Time was, you could order a Corvette whose factory engine produced more than 400 horsepower.
That doesn’t sound so farfetched these days, as engines with that level of power—and more—have been available in Chevy’s sports car since 2002. But following the 1971 model run, the truly big power numbers—and the engines that produced them—simply disappeared from the Corvette option sheet.
GM management had ordered the corporation’s five passenger-car divisions to make all of their engines run on low-lead and no-lead gasolines starting with the ’71 model year, which meant compression ratios dropped below 10:1. Also, horsepower-measuring standards used industry wide were changing from “gross” (measured under optimum conditions) to “net” (measured with exhaust systems, emissions components, and other power-robbing accessories installed), which led to further drops in advertised output numbers.
Plus, with ever-more-stringent Federal emissions regulations on the horizon, more of GM’s and Chevy’s engineering resources were diverted to making “clean” production engines. Also stealing R&D time from the Corvette was a top-priority small-car program the brand had recently “inherited” from GM Advanced Engineering: the Vega.
It’s amazing, then, that cars like this ’71 Stingray—with its 425hp LS6 454 and Muncie M22 “Rock Crusher” four-speed—were even built.
Offered exclusively as an option in the Chevelle SS454 for 1970, the LS6 was a 450-horse tire-fryer that made it into around 4,400 of the midsize Chevys that year.
Unfortunately, high insurance rates for anything remotely resembling a muscle car—plus surcharges for items such as four-speeds or engines with high factory power ratings—hurt SS454 sales enough that the LS6 was gone for good from the Chevelle option list after the ’70 model run.
It ended up in the Corvette, but not before some significant changes. One was lower compression, dropped from 11.0:1 to 9.0:1, per the edict from The 14th Floor. But one bigger change was with the LS6’s cylinder heads. Now cast in aluminum—which shaved about 50 pounds off the front end, compared with iron—they featured an open-chamber design that gave back the power the compression drop took away.
The LS6 was offered as a Corvette factory option for ’71, but only 188 buyers chose it. A dozen LS6s went into ’71 Vettes ordered with the RPO ZR2 “Special Purpose Engine Package,” which added special handling hardware to the chassis while leaving off all power accessories, AC, and a factory radio.
Another rare ’71 Corvette option was the Muncie M22 “Rock Crusher” four-speed manual transmission, designed and engineered for use behind the highest-output GM V-8s. Per the Corvette Black Book, only 215 Corvettes were factory equipped with RPO M22 from 1966 to 1970. The ’71 totals did little to keep the bean counters happy: Only 130 Corvettes were ordered with the transmission that year, 36 of which went behind LS6s.
Those low numbers—and a lack of nerve in GM’s upper management—led to the discontinuations of the LS6 and M22 after ’71. But not before this Stingray rolled out of St. Louis Assembly, with both an LS6 and an M22 under its Mulsanne Blue–painted fiberglass.
The big, factory-issue Holley four-barrel still wears its original part number and other i
Looking for more big numbers? How about that 6,500-rpm redline on the tach?
Other than the “454” emblems, the shark’s big-block hood gives no clues about the 425hp ti
Ordered new by a customer in Phoenix, it spent most of its early years in Arizona and was rarely driven. By the time third owner Steven Rabitz located and acquired it in 1987, from an apple barn in Michigan, it had only covered about 18,500 miles since new. It racked up maybe a thousand more before Bill Erdman shot these pictures of it.
When found, the Stingray was in need of a good cleaning, but it was complete and intact. “The car has been left in its original condition, meaning that [it] has its original paint, interior, undercarriage, and engine compartment,” said Rabitz in a statement attesting to the car’s mileage and condition. “The frame stencil markings, undercarriage option codes, and original tags on the rear springs are all visible.”
The 1971 model year was the final one for the Vette’s fiber-optic light-monitoring system,
It also had plenty of documentation, including a warranty card and Protect-O-Plate, sales brochures, service records and registration history, plus a bill of sale from when it passed to its second owner.
Kevin Mackay at Corvette Repair, Inc. didn’t need to do anything more than give the ’71 a thorough cleaning and detailing at his Valley Stream, New York shop, and this shark went on to gain NCRS Top Flight status in 2010.
Since then—and since our photo shoot—the car has changed hands again, having been sold at a Barrett-Jackson auction in Arizona.
Take particular note of two of the car’s original features. One is its rolling stock, with 70-series bias-ply tires on 15x8-inch steel Rally wheels. Considered state-of-the-art way back when, these were likely a limiting factor when it came to straight-line performance. Car Craft tested a four-speed, LS6-powered ’71 Corvette in its August ’71 issue, recording a best 0-60 mph time of 6.5 seconds and a quarter-mile run of 13.72 seconds at 104 mph. Those numbers might seem slow by today’s standards, but it was common knowledge back in the day that a pair of racing slicks, a shorter gearset, open headers, and a few other tuning tweaks could slash more than a second off that e.t.—sometimes a lot more.
It’s also interesting to note that this ’71 is equipped with a factory AM/FM radio, like all but about 300 of that year’s sharks. Given that sound-system technology back then was about as advanced as tire technology was, it’s a wonder anyone could hear anything from that radio, especially at full throttle with the windows open and T-tops off! vette
“The car has been left in its original condition. The frame stencil markings, undercarriage option codes, and original tags on the rear springs are all visible.”—Steven Rabitz
1971 Corvette coupe
||LS6 cast iron (casting no. 3963512)
||LS6 open-chamber aluminum (casting no. 3946074
||LS6 solid lifter
||Holley R4802A four-barrel
||GM/Delco transistorized points-style
||Muncie M22 four-speed manual
||Stock with Positraction and 3.70 gears
||Heavy duty coil springs, sway bar, and tubular shocks (front); transverse leaf-spring bundle and tubular shocks (rear)
||Four-wheel disc with RPO J50 power assist
||Stamped-steel Rally with chrome center caps and trim rings, 15x8-in (front and rear)
||Firestone Wide Oval blackwall bias-ply, F70-15 (front and rear)