RPO AQ9, Leather Sport Seats
  • RPO FX3, electronic Selective Ride and Handling
  • RPO UIF, Delco-Bose Stereo System with CD
  • RPO UJ6, Low Tire Pressure Warning Indicator

ZR1s also had a unique specially laminated “solar” windshield, better to block the suns blinding glare at 175mph.

Of course all this unique and exotic hardware wouldn’t amount to much, if the performance numbers didn’t add-up, and boy did they add-up.

As with the aforementioned top speed of 175mph, Car and Driver magazine recorded a 0-60mph sprint of 4.6-seconds and a 12.9 in the 1/4-mile, manufacturers numbers were a couple of tenths quicker.

Even at a total cost of $60,000 and with some dealers asking and getting close to six figures early on, the ZR1 equaled or surpassed Europe’s finest on the road and track, for tens of thousands less.

Perhaps the LT5-powered ZR1s greatest claim to fame occurred at Firestone test track, Stockton Texas in early March 1990.

Setting out to brake a 50-year-old endurance record set by Abe Jenkins’ “Mormon Meteor III”, running all out at 161.181mph for 24 hours on the Bonneville Salt Flats, an LT5/ZR1 specially prepared by Corvette Development Manager John Heinricy and piloted by race driver Tommy Morrison, ran for a full day at 175mph for 4,200 miles, setting three new world records at varying distances and classes.

In just it’s first model year, the ZR1s claim to the throne was deemed legitimate and was undisputed, until the end of the line in 1995, it would remain at the helm of Corvette performance.

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CERV III:

The successor to the 1986 Corvette Indy show car, the CERV III, standing for “corporate experimental research vehicle” was the natural progression of Chevrolet and Lotus’ efforts to showcase new high-tech engineering and features, some of which would be found in the C4 and planned for the C5 Corvette.

After a second Corvette Indy was presented by Lotus in late 1986, this time a running/driving example fitted with an LT5 V8, work began on an even more-polished version that would be functional by early 1988.

The CERV III had all the Corvette Indy’s advanced goodies, but resembled a more doable production car, albeit a super car. By the time it was introduced at the Detroit Auto Show in Jan 1990, the CERV III had seen 2000 test/tune miles.1986-Concept-Car-Chevrolet-Corvette-Indy-50351

Really setting it apart from the Indy cars, the CERV III had a roomier cockpit with Lamborghini-style scissor doors and was powered by a transverse-mounted LT5 dressed with two, yes that’s dual, Garret turbochargers, making 650hp/655lb-ft.

Appearance-wise, the front fascia was redesigned with pop-up headlights, strongly-resembling the nose of what would be the 1997 C5 Corvette.

Without a doubt, the CERV III represented a highly advanced look at the future direction of the Corvette. As Chevrolet Chief Engineer Don Runkle told Car and Driver magazine in 1990, “The CERV III was a business case, not really meant for production. Rather, we put production specs on the design because it’s more interesting to build cars like that, instead of cars like the Indy, that act as sculpture”.

Notable production changes for 1990 included:

  • A change from mass-air to a speed-density air intake system, a revised camshaft and increased compression provided for a 5hp bump for the L98, up from 240hp-to-245hp. Corvette coupes with 3.07/3.33 rear axle ratio gears and free-flowing exhaust, went from 245hp-to-250-horses
  • An engine oil life monitor was added, measuring useful oil life on engine temperature/revolutions. An instrument panel display told the driver when an oil change was needed
  • The ABS system was improved for 1990, as was yaw control and the ABS “Active” light was removed from the display
  • All 1990 Corvettes got a revised instrument cluster, combining a digital speedometer with all analog gauges. A (SIR) supplemental inflatable restraint system with air bag was installed on the driver’s side and a glove box added to the top of the passenger side dash
  • RPO AQ9 Leather Sport Seats became available with all models and suspensions
  • All 1990 Corvettes received slightly revised wheels, devoid of locking center caps, with exposed lugs

Even with power output now at 390hp/562lb-ft, the advent of the new ZR1 at relatively the same price, equated to only 58 B2K Callaway Twin Turbo Corvettes ordered.

On the color chart for 1990, Medium Blue, Dark Blue and Gray Metallic were gone, with Steel Blue Metallic, Turquoise Metallic, Competition Yellow, Quasar Blue Metallic and Polo Green added. Even with the dropping build numbers, the C4 was only half way through its tenure and more changes/improvements were on the way.

Total production for the 1990 C4 was 23,646 of which 3,032 were the ultra high-performance ZR1.

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PLASTIC SURGERY: 1991

Going into its eighth year of production, the C4’s appearance had become a bit dated and in need of a freshening-up. That said it would go under the knife for ’91 receiving a face-lift, butt implants and some new-style shoes.

For 1991 all Corvettes got a revised front fascia with more rounded edges, wraparound driving/parking-fog lights, four horizontal front fender louvers replacing the former two vertical ones and a new wider body-color rub molding.

Out back, the base C4 was given the ZR-1 treatment with the rounder-edged, up-turned tail section and ever-famous rounded-rectangular lights, although made to fit the normal C4 body. The ZR-1 retained its exclusive wider doors, rockers and rear section, all to accommodate its massive rear rollers.

The ZR-1 could still be readily identified by a roof-mounted third brake light, quad tailpipes and of course it’s rear fascia “ZR-1” callout badges.

Along with a rear fascia-integrated third brake light, the base C4’s tail badge was changed from raised “Corvette” lettering to an indented stamp within the fascia. All ’91 Vettes were fitted with new “saw blade” design wheels with an open lug center section.

Starting in 1991, RPO Z51 would take a five-year sabbatical and RPO Z07 Adjustable Suspension Package would take its place. Tagged at $2,155, Z07 included RPO KC4 engine oil cooler and RPO FX3 electronic Selective Ride and Handling, along with Z51 heavy-duty brakes and suspension components.

Differing from 1989-‘90’s Z51/FX3, Z07 did not use any base components for soft-to-firm ride adjustments, but rather, only heavy-duty stuff, for firm-to-“holy-s**t”-firm.Intended for spirited driving or competition, RPO Z07 like Z51 before it, was specified for manual-shifted coupes only, but build records show 169 of the 733 ’91 Z07s built were automatics.

Other changes/upgrades for ’91 included:

  • Mufflers were revised featuring improved flow characteristics from larger sections, lower backpressure and a tuned exhaust note. Power output remained unchanged
  • All Corvettes receive a finned power steering cooler as standard
  • A power connection for 12-volt devices including “cell phones” was added
  • All models received a power-delay feature that allowed the stereo/power windows to work after the ignition was turned to “off” or “lock”. Power was cut upon opening the drivers door or after 15-minutes
  • An oil pan float with sensor was added to all models to aid in more accurate oil life calculations
  • The AM radio band was expanded to receive greater frequencies
  • The ZR1s power access system (valet key), was revised to default to “normal” upon each ignition start, regardless of key position and the full power light was moved next to the key location

This was the last year for RPO B2K, with the Callaway Twin Turbo now putting-down 403hp/575lb-ft at an option cost of $33,000. In September ’91, the 500th Twin Turbo was built, 71 in total for the year.

Exterior color choices remained the same as 1990, with four convertible soft top colors available including, white, black, blue and beige (replacing saddle).

Despite the C4 being improved-upon for every model year, it’s rising base price, now $32,455 seemed to designate a wealthier buyer.

Even with the freshened exterior, total production for ‘91 fell by 3000 units to 20,639 and ZR-1 sales also decreased by 1000, with 2,044 sold. For the coming year, prices would continue to elevate, but thankfully, so would horsepower.

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THE “300” CLUB: 1992

Although the financially gifted, could since 1987 buy a C4 with well over 300-horses by way of Callaway’s B2K Twin Turbo option or a ZR1 since 1990- for most, shelling-out basically double the price of a base Vette for the additional grunt just wasn’t in the cards.

For 1992, all base Corvettes were fitted with a new Gen II small block V8, designated LT1. Not only was the engines name a throwback to its 1970-’72 usage, but also 300-ponies hadn’t been standard issue since then either.

The new iron block/aluminum head 350ci 5.7L LT1 made 300hp at 5000 rpm and 330lb-ft at 4000 rpm with a 5700 rpm redline, a 700-rpm rev increase over the L98 it replaced. In one single leap of technology, the base Corvette had gained 50-horsepower and a new level of performance equal to it’s name and chassis /suspension. Recorded stats had the LT1 C4 running 0-60mph in a hair over 5-seconds and the 1/4-mile in 13.7 at 103.5 mph.

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Many factors contributed to the new small blocks greater performance including a higher compression ratio, 10.5:1 up from the L98’s 9.5:1, a new more efficient intake system, plenum and throttle body, new computer-controlled Optispark distributor ignition with (MPFI) multi-port-fuel-injection, a more aggressive camshaft profile, better flowing heads and a new low-restriction exhaust with two catalytic coverters/O2 sensors, one for each row of cylinders.

Another power-making innovation on the LT1 and a first for Chevrolet was reverse-flow cooling. Instead of coolant first flowing through the hot block then to the cylinder heads like on the Gen I L98, the LT1s coolant ran through a crossover from head-to-head first, then to the block and back to the pump. This allowed the bore temp to remain high, while reducing ring friction and cooling the top areas like the valve seats and spark plug connections.

With the new serious motor was required more serious lubrication, thus all Vettes now came factory-filled with Mobil 1 synthetic oil. The use of man-made oil deemed RPO KC4 engine oil cooler unnecessary, removing it from the options list.

With increased engine output came a new standard Bosch-made (ASR) acceleration slip regulation or traction control system that utilized spark retard, throttle regulation and brake-modulation to limit wheel spin. The gas pedals refusal to obey your heavy right foot, let you know the system was working and had not been deactivated by the dash-mounted switch.

 

Also new and standard on ’92 C4s, were directional and asymmetrical Goodyear GS-C high-performance tires.

Further refinements addressed the driving experience with improved weather striping seals and increased interior sound deadening insulation around the transmission tunnel and inner door panels on all 1992 Corvettes.

Also new was the availability of a white interior with white leather base/sport seats, although not until mid-year, after ’93 this interior color option was cancelled.

Furthermore, the instrument face surrounds and control buttons were changed to all black for ’92, replacing 1990-‘91s gray/black, and the speedometer was moved above the fuel gauge, with all gauge graphics refined for better legibility.

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Minor but mentionable appearance changes to the ZR-1 were made in ’92 including “ZR-1” badges above the fender gills and the quad tail pipes were replaced by the standard C4 dual rectangular pieces. RPO Z07 adjustable suspension package, formerly available on manual coupes only, became optional for automatic coupes in 1992.

On the color chart, Steel Blue, Turquoise, Charcoal and Polo Green Metallic were out and Bright Aqua, Black Rose and Polo Green II were in.

With the trend continuing of more refinements/improvements and higher cost, the total number of C4s produced for ’92 was 20,479, about the same from the previous year. The mighty ZR1 however, was granted to only 502 deep-pocketed buyers, down drastically from 1991s 2044 king Corvettes built.

With the 1-millionth Corvette built, a white ragtop, rolling-off the Bowling Green assembly line on July 2, 1992, the coming year would see another milestone celebrated by the C4, a very special Corvette birthday.

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RUBY RED ANNIVERSARY: 1993

With 1993 marking 40-years of production for America’s sports car, Chevrolet offered the 40th-Anniversary package for coupes, convertibles and the big dog ZR1. Basically a commemorative appearance package, the attractive and affordable at $1,455 RPO Z25 included:

  • Exclusive Ruby Red Metallic paint
  • Chrome “40” emblems on hood, front fenders and gas filler door
  • Unique Ruby Red Leather Sport seats with “40” embroidered headrests and RPO AC3 (power driver seat)
  • Specific color-keyed wheel center caps

Of the 6,749 Z25-optioned Corvettes built for ’93, 4,333 were coupes, 2,171 were convertibles and 245 wore the ZR-1 badge. Also included in these totals were 257 Z25sautowp.ru_corvette_convertible_40th_anniversary_4 built for export. All Leather seats for 1993 (except base cloth) got the “40” embroidery regardless of being Z25 cars or not.

For it’s second year the LT1 received some revisions/upgrades to help the new lump run quieter, they included:

  • The previous years one-piece stamped heat shield was changed to a two-piece self-damping unit
  • Valve covers were now made of thermoset polyester, replacing the magnesium covers used from 1984-’92. These covers were isolated by head gaskets and gaskets under the mounting hardware
  • A revised camshaft was installed, which reduced the exhaust valve closing speed and increased duration with no overlap

The new camshaft did not aversely effect emissions or idle, but did allow for a bump to 340lb-ft from 330lb-ft of maximum torque.

Significant changes surrounded the C4s wheels/tires for 1993, including a more brilliant finish resulting from an improved machining process. All base Corvettes were fitted with smaller diameter front wheels, now 17×8.5-inches instead of 17×9.5s with slightly thinner rubber at P255/45ZR17 instead P275/40ZR17s. Rear wheel size remained at 17×9.5 but got wrapped by fatter P285/40ZR17 tires. Corvettes with RPO Z07 rolled-on as before, wearing 17×9.5s with P275/40ZR17 rubber at all four corners.

The base C4 also received beefier binders in ’93, with 12-inch discs replacing the 11.5-inchers worn since 1984.

Another Corvette/Chevrolet milestone occurred in ’93, with the introduction of GMs first (PKE) passive keyless entry system.

Using a battery-operated key-fob with a transmitter, a code was sent upon closing proximity to a pair of antenna/sensors (in coupes drivers door/rear deck lid, convertibles in both doors). As the owner approached, the doors would unlock, the interior lights would illuminate and the alarm would be deactivated. Upon leaving the vehicle, the opposite would occur after time, followed by a brief horn burst as a reminder. The system was programmable as to the owner’s preferences and Coupes got an extra rear hatch release button on their key-fob.

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Although it was still good to be the king, the ZR-1s claim to the throne was challenged in 1992 by the Dodge Viper R/T with it’s 400-horse V-10. Thus in retaliation, the vaunted ZR1 became even more powerful, producing 405hp/385lb-ft. With revised heads to increase flow and more heavy-duty pistons and stronger 4-bolt main bearings replacing the previous 2-bolt set-up- the ZR-1s LT5 motor became the first naturally aspirated Vette engine to surpass 400-ponies since the 1971 454ci LS6 made 425hp.

On top of it all, the LT5 received a Mobil 1 synthetic oil requirement, platinum-tipped spark plugs and an electrical linear (EGR) exhaust gas recirculation system that improved emissions. Even with the improvements and increased grunt, RPO ZR1 stayed-put at $31,683, the same pricing as ‘91/’92.

Colors for ’93 included the return of Competition Yellow and the addition of Torch Red and Ruby Red (40th-Anniversary Z25 only). Regular Yellow and Bright Red were discontinued.

Total production for 1993 was 21,590, up a bit from the previous year.

As a result of Mercury Marine ending LT5 engine production on November 23, 1993, ZR-1 build totals became predetermined at 448 units for 1993, ’94 and ’95.

HIGHER-TECH AND HIGHER COST: 1994

For 1994, upgrades were lavished upon the C4s interior and further refined the operation of the LT1 engine.

All 1994 C4s received a new passenger-side air bag (prompting removal of the glove box present since 1990), driver’s power window express-down feature, revised seat contours and door trim panel designs, a new two-spoke air bag–equipped steering wheel and white instrument read-out graphics that glowed “tangerine” for night driving.

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All C4 seats were now leather, with the discontinuation of the base cloth versions and all power seat adjustment controls (base/sport) were located on the center console. All Seat bolsters were revised/widened to allow for better entry/exit and the reclining feature on all ’94 seats was manually operated.

Further cabin-oriented upgrades included:

  • A new glass rear window with defogger grid for convertibles replacing the plastic one
  • Use of non-ozone depleting R-134a refrigerant for the AC system
  • Relocation of the tire jack from the spare tire well, to a compartment rear of the passenger seat

As for revisions to the LT1, they included a new sequential fuel injection system that working in conjunction with a new (MAF) mass airflow sensor would activate the fuel injectors in “sequence” with the motors firing order. This more direct form of injection offered improved throttle response, idle characteristics and better overall drivability and emissions.

A new more potent ignition system was also installed, reducing engine crank times, especially in cold temperatures.LPEZR102

Catching up with the C4s improved LT1 small block, the 4L60 automatic transmission now gained electronic controls thus the new title, 4L60-E. The new tranny provided better shift quality and consistency and was fitted with a shift-lock safety feature that required the brake pedal to be pushed forward to engage the driving gears from “park”.

Underneath it all, the FX3 electronic Selective Ride and handling package now featured softer spring rates, along with a drop in recommended tire pressure from 35-30psi, (not ZR1) was meant to provide a more comfortable ride.

A new tire option became available in ’94 and was the first of it’s kind in the world. RPO WY5 Extended Mobility Tires, (run flats) allowed a C4 with a wounded paw or four, to drive safely at 55mph for up to 200-miles, without any air pressure.

RPO UJ6 Low Tire Pressure Warning Indicator was required with WY5, since there was no visual difference between a full or empty run flat tire. Extended Mobility Rubber was not available with RPO Z07 or ZR-1.

New for the ZR1 was an awesome set of exclusive five-spoke wheels, soon to be called (ZR-1 style), not available on base C4s.

For ’94 there were still as many color choices as you have fingers, with Admiral Blue and Copper Metallic the newcomers and Polo Green II Metallic dropping the II and Quasar Blue Metallic gone. Copper Metallic draped only 116 C4s for ’94 and then was cancelled for poor quality concerns, it did not return.

On a historical footnote, after years of planning and funds collection, the National Corvette Museum opened it’s doors on July 2,1994 in Bowling Green Kentucky, right down the road from the Corvette assembly plant.

GM/Chevrolet big wigs were in attendance, including the undisputed father of America’s sports car, Zora Arkus Duntov.

The gala event took place during the C4s reign and more than a few examples grace the museum.

Total build numbers for 1994 stand at 23,330, up 1740 units from 1993. Now tipping the scales at $36,185 for a base Vette and more than $42-grand for a topless version, the Corvette’s refinement was welcome, but expensive.

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STILL THE ONE: 1995

With the C4 entering it’s 12th-year of production, much stayed the same, (not a bad thing) and many more refinements were made to America’s flagship auto.

Visually, the only change to the C4s exterior was the re-sculptured front fender “gills” now a more subtle and integrated design harkening those of the 1958-’62 C2s.

The LT1 continued to receive upgrades, including new, stronger and lighter weight powdered-metal connecting rods in place of the previous forged pieces. The fuel-injectors were also revised to better handle alcohol-blend gas and limit fuel drip after engine shutoff and the engines cooling fan was modified for quieter operation.

Both transmissions were upgraded, with the 4L60-E automatic getting improved clutch controls for smoother shifting and a lighter yet stronger torque converter. The six-speed stick was redesigned with a high-detent operating mechanism, replacing the reverse lockout for easier operation.

More refinements graced the C4s cockpit for ’95 including stronger “French” seams for the optional Sport seats, a new automatic transmission fluid temp gauge added to the instrument cluster, numerous hidden Velcro strap binders to limit squeaks/rattles and a stiffer radio mount to reduce CD skippage. A drip tube was also integrated into the A-pillar weather-stripping to help deter water invasion into the cabin.

Usually when a platform is in it’s final build period, those options formerly relegated to higher cost models/packages become standard equipment across the line. That said, for ’95 all Corvettes were fitted with the beefy binders that donned the ZR1 and Z07-optioned cars, with their 13-inch front rotors replacing the previous 12-inchers. Further aiding the C4s stopping prowess was a revised Bosch ABS/ASR 5 system, while the last ZR-1s retained the former Bosch ABS/ASR-2S.

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Other upgrades for ’95 included:

  • Softer-tune DeCarbon shocks and softer front/rear spring rates for base Corvettes
  • Windshield wipers had revised angles of contact with increased force to reduce movement and lift at high speeds
  • Available in ’95 with RPO WY5 Extended Mobility Tires, RPO N84 spare tire delete, addressed the lack of need for a spare tire with “run flats”, N84 reduced vehicle weight and gave the buyer a $100 credit
  • Automatic transmission C4s with RPO Z07 now required G92 performance rear axle
  • New color Deep Purple Metallic was added, Copper Metallic And Black Rose were cancelled

For the third time overall and the second C4 to hold the honor, the ‘95 Corvette was the chosen to pace the Indy 500 on May 28, 1995.

Again as before in 1978 and ’86 Chevy offered a pace car replica for public consumption.

All RPO Z47 Indy 500 Pace Car replicas were convertibles, featuring a unique/exclusive two-tone Dark Purple over White paint scheme with “checkered flag” streaming graphics, Indy 500 door writing, rear panel logos, white convertible tops and special leather Sport seats with “Indy 500” headrest embroidery. At a cost of $2,816, 527 examples were built.

 

Farewell to the King:

As the last ZR-1, a Torch Red example was piloted off the Bowling Green assembly line and over to the National Corvette Museum on April 28,1995-there was no surprise that the King of Corvettes dynasty of dominance had come to an end. Discussions between GM and Lotus had begun as early as 1991, stating the fact that ’95 would be the end of the royal run.

Waning super car sales, retirements and changing hands at GM, its astronomical price, not to mention the cost to bring its emissions up to specs for 1996, all contributed to the ZR-1’s exit. Even with Lotus’ engineers working on a new LT5 capable of 450-475hp, the decision was made and the ZR-1 was history.

Between 1990-’95 6939 ZR-1s were built, all to be serviced by Chevrolet after Mercury Marines contract was up in 1994.

Widely accepted as the greatest C4 and one of the greatest Vettes period- ZR-1s in both 375hp and 405-horse configurations can equal or surpass the performance of many of today’s 21st-century machines. And they’re still not getting their “divine right” on the auction block, with early C4 ZR-1s being snatched-up for $25-30k, there’s still a chance for the common man to become royalty.

Total production for 1995 was 20,742 down from ‘94s totals. The coming year would be the C4s last and it would offer some very special goodbye models.

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A GRAND DEPARTURE: 1996

For it’s finale in 1996 the C4 would offer two special editions, a new engine option, revised suspensions and it’s highest price yet.

In its last year, a re-worked version of the LT1 called the LT4 became available only to C4’s with manual transmissions, while all LT1s came married to the 4L60-E Automatic. The 5.7L 350ci LT4 V8 was rated at 330hp/340lb-ft, a 30-horse and 5-lb-ft bump from your standard LT1.

The LT4s upgrades included a higher compression ratio (10.8:1 from 10.4:1), revised cylinder heads with deeper ports and larger hollow-stemmed valves, oval-shaped springs, Crane higher-ratio roller Rockers, a revised camshaft with higher duration specs, a higher-flow intake with ports matched to the heads and a roller-style timing chain.

To further bulletproof the new motor, the LT4s crank, water pump, main bearing caps, drive gear and head gaskets were all strengthened to endure the higher compression.

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Both LT1s and LT4s received a new throttle body in ’96, with LT4s getting red “Grand Sport”-labeled top plates no matter the application, more on that later.

Suspension options for ’96 were revised and included the return of RPO Z51 Performance Handling Package (1984-’90), replacing RPO Z07 Adjustable Suspension Package and new was RPO F45 electronic, Selective Real Time Damping, giving the bounce to RPO FX3 electronic, Selective Ride and Handling Package.

Exclusive to coupes, at $350 the updated Z51 package was a bargain and included new Bilstein shocks, special-tuned front/rear springs, beefier stabilizer bars and stiffer bushings.1996_Chevrolet_CorvetteCollectorsEdition2

All Z51-equipped C4s came with 17×9.5-inch wheels with P275/40ZR17s all-around, except when paired with RPO Z16 “Grand Sport”, with 17×11-inch rear wheels wrapped in P315/35ZR17 rubber. Automatic-equipped Z51s required the G92 Performance Rear Axle with 3.07 gears.

Improving upon what was offered with the FX3 package, F45 electronic, Selective Real Time Damping, was a huge techno-leap in driver-adjustable suspensions.

Developed by Delco, the new system operated via sensors in each wheel, relaying information through a (PCM) powertrain control module to a central computer and adjusting each of the four special shock absorbers individually (FX3 adjusted all shocks in unison) at an astonishing “real time” rate, every 10-15 milliseconds-or each foot of road surpassed at 60mph.

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Collector Edition Corvette:

Similar to Chevy’s special edition send-off for the C3 in 1982, RPO Z15 would designate the Collector Edition C4 as a proper parting gift in ’96.

Costing $1,250 RPO Z15 was available on coupes/convertibles and included:

  • Exclusive Sebring Silver Metallic paint
  • Silver-Painted ZR1-style five-spoke aluminum wheels with specific center caps
  • Black-painted brake calipers with silver “Corvette” stenciling
  • Special “Collector Edition” emblems on front/sides of hood and gas filler door
  • Perforated Sport Seats with “Collector Edition” headrest embroidery in available Black, Red or Gray interior color

Z15s could be ordered with all available RPOs including the LT4 engine, making those very desirable to collectors. In total, 5,412 ’96 Collector Edition Corvettes were built, comprising 4,031 coupes and 1,381 ragtops.

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Captain America’s Corvette: Grand Sport

Definitely looking like a ride designed for the first Avenger, the 1996 Grand Sport paid homage to the original lightweight racing GS Corvettes designed by Zora Duntov in 1962-’63.

For street use, RPO Z16 was available in coupe or convertible form, but only equipped with the ZF six-speed, leading to a pleasurable default that all Z16s were fitted with the 330-horse LT4 engine.1996-Chevrolet-Corvette-LT4-Engine

RPO Z16 included:

  • Admiral Blue paint (exclusive to GS for ’96) with body length white center stripe on hood/rear deck and red race-inspired hash marks on left side hood (fender)
  • Exclusive Black-painted ZR1-style five-spoke aluminum wheels with unique center caps. Coupes got 17×9.5-inch front wheels with 275/40ZR17 tires and 17×11-inch rear wheels with 315/35ZR17 tires. Grand Sport convertibles wore the standard wheel/tire package, 17×8.5-inch front wheels with 255/45ZR17 tires and 17×9.5-inch rear wheels with 285/40ZR17 tires
  • *Unique rear fender flares (Z16 coupes only)
  • Black-painted brake calipers with silver “Corvette” lettering
  • Unique “Grand Sport” fender badges
  • Perforated Leather Sport Seats with headrest embroidery in black or red/black interior color combination

Utilizing the same wheel/tire combination as the ZR-1, Grand Sport coupes were fitted with unique rear fender flares to better encase the huge rear rollers, therefore widening the entire rear section of the car as with ZR-1 was not necessary. All 1996 Grand Sport Corvettes were built with a special serial number sequence, differentiating them from other C4s.

Only 1,000 RPO Z16 Grand Sports were made, comprising 810 coupes at $3,250 and 190 convertibles at $2,880. The ‘96 Grand Sport is at the top of the list of most sought after C4s. The only color changes for ’96 were the cancellation of Dark Red Metallic and the above-mentioned exclusivity of Admiral Blue for the Grand Sport.

Total last year production for the C4 Corvette stands at 21,536, up a tad from ’95.

Final years costs for the C4 were $37,225 for a base coupe and a whopping $45,060 for a convertible. Even with the high cost of Corvette ownership, the C4 definitely went out on a high note, offering two of the best and most coveted special editions of its long run.

Race History:

The C4 Corvette compiled an impressive race resume over its 13-years of production.

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Starting in 1985, a C4-based race platform competed in the (IMSA) International Motor Sports Association Grand Touring Prototype class (GTP) run predominantly by Hendrick Motorsports. Although the racecars were a departure from their street-driven brethren, actually running a 1200hp turbocharged Chevy V6 capable of 200mph, the association with the new C4 Corvette was evident. Later versions raced by Peerless Automotive went back to the V8 engine, but this was towards the end of the C4 GTPs short IMSA career. The GTP Corvettes ran until 1989 with more speed and track records than actual race victories to their credit.

From the onset of its introduction as a 1984 model, the C4 Corvette raced in the Sports Car Club of America (SCCA) Showroom stock GT class and was dominant to say the least. Pitted against competition from Porsche, Datsun, Ford and others, the Corvettes secured victory for four straight seasons, leading to their kind dismissal from eligibility for the series in 1987.vemp_0705_03_z+the_corvette_challenge+c4_corvettes

Soured by the C4 being expelled from Showroom Stock racing because it won to much, Canadian race promoter John Powell had the great idea of running 50 identically set-up L98 Corvettes against each other (ala’ IROC), showcasing the C4 and driver skill in pursuit of a $1-million dollar purse.

For ’88 Chevrolet built 56 race-ready Corvettes, with standard engines built for equal output at the CPC Flint Engine plant and shipped to Bowling Green for install. Once complete, 50 of these cars traveled to Protofab in Wixom Michigan to receive roll bars and other race-oriented components.

For 1989 60 more Challenge cars were built, this time with half getting special high-horsepower motors built at Flint and equalized/ sealed by Specialized Vehicles Inc, in Troy Michigan.

The race Vettes and the special motors were introduced at Powell Development America in Wixom Michigan where the engine swap took place and all safety equipment was installed. Once the ’89 campaign was completed, the original factory motors were returned to their owners.

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For 1990, the series name was changed to the SCCA World Challenge series and Chevrolet discontinued building special race-tuned C4s.

For a short time in 1990 however, customers could order/build there own World Challenge Corvettes, by specifying code R9G at their dealer. This would provide a C4 with heavy-duty suspensions, brakes, FX3 and certain deletions necessary for racing. Special sealed race engines could be ordered from Chevy, but upgrades were up to the owner, 23 R9G-Corvettes were built.

World Challenge continued in 1991, but Chevy’s involvement was nil, with all race modifications the responsibility of the race team/owner.

Further flexing it’s international muscle, a C4 in full-out ZR1 race trim competed at the 24-hours of LeMans in ’95. The brainchild and dream of former Corvette Challenge racer Doug Rippie, the ZR1 raced GT1 class and although the end result was a DNF (did-not-finish), there was no question the C4 ZR1 could challenge the worlds best.

World Wide Appeal: C4 Exports 1984-1996

Throughout the Corvettes first two generations and well into it’s third, export to anywhere but North of the border (Canada) was rare and usually a special affair. The C4 was the first representative of America’s sports car to see widespread export, not only on the two American continents, but also all over the world.

During it’s thirteen year run, C4 Corvettes were exported in large numbers to Canada, Mexico, Latin America, Japan, Saudi Arabia (and other Gulf states) and many European nations including, Germany, Switzerland, Austria, Belgium, Luxembourg, the Netherlands (Holland), England and France.

Although the Chevrolet Corvette was already a living/driving legend in it’s home country by 1984, it was the C4 that introduced the world to a new more modern iteration, sparking an international appeal that carries-on to this day.

RETROSPECT:

Second only to the C3s 15-year production run, the C4s thirteen-year tenure proved to be one of the most significant and groundbreaking in Corvette history. From the get-go, the C4 depicted a sleek, forward-thinking design one that Chevrolet would constantly upgrade and improve through its build period.

The C4 presented many firsts for Corvette; including, electronic fuel-injection, electronic four-speed automatic transmissions and six-speed manuals, four-wheel (ABS) anti-lock brakes, traction control (ASR), 16- and 17-inch wheels/tires, electronic driver-adjustable suspensions, run flat tires, air bags, passive theft deterrent systems and more.

The C4 platform offered multiple special editions including the ’86 Pace Car, 1988 35th- and 1993 40th-Anniversary cars, ’95 Indy Pace Car and ’96 Collector Edition and Grand Sport Corvettes. The C4 saw the only GM-sponsored specialty-manufactured high-performance RPO in Chevrolet history with the advent of the B2K Callaway Twin Turbo option for 1987-’91.

And last but certainly not least, the C4 ZR-1 with its LT5 engine, widened rear-end and world-class performance will forever be remembered as the king of its day and a legend that endures forever.

The accolades are there and so is the unmistakable reality that for more than a decade. The C4 Corvette was the leading edge of GMs sword of automotive technology, creating a performance trickle-down effect on other GM models and hatching a huge tuner base and performance product aftermarket that still thrives today. With America’s sports car now in it’s seventh-generation and development of the eighth swiftly commencing, the Corvette has become a world leader in every aspect of automotive endeavor.

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