When sports car races were organised on the Canadian and American tracks in 1966, Chinetti asked Ferrari to come up with a suitable car. A P3/4 series chassis mounted with a slightly larger engine than the original four-litre was selected for the role, and the car hit the tracks during the 1967 season. However, there was such a difference in displacement compared to the American cars fitted with 7- and 8-litre engines, with their massive torque, that a second model was built for the following year.