The 12A is an "elongated" version of the 10A: the rotor radius was the same, but the depth was increased by to . It continued the two-rotor design; with the depth increase each chamber displaced so two chambers (one per rotor) would displace ; the series name continues earlier practice and reflects this value ("12" suggesting 1.2 litres). The 12A series was produced for 15 years, from May 1970 through 1985. In 1974, a 12A became the first engine built outside of western Europe or the U.S to finish the 24 hours of Le Mans.