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When Harley Earl first envisioned his two-seat roadster in 1953, it is unlikely that even he would have been able to fathom the long term commercial success the Corvette would achieve. Both on the road and on the racetrack, the Corvette had demonstrated again and again that it could compete with some of the fiercest automotive competitors from around the world. From its earliest days racing against the Porsche 356 at the 24 Hours of LeMans to competing at some of the most grueling road courses of the day, the Corvette had become a world leader that had celebrated decades long victories in sales, showmanship and performance. Now, as the Corvette prepared to turn 40, Chevrolet decided to honor the milestone by releasing a special edition Corvette to pay homage to the American legend.
The 40th Anniversary Edition Corvette was introduced as a special option (RPO Z25) for the 1993 model year. It featured a special Ruby Red exterior with matching leather seats and wheel centers, and special badging that featured the 40th Anniversary Corvette logo. Option Z25 sold for an additional $1,455.00 and was available on both coupes (including the ZR-1) and convertibles. It was ordered on more than a quarter of the Corvettes built in 1993 – a total of 6,749 40th Anniversary Corvettes were built in all. Additionally, all of the Corvettes that were ordered with leather seats came equipped with specially embroidered headrests that featured the 40th Anniversary emblem. However, Corvettes ordered with the standard (and increasingly unpopular) black cloth seats remained unadorned with any commemorative badging.
While the official 40th Anniversary Edition Corvette was ordered by many Corvette purists to celebrate the momentous occasion, there was another Corvette package offered in 1993 that catered more to the performance fanatics. Florida-based Greenwood Automotive Performance unveiled a bolstered Corvette coupe. Named only with the distinction “G572” (so named for the size of the engine), the Corvette featured functional aero body panels and a reinforced chassis that were specifically modified to support the massive torque put on them by the car’s 575 horsepower engine. Under the car’s hood lived a 9.4-Liter (572 cubic inch) Chevy V-8 that was mated to a GM four-speed automatic transmission. When this special edition Corvette was run with the throttle full open, the Corvette could accelerate from zero-to-60 miles per hour in just 3.4 seconds, and best a quarter mile at just 11.5 seconds at a speed of 135 miles per hour. Additionally, when running fully open, the Corvette could hit and maintain a speed of 218 miles per hour. Of course, achieving that level of incredible power has always been an expensive undertaking, as was the case with the G572, which carried a price tag of $179,333.
Sadly, the base model coupes received virtually no cosmetic upkeep from the previous model year – but with just two exceptions: First, while the wheels on the Corvette included the same rotary cut pattern as that of the 1992 Corvette, the wheels still reflected a different physical appearance because they were machined differently than the wheels found on the 1992 Corvette. Additionally, the 1993 Corvette would be the last model year that consumers could order cloth seats as an option, and it was a sound decision on the part of GM to eliminate this RPO from all future models, especially given the fact that only 426 Corvettes were ordered with that option. Finally, the size of the front wheels on the base model Corvette coupe and convertible were reduced in size from 9.5x17 to 8.5x17 and the corresponding front tire sizes were reduced from P275/40ZR17 to P255/45ZR17. Similarly, the rear tire size was increased from P275/40ZR17 to P285/40ZR17. For Corvettes that included RPO Z07, 9.5x17 wheels and P275/40ZR17 tires were used on both the front and rear.
As in years past, the tires were courtesy of Good Year and were directional, asymmetric Eagle GS-C’s that were utilized exclusively on the Corvette during their first year of production. While new, these tires did utilize a similar tread pattern as in earlier models, though the tires designed for the 1993 Corvette were better equipped to handle the cornering stresses that occurred on both the inner and outer edges of the tire. Having specially balanced tires was a tremendous improvement to the Corvette’s drivability, though given the unique nature of each tire, owners had to be cautious about replacement given that no tire was interchangeable with another.
Mechanically the 1993 Corvette Coupe also remained virtually unchanged, although some small, but significant improvements had been made to make the Corvette continually more competitive on the racetrack. While the LT-1’s horsepower remained at 300, several modifications were made to make the engine quieter. First, the heat shield design was changed from a single piece stamping to a two-piece sandwich type shield that was self-damping. Second, the LT-1 camshaft exhaust lobe profile was modified to reduce the exhaust valve closing velocity. Additionally, a shortening of the inlet stroke duration allowed a longer exhaust stroke duration with no increase in overlap area between the two strokes. A side benefit of this modification resulted in a small, but significant, increase in torque from 330 to 340 lbs/ft of torque at 3,600rpms. Third, new thermostat polyester valve covers replaced the 1984-1992 magnesium covers. These covers were isolated from the heads by a gasket in the normal location, but also by gaskets under the heads of the mounting hardware.
Perhaps one of the most notable improvements to the 1993 Corvette was the introduction of a passive keyless entry (PKE) system. Unlike other keyless entry systems, which required the vehicle owner/operator to unlock the vehicle by pressing a “LOCK/UNLOCK” button on a small transmitter, the PKE system automatically communicated with the Corvette when the driver was in the general proximity of the vehicle. The battery operated transmitter would simply transmit a unique code which could be picked up by the Corvette through one of two antennas – in coupes, the antennas were located in the driver door and the rear deck lid, - in convertibles, the antennas were located in both the driver and passenger doors. When a
driver approached the Corvette, the PKE would unlock the doors, turn on the interior lights, and deactivate the theft deterrent system. The PKE system could be turned off completely, and could also be programmed to lock or unlock the driver’s door only, or both the driver and passenger doors. Coupes that were equipped with the PKE system included an extra button on the transmitter that would unlock the rear hatch.
The LT5 engine (featured in the ZR-1 Corvette) received a minor boost in power. For 1993, the ZR-1 Corvette’s horsepower was increased from 375hp to 405hp. Given the overall lack of ZR-1 sales, many questioned the decision to improve upon the performance of the LT5 engine at all, though most critics agreed that doing so would again increase the performance gap between
between the ZR-1 and the base coupe, putting the ZR-1 back in a class of its own. This power increase was achieved as the result of a series of changes to the LT5’s cylinder heads and valvetrain. Additional modifications were made to the LT5 as well including the introduction of four bolt main bearings, platinum tipped sparkplugs, an electrical, linear EGR (Exhaust Gas Recirculation) system for improved emission control and the requirement of using Mobil 1 synthetic oil as the only spec compliant engine lubricant. These improvements would help propel the ZR-1 to set a new top speed record of 179 miles per hour, which was faster than any other unmolested Corvette ever.
Despite the absence of notable, physical changes to the design of the car, the overall sales numbers of the 1993 Corvette actually increased over previous years. A total of 21,590 Corvettes were manufactured and sold, marking 1993 the first model year in four years to actually witness an increase in its numbers. Additionally, the ZR-1 Corvette received the accolades of being the winner of the top speed category of Car & Driver’s “Ten Best” issue (January, 1994). Despite this, the ZR-1’s numbers continued to head south, with just 448 units being produced that year.
1.) The Pocket Book of the Corvette: The Definitive Guide to the All American Sports Car - Copyright 2003, Barnes & Noble
3.) Corvette Black Book - Copyright 2009, Michael Bruce Associates, Inc.
4.) The Complete Book of Corvette, Every Model Since 1953 - Copyright 2005, Mike Mueller - MBI Publishing
DID YOU KNOW:
The 1993 ZR-1 Chevy Corvette received a huge power boost jumping 15 horsepower from 385hp to 405hp. Torque was also improved from 370 lb-ft to 385 lb-ft. This was accomplished through porting changes on the head and valvetrain, an electric EGR valve improving emissions, platinum tipped spark plugs, and four bolt main bearing caps.