Why The 1971 Chevy Corvette LS6 Is So Special

Why The 1971 Chevy Corvette LS6 Is So Special

The 1971 LS6-powered Corvette is both rare and significant. Its high-compression engine marked the peak of the muscle-car era. And this Chevy contained a last-of-kind powerplant that would be no longer viable as a heavy hand of federal emission regulations began to take its grip.

Background

The year 1971 was not a friendly one. Not for the car manufacturers, at least. It was a time when automakers, including General Motors, had to stop making high-compression engines. This came about as new emission standards banned the use of leaded fuel. The prohibition was due to concerns about exposing children to lead and then-new catalytic converters requiring lead-free gasoline.

Lead was added to fuel to help reduce engine knocking. At the same time, leaded high-octane fuel prevented premature combustion in high-compression engines. But, the ban effectively killed the production of these power plants and launched an era of underpowered and anemic engines.

So, the 1971 Corvette offered Chevrolet one last opportunity to equip its sports car with something that was robust and performance-oriented. The effort was a one-year-only undertaking, and a high-compression engine wouldn’t grace a Chevrolet again until 30 years later (thanks to more advanced emission controls and sophisticated electronics). Only 188 units of the LS6 Corvette were built, and this limited run is just part of the story.

What Makes the 1971 Chevy Corvette LS6 so Special?

Chevrolet has unofficially arranged its lineup so that the Corvette was always positioned to be its flagship performance car. But things got a little sidetracked with the Corvette C3 (1968-1982). The automaker had plans to introduce the LS7 engine, its most powerful big-block V-8 at the time, for the 1970 model year. But, releasing this 454 cubic-inch power plant would run afoul of these pesky emission laws (the engine would eventually hit the streets in 2006, but that’s another story). So, Chevy turned to its next best thing, the LS6.

Curiously, however, the LS6 got loaded into the 1970 Chevelle and offered 450 horsepower. In contrast, the Corvette was fitted with a high-revving LT1 engine making 370 horsepower. This break with tradition came about because the LS7 originally planned for the Vette never happened. To correct this dilemma, Chevrolet went to work and adapted the LS6 for the Corvette for a 1971 model year-only appearance.

The Story of the LS6 Engine

GM’s LS6 engine was among the most powerful engines available in 1970 and competed closely with Chrysler’s Hemi offerings. GM’s beast, the LS6, was developed by legendary designer Zora Arkus-Duntov (considered the father of the Corvette). Made out of cast iron, the engine used aluminum cylinder heads with a four-barrel 800 cfm Holley carburetor fitted on top of the aluminum manifold.

With a compression ratio of 11.25:1, the LS6 (in peak form) redlined at 6500 RPMs to produce 450 hp and 500 lb-ft of torque. A forged steel crankshaft with forged aluminum connecting rods was used to maximize the output of this high revving engine. And to control emissions, engineers installed an air injection reactor pump to increase air into the exhaust system.

In the 1970 Chevelle, the LS6 was paired with either a four-speed Muncie M22 manual or an M40 Turbo three-speed automatic transmission. While the LS6 Corvette was available with both drivetrain options, the vast majority were built with the Muncie M22 four-speed. To accommodate the Corvette’s structure, Chevy had to detune the LS6.

The reworked LS6 now had a 9.0:1 compression ratio and produced 425 horsepower @5600 RPM and 475 lb-ft of torque @ 4000 RPM. Despite the reduced output, the LS6-equipped 1971 Corvette could still hit 0-60 mph in 5.3 seconds, only 0.3 seconds slower than the LS6 Chevelle from the previous year.

1971 Chevy Corvette LS6

The placement of the LS6 engine in the 1971 Vette was one of the few features that helped distinguish this model year from the 1970 edition. Chevy engineers were preoccupied with making other Corvette power plants compliant with the new regulations.

That meant that these engines now had to work without leaded fuel and needed to produce lower emissions. The base L48 V-8 was cut down to 270 horsepower (from 300 horsepower), while the LT1 was brought down to 330 horsepower (from 370 horsepower). There was little time or resources to change anything else with so much focus on redesigning Corvette engines.

The 1971 Corvette LS6 followed the same lines as the 1970 LT1. The sleek front chrome bumper was emphasized with the egg crate-shaped inserts below each headlight pod. Similarly, the cheese grater air vent was positioned at the back of each front fender. And, of course, the car’s classic coke bottle shape continued unchanged. How do you spot a Corvette LS6? Assuming it’s authentic, look for the slightly raised hood with the dual air scoops flanked by “454” badging.

The rear arches carrying on to the classic ducktail spoiler gave the back end a clean look highlighted by chrome bumpers and dual exhaust. To keep it lightweight, the car carried forth with the traditional Corvette fiberglass body resting on a steel chassis. Mechanical components included a performance-tuned front suspension and an independent rear end sitting on 15-inch rally-style wheels.

On the inside, the cockpit-style interior embraced the classic two-seat format. Gauges include readings for fuel, battery, oil pressure, and temperature. An analog clock was present, too. Available extras included an AM/FM radio as well as power steering and power brakes.

Chevrolet offered the Corvette in ten colors with four powertrain options. The most powerful was the LS6 and its infamous fuel economy rating of 9-14 mpg. In addition to making a sacrifice at the pump, the LS6 added a hefty $1,221 premium to the Corvette’s $5,500 base price. That $6,721 total works out to about $46,300 in today’s money, a relative bargain compared to the $60,000+ starting price of the modern Corvette. But, it’s easy to argue that this is an apples-to-oranges comparison.

For 1971, Chevy also offered a ZR2 Pro package for customers wanting to get the true feel of the Corvette. The $1,747 option included an M-22 four-speed manual with a dual-disc clutch, aluminum radiator, an electronic ignition, power brakes, and a stabilizer bar with upgraded shocks and springs.

While enthusiasts drooled over the LS6 Corvette, buyers were less enamored thanks to poor fuel economy and high insurance rates. It’s no wonder only 188 were built out of the total 21,801-unit production run for the 1971 model year.

How Rare is the LS6 Corvette Today?

Of the eight generations of Corvettes that have been built since 1953, the C3 version has the longest production run of 15 model years. During these 3 years, the industry experienced the rise and fall of the muscle car. And while Ford and Chrysler cranked out their share of performance cars, nothing came close to the Corvette with its pure sports-car orientation.

The LS6 Corvette is coveted because it represents a small total (188) out of the more than 500,000 C3 Corvettes produced. And there are even more rare LS6 variants. Fewer than 50 convertibles were built, and only seven had an automatic transmission. In addition, only 12 were sold with the ZR2 Pro package. That makes these two (the convertible LS6 automatic and the ZR2) the most exclusive of the bunch.

And this rarity extends to the auction scene, where examples include an LS6 coupe going for more than $140,00 in 2018 and a ZR2 selling for an eye-popping $380,000 a year later. Clearly, the Corvette LS6 is more sought after today than 50 years ago.

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