The Evolution of the Historical, Visual and Mechanical Beauty of the Corvette

July 27, 2015
During WWII, American G.I.’s stationed in Europe had the opportunity to drive European sports cars. They were impressed with the nimble abilities of these lightweight corner carvers, and many even found ways to ship a few back to the United States. In the 1950’s, General Motors was the biggest corporation in the United States, and despite its enormous amount of success, GM did not have a sports car. In 1951, GM’s chief designer, Harley Earl, had a dream. He wanted to create an open-top roadster that was affordable for Americans and could handle itself around the track. With a

During WWII, American G.I.’s stationed in Europe had the opportunity to drive European sports cars. They were impressed with the nimble abilities of these lightweight corner carvers, and many even found ways to ship a few back to the United States.

In the 1950’s, General Motors was the biggest corporation in the United States, and despite its enormous amount of success, GM did not have a sports car. In 1951, GM’s chief designer, Harley Earl, had a dream. He wanted to create an open-top roadster that was affordable for Americans and could handle itself around the track. With a design in mind, he handed the project over to GM’s styling genius Robert McLean, and the car we know and love began to take shape.

With an oxymoronic approach of exotic affordability, the chassis and power plant for the car were built using the existing mechanical technology Chevrolet already had at its disposal. The original design was just a shortened version of the 1952 sedans already on the road, with the drivetrain and passenger compartment moved further to the rear. After little debate with the GM’s advertising department, the roadster was christened the Corvette after the small, quick Navy vessels of WWII.

To power the concept, Chevy used its reliable, but gutless, 235 cubic-inch inline-six engine. To squeeze more power out of the little motor, the compression was raised, triple carter side-draft carbs were added and a more aggressive cam was swapped into the motor. These modifications were a valiant effort, but only brought the engine to 150 horsepower.  This was no tire burner, even in 1953. No four-speed transmissions existed at the time, so the slant six was thrown in front of a two-speed power glide automatic. It had a top speed of 108 mph and 0-60 of 11 seconds.

In a further effort to cut costs, the car’s body was designed and made out of fiberglass instead of steel. While the standard Chevrolet drivetrain components of the first Corvette made it easy to maintain, the fiberglass bodies were something that had never been tried before. Even from the factory, few Corvettes looked exactly the same. The early cars were put together in a hurry to increase production, and body gaps were a common issue. Additionally, the suspension for the first-generation Corvettes was based largely off of Chevy sedans of the time. Rear leaf springs and independent front suspension made for sedans, resulted in sedan-like handling for the first Corvettes.

The Corvette was unveiled at GM’s Motorama at the Waldorf-Astoria hotel in New York City on January 17, 1953. When Ed Cole, the chief engineer at Chevrolet, saw the little roadster for the first time, he loved the car and knew the design could be improved upon.

Luckily, for performance enthusiasts, the 235 cubic-inch inline-six didn’t find a permanent home in the Corvette. Inspired by the desire to see his brainchild outrace the competition, Cole began work on the — soon-to-be-legendary —Chevrolet small-block V8.

The 1954 Corvette was only produced in the open-top convertible model and still came only with a two-speed power glide transmission. It could be had with the same 235 cubic-inch six-cylinder engine that now pumped out 185 horsepower.

The 1955 Corvette was the first model to offer a V8 and a three-speed manual transmission. With 210 horsepower, the 265 small-block V8 grossly out performed the original six-cylinder and was the first V8 produced by GM following WWII. In 1956 The Corvette was available with the same V8, but the horsepower had been bumped up to 240. Zora Duntov, an engineer from Belgium, improved upon the Corvette’s body by adding the famous side indention. Duntov was eventually named “The Father of the Corvette”.

By 1957 the Corvette had not only captured America’s attention, but was making waves over seas as well. Racing at Sebring, the Corvette won its class 20 laps ahead of the nearest Mercedes 300. 1957 was also revolutionary for the mechanics of the Corvette. It was offered with Ramjet fuel injection, designed by Duntov and John Doza. The sports car was finally available with a four-speed transmission and a 283 cubic-inch, 240 horsepower engine. The fuel injection system on the ’57 Corvette was way ahead of its time and made the little roadster the quickest production car in the world.

The Rochester mechanical continuous-port injection system wasn’t actually designed by Rochester. It was one of Duntov and Cole’s creations. The fuel injection system achieved 20 mpg on top of the small-block Chevy and offered a power band with no flat spots. It rocketed to 60 mph in just 5.7 seconds and sped down the .25-mile in 14.3 seconds.

By 1958, you could have your Corvette with five different engine packages, as long as it was a 283 cubic-inch. You could choose from the 245 horsepower dual-quad option, 270 horsepower dual-quad option, 240 horsepower fuel-injected option or a 290 horsepower fuel-injected option.

In 1959, Chevrolet finally decided to upgrade the Corvette’s spongy sedan suspension.

Ramjet Tuning for Old-School Corvette Fuel Injection

Even though the Ramjet fuel injection was revolutionary, it was also rather touchy and came with a few problems. Many mechanics suggested replacing it with a four-barrel carburetor when a ’vette was brought back into the shop with problems. If they had known how to repair the fuel injection system, they wouldn’t have done the car that disservice. The unit required special calibration, just like selecting the right jets, power valve and accelerator pump for a carbureted application. The enrichment lever stops have a very wide range of adjustment and can be adjusted to higher or lower pressure than the manufacturer designed them for.

Many fulie fans were, or are, under the impression that the stop positions can be set easily on a workbench using a plumbed vacuum gauge fastened to the enrichment diaphragm. The only correct way to calibrate the right stop positions is to measure the nozzle fuel pressure or gauge the air/fuel ratio with an exhaust gas analyzer with the fuel injection unit installed on a running engine. Once they are set, a vacuum gauge is used to set the length of the enrichment diaphragm rod. The length controls the timing of the enrichment lever travel from the economy stop to the power stop. This is analogous to calibrating the timing of the accelerator pump shot on a carburetor.

The 1960s, Sea Creatures and Muscle Cars

In 1960 Corvette sold over 10,000 units. That same year, Corvette competed in the Le Mans — and while the Mercedes were trailered in, the reliable little American roadsters drove to the Le Mans, fueled up and hit the track. On a fishing trip in the Bahamas in 1960, GM designer Bill Mitchell caught a shark that gave him the inspiration for the Mako Shark lines of the 1960’s Corvettes and ultimately defined the iconic image of the Stingray. It was said the designers couldn’t get the paint job on the ’60 model to match the coloration of the shark, so Mitchell had his shark painted to mimic the Corvette.

The 1961 Corvette saw many different design changes, but mechanically was not all that different from the previous years. The fuel-injected 283 cubic-inch V8 now came with 315 horsepower and gave Chevrolet the opportunity to be one of the first offering more than 1 horsepower per cubic inch, while the carbureted 283 cubic-inch models put out only 230 horsepower.

The 1962 corvette was the last of the first-generation body style. For power, it offered a 340 horsepower 327 behind a four-speed manual T-10 transmission and was the last year for exposed headlights. This same year, Operation Mongoose built a Corvette to challenge the Shelby Cobra Grand Sport. Raced by Doug Hooper, the 550 horsepower Corvette whooped up on the Cobras. Sadly only five were ever produced.

In 1963, a new generation of Corvettes debuted, and everything changed.  The Stingray doubled production and was available with a 327 cubic-inch small-block Chevy engine with 250 horsepower, 300 horsepower, 340 horsepower or the 360 horsepower fuel-injected engine. By now, Chevrolet had managed to fix a lot of the problems with the Ramjet FI units, which were still leading technology at the time. From 1963-1967 there were only mild changes in trim in addition to the availability of posi-trac rear ends and alloy wheels. The only change made for 1964 was a quieter, smoother ride accomplished with more advanced suspension technology.

1965 was the first year for the Corvette to be offered with four-wheel disc breaks and a big-block Chevy, 425 horsepower turbo jet porcupine-head 396 cubic-inch V8.

The small block Chevy engine is the most iconic block for GM and lived up to its reputation through the ’50s and ’60s as reliable, powerful and cheap to maintain, but the big-block game was growing strong out on the streets.

By 1967, the muscle car era was in full swing, and big-blocks were the focus of power. The Corvette could be had with a 425 horsepower 3x2 big-block 427 and a fully functional hood scoop.

1968 marked the end of the shark-bodied Stingray era. The Corvette had something new in store for the racetrack, and from 1967-1968 Chevrolet built a limited number of L88 aluminum headed 500 horsepower 427s. This big-block was one of the first attempts at factory aluminum heads on an engine. It had 12.5:1 compression and a .600 lift cam paired with 3.36 racing gears. The high-compression engine required 100-105 octane fuel and had no fan shroud, which led to repetitive overheating. The car was never intended to be driven on the street, and in order to discourage such activity, the ZL1 model came with J56 racing brakes and no heater, power steering or air conditioning.

The 1969 Corvette turned Stingray into one word and was offered with a 300 horsepower, 350 cubic-inch engine, marking the 17th anniversary of the Corvette.

The 1970s Downward Spiral

The 1970 Corvette won Car and Driver’s most popular car. It utilized a 390 horsepower big-block 454, the largest power plant ever offered in a Corvette. 1970 also marked the introduction of the LT1 370 horsepower, 350 cubic-inch small block. Additional creature comforts for this year included power windows and power steering. This was the last year for the big-block/big power Corvettes.

In 1973 the United States stumbled into an oil shortage, which many blame for the death of the muscle car. Corvette lovers could no longer afford to pay the high prices for gas guzzling, high-performance engines. New laws were passed regarding exhaust emissions, and unions began to have a negative effect on the auto manufacturing industry in America. The power plants for the Corvette continued to decline into the ’70s. In 1976 Chevrolet stopped production of the Stingray model and all convertibles, and the V8s of the ’70s were choked up with low-compression heads and emission vacuum hoses. These laced their way through the engine in a leaking, confusing frenzy that made them quite confusing to work on. The base 350 cubic-inch engine for the 1976 model spat out a measly 180 horsepower.

The ’80s and Aerovettes

In 1981, Chevy produced its last carbureted engine for the Corvette: a mild 350 cubic-inch behind a four-speed transmission, putting out a measly 190hp. In 1982, the Corvette introduced a new generation of fuel injection with the 190 horsepower Crossfire 5.7L engine. Unfortunately, it was only available with an automatic transmission.

In 1983, the Aerovette was born. Inspired by aerodynamics and tested in a jet plane wind tunnel, this new generation offered more than brute power. It was the first generation to offer rack and pinion steering and came with a 205 horsepower, 5.7L engine and a four-speed manual transmission with computer-controlled overdrive. In addition to the engine and steering changes, many of the steel suspension parts were replaced with aluminum, which made the car lighter and subsequently quicker than the year before. The 5.7L SFI fuel-injected small-block offered in the 1996 model offered 300-330 horsepower with a cast aluminum cylinder head and roller camshaft. The Aerovette generation ran until 1997 and ended with production of the C5 generation.

A Vette’s Lifeblood

In the early days of the Corvette, oil was less specifically designed. Most old cast iron V8s worked well with two options: 30W or 50W oil. 30W oil was intended for colder climates, and 50W for warmer climates. Technology advances the field of motor oil have allowed engine development to be more fine tuned to the viscosity of the oil, and Mobil 1 has been on the forefront of lubricant technology with GM’s Corvette for over two decades.

In 1992, Corvette joined into a partnership with ExxonMobil. At the time, GM was working on perfecting its LT1 engine for the new model of that year. The LT1 was experiencing problems with overheating, so Mobil 1 was tested, and it maintained enough viscosity to cool the engine without the addition of external oil cooler. This led to Mobil 1 being chosen as the factory-fill oil for the Corvette. Andrew Moran, of ExxonMobil’s Research & Engineering Department, talked about much of the history and technology behind Mobil 1 and the Corvette.

“Mobil 1 has evolved alongside the Corvette to meet the demands of modern high-performance engines found in the current world-class Corvette models,” Moran said.

David Tsurusaki, strategic global alliance manager at ExxonMobil Fuels and Lubricants, said, “It is a testament to ExxonMobil’s commitment to advanced lubricant technology that Chevrolet has Chosen Mobile 1 Synthetic Motor Oil for the high-performance Corvette engines”.

Mobil 1’s partnership with the Corvette line established the “GM High Temperature Engine Oil Engineering Standard” or GM 4718M.

Corvette, Mobil 1 and LeMans

While Mobil 1 did not become the factory oil fill or Corvettes until 1993, the history between GM and the company goes back almost 10 years before that. Moran recalled in 1985, Reeves Callaway used Mobil 1 in his twin turbo Corvette at LeMans and helped set the 24 Hour World Endurance Speed. During the race, he averaged 175.85 mph at Fort Stockton, Texas in 1990.Under the stewardship of former American racer Doug Fehan, GM established the factory Corvette Racing program in 1996. Doug often said, “Every engine revolution, every lap, every race win, every championship and every 24hrs of LeMans win has been with Mobil 1.”

The Corvette has and always will be America’s No. 1 two-seater roadster. Even with the dark ages of the ’70s and ’80s, the modern Corvette has finally come back out on top.