The C3 ZR-1
The 1970s and early ‘80s were a tumultuous time for American auto manufacturers. They found themselves squeezed by new emissions regulations and changing consumer tastes. By the end of its run, the third-generation (C3) Corvette was only making around 200 horsepower.
But before all that, as the muscle car era breathed its last breaths, was the C3 ZR-1. Produced from 1970 to 1972, the ZR-1 was introduced as a performance package that could be added to Corvettes that already had the LT-1 engine, Chevrolet’s famous 350 small block, which was then rated at 370 horsepower. The ZR-1 package ($1,010) added stabilizer bars, plus a racing suspension and brakes.
In an era when it’s fair to say handling and braking were not major priorities for manufacturers of American performance cars, the ZR-1 stood out as a muscle car with attributes besides displacement and horsepower.
Rare, Bare Race Car
The ZR-1 was conceived as a car for people who were serious about going fast and didn’t care about a whole lot else. You couldn’t order the ZR-1 with power windows, power steering, air conditioning (until 1972), or even a radio. Everybody who ordered a Corvette ZR-1 from 1970 to 1972 got pretty much the same car, though there is a note to make here.
In 1971, you could order the ZR-1 with a 454 big block instead of the 350. That boosted horsepower to 425 and restricted you to a four-speed manual transmission. Those were called ZR2 Corvettes. Not many were ordered that way, and if you see a nice one today, you’re looking at a car worth potentially hundreds of thousands of dollars.
Discontinued for the First Time
Chevrolet dropped the ZR-1 option from the Corvette lineup in 1973. A switch from measuring gross horsepower to net horsepower dropped power figures all across the market in 1973, which was also the year of the first OPEC oil embargo against the United States. Oil prices rose, and quickly consumers became more interested in fuel economy and less interested in horsepower figures that were already dropping, and only going to get worse. This was not a good time to be selling a race car for the street. Even the 454 engine was making less than 300 horsepower in 1973.
Revival in the '90s
The years that followed the oil embargo are commonly referred to as the Malaise Era, when American manufacturers struggled to reconcile their muscular pasts with a new world that demanded a different kind of car. But by the late 1980s and early ‘90s, oil was cheap again, and auto engineers had figured out new ways to pass emissions tests without sacrificing as much horsepower. When the ZR-1 returned for the 1990 model year, it came with a 375 horsepower small-block V8 engine and a performance suspension. The ZR-1 was back.
Lotus Brings Aluminum, Ditches Pushrods
General Motors had purchased Lotus a few years earlier, and together they hatched a plan to make the Corvette ZR-1 the world’s fastest production car. Plans to use turbochargers to increase power were scrapped, so Lotus was consulted for a re-engineering of the Chevrolet small block. What came out was a significant re-working. The block was now aluminum, and the pushrods were gone, replaced by a dual overhead cam engine with a smaller bore and longer stroke than the pushrod 350. At a time when the base Corvette was making 250 horsepower, the 375 horsepower made by the new LT5 engine put it within five horsepower of a Ferrari Testarossa. Without the pushrods, this Corvette could rev like never before. When Car and Driver tested the ZR-1, it went from zero to 60 in 4.5 seconds, and all the way to 150 in less than 30 seconds.
End of Another Era
Considering it was a special model that cost a lot more than the base Corvette, the ZR-1 was a hit, with almost 7,000 cars produced from 1990 to 1995. But by the mid-’90s, something else had changed.
Dodge had introduced the Viper in 1992. The Viper had a V10 engine that made 400 horsepower, but the greater significance was that the Corvette could no longer claim to be the only true American sports car.
Another era for the ZR-1 was coming to a close, as Chevrolet prepared to release the next generation (C5) Corvette in 1997.
Successor: The Z06
Although the ZR-1 package had come and gone since 1970, it didn’t skip an entire generation until the C5 (1997-2004), when even the base model was capable of accomplishing zero-to-60 sprints in 4.5 seconds. Rather than revive the ZR-1 package, Chevrolet created the Z06 Corvette. It was lighter and had slightly less horsepower. But with a curb weight of just 3,100 pounds, the Z06 could nonetheless outperform the best ZR-1, and essentially took the ZR-1’s spot in the Corvette lineup.
The ZR-1 Returns
While the ZR-1 badge was sitting out the Corvette’s fifth generation, a lot changed. A 400-horsepower engine was no longer enough to make a splash. So in 2009, GM revealed a new Corvette ZR1 (no hyphen this time around) with a supercharged 6.2-liter small block making 638 horsepower. It was capable of reaching 205 mph. The ZR1 badge was back, and anybody could see it meant something serious.
What’s Next for the ZR1?
Chevrolet discontinued the ZR1 again in 2013. As Chevy prepares to say goodbye to the Corvette C7 after 2018, it decided to bring back the ZR1 to close out the generation. Many of the details are still in the “educated speculation” stage, but Car and Driver expects the new ZR1 will make something on the order of 750 horsepower and, once again, come fitted with suspension and braking system to match.
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Chevy’s Top Corvette
The ZR-1 designation has come and gone from the Corvette lineup over the years. It first showed up in 1970, indicating a Corvette that had been infused with a racing powertrain and chassis. That lasted a couple years, then the ZR-1 disappeared until 1990. A Lotus-designed 5.7-liter V8 had replaced the old pushrod small-block 350. After 1995, the ZR-1 disappeared again, only to return for 2009 without its hyphen.
When we last saw the Corvette ZR1 in 2013, it was making 638 horsepower and was the first factory Corvette capable of reaching 200 mph.
Well, the ZR1 is back for 2018, and it finds itself in the middle of some modern-day horsepower wars. Dodge grabbed a million headlines by breaking the 700 horsepower barrier with its Hellcat engines; the new ZR1 is expected to produce something on the order of 750 horsepower.
The ZR1, in other words, is all about power. As Chevrolet closes the book on the Corvette’s seventh generation with a ZR1 swan song, let’s take a look at the ZR1’s past.