Considering the vast array of fast and capable factory-built Corvettes that have been built over the past six and a half decades – andChevrolets’s habit of changing up where different models sit in hierarchy along the way – it can be a little bit tricky to discern a particular Corvette’s position in the performance food chain.
Packing a 755 horsepower supercharged V8, the 2019 ZR1 is the most powerful factory-produced Corvette to date. Top speed estimates are in the 210 mph range, also making it the fastest factory-produced Corvette ever built. Image: General Motors
Of course there’s no mistaking that the recently announced 2019 ZR1 will be the current Corvette lineup’s top dog. The C4 generation ZR-1 helped establish the badge as denoting the “King of the Hill” Corvette, and it put the rest of the sports car world on notice when it began terrorizing the streets and road courses of America back in 1990, as did the C6 ZR1 when it debuted in 2008. So it stands to reason that the tradition would continue on today.
While it’s easy to think of the ZR1 as a fairly modern addition to Corvette folklore, its origins actually date all the way back to the original muscle car era. The designation first graced a very limited number of C3 models built from 1970 to 1972 that were tuned specifically for track use, resulting in hair raising performance whether a would-be ZR1 pilot found themselves on a road course or out cruising the boulevards.
The Original ZR1
By the close of the 1960s domestic performance was in full swing, as evidenced by the fact that even the small block V8s that General Motors was producing were capable of churning out some serious numbers. Sitting at the top of the small-cube totem pole for the 1970 model year was the new LT-1. The 350-cubic inch mill was outfitted with solid lifters, a forged steel crankshaft, 11:1 compression, a high-lift camshaft, a low restriction exhaust system, and a big four-barrel carburetor paired with an aluminum intake manifold, yielding a factory-rated output of 370 horsepower and 380 pound-feet of torque. With a 6500 rpm redline, the small-block screamer was ripe for track work.
The 454-cubic inch, 460hp LS7 big block was supposed to debut alongside the LT-1 seen here in 1970, but the mill never found its way into a production car, so the LT-1 had the spotlight to itself that year. The relatively light, high-winding small block was the perfect power plant for owners who wanted to attack road courses with their C3s. Image: Mecum
That last bit certainly wasn’t lost on Corvette chief engineer Zora Arkus-Duntov, who had been developing track focused Corvettes for well over a decade by then – sometimes even in secret, due to an earlier corporate edict banning factory-backed racing efforts. But GM’s brass had eased the rules a bit by the close of the 1960s, so Duntov set about developing a Corvette aimed directly at the SCCA’s B-Production class.
The new racer would be equipped with everything drivers needed for performance capability and very little else – the M22 “Rock Crusher” close-ratio four-speed gearbox, J56 heavy-duty brake package, F41 suspension package, and an uprated cooling system that consisted of a bigger aluminum radiator and an expansion tank were all part of the package, but air conditioning, power steering, power brakes, and a radio were not.
Visually there wasn't much to clearly discern a ZR1 from a garden variety Corvette. Part of the rationale behind that was the package's intended purpose as an SCCA B-Production racer rather than a street car. Images: Barrett Jackson
Aimed directly at gentlemen racers, the ZR1 looked more or less identical to a typical Corvette externally but commanded an additional $1221 over the price of a standard model for its performance prowess. The low-frills package would prove to be a rarely chosen option, resulting in only 53 examples being built in total between 1970 and 1972. Despite its rarity, the purposeful nature of the package had clearly established what “would-be” drivers could expect from a ZR1-badged Corvette.
By the close of the 1980s, automakers were starting to get their bearings again when it came to performance, and with Dodge set to unleash the new Viper, Chevrolet needed to ready a proper response.
Chevrolet turned to the folks at Lotus, the British sports car maker they’d recently acquired, for assistance elevating the C4’s performance to an entirely new level. And with Dodge’s new sports car delivering 400 horsepower right out of the box, GM knew this upcoming Corvette would need some potent firepower to match that big V10.
Like the C3 ZR1, the C4 ZR-1's aesthetic wasn't a dramatic departure from a standard Corvette. Its performance capability was though, and that helped justify the fact that the package nearly doubled the base car's price. Images: General Motors
Rather than extensively overhauling the standard 350-cubic inch L98 V8 used in the standard Corvette, Lotus engineers looked to a dual-overhead camshaft design they’d been toying with. The result was a four cam, 32-valve beast dubbed the LT5, which initially delivered 375 horsepower and 370 pound of torque (output would be bumped to 405hp a few years later). The new motor differed so dramatically from the L98 that Chevrolet needed to outsource the production of the LT5 motors to Mercury Marine in Stillwater, Oklahoma, who then shipped the motors to GM’s Bowling Green, Kentucky factory for final installation.
Like the original ZR1, the new ZR-1 (the name was hyphenated in the C4 era) wasn’t just a high output motor in a standard Corvette. Among other upgrades, the car was outfitted with a three-inch wider rear track, a new adjustable active suspension system, and unique steering and brake systems to ensure that the chassis could keep up with the capability of the engine.
Despite its considerable price tag – which was nearly double that of a base Corvette – the C4 ZR-1 proved to be a much more successful endeavor than the C3 ZR1 had been, and Chevrolet went on to build nearly 7000 examples during the model’s six-year production run.
It would be more than a decade before the ZR1 badge would return to a factory-built Corvette, but it would prove to be well worth the wait. Chevrolet’s “King of the Hill” Corvette returned in 2009, and this time, Chevrolet wanted to make the model’s intentions clear as a world-class performance machine. The exterior design approach was decidedly less subtle than it had been with the C3 and C4 cars, boasting an aggressive body kit, low stance, and a unique hood with a clear center section that showcased the new supercharged 6.2-liter LS9 V8 under the hood.
When the ZR1 treatment was brought to the sixth generation Corvette, designs decided to give the car's look an extra dose of aggression to help the top-spec Corvette stand out a bit more. Images: General Motors
Churning out 638 horsepower, it was the most powerful production engine GM had built to date. The car it was installed in was an equally impressive machine, equipped with carbon ceramic brakes, a uniquely tuned Magnetic Ride Control suspension system, and light weight carbon fiber body components throughout.
The 6.2-liter, 638 horsepower supercharged LS9 V8. Image: General Motors
If the C6 ZR1’s performance credentials weren’t clear from the spec sheet, its capability was made indisputable when Chevrolet set the production car lap record around Germany’s Nurburgring Road course with the car in the summer of 2008, posting a time of seven minutes and 26.4 seconds. They’d improve upon that figure a few years later with a set of then-new Michelin Pilot Super Sport tires, knocking out a 7:19.63 elapsed time in 2012.
After years of speculation, rumors, and spy shots, the latest iteration of the Corvette ZR1 finally broke cover at the 2017 Dubai Motor Show, and it also marked the return of the famed LT5 engine designation. But rather than outsourcing the engine design, GM engineers built upon the foundation of the supercharged LT4, resulting in a brutal direct injected 6.2-liter pushrod V8 that outputs a scarcely believable 755 horsepower and 715 pound-feet of torque, once again making the ZR1’s motor the most powerful production engine in General Motors’ history.
They’ve also ensured that no one will confuse the C7 ZR1 with any other seventh generation Corvette by way of a wild aero kit that emphasizes both the enhanced cooling capability and additional downforce provided by the ZR1 package, most notably showcased by the carbon fiber “halo” hood allowing the blower to stick out above the rest of the body work and the optional “High Wing” on the rear deck that delivers almost half a ton of downforce at speed.
For the seventh generation car, the ZR1 package is more aggressive than ever, both aesthetically and mechanically. Images: General Motors
While we’ll have to wait until next year to find out just what the ZR1 is capable of for ourselves, Chevrolet promises a 0-60 sprint in well under three-seconds, a quarter mile time deep into 10-second territory, and a top speed of about 210 mph, the latter of which makes it the fastest factory-produced Corvette in history.
Will it be enough to recapture the Nurburgring production car lap record from Porsche, who set a blistering 6:47.3 lap time earlier this year with the 911 GT2 RS? Only time will tell.
One thing’s for sure, though: The story of the ZR1 is still being written.