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« on: December 22, 2022, 07:16:08 PM »
The ghost of Jim Hall's 2J CanAm car.......
The Chaparral 2J is powered by an aluminum Chevrolet ZL1 engine, 427 cubic inches and producing 650 horsepower at 7000 RPM. It is paired to a clutchless semi-automatic three-speed transaxle. With a fiberglass resin body, it weighs hardly over 1800 pounds. The auxiliary engine, mounted behind the rear wheels, is a Rockwell JLO 247cc two-stroke, two-cylinder, 45-horsepower engine, usually found powering snowmobiles. At full power, it makes an ear-splitting, high-pitched drone, like the buzzing of mechanical wasps from hell. The two rear fans are lifted from a M-109 Howitzer and capable of pushing out 9650 cubic feet of air per minute at 6000 RPM. With the Chevrolet engine off, rumor has it, they can even push the car forward at 25 to 40 miles per hour. The fans draw air from the bottom of the car and send it—along with dust, debris, oil sprays, and the occasional grass clippings—to the back, presumably into the faces of other drivers. These drivers inevitably raised a stink to Hall about it: we can't see when you're in front, we're getting sprayed with all of this debris. "Well," said the taciturn Hall, "why don't you pass me then?"
There's more. To create a negative pressure vacuum that would suck the car to the ground, the car featured skirts around the rear three-quarters of the car. Hall approached General Electric to use its relatively new invention, Lexan: a polycarbonate plastic material that was light, flexible, strong, and most importantly, unbreakable. The skirts moved up and down through a system of cables, pulleys, and machined arms that were bolted to the suspension. The result was a near-constant alignment to the road surface. With the fans on, the car would hunker down by two inches.
The result of all this complexity was constant downforce—at any speed, through any corner. Theoretically, the 2J could generate up to 2200 pounds of downforce. Fully fueled, the 2J could pull from 1.25 to 1.5gs through turns. "We can go full throttle without wheelspin or uncontrollable oversteer," Hall told Competition Press in 1970. "You can't imagine the car can stop as fast or corner as hard as this one does."