[8] In September 1972, Nissan introduced the fourth generation Skyline (chassis code C110) powered by the L series of engines.

A KPGC110 "Skyline 2000GT-R Racing Concept" powered by the S20 was shown at the 1972 Tokyo Motor Show after the commercial models were introduced; although the concept's number (73) hinted at Nissan's racing efforts for 1973, Nissan dropped its factory team that year in favor of developing anti-pollution technology and improving fuel efficiency.

[9] Less than 200 examples of the KPGC110 GT-R would be built from January through April 1973, due to increasingly stringent emissions laws;[10] in addition, the contemporary oil crisis of that year created a wasteful perception of auto racing and high-performance vehicles by many people.

It features a dual overhead cam, cross-flow head with pent-roof combustion chamber and four valves per cylinder.

Heads were ported and polished manually, and the motors were bench tested for consistent power production before installation.

[2] Most engines utilized triple Mikuni-Solex 40PHH dual-choke carburetors;[2] models after 1969 offered optional Lucas mechanical fuel injection.

Due to its simpler and more robust design, the L-series went on to become the most favored engine in motorsport and tuning,[17] while the S20 remains relatively obscure.