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1990   1991   1992   1993   1994   1995   Production Numbers

1990    The ZR-1 (RPO ZR1) arrived as a 1990 model after much anticipation. At the heart of the ZR-1 was the 375hp LT5 engine. It was designed with the same V-S configuration and 4.4-inch bore spacing as the standard L98 Corvette engine, but was an otherwise new design with four overhead camshaft~ and 32 valves. LT5 engines were manufactured and assembled by Mercury Marine in Stillwater, Oklahoma, then shipped to the Corvette Bowling Green assembly plant for ZR-1 vehicle assembly.

For a limited time during 1990, dealers could order Corvettes destined for the new World Challenge race series. Merchandising code R9G triggered deviations from normal build, such as heavy-duty springs with FX 3. Owners could buy race engines from Chevrolet or build their own, and all race modifications were the owner's responsibility. Twenty-three 1990 R9G Corvettes were built.

An air intake speed density control system, camshaft revision, and compression ratio increase added 5hp to base-engines, up from 240hp to245hp (except coupes with 3.07:1 or 3.33:1 axle ratios which increased from 245hp to 250hp because of their less restrictive exhaust systems).

1990 Corvettes had improved ABS and improved yaw control.

An engine oil life monitor calculated useful oil life based on engine temperatures and revolutions. An instrument panel display alerted the driver when an oil change was recommended.

The RPO VOL radiator and B4P boost fan were not optional in 1990, both made unnecessary by 1990's more efficient, sloped-back radiator design.

Two premium 200-watt Delco-Bose stereo systems were available, the top unit featuring a compact disc player. To discourage theft, the CD required electronic security code input after battery disconnect.

The instrument panel for 1990 was redesigned as a "hybrid," combining a digital speedometer with analog tachometer and secondary gauges. A supplemental inflatable restraint system (SIR) with airbag was added to the driver side, a glove box to the passenger side.

The "ABS Active" light was removed from the driver information center.

Seat designs were the same for 1990 as the previous year, except the backs would latch in the forward position.

Chevrolet service departments returned LT5 engines to Mercury Marine for certain repairs. Customers had the choice of a replacement engine, or return of their original engine if repairable.

1991  All 1991 Corvettes had restyled rear exteriors which are similar in appe&ance to the 1990 ZR-1 because both had convex rear fascias with four rectangular tall lamps. Both standard models and ZR-1 is also featured new front designs with wraparound parking-cornering-fog lamps, new side panel louvers, and wider body-side moldings in body color.

Despite similar appearance, the 1991 ZR-1 still received unique doors and rear body panels to accept il-inch wide rear wheels. The high-mount center stop lamp for 1991 ZR-1 is continued to be roof-mounted. For all other than ZR-1, the lamp was integrated into the new rear fascia.

Base wheels were same size as 1990 (17 9.5), but a new design.

Finned power steering coolers were included with all 1991 models.

A new option, RPO Z07, essentially combined the previously available Z51 performance handling package with FX3 selective ride/handling. But there were differences. In 1990, if FX3 and Z51 were combined, some base suspension components were used to provide an adjustable suspension range from soft to firm. The new RPO Z07 option used all heavy duty suspension parts so the ride adjusted from firm to very firm. Intended for aggressive driving or competition, Z07 was limited to coupes.

The World Challenge race series continued in 1991, but Bowling Green did not build specific Corvettes for the series. All race modifications were the owners' responsibility.

Callaway Twin-Turbo conversions ended with the 1991 model year. Callaway built the 500th twin-turbo on 9-26-91 and subsequent builds were specially badged and optioned (extra $600) as "Callaway 500."

A power wire for cellular phones or other 12-volt devices was added.

A power delay feature was added to all models which permitted the stereo system and power windows to operate after the ignition was switched to "off" or "lock." Power was cut after the driver door was opened, or after fifteen minutes, whichever occurred first.

A sensor utilizing an oil pan float was added to all models. The words "low oil" appeared on the driver information center to signal a low oil condition.

Mufflers were revised for 1991 with larger section sizes and better control tuning of exhaust note. The mufflers had lower back pressure for improved performance, but power ratings were not changed.

The AM band for radios was expanded to receive more frequencies.

The ZR-1 "valet" power access system continued, but was revised to default to normal power on each ignition cycle. The full power light was relocated next to the valet key.

1992  Exterior appearance for 1992 was little changed. For the ZR-1, "ZR-1" emblems were added above the side fender vents. Two rectangular exhaust outlets were used for ZR1-is and for standard models. Instrument face plates and buttons were changed to all-black, replacing 1990-1991's gray black. The digital speedometer was relocated above the fuel gauge. Gauge graphics were refined for better legibility.

The base engine for 1992 was the LT1, a new generation small block. In 1992 Corvettes, the engine developed 3OOhp (net) at 5000 rpm. Torque was 330 lb.-ft at 40000 rpm. Redline was 5700 rpm, 700 higher than the L98. There was an automatic fuel cutoff at 5800 rpm. Power increases were attributed to computer-controlled ignition timing, a low-restriction exhaust system employing two catalytic converters and two oxygen sensors (one converter and one oxygen sensor for each cylinder bank), higher compression ratio, new camshaft profile, free-flow cylinder heads, and a new multiport fuel injection (MFI) system. At 452 pounds, the 1992 LT1 outweighed the 1991 L98 base engine by twenty-one pounds, due partly to replacement of stainless steel to exhaust manifolds with cast iron.

Corvette's new LT1 engine employed reverse flow cooling, a Chevrolet first. Rather than route coolant from the pump through the block to the heads, the LT1 routed coolant to the heads first. This permitted higher bore temperatures and reduced ring friction, and helped cooling around the valve seats and spark plug bosses.

Synthetic oil was recommended for the LT1. An engine oil cooler was no longer available, thought unnecessary when synthetic oil was used.

Traction control was introduced as standard equipment on all 1992 Corvette models. Called Acceleration Slip Regulation (ASR), Corvette's system was created by Bosch and developed in cooperation with Corvette engineers. It was engaged automatically with the ignition, but could be turned off by an instrument panel switch. Corvette's ASR used engine spark retard, throttle close down, and brake intervention to limit wheel spin when accelerating. When the system was on and active, the driver could feel a slight accelerator pedal pushback.

New Goodyear GS-C tires were introduced as standard equipment on all 1992 Corvettes and were exclusive to Corvettes worldwide for 1992. The GS-C tread design was directional and asymmetrical.

Improvements in weather sealing were achieved with improved weather-strip seals. Road noise reduction came from additional insulation in doors and improved insulation over the transmission tunnel.

The power delay feature was modified so that the passenger door also cut power, in addition to the driver door or fifteen minute time period.

The 1-millionth Corvette, a 1992 white convertible, was built July 2, 1992.

1993  Exterior appearance continued virtually unchanged for 1993 , but a 40th Anniversary Package (RPO Z25) was optional with all models. The package included a Ruby Red metallic exterior, Ruby Red leather sport seats, power driver seat, special wheel center trim and emblems.

All leather seats in 1993 Corvettes had "4Oth" anniversary embroidery in the headrest area. The base black cloth seats did not.

Horsepower for the base LT1 engine remained 300, but three changes made the engine quieter. First, the heat shield design changed from a single-piece stamping to a two-piece sandwich type that was self-damping. Second, new thermostat polyester valve covers with "isolated" mounts replaced 1992's magnesium covers. Third' the LT1 camshaft exhaust lobe profile was modified to reduce the exhaust valve closing velocity. Also, a shortening of the inlet duration permitted more duration for the exhaust so there was no increase in overlap area. Emissions and idle quality weren't adversely affected. A side benefit of closing the inlet valve sooner was an increase in torque from 330 to 340 lb.-ft at 3600 rpm.

Horsepower increased for the optional ZR1's LT5 engine from 375 to 405hp, a result of modifications to the cylinder heads and valve train. Other changes included four-bolt main bearings, a Mobil 1 synthetic oil requirement, platinum-tipped spark plugs, and an electrical, linear exhaust gas recirculation (EGR) system for improved emission control.

The 1993 Corvette was the first auto sold by GM to feature a passive keyless entry (PKE) system. Working by proximity, a battery-operated key-fob transmitter sent a unique code picked up by a receiver in the Corvette through one of the two antennas ( in coupes, antennas were in the driver door and rear deck; in convertibles, antennas were in both doors). The transmitter required no specific action by the owner; approaching the vehicle with the transmitter would unlock the doors, turn on the interior light, and disarm the theft-deterrent. Leaving an unlocked vehicle with the transmitter would lock the doors and arm the theft-deterrent. The PKE could be turned off completely and transmitters were programmable for locking and unlocking just the driver door, or both driver and passenger doors. Transmitters for convertibles had a single button for programming and driver/passenger door unlocking; transmitters for coupes had an extra button for rear hatch release.

Front wheels for base cars were decreased from 9.5x17 to 8.5x17 and the front tire size from P275/40ZR17 to P255/425ZR17. Rear tire size was increased from P275140ZR17 to P285140ZR17. For RPO Z07, 9.5x17 wheels and P275140ZR17 tires were used front and rear.

Although the same in design as the previous model, 1993's wheels had a different surface appearance due to a change in finish machining.

1994  The exterior design for 1994 was carried over from 1993, but two new exterior colors were available, Admiral Blue and Copper Metallic. Also, new non-directional wheels were included with ZR1 models.

Power output of the base LT1 engine remained 3OOhp, but several refinements were added. A new sequential lull injection system improved response, idle quality, drive ability and emissions by firing injectors in sequence with the engine's firing order. A more powerful ignition system reduced engine start times, especially in cold temperatures.

The standard 4-speed automatic transmission was redesigned with electronic controls for improved shift quality and rpm shift-point consistency. Also, a safety interlock was added which required depression of the brake pedal in order to shift from "park."

Interior revisions included addition of a passenger-side airbag and knee bolster (and removal of the instrument panel glove box), new seat and door trim panel designs, finer-weave carpeting, "express down" driver's power window, and a redesigned two-spoke airbag steering wheel. New white instrument graphics turned to tangerine at night. The tire jack was relocated from the exterior spare tire well to an inside compartment behind the passenger seat.

For 1994, all seats were leather. Base and optional "sport" styles were available. Both featured less restrictive bolsters to accommodate a wider range of occupant sizes and for improved entry and exit. Controls for base seats with optional power assist were console-mounted with individual controls for driver and passenger. With sport seats, a single set of power assist controls for both seats was console-mounted. Also, individual motors adjusted the lumbar support for sport seats and these controls (and the side bolster control) were relocated from the seat to the console for 1994. Reclining mechanisms for all 1994 seats were manual.

The rear window for convertibles was changed from plastic to glass and included an in-glass defogger.

Spring rates for RPO FX3 (selective ride control) were lowered to improve ride quality. For the same reason, recommended tire pressures were reduced from 35psi to 3Opsi (except ZR-1).

Air conditioning systems were revised to use R-134A refrigerant, a non-ozone depleting CFC substitute.

Optional Goodyear Extended Mobility Tires (RPO WY5) had special bead construction to permit use with no air pressure. The low tire pressure warning system (RPO UJ6) was required because if the tire was run deflated more than about fifty miles, damage could result. However, the safe driving range was substantially farther.

1995  The 1995 exterior was distinguished from 1994 by restyling of the front fender "gill" air vents. A new exterior color, Dark Purple Metallic, was added, but 1994's Copper Metallic and Black Rose Metallic were deleted.

Corvette paced the Indianapolis 500 race in 1995. A replica, Dark Purple and White (convertible only) with special accents, sold 527 units.

Optional Sport Seats had stronger "french" seam stitching. A readout for automatic fluid temperature was added to the instrument display. Out of sight were numerous Velcro straps to reduce rattles, and a stronger radio mount for less CD skipping. A drip tube was designed into the A-pillar weather-strip for improved water intrusion control.

The base LTl engine continued with the same 3OOhp and 340 lb-ft torque ratings, but there were refinement 5. Late in 1994 production, connecting rods were changed to a powdered-metal design to improve both strength and weight uniformity. Fuel injectors were revised to better cope with alcohol blend fuels and to reduce fuels dripping after engine shutdown. The engine cooling fan was modified for quieter operation.

This was the ZR-1's last year. Mercury Marine in Stilliwater, Oklahoma, completed all LTS engines in November 1993. Tooling, owned by GM, was removed from Marine's factory and all engines, specially sealed, were shipped to Corvette's Bowling Green assembly plant for storage until needed. Before September 1, 1993, all internal engine warranty repair was done by Mercury Marine. Between September 1, 1993 and December31, 1993, internal repairs were done by Mercury Marine if engines had under 12,000 miles or 12 months service. Chevrolet handled service not performed by Mercury Marine, including all after January 1, 1994. Total 1995 ZR-1 production was predetermined at 448 units, the same as 1993 and 1994. Total ZR-1 production for 1990 through 1995 was 6,939.

Clutch controls in the four-speed automatic transmission were improved for smoother shifting, and its torque converter was both lighter and stronger. The 6 speed manual was redesigned by replacement of the reverse lockout with a high-detent design for easier operation.

The larger brake package, included previously with Z07 and ZR-1 performance options, was included for 1995 with all models. And all 1995's had the latest anti-lock/traction control (ABS/ASR-5) system.

The extended mobility "run flat" tires introduced as a 1994 option minimized the need for a spare tire. So 1995's RPO N84 created a~delete spare option which reduced weight and included a credit of $100.00.

Base suspension models had lower front and rear spring rates.

Windshield wiper arms were redesigned with revised contact angles and higher contact force to reduce chatter at all speeds, and lift at high speeds.