Input (grade 13): This design was very influential for racing engines as it featured for the first time dual overhead camshafts (DOHC) and four valves per cylinder, a layout that would become the standard until today for racing inline-four engines.
Output (grade 7): It was the first to use dual overhead camshafts (DOHC) and four valves per cylinder. This became the standard design for racing inline-four engines.