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Here's the story...
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 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 reed"
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.
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