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.
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.
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.