DETROIT — The Big Three horsepower race was at full gallop when a one-of-a-kind 1968 Corvette bolted from the starting line of a temporary dragstrip at the General Motors proving ground in Milford, Mich., accelerating with a fury that would have many of today’s supercars inhaling its exhaust fumes. Cobbled together with a prototype engine, some G.M. performance parts and a lot of hot-rodder handiwork, this Chevrolet engineering project never advanced to production. Nor was it intended to. Its only purpose, says Gib Hufstader, a retired G.M. engineer who helped manage the project, was to impress reporters at the automaker’s annual new-model previews. And impress it did, each writer getting a chance behind the wheel on the makeshift track. Its mission accomplished, the Corvette disappeared, remembered mainly by the band of engineers who built it and the reporters who wrote about their drives.
Because of the enthusiasm of Dave Miller, a Shell Beach, Calif., collector — and avid reader of publications that cover high-performance cars — the story of this one-off machine is being retold in the form of an especially faithful replica. Far more than a typical cosmetic recreation, this car is based on extensive research into that engineering project of long ago. Mr. Miller’s cloned Corvette was built to specifications from the original car’s documentation. While it’s undoubtedly fun to drive, the clone Corvette and the car that inspired it are significant mainly because they symbolize a time when rules were stretched in the battle for sales. In the 1960s, Detroit discovered that horsepower did more than move machines: It filled coffers. Automakers angled to outdo one another in a decade that produced the Mustang from Ford and bruisers like the Pontiac GTO, Chevy Camaro and Hemi-powered Dodges and Plymouths among a flood of machines meant to tempt power-hungry buyers. It was the car magazines that automakers counted on to push shoppers from want to must-have. Each summer, G.M. held an event for the so-called long-lead journalists, whose publications worked some three months in advance. The young and enthusiastic writers who attended weren’t there for the pittance they earned; they came for the cars. “When you arrived at the long lead and came down the hill from the administration building, it looked like the circus had come to town,” Eric Dahlquist, a former Motor Trend editor, said in a phone interview, referring to the tents set up on a asphalt-covered area of the proving ground. “It was a reflection of the times.” Others recalled the week less affectionately. “I called it hell week,” Joe Oldham, the former editor of Popular Mechanics, said. “It was usually hot and humid. You spent hours on Black Lake, a huge expanse of proving-grounds asphalt that radiated heat. If there was nothing great to drive, you were not happy.” Unhappy writers don’t produce glowing reviews, and G.M. knew it had to show off serious horsepower to help journalists forget the heat and praise the brands. If nothing awesome was scheduled for introduction, awesome could be cobbled together. For the 1968 long-lead program, Chevrolet took things to the next level and paired a stripped, lightweight Corvette with an engine that was not yet available, the all-aluminum 427-cubic-inch ZL-1. To make it look like a production cast-iron engine, the aluminum engine block was painted. Jim McFarland of Hot Rod Magazine was prepared for just such shenanigans: His magnet gave the game away. “Detroit automakers were modifying cars to impress journalists,” Mr. McFarland said in a telephone interview. “I got in the habit of carrying a magnet to check for aluminum parts.” On the temporary dragstrip, the car rocketed well past 100 m.p.h. in the quarter-mile runs, and with a 3-speed automatic transmission it was easy to drive. Smiles were everywhere, Mr. Hofstader said. Those smiles must have pleased G.M. management, because the car appeared again the next year, this time with an experimental engine that would never be offered, an all-aluminum 454-cubic-inch V8 designated LT-2 in G.M. documents. Among its many special parts was an elaborately plumbed exhaust system pairing cylinders that fired 180 degrees apart. A 1969 dynamometer test registered 584 horsepower. Writer after writer drove the quarter mile in the potent machine. A total of 71 runs were recorded by Mr. Hufstader; the best time for the quarter-mile was 10.89 seconds, and the average was 12.13 seconds, skewed by poor clockings from drivers whose heavy foot resulted in more tire smoke than forward motion. A blocking plate installed on the transmission shifter made manual shifting — and over-revving of the engine — impossible, so the car survived the abuse. A former Car Craft magazine editor, Don Green, remembers the day. “In 1969 I went to the long-lead with a fellow writer, A.B. Shuman,” Mr. Green said in a telephone interview. “Early in the week we heard a car screaming like a banshee as it was driven on test-track roads. We spotted a Corvette and figured it was for us. On Chevy’s day, we positioned ourselves at the front of the proving-grounds bus. A.B. drove first and clocked an 11-second-flat run. I walked into the throttle and kept it from spinning the tires. That yielded a 10.92 at 127 m.p.h.” Mr. Dahlquist wrote about the long-lead Corvette in the October 1969 issue of Motor Trend — and that was the last anyone heard of it. Today, no one can be certain of the car’s fate, but it was most likely sent to the crusher in keeping with G.M.’s policy regarding cars that did not comply with federal standards. The story would have ended there if Mr. Miller, 70, had not traced the serial number of a Chevrolet ZL-1 engine he acquired for a project back to Kevin Lambert, a Corvette enthusiast and engineer. When Mr. Miller was in Michigan on business in 2010, Mr. Lambert invited him to dinner at a Troy, Mich., restaurant. In retrospect, it was something of a setup: Mr. Lambert had slyly invited Mr. Hufstader and Tom Langdon, another former G.M. engineer, to join them. Before dinner ended, the creators of the ringer Corvette had persuaded Mr. Miller to build a clone. Mr. Miller said that the enthusiasm of the engineers led him to build his replica. “The story of the car got me going,” he said. Another G.M. retiree, Werner Meier, owner of Masterworks Automotive Services in Madison Heights, Mich., who has restored hundreds of collectible Corvettes, was chosen to build the car. A copy of the original build order, along with specifications provided by Mr. Hufstader and Mr. Langdon, ensured it would be as close as possible to the original. Among the components needed was an LT-2 454 engine — the power plant that never existed.
Masterworks asked Denny Hummel, whose engine shop is in Clinton Township, Mich., to build an LT-2 for the car. “I told them I could if I knew what an LT-2 was,” Mr. Hummel said. “They explained it was essentially an aluminum ZL-1 427-cubic-inch Chevy engine with the internal parts of a 454. I modernized it, but it’s a near duplicate of the 1969 engine.” The replica engine is at least as potent as the original, testing out at 624 horsepower. Like the original car, the replica was built with lightened parts, and where the original was rough around the edges, the clone is likewise, mimicking that cobbled-together look. (Mr. Meier, a perfectionist at heart, said that building a car from the ground up that retains an element of grunge was the toughest part of the job.) In a dragstrip test, the clone recorded a 10.84-second elapsed time at 124 m.p.h., just a hair quicker than the original. In an interview at his shop in June, Mr. Meier said that the work on the car had not concluded — and that the car would never be finished. “Every time the engineers who built the original stop by, they remember something else,” he said. “But that’s good, because it’s an ongoing adventure, a trip back in time to a special day.”