From Wikipedia:
"In 1970 the 917 gave Porsche its first overall win at the 24 Hours of Le Mans, a feat it would repeat in 1971. It would be chiefly responsible for Porsche winning the International Championship for Makes in 1970 and 1971. Porsche went on to develop the 917 for Can-Am racing, culminating in the twin-turbocharged 917/30 which was even more dominant in the role. Porsche drivers would win the Can-Am championship in 1972 and 1973. 917 drivers also won the Interserie championship every year from 1969 to 1975."