1967 and 1968, downforce was more important than low drag. Had the 2H kept the low drag shape but with a wider track it most likely would have been very competitive, but the true monocoque construction made changes to the chassis almost impossible. Beautifully constructed, the 2H looks as if it was made by NASA. 2J The most unusual Chaparral was the 2J. On the chassis' sides bottom edges were articulated plastic skirts that sealed against the ground (a technology that would later appear in Formula One). Two fans adapted from a military tank engine were housed at the rear, driven by a single two-stroke twin-cylinder engine. The car had a "skirt" made of Lexan extending to the ground on both sides, laterally on the back of the car, and laterally from just aft of the front wheels. It was integrated with the suspension system so the bottom of the skirt would maintain a distance of one inch from the ground regardless of g-forces or anomalies in the road surface. The skirting produced a zone within which the fans could create a vacuum producing downforce on the order of 1.25 to 1.50 g when the car was fully loaded (fuel, oil, coolant). Tremendous gripping power and greater maneuverability at all speeds were produced. Since it created the same levels of low pressure under the car at all speeds, downforce did not decrease at lower speeds. With other aerodynamic devices, downforce decreased as the car slowed or reached too much of a slip angle. The 2J competed in the Can-Am series and qualified at least two seconds quicker than the next fastest car, but mechanical problems limited its success. It only ran in the 1970 season, after which it was outlawed by the Sports Car Club of America (SCCA). Although originally approved by the SCCA, they succumbed to pressure from other teams who argued that the fans constituted "movable aerodynamic devices". Sanctioning body FIA had banned such devices beginning with the 2E. There were also complaints of debris generated by the fans damaging the following cars. McLaren argued that if the 2J were not outlawed, the Can-Am series would be ruined by its dominance – something McLaren had been doing since 1967. Unusually, the Chaparral 2J only had three gears, being fitted in an automatic transmission, with the first gear providing 110kmh. The engine overall was capable of producing 680 bhp