Sports car racing went through some turbulent times in the early 1970’s. At the start (1970) the world championship was decided by the 5.0 liter sports cars such as the Porsche 917 and the Ferrari 512. The FIA /CSI (International rules body) at first did not think anyone would build any new 5.0 liter cars, as the regulations specified that a minimum of 25 cars had to be built. But of course, Porsche and Ferrari did build them, and the rest was, as they say, history. Porsche won the title in both 1970 and 1971 with the 917.
The FIA soon changed the rules effective 1972 to use 3.0 liter engine, open top cars. Ferrari, Matra and Alfa Romeo built cars, but interest waned by 1974 and no other manufacturers were interested.
