Corvette Turbo History

GM has continually upgraded and refined the Corvette to keep up, if not ahead of the powerful sports cars of the world.

To this end, GM is continually experimenting with aspects of the Corvette that will increase speed, economy, safety and handling. Reduction of weight, increase of horsepower, fuel delivery systems, suspension, aerodynamics, and ergonomics are all constantly changed and rearranged to bring a superior product to the road.

In the 1980's due to constraints on fuel use, horsepower dropped to a shocking low of 190 hp for the base 350 engine, with 230 hp the maximum available. This was hard to digest after the 435hp beasts of the 60's and 70's with massive servings of low end torque.

In an effort to remedy the girly-man Corvette of the early 80's, engineers at the Warren Technical center in Michigan began to experiment with turbo charging their basic 350 block. Starting in 1979 they turbocharged a number of cars, including a V6 Citation, turbocharged with a Borg-Warner Turbo, and a 350ci Corvette with an AiResearch turbo. You can find the turbo experiment noted on Ken Polsson's "Chronology of Chevrolet Corvettes (1980)" (see bullet between "month unknown" and "July 4").

The first turbo corvette was built with the AiReasearch turbo blowing into a Holly double pumper carburetor on a 350 block. In the second experiments, the engineers used a fuel injected 350.

There are pictures and descriptions of these turbo Corvettes in these books: Corvette _Chronicle, by James M Flammang and The Auto Editors of Consumer Guide, Corvette, America's Sports Car, by Jay Koblenz and Corvette, the Definitive Guide to the All-American Sports Car, by Andrew Montgomery.

A number of turbocharged corvettes were made by GM in the late 70's and early 80's, but I am aware of only one other that is out on the street . That street car is a second phase turbo car, still using the 350ci block, but with fuel injection instead of carburetion.

Some more pictures of this car are here.

The Turbocharged Corvette Prototypes - Early Aspirations web site gives a good overview of the GM experiments in turbo charging. Both phase one and phase two prototypes are discussed. The L82 turbo on my website is from the first phase, when the turbocharger blew into the top of a Holly double pumper, This approach had some problems that were evident in my car which are discussed below.

Later in the early 80's aftermarket turbos were manufactured by Duntov, with GM's blessing. He built about 90 of these cars powered with a Martin turbocharger. Sun ‘n Fun Vettes has information about a 1980 Duntov turbo.

For the most part, these experiments at the Warren Tech center did not reach the streets. The Duntov turbo did, as it was a commercial venture, and not experimental.

L82 Turbo History

In September of 1979, a Corporate Assistant Director of the General Motors Information Services and Computer Activity (GMISCA), at the GM technical center in Warren, Michigan put in a request to purchase a turbo Corvette.

That was the beginning of the Corvette That Never Was.

He was delivered the car in April, 1980.

In November of 1980 an article about this car appeared in Road Test.

I purchased the car in 1986, at the time it had less than 12k miles. It was very fast, something like a slingshot that gained speed rapidly. It made a remarkable jet-like sound as it accelerated and the turbo forced air into the engine. I had previously owned a 1966 427ci Corvette, and that car had more impressive low end torque, but this car seemed quicker to high speed. It had a 3 speed auto transmission, and although I missed the shifting of my 427, I was glad not to have to shift this car when under full boost. I experimented with adjusting the waste gate to produce more boost. The engine did make more power but pump gas produced pinging. Running 7psi was fine, and the engine seemed happy.

It could burn an amazing amount of fuel when using boost. If the car was accelerated modestly, no boost came on, the vacuum of course, would diminish, but nothing extraordinary would happen. When the vacuum was exchanged for lots of positive pressure, the electric fuel pump would kick in, and the fuel gauge would move in short order. I could see why it made sense that GM replaced these original carbureted turbo systems to fuel injection in their sencond phase to find better gas mileage.

Problems were noticeable from the first. When the engine was on boost, the stock fuel pump was assisted by an electric fuel pump to overcome the pressure inside the carb. This pump would pump over 10 pounds of gas pressure. Once the boost was over, the electric pump would stop. Once in a while the electric pump would stop in a position that impaired the flow of gas. When that happened, the car would run very poorly, and sometimes stop.

So in 1986 I had the fuel lines modified, and a switching valve installed. That fixed that.

Since the carburetor was under pressure, it had a tendency to leak, I noticed the gaskets had been glued in place, and when I replaced them without the glue, they needed replacing often. Like every few months. In 1987 I had a procedure done to the carburetor that equalized pressure within the carb. and since then, OK.

When the car was under boost, it caused the headlights to retract back into the body. If I used boost at night, the road would go dark. At the end of 1987, a check valve was installed to hold vacuum in the headlight mechanism. I was glad when that was fixed.

In these first two years, small things needed to be fixed, they mostly seemed like normal maintenance items, maybe a little premature for the young age of the car and its low mileage. The last thing I did was have the transmission rebuilt with a heavier shift kit and a heavy duty torque converter.

From 1988 on the car had no major issues, and few minor ones. In 1997 the carb started leaking again, but before the pressure equalization it had leaked every month or so.

Over the next ten years I drove the car less and less to preserve what I knew was a piece of GM history. In 2000, I basically stopped driving the car, except briefly to keep the engine massaged and lubricated.