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Illustrated Corvette Series No. 174 -
1996 LT4 Small-Block Chevy - "The Finished Classic SBC?"
The ‘97 C5 Corvette was introduced to the press in November ‘96 at Road Atlanta Raceway, in Georgia and went on sale at Chevrolet dealers on March 7, 1997. Not only was the body, interior, chassis, and suspension all-new, there was a totally new engine and transaxle. The splash the new C5 created, followed up with roadsters, Pace Cars, hardtops, race cars, and a Le Mans win in ‘01, was so huge that the highlights and achievements of the C4s quickly faded. While the jewel-like LT-5 that powered the exotic ZR-1 still stands as the high watermark of the C4 generation, there was a quieter high watermark that took place. Had the LT4 engine option arrived a few years before, there would have been another Chevy legend.
The C5 program was an on-and-off-and-on again project due to GM’s financial troubles in the early ‘90s. Initial sorties began in ‘88 with the intention of an all-new C5 a ‘93 model. Corvette chief engineer, Dave McLellan was given a budget of $250 million, but that number turned into a roller coaster ride with the C5 being pushed back year after year. GM’s miracle of the ‘90s was that there even was a C5 Corvette. All of this makes the LT4 even more amazing.
The LT4 engine was offered as part of the $3,250 ‘96 Grand Sport package, plus as a $1,450 option on all ‘96 Corvettes, but only coupled with the 6-speed manual transmission. So, if the ‘96 Corvette production started sometime in the summer of ‘95, that means that the LT4 engine was probably in development maybe a year earlier, around the height of the C5 development. With an all-new car, plus an all-new engine in development, it’s incredible that any attention was given to revising LT1. They could have let the LT1 ride out the C4 generation and no one would have noticed.
The LT1 engine that arrived as the base ‘92 Corvette engine was a marvel itself, but was unfortunately in the shadow of the ZR-1’s 24-valve, double-overhead cam LT-5. Buyers of ‘92 Vettes received an additional 50-HP over the L98 engine from previous Corvettes! The 300-HP LT1 featured reverse cooling that pumped cooled radiator fluid into the heads first, then the rest of the engine, allowing higher compression, more spark advance, and more consistent cylinder temps. Other improvements included improved computer controls, reduced exhaust back pressure, new camshaft profile, improved breathing in the cylinder heads, and a new multi-port fuel injection system. The ‘96 LT4 started where the LT1 left off, by using classic hot rod techniques. The basic rules apply to all internal combustion engines: improved breathing, combined with better fuel delivery, equals more efficiency, and horsepower. Engineers tweaked a little here and there, and ended up with a nice 30-HP bump. Here’s what they did.
To keep the package together, stronger nodular iron main bearing caps were used and a new teflon rear crank seal was employed for greater durability. Compression was increased slightly from 10.4:1 to 10.8:1 with revised pistons with matching valve pockets. The LT4’s camshaft has slightly more lift and duration, with valve overlap increased from 41 to 46-degrees. In front of the LT4 the torsion damper is a dual unit, while the LT1’s is a single unit. The timing chain used a roller chain and steel sprockets.
The intake manifold was modified to better match the improved head ports. Although the manifold was ported to match, there was enough extra material for safe porting. Fuel injectors were enlarged from 3.0 grams per second to 3.5 GPS. The revised manifold was then powder coated red to differentiate the LT4 from the LT1.
Big improvements were made inside the heads. The intake and exhaust ports have larger radius bends for smoother flow and less back pressure. Each intake port volume was increased 25cc to 195cc and the combustion chamber roof was slightly lowered and the walls were moved back, unshrouding the the valves. With the valve covers off, the top of the heads looks like a racing engine with modified Crane roller rockers replacing the LT1 stamped steel rockers. Valve springs are oval section and have higher closing force. Deeper inside the heads, the intake valve was increased from 1.94 to 2.0-inches and the exhaust increased from 1.50 to 1.55-inches. Arguably, the only thing missing from the LT4 package was a set of steel tube headers.
Each improvement by itself might not seem like much, but the combination netted out 30 extra horsepower. While the torque rating is the same as the LT1, the engine’s redline was up 800 to 5,800 rpm. It’s also worth noting that the LT4’s horsepower rating is “net” 330-HP, putting the gross somewhere in the low 400 range, making the LT4 nearly as stout as an old 427 big-block.
Even though the public knew that a new Corvette was coming soon, sales of the ‘96 model were up slightly over ‘95, to 21,536 with 6,359 cars optioned with the LT4. Actually, everything that was done to the LT4 could be considered standard hot rod engine building. The only complaint that one could level at the LT4 is that it wasn’t release sooner, or better yet, in ‘92 as the LT1. - KST
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Illustrated Corvette Series No. 150 1963, 1996, & 2010 Grand Sport Corvette -
"'Three Generations of Grand Sport Corvettes"
There’s nothing quite like a surprise at a birthday party. On April 24, 2009, at the National Corvette Museum’s C5/C6 Registry Birthday Bash, GM officials floored the audience with the unveiling of the 2010 Grand Sport Corvette. The last time we saw a Grand Sport was more than 13 years ago, in 1996. Times were very different then, as the C4 was making its last appearance. Spy photos of the C5 were all over the car magazines, so Chevrolet’s challenge was maintaining customer interest in a car that was in its final year of production. The solution came in two parts: the Collector Edition—a special paint-and-trim option—and the stunning Grand Sport model. The Admiral Blue Grand Sport—with its white center stripes, red hash marks, black wheels, and other assorted details—was an instant classic. Production was limited to just 1,000 units, and the $3,250 price made it the most expensive option for the ‘96 Corvette. But after six years of the $31,000-plus ZR-1 package, the Grand Sport seemed like a bargain. Since then, the C4 Grand Sport “look” has been applied to all sorts of Corvettes, with many delightful results.
But the Grand Sport story goes back much further than 1996. In fact, it stretches back 34 years, to late 1962 and a test session at Riverside Raceway. It was there that a disheartened Zora Arkus-Duntov saw his latest effort come up short against a formidable new challenge: the Shelby Cobra. Duntov and his team were “field testing” a new ’63 Sting Ray equipped with their latest racer kit, the Z06 option. Since 1957 Duntov had made sure that Corvette racers had an excellent foundation for competition. The 283 fuelie engine provided plenty of grunt, while RPO 684 provided suspension and braking improvements. The package was very successful and was the foundation for Corvette dominance in several SCCA racing classes. Duntov was very happy with the performance of the Z06-equipped ’63, thanks to a new frame that allowed the engine and driveline to sit lower, improving the car’s center of gravity. The four-wheel independent suspension was far superior to the earlier layout, which was described by many racers as, “stab ‘n’ steer.” While most drivers were able to adjust their driving style to fit the Corvette’s unique handling characteristics, it was still a crude way of getting around the track. Many a track official had his wits scared out of him by a Corvette coming around a curve sideways, seemingly out of control. But the presence of the Cobra stopped the new Corvette in its tracks. Duntov and his crew had expected to be several steps ahead of the competition with their new car. Instead, they found themselves seriously outclassed. But Duntov always had another plan.
What happened then could never have taken place in the modern era. Fortunately, Duntov had very powerful friends at the top of GM’s food chain—namely, Ed Cole and Semon “Bunkie” Knudsen. It was Cole who hired Duntov in 1953 with instructions to do something with the fledgling Corvette. And although Knudsen was the son of William “Big Bill” Knudsen, the man responsible for GM’s quick turnaround during the war effort in 1940, he was no privileged rich kid. Knudsen learned the car business from the bottom up, working on the assembly line during his summer breaks from college. He also liked fast cars and was solidly behind Duntov’s racing efforts, so he understood the Corvette chief engineer’s dilemma with the new Sting Ray and the quicker Cobra. The obvious solution to level the playing field was to build a lightweight Corvette. Knudsen agreed and approved Duntov’s ambitious plans for the Grand Sport model. While the move might not seem like a big deal today, in 1962 GM was on board with the infamous AMA ban on factory-supported racing. The Grand Sport proposal was in direct violation of the ban and ran counter to GM’s official position. Duntov knew it, and Cole and Knudsen looked the other way.
Knudsen approved the construction of six lightweight Corvettes of Duntov’s design. After the six initial cars, 125 more Grand Sports were to be built to qualify for FIA homologation. Another 1,000 units would be produced for public consumption.
Duntov started with what was then a state-of-the-art ladder-type frame made from large-diameter steel tubing. The front suspension was similar to, but much lighter than, the stock Corvette setup. The rear suspension used the new Sting Ray independent design, but with an aluminum differential and drilled-out trailing arms. Girling disc brakes were used with Halibrand lightweight magnesium wheels and contemporary racing tires. The body was very close to the production Sting Ray, but used much thinner fiberglass. The final weight of the new Grand Sport was around 2,000 pounds. Duntov had several exotic small-block engines in development, including one with hemi-style heads, another with double overhead cams, and even an all-aluminum fuelie. But none of Duntov’s exotic engines were anywhere close to being ready for competition, so a slightly modified 360hp fuelie was installed for initial shakedown runs. The first versions of the car looked almost stock, but by the time the Grand Sports arrived for the Nassau Speed Week races, they had a full complement of flares, scoops, and fat tires. The cars looked tough and pounded the Cobras. Then GM’s top brass found out and killed the program—officially, anyway.
It’s amazing that Duntov wasn’t fired on the spot, but as I mentioned earlier, he had friends in high places at GM. Even more amazing was that the cars were not sent to the crusher. Grand Sports 003, 004, and 005 boasted 377ci aluminum small-blocks that breathed through four 58mm Weber carbs each and made 485 hp. Cars 001 and 002, meanwhile, had been converted to roadsters. When GM discontinued the program, the cars began passing from racer to racer, as various privateers tried to make the Grand Sport into a serious competitor. But the mid-’60s were a time of tremendous advancement in race-car technology, and in just four years, the Grand Sports were seriously outdated. They had numerous problems that were never fully sorted out, including a terrible front-end lift that would occasionally pull the tires off the ground at high speed. Many famous drivers spent time behind the wheel of a Grand Sport, including A.J. Foyt, Augie Pabst, Jim Hall, Dick Thompson, and George Winterstein. In 1967 Alan Sevadjian bought one of the cars for just $7,500. By the 1970s the Grand Sports were all but forgotten and their whereabouts mostly unknown. The cars began to surface in the late-‘70s, and today all five are accounted for. In January 2009, at RM’s Automobiles of Arizona, Grand Sport 002, one of the two roadsters, was a no-sale at $4.9 million.
Fast-forward to 1996, and the revival of the Grand Sport option. Obviously the C4 edition couldn’t be a lightweight, tube-chassis racer. But it was an extremely well-executed collection of off-the-shelf parts. Under the hood was the new LT4 engine, an enhanced version of the base LT1 that made an additional 30 hp (up to 330 total) with basic hot-rod hardware. These included a higher (10.8:1) compression ratio, new aluminum heads with bigger ports and valves, a revised camshaft, Crane roller rocker arms, and higher-flow fuel injectors. The new engine redlined at 6,300 rpm and had an 8,000-rpm tach. All 1,000 Grand Sports were painted with Admiral Blue paint and had a wide white stripe that ran from the nose to the tail. The ZR-1–style 17-inch wheels were painted black, and flares originally developed for the Japanese export market were installed on the rear fenders. As a salute to the Grand Sport racers, red hash marks were applied to the left front fender. The Z51 suspension option was available to stiffen up the car’s handling. Of the 1,000 cars built, 810 were coupes and 190 were convertibles. (The latter didn’t have the wider tires and the rear fender flares.) Priced at $3,250 for the coupe and $2,880 for the droptop, option Z16 became an instant classic. These days, show organizers like to put all the C4 Grand Sports together in rows, where they make for a dazzling presentation.
The C6 Grand Sport is a completely different animal. The base LS3 engine produces 430 hp—100 more than the old LT4. The new option fits neatly between the base Corvette and the Z06 and is available on both coupe and convertible models, in all color combinations. Oddly enough, the signature fender hash marks are optional. Perhaps most notable are the Z06 body panels, which include front and rear flared fenders, a front air-splitter, and a rear spoiler. The rear brake-cooling scoops are functional, but the front nose scoop is not. Visually separating the Grand Sport from the Z06 are a set of revised front-fender vents, with their ’67-inspired vertical slats. Model-specific five-spoke wheels are available in silver, Competition Gray, or chrome. The fronts measure 9.5 x 18 inches and are shod with Goodyear F1 run-flat tires sized 275/35ZR18. The 12 x 19-inch rears, meanwhile, get massive 325/30ZR19s. The front brakes have been enhanced with cross-drilled 14-inch front rotors and six-piston calipers, while the rears boast 13.5-inch rotors with four-piston binders. All four calipers are painted silver and wear red “Corvette” lettering.
Since the Grand Sport replaces the Z51 Performance Option, all of the Z51 goodies—heavy-duty springs, shocks, and stabilizer bars, along with coolers for the engine oil, transmission fluid, and steering fluid—are included. Additionally, all six-speed manual cars come with the Z52 option, which adds a dry-sump oil system, a rear-mounted battery, and a differential cooler. Manual cars also receive a new launch-control system. This system allows the driver to simply floor the gas, at which point the computer automatically selects the optimum launch rpm. All that’s left for the driver to do is drop the clutch and start shifting. All of the standard Corvette options are available on the Grand Sport, including four trim packages and the Dual Mode Exhaust System. Priced at $55,720 for the coupe and $59,530 for the convertible, the new Grand Sport is still around $15,000 less than a Z06. Zero-to-60 times clock in at 4 seconds flat, with quarter-miles in the low 13s or better. The car generates 1.0g on the skidpad and has an EPA rating of 26 mpg on the highway. Top speed is between 185 and 190 mph, making the latest Grand Sport faster than even the old racing versions.
For at least the first 20 years of its existence, the Corvette was always a hair’s breadth away from being canceled. Thanks to dedicated engineers like Duntov, McClellan, Hill, Juechter, and many others, the C6 Grand Sport can take its place among the greats of Corvette history. - KST
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Illustrated Corvette Series No. 100 1996 Grand Sport Corvette -
"'Finally, A Production Grand Sport"
The new C5 Corvette was behind schedule, but that didn't stop Dave Hill and his crew from dishing up the stunning '96 Grand Sport option. The 1963 Grand Sport was arguably the ultimate "could have been great" Corvette. And while the '96 Grand Sport option was a long way from the 2,000-pound 1963 road racer, it was "official" and available to the public.
There were three hot-ticket options for the '96 Corvette. As an interim step for the C5 model, there was the new LT4 engine that was available on all manual transmission Corvettes. This 330-horsepower option put the '96 Corvette in the 13.5-second quarter-mile range. Then there was the Collector's Edition with its Sebring Silver paint and ZR-1-style 17-inch wheels. And for the historic racing crowd, there was the Grand Sport option.
In 1963, then Chief Engineer Zora Arkus-Duntov, built five, 2,000-pound Corvette replica race cars to battle Carroll Shelby's 298 Cobras. When the GM brass found out about Duntov's back door racing program, the axe fell and the five Grand Sports were thankfully sold and not put into the crusher.
In the late '80s Corvette racer and engineer Dick Guldstrand built modified Corvettes that he called "Grand Sport 80," followed by his stunning "GS90 Corvette" in the mid-'90s. But for some odd reason, Chevrolet stayed away from using the Grand Sport tag until 1996.
The Grand Sport option was available on the coupe for $$3,250 and on the roadster for $2,880. Included with the Grand Sport option was the $1,450 optional LT4 engine with 330-horsepower. The most noticeable features were the Admiral Blue paint and bold white stripe that ran over the hood, top, and tail, and the blacked-out ZR-1 5-spoke wheels that wore Goodyear P255/45ZR17 tires in the front and P315/35ZR17 tires in the rear. Rather than use the ZR-1's wide rear body parts, the rear tires were covered with fender flares designed for Japanese export Corvettes. The roadsters all had smaller tires and no rear fender flares. The interior could be either all black, or red and black with unbraided "Grand Sport" trim. Other GS details included black brake calibers with raised Corvette lettering and special serial number sequences, similar to the ZR-1. Red hash marks were added to the driver's side front fender as a salute to the racing '63 Grand Sports.
The new LT4 engine also saluted the Grand Sport with a bright red throttle body with "Grand Sport" lettering. All of the other Corvette performance options were available with the Grand Sport.
A loaded Grand Sport coupe cost nearly $45,000 and a roadster went for over $53,000. To insure exclusivity, only 1,000 Grand Sports were built - 810 coupes and 190 roadsters. The Grand Sport option was part of the 3-part swan song for the C4 Corvette. Duntov would have been very happy. - K. Scott Teeters
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lllustrated Corvette Series No. 101 1996 Collector's Edition Corvette
"Going Out In Style"
By 1996, car magazines were teasing readers with "spy photos" of the '97 Corvette. Meanwhile at Chevrolet dealer showrooms, there were two delicious optional special edition Corvettes. The Grand Sport was a salute to the 1963 Grand Sport racers. The Collector's Edition was just plane gorgeous.
The 1984 model was a huge leap in technology for the Corvette. After all, the '82 Corvette was riding around on a chassis and suspension that was designed in the early '60s and introduced in 1963! While the '84 Corvette only had a 30-horsepower power increase over the '82 model, it was only packing 230-horsepower under the hood. Fast forward to '96 and the optional LT4 engine produced 330-horsepower! And remember, that was "net" horsepower. In the golden days of "gross" power ratings, the new LT4 engine would have been in the low 400-horsepower range. That means that a '96 LT4 Corvette was in the performance range of the old 427/435 L71 big-block Corvette.
Actual performance figures prove this out with 0-to-60 times in the low 5-second range and quarter-miles numbers in the mid-13's! High performance was back folks, and the car handled better and got better gas mileage - it just wasn't as loud. And another thing is that the 1996 Corvette got double the gas milage of a '67 big-block Vette!
A '96 Corvette Collector's Edition could be ordered with the optional LT4 engine and other performance options that made this one of the sweetest package Corvettes made to that point. Performance was just a tick off the stump puller ZR-1 and 2/3s the price. The Sebring Silver paint and the ZR-1-styled allow wheels gave the car beauty to go along with its new LT4 brawn.
The Z15 Collector's Edition package was very reasonably priced at $1,250. Included was the special Sebring Silver paint, painted ZR-1 5-spoke alloy wheels, black brake calipers with polished raised "Corvette" lettering, and embroidered seats. Available interior colors were black, red, or gray. Convertible optioned cars all had black tops. Since there were no production limits for the Collector's Edition, a total of 5,412 units were sold, accounting for 25-percent of the total '96 Corvette production run.
The C4's life cycle saw one revolutionary leap (the ZR-1) and evolutionary growth every year and 1996 was no exception. The optional 330-horsepower LT4 engine was an intermediary step towards what would be the standard engine in the '97 C5 model. The F45 Selective Real Time Dampening system was a $1,695 option that provided Corvettes with a mechanical-electronic active suspension. The Bosch ABS/ASR, anti-locking and acceleration slip system was standard, as were Goodyear run-flat tires, and a low tire pressure sensor. The passive-keyless entry Pass-Key II was also standard. And remember, these improvements were on top of 12 previous years of improvements.
Through the '80s and '90s car magazines kept announcing, "The Best Vette Yet!" And each year it was true. A loaded '96 Collectors Edition coupe cost slightly over $43,000 and a roadster close to $51,000. Still twice as much as a regular Chevy, but 2/3s the cost of some of the sacred cows from Europe. Plus, the Corvette did nearly everything better and had a solid 43-year heritage! - K. Scott Teeters
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lllustrated Corvette Series No. 102 - 1996 Corvette - The Last C4
"Farwell to the Amazing C4 Corvette"
Corvette people are brilliant. Mike Yeager of Mid America Motorworks came up with a novel idea. While most collectors think of " special editions" and "firsts," Mike thought of the "last" C4 Corvette off the production line. No one had ever considered that before. Here's food for thought - imagine how valuable the last production line C1, C2, and C3 Corvettes would be today. Mike must have been thinking along that line when he approached Chevrolet with his unique proposal.
As the '90s progressed, the rumors of a replacement for the aging Corvette began to build. When GM announced in mid-'95 that the '96 model would be the last of the C4 Corvettes, Yeager launched his plan. Mike leveraged his relationship with Chevrolet with a unique proposal. Yeager's request was to be permitted to buy the very last Corvette to roll off the production line, on the condition that the he would retain ownership of the car and display it at his "MY Garage" (Mike Yeager Garage). Mike has an impressive collection Corvettes and other cars. GM liked the proposal, had nothing to lose, and a lot of publicity to gain. So a deal was struck and Mike began his plans to make the "Last C4" a very special car.
Yeager decided that the Last C4 should be visually unique. In honor of the first Corvette, he chose polo white as the body color. From there he added the Grand Sport rear fender flares, white ZR-1 wheels, red Grand Sport front fender hash marks, special embroidery for the seats, and special "Last C4" decals for the front fenders and the windshield. Under the hood was a standard LT1 engine and an automatic transmission. The overall look was clean and unique.
June 19, 1996 must have been a strange day at the Bowling Green Corvette assembly plant. Yeager was on hand to watch and video tape the Last C4 as it made its way down the assemble line. As each station completed its tasks, workers began disassembling the production line equipment behind the car. It took two days to build the Last C4 and Mike helped assemble the right front suspension and rear shock assemblies.
Even the engine for the Last C4 was special, as it was the last Corvette engine to come from the Flint, Michigan Corvette engine assembly facility. The tag on the shipping crate read, "After 41 years - the end." As the car left each assembly station, Yeager asked each of the workers to sign the car. Signatures are all over the inside of the car. When the car was complete, all of the assembly workers gathered for a group photo. Then the car was transported to the National Corvette Museum for a party and a memorial service for Zora Arkus-Duntov. Two months later, The Last C4 won the "Chip's Choice" award at the 1996 Carlisle Corvette Show.
When the Last C4 came home to MY Garage, Mike had stacks of documentation for the car. The Last C4 has NEVER been driven and still has the plastic seat covers. Yeager then bought the "First C5" and had it trimmed out like the Last C4 - polo white with white wheels and red fender hash marks. Simply brilliant! - K. Scott Teeters
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lllustrated Corvette Series No. 103 - The C4 Review
"Farwell to the Amazing C4 Corvette"
Perhaps we should call the C4 Corvettes the "come back" generation. In terms of performance enhancement, you have to go all the way back to the C1 Corvettes to see a more dramatic improvement. Take a look back at the darkest days of the Corvette story to 1980. The only engine available for California buyers was the LG4, a 180 horsepower, 305 passenger car engine with an automatic transmission!
Then fast-forward to 1995 and have a look at the last ZR-1 with 405 horsepower. The change is nothing less than mind- blowing. Given the climate of the automotive industry of the early '80s, it's amazing that GM actually approved the development of the C4 Corvette. Fortunately, thanks to the keen minds of Chief Engineers Dave McLean, Dave Hill, and many dedicated Corvette designers, the C4 didn't just survive, it thrived!
Back in the golden days, Chevrolet never made enough cars to meet the demand for new Corvettes. There was always a waiting list. In 1982 it was decided that while the new '84 model was being finalized there would be no '83 Corvette . There actually were "left over" '82 cars that were sold into '83.
The new C4 Corvette had several design parameters that included: more ground clearance, lower height, lower center of gravity, and improved front-to-rear weight distribution. To achieve these goals, the engine was moved back into a "front-mid-engine" position, and the exhaust system was stuffed up into a wider transmission tunnel.
The roadster option left Corvette catalog after 1975. In the name of safety, car makers were abandoning open-air motoring. Since the C4 hadn't been designed to be a roadster, engineering came up with a unique fix to add structural rigidity.
A large "X" brace was added to the bottom of the chassis under the driver's compartment. Transverse cross members were also added to the engine cradle and between the b-pillars behind the driver. Ride height was increased 10mm to maintain ground clearance. Many other adjustments were made to make up for structural integrity, including lowering tire pressure to 30psi to soften up the ride.
But despite the $5,000 premium for the roadster, 7,315 units were sold and famed test pilot, Chuck Yeager drove a Corvette roadster to pace the 1986 Indy 500.
Horsepower was up to 230 by '85 and anti-lock brakes were standard on all '86 Corvettes. Chevrolet was also warming up to the idea of "officially" racing Corvettes. The Showroom Stock series was being dominated by Corvettes!
Corvettes have always had a weight problem. Remember that the '82 Corvette was using heavy suspension parts that were introduced in 1963! With a combination of improved construction techniques, and the use of aluminum alloy parts, the '84 Corvette weighed 295-pounds less than the '82 model. Then added into the mix was a vastly improved suspension, new brakes, and better weight distribution. The end result was that new C4 handled like a SCCA race car.
Restyling a Corvette is one of the toughest design jobs in the automotive business. The new design had to look "new," but at the same time has to look like an older Corvette. The '84 Corvette was met with rave reviews, despite the increase of only 5 horsepower. But hey, the car looked great and it was a great start
To slam the Corvette into the realm of "super car," something wild was needed under the hood. Dave McLean enlisted the help of newly acquired Lotus to design a jewel-like engine. The new ZR-1 was to have everything an exotic engine should have: all-aluminum block and heads, double overhead cams, and electronic fuel injection. When Lotus was finished, they had a 345 hp horsepower powerplant, dubbed the LT5. Chevrolet contracted aluminum engine specialists Mercury Marine to cast and built the exotic new engines.
Adding an extra 125 horsepower meant the complete drive train and suspension had to be beefed up and using wider rear tires. Not wanting to make add-on rear fender flares, designers instead widened the entire rear section of the car from the doors back. Except for the shape of the tail lights, everything looked like a normal Corvette - just a bit wider.
The ZR-1 enters the record books as the most expensive Corvette option, ever! The base price of a '90 Corvette was $31,979. The ZR-1 option cost $27,016. Buyers were looking at a $60,000 Corvette! But back to the good parts, the ZR-1 was a real rocket. From a performance perspective, the ZR-1 did everything much better than a stock Corvette - it just cost twice as much.
From 1990 to 1995 Chevrolet sold 6,939 ZR-1 optioned Corvettes. The final '95 ZR-1s packed 405 horsepower. Stock Corvettes had improved so much that the expensive ZR-1 was only a few ticks quicker and faster and quicker.
In March of '90, Tommy Morrison drove a race-prepared ZR-1 to smash Ab Jenkins nearly half-century land speed record, with an average sustained speed of 175.885 for 24 hours! Jenkins' car as a special-built racer, not a production car.
Chevrolet was enjoying their new performance freedom with the C4 Corvette. Reeves Callaway pitched Chevrolet to let him offer Callaway Twin-Turbo Corvettes as an official Corvette option. GM wanted all engines to pass EPA regulations. Callaway complied and from 1987 to 1991 the Callaway Twin-Turbo was an official $33,000 Corvette option, selling 497 units in five years. Callaway even offered a topless speedster version of his twin-turbo cars.
To understand the development of the Corvette, keep two things in mind. First, Corvettes are made by GM and nothing happens quickly at GM. And second, "evolutionary, not revolutionary." Progress can feel frustrating, but in the long term, the car keeps getting better.
Every year, engineers kept improving the mechanics of the car. Every few years, stylists would change wheels, front and rear fascia, and side gills. The interior was in a constant state of being improved with little details.
The 40th Anniversary Package was unofficially known as "Ruby Red" because of its bright red metallic paint. This was a gorgeous package, even though it was available on all Corvettes for '93. The $1,455 package included the ruby red paint, red interior, and special trim. A whopping 6,749 units were sold. Only 245 were ZR-1 Coupes.
Aside from its styling, one of the most important aspects of the Corvette has always been, "what's under the hood." The '91 Corvette packed 245 horsepower with its cast iron L98 engine. In '92 the LT1 engine with aluminum heads with 300 horsepower was stock. Finally, in 1996 we saw the optional LT4 with 330 horsepower.
We also saw a lot of experimentals, engineering studies, racing versions, and show cars from 1984 to 1996. Here's a list of the special Corvettes that wetted our performance appetites: 1985 to 1988 Showroom Stock racers, 1987 Indy Corvette Concept Car, the 1988 running version of the Indy Corvette, the 1988 Geneve Corvette Show Car, the 1988 Corvette Challenge racers, the 1989 GTP Corvette racer, the 1990 Stingray III Show Car, the 1990 CERV III engineering study, the ZR-2 454 big-block engineering study, and the amazing 1992 aluminum engine, Falconer V-12 engineering study.
In 1995 a Corvette was to pace the Indy 500 for the third time. "Pace Car Specials" have always been a sticky issue with Chevrolet. The '78 Pace Car Special saw wild speculation as a collectible car. A few buyers paid nearly double thinking that the car would become a valuable commodity. When the Corvette Roadster was chosen to be the pace car at the '86 Indy 500, Chevrolet decided that all '86 Roadsters were "Pace Car Replicas." The door decals were to be applied by the owner.
When the Corvette was chosen for the 1995 Indy 500, Chevrolet decided to make the "Pace Car Special" a real collectible, and this wasn't a "sticker for the doors" deal. The car was treated to a beautiful white and burgundy paint job with a brilliant Indy 500 ribbon graphic, ZR-1 wheels and special interior trim. The best part was that only 527 were built, making them the rarest of the pace car Corvettes.
In mid-1995, Chevrolet gave the green light for the development of the C5 Corvette for 1997. Dave Hill had taken over as Corvette Chief of Engineering in '92 from Dave McLellan. Hill certainly had a better car to work with than when McClellan took over from Duntov in '75. Dave Hill and his team went over every part on the C4, looking for ways to improve the overall package and laying the groundwork for the C5.
Hill made sure that 1996 would be an excellent year with two special options and a major engine improvement. Enter the LT5 engine, a hot rodder's dream. The new engine had higher compression, new aluminum heads, Crane rollers rocker arms, and a new camshaft. Let's not forget an extra 30 horsepower. The 330 horsepower LT4 was available on all Corvettes, including the optional Grand Sport.
This was a salute to Zora Arkus-Duntov's ultimate "could have been" Corvette, the '63 Grand Sport. The '96 Grand Sport option was intended to be rare and was limited to 1,000 units.. The package included the 330 horsepower LT4 engine, wide, painted black-spoked ZR-1 wheels and tires, special interior trim, special Admiral Blue paint with red hash marks on the driver's side front fender, and wheel flares on the rear fenders. The overall look was very cool and priced at $3,250 for the coupe and $2,880 for the roadster.
The Collector's Edition was a reasonably priced, $1,250 option that dressed the Corvette with Sebring Silver paint, silver painted ZR-1-like wheels, special emblems, and special embroidery on the seats. A very clean deal. Only 5,412 units were sold.
The end of the C3 line reminded me of Rodney Dangerfield, all it wanted was a little respect. From '84 to '86 we saw engine power rise from 205 to 330 horsepower and the car only gained 98 pounds. The base price went from $21,800 to $37,225. The best part was that the Corvette had regained its status as a true, high performance sports car. Things were only going to get better. - K. Scott Teeters