6-71N  (1938): 130hp, 2,215 pounds without transmission
Above: 8v71 N  (1957): 335hp, 3,130 pounds without transmission
General Motors’ 6-71N (inline 6-cylinder design, displacing 71 cubic inches per cylinder) debuted at the New York boat show in 1938 producing a then-remarkable 130 horsepower from 2,740 pounds including a marine transmission.

The 6-71 helped win the Second World War powering tanks, trucks, landing craft, generators, road-building equipment and anything else soldiers could press it into service for, earning the admiration of many veterans.

While the model designator “N” refers to “natural aspiration,” two-cycle General Motors and later Detroit Diesel engines in fact included one or two superchargers to force fresh air into the cylinders.

In 1957, an 8-cylinder V-configuration was built. The first 8v71N marine engine (pictured here) offering in 1962 provided 335 horsepower and weighed 3,800 pounds with its transmission.

In 1965, GM spun off the Detroit Diesel Engine Division.