Renaissance Racer

John Greenwood was a talented driver and engineer who built the fastest racing Corvettes of the 1970s.

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December 31, 2015
It would be fair to say that John Greenwood was born with gasoline in his veins and speed in his heart. His father, who served as a fighter pilot during World War II, worked at the GM Technical Center in Warren, Michigan, and some of John’s earliest childhood memories centered on cars. In 1954, when he was only nine, Greenwood used money earned from delivering newspapers to build a small, tube-frame car powered by a 2.5-horsepower Briggs & Stratton engine.

In the 1950s and ’60s Detroit was a hotbed of high-performance cars, and Woodward Avenue was ground zero for illicit street racing. Greenwood began cruising Woodward in 1960 with a 1955 Pontiac fitted with a 421-ci engine. A fuel-injected 1958 Pontiac, then a ‘57 Chevy and eventually a 409 Impala SS followed. He developed considerable expertise building engines, at first boring and stroking 409 Chevys and then graduating to NASCAR-spec big-blocks. As soon as he’d conjure up a way to squeeze out more power, he would sell his old engine to finance the build-up of a new one.

Realizing he could get far better performance with the same engine if it was in a much lighter car, Greenwood sold his Impala and bought a 1964 Corvette, which weighed almost a thousand pounds less than the full-size Chevy. He managed to get his hands on an early 427 engine, which he rebuilt with higher-compression pistons, a hotter cam and a stronger bottom end. Although he quickly discovered that the ’64 Corvette was not designed to accommodate his new “Mark IV” big-block, Greenwood was never one to shy away from a challenge. He modified the front chassis crossmember with an oxy-acetylene torch and a ball peen hammer to provide clearance for the harmonic balancer and crank pulley.
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A few years later Greenwood bought a 1968 Corvette optioned with RPO L71, a 427/435-hp engine that featured 11:1 compression, a high-lift cam and three two-barrel Holley carburetors. Tri-power big-block Corvettes were plenty fast for most Woodward street racers, but those who wanted to ratchet up performance typically did so with headers, traction bars, wider tires and various other bolt-ons. Not surprisingly however, Greenwood saw things differently. The very same day this new Corvette came home, he removed the L71 and installed an L88, Chevy’s all-out, fire-breathing race engine.

Shortly after Greenwood buttoned up the L88 swap, his wife happened to see an ad for a parking-lot autocross at a local grocery store, and she half jokingly dared him to enter it. He accepted the challenge and handily won, despite having no autocross experience whatsoever. He returned the following weekend and won again, and then did the same a week later. While there were a lot of novices and club-level weekend warriors at these events, there were also plenty of seasoned road racers running competition-prepped cars that came in on trailers. Greenwood’s wins said a lot about both his driving talent and his car-building skills.

Greenwood’s competitors encouraged him to take things to the next level, suggesting he sign up for a road-racing school at Waterford Hills in Waterford, Michigan. Frank Cipelli, who was one of his instructors, saw great potential in Greenwood, but the young street-racer-turned-autocrosser initially found it very difficult to adapt his driving style to a road circuit. “The guys instructing me did things differently than I was used to,” he later wrote, “and I seemed to go backwards. There were women in Fiats beating me. I went through two sets of tires one weekend just trying to keep up.” Interestingly, a few years later Frank Cipelli and Greenwood crossed paths again when Cipelli, who was then general manager of Michigan International Speedway, helped forge the young racer’s landmark sponsorship deal with BFGoodrich.
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Greenwood came away from the driver’s school discouraged, but in the ensuing months he had something of an epiphany regarding how he could improve his performance. Besides being a very skilled engine builder, Greenwood also possessed a highly developed understanding of vehicle dynamics, and while ruminating over his poor performance at Waterford Hills, he visualized exactly what he needed to do. Instead of adapting his driving style to fit the car he had, he needed to modify his car so that it conformed to his driving style. Over the winter of 1968-69, he went through the Corvette’s chassis, tweaking and tuning its suspension in a host of subtle but effective ways.

Toward the end of 1968, Greenwood and his brother Burt also set up Auto Research Engineering (ARE), a business devoted to high-performance and competition engine services. When the spring of 1969 rolled around, the combination of Greenwood’s potent engines and his retuned Corvette proved formidable. He earned his regional and national competition licenses in ’69, and did a lot of racing that year, setting numerous track records and earning several confidence-boosting wins.

Greenwood had a well-deserved reputation as an innovator. His mind was constantly working, and his inventive ideas covered not only the engines that ARE built, but also the Corvette’s drivetrain, chassis and body. Greenwood’s innovative thinking produced an extremely fast, but sometimes vulnerable, car. He experienced more than his fair share of parts breakage in the 1970 long-distance events at Daytona, Sebring and Watkins Glen, but when his car didn’t break it almost always won. At the end of the ’70 season, he had enough points to win the highly competitive SCCA Central Division Championship, which awarded him an automatic invitation to the national runoffs at Road Atlanta. He led from flag to flag, finishing ahead of the previously unbeatable Owens Corning–sponsored Corvettes of Jerry Thompson and Tony DeLorenzo. This win earned him the A-Production National Championship in only his second year of SCCA racing.
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The Corvette that Greenwood raced in 1969 was a coupe. Halfway through the 1970 season, following a devastating crash by a fellow competitor whom Greenwood had let drive his car, he converted it to a convertible. He built another convertible for the 1971 season, with numerous modifications to optimize its performance at Sebring, Daytona and the other endurance races. He also continued racing the coupe-turned-convertible in 1971 because it was set up specifically for sprint races. At some races his team ran both cars, and at others he leased one or both cars to other drivers.

In addition to contesting SCCA-sanctioned races in 1971, Greenwood’s team competed in IMSA events that year. IMSA rules were considerably more liberal, allowing greater leeway for creative thinkers to dream up and implement new ideas.

Greenwood’s Corvettes had considerable success in the ’71 long-distance events. At the Daytona 24-hour, he and co-drivers Alan Barker and Dick Lang finished 10th overall and Third in class. At the 12 Hours of Sebring, Greenwood and Dick Smothers co-drove to the GTO win. At the six-hour FIA race at Watkins Glen, the No. 50 Greenwood team car, driven by Richard Hoffman and Frank Cipelli, was the first to drop out after experiencing a suspension failure after only six laps. In contrast, the No. 49 Corvette, driven by Greenwood and Bob Johnson, thoroughly spanked the competition, taking the GTO-class win eight laps ahead of its closest competitor, the No. 57 Corvette piloted by Don Yenko and Dave Heinz. In fact, the only cars to finish ahead of Greenwood’s thundering big-block Corvette were four prototypes: the winning Alfa Romeo T33/3, two Porsche 917s and a Ferrari 512.
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Later in the 1971 season, BFGoodrich sponsored a six-hour endurance race at Michigan International Speedway. All competitors were given BFG Lifesaver T/A radials, which were DOT-compliant passenger-car tires modified with a shallower tread depth. Greenwood and Johnson handily won the race. Greenwood finished up the ’71 season at Road Atlanta on November 28th with a win at the SCCA runoffs. This “American Road Race of Champions” victory gave him his second consecutive A-Production national title.

Following Greenwood’s win on street radials at MIS, he landed a sponsorship deal with BFG for the 1972 and ’73 seasons. The deal, announced at the November ’71 Daytona race, entailed running two and sometimes three Corvettes at five long-distance races in 1972, including Le Mans, Sebring, Daytona and Watkins Glen. By the end of ’71, both of the team’s Corvettes were sold and three new cars were under construction. According to Burt Greenwood, two were built with a combination of brand-new chassis and convertible bodies acquired from local wrecking yards. The third was made from the team’s “public relations” promotional coupe. In keeping with the rules of the time, all three cars had stock bodies with integral FIA-approved wheel flares, and all three featured fairly extensive mechanical modifications, including notched rear trailing arms and a fully boxed and triangulated roll cage. The trio also benefited from GM designer Randy Wittine’s interpretation of Greenwood’s request to create an American-flag livery, leading to the instantly famous “Stars and Stripes” BFGoodrich paint scheme.

But while the Greenwood Corvettes looked spectacular, their performance in 1972 didn’t follow suit. Mechanical problems ranging from starter-motor failure to oil-pressure loss took them out of contention at Daytona. Lack of grip at Sebring, where the notoriously rough track surface wreaked havoc with the street tires, made them uncompetitive in the 12-hour classic. At Le Mans Greenwood qualified the No. 72 BFG team car on the GT pole, but unfortunately engine failures put both team cars out.
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Greenwood fielded the BFG Corvettes at Daytona, Sebring and Le Mans in 1973, with a best finish of Third overall at Sebring. The two team cars found further success at Mid-Ohio’s six-hour IMSA race, finishing First and Second in class.

Racing-tire technology was progressing very rapidly, and the gap between shaved, stock-compound street radials and competition slicks grew ever wider, erasing all hope for major wins with the BFG Lifesavers. After Le Mans the team switched to slicks and had several good finishes, including wins at Road America and Edmonton.

Professional road racing changed dramatically in 1973 after IMSA replaced the FIA as the sanctioning organization for Daytona, Sebring and several other major events. Considerably more expansive rules suddenly allowed for larger-displacement engines, wider wheels and tires, and extensive body modifications. This was all fertile ground for Greenwood’s creativity, leading to the famous wide-body Corvettes that he unveiled in Cobo Hall at the Detroit Auto Show in January 1974.
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Taking full advantage of every word in, and absent from, the new rulebook, Greenwood collaborated with Zora Duntov and GM designers Randy Wittine and Jerry Palmer to turn the liberal allowance for very wide fender flares into a radically shaped body that generated extreme downforce. The effectiveness of the shape was increased by wrapping the front fiberglass around the chassis instead of bolting it on top, giving the body an extreme rake. Additional downforce was garnered by an adjustable rear wing. The car also had a belly pan with an integral wing of its own at the groundplane, which in effect constituted a rear diffuser. But this “underwing” was a sacrificial lamb, according to Burt Greenwood: “It was something that would be seen by IMSA, [and] they would say we can’t run it, [but] it would improve our chances that they’d leave the flares alone, rule-wise.” It worked, as IMSA did order removal of the clever underwing while permitting the team to keep the flares.

Greenwood turned to legendary racecar engineer Bob Riley for help with chassis modifications. The most extreme—and most effective—iteration of Riley’s design incorporated a sophisticated multi-link, anti-dive front/anti-squat rear suspension and coil-overs at all four corners, along with a complex, fantastically strong roll cage.

Greenwood sold a number of wide-body cars, as well as the parts needed to build one, to other racers. He also built two complete team cars and a third chassis for his own team, with each featuring Riley’s most radical suspension and every other trick Greenwood and his coconspirators could conjure up. The team cars initially wore the familiar stars-and-stripes livery, but after Greenwood contracted to be the promoter for Sebring in 1975 and ’76, the cars were repainted in “Spirit of Sebring ’75” and then “Spirit of Sebring ’76” livery.
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In accordance with the rules, engines for the wide-bodies were built up with stock Chevrolet aluminum blocks cast at the Winters foundry, just like the ones used in the 1969 ZL1 Corvettes and Camaros. Greenwood ran the opening races of 1974 with 850-cfm Holley carburetors but switched to a custom fuel-injection setup of his own design toward the end of the year. Chevrolet Engineering’s Gib Hufstader lent Greenwood a cross-ram, side-draft, fuel-injection intake manifold created for the Chaparral 2H, and after analyzing it the intrepid innovator determined how it could be improved. He had Charlie Selix and Gary Pratt fabricate a non-functional “mock up” manifold from aluminum, and used that to work out the design of the tubes, injector angles and other details.

Adding to the challenge, Greenwood had to figure out how to create the most effective system that would still fit underneath the stock Chevrolet high-rise hood, as required by the rules. The rules also required Greenwood to use a stock distributor, so he turned to noted fuel-injection expert Jim Kinsler to modify the Chevy distributor so it could handle the timing for the induction system.

After Greenwood finalized the design for the FI setup, he paid a Chevrolet engineer who specialized in tooling to create a drawing and then an impregnated-mahogany master model of the intake manifold. The aluminum castings of Greenwood’s innovative cross-ram intake manifold design were then produced from this model.
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Greenwood’s injected big-blocks engines easily generated more than 700 hp, making his wild-looking wide-body Corvettes ferociously fast. In the face of very strong competition from other Corvettes, as well as the radical, factory-supported GT cars from BMW and Porsche, Greenwood managed to chalk up numerous track records and victories, with the first win coming in the Bama 200 at Talladega. This was followed by a First Place finish at the season finale in Daytona, where the utter brutality of Greenwood’s wide-bodies was amply demonstrated for anyone who still harbored any doubts: It set new track records in both qualifying and the race, reaching top speeds of more than 234 mph.

Greenwood’s final appearance at Le Mans came in 1976, when he raced a wide-body with his brother Burt and Frenchman Bernard Darniche. They ran up front until a tire puncture caused a slow leak. The deflating tire’s sidewall rubbed against the fuel cell and generated enough heat to cause it to leak. The leaking fuel cell took them out of the race.

Another dramatic change to IMSA’s rules came in 1977, allowing for full-tube-frame cars that shared very little with their production counterparts. Greenwood again collaborated with Riley, Selix, Pratt and others to build two new, tube-frame Corvettes for the ’77 season. Though faster than his production-frame wide-bodies, they could not keep pace with the factory-supported Porsches and BMWs. Both went to new owners by the end of the year. Greenwood continued racing sporadically after the ’77 season, driving C4s in the Playboy Escort Endurance Series, the 1988 Corvette Challenge Series and the IMSA Supercar series. In later years he also developed an enhanced-performance C4 for the street and, together with brother Burt, operated a successful Corvette-tuning and -parts business.
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On July 7, 2015, Greenwood passed away at the age of 71. While he faded from the racing scene many years ago, he’s still remembered with reverence by anyone fortunate enough to have seen him, his team or any of his ground-pounding Corvettes driven in anger. And though most don’t realize it, a whole new generation of Corvette-racing fans owes a debt of gratitude to Greenwood. He was a brilliant gearhead and highly talented driver whose innovative ideas, technical collaborations and sheer force of will to keep Corvettes racing in the dark days of the 1970s all contributed to today’s Corvette Racing program. In that regard, his legacy will endure well into the future.
Corvette magazine 103 cover

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