A Place For Fun With Old Engines
This subject spans many decades...
DETROIT DIESEL INLINE 71 SERIES
In the late 1930s the brilliant
engineering design team at the GM Research Laboratories, led by
Charles Kettering, set out to develop a versatile small high speed
diesel engine that would be suitable for a wide range of automotive,
marine, and industrial applications. The result was the GM Detroit
Diesel 71 series, one of the most successful and long lived diesel
engine designs ever produced. The 71 series engines are named
for their swept displacement per cylinder (in cubic inches), a
naming practice that Detroit Diesel also shared with the Electro-Motive
Division of General Motors.
The main incentive for the development
of the 71 series was GM's truck production and their partial ownership
of Yellow Coach. This provided an immediate market for thousands
of the engines, but the designers also made advance provision
in the design to accomodate marine exhaust manifolds, pump and
power takeoff units, a wide range of engine mountings, generators,
and marine transmissions. Consequently the engines could also
be used for an impressive variety of marine or stationary power
generating, power takeoff, and pumping applications.
The 71 series are two-stroke cycle
uniflow scavenged engines, with the air entering the cylinders
through a ring of ports in the cylinder liners, and the exhaust
exiting through valves in the cylinder head. In early production
all the engines were fitted with engine-driven Roots blowers,
but late production some models of the 71 series were available
in versions having a turbocharger in series with the Roots blower
for higher power output.
Eventually the series would be
built in one, two, three, four, and six cylinder inline models.
The four larger engines were well equipped for use as ships service
engines on tugboats, and the 4-71 and 6-71 were often used for
propulsion in smaller tugs and workboats, singly or in twin or
quad sets. When the US entered World War Two, the 71 series diesel
were adapted to many military applications, including propulsion
packages for tanks and use in landing craft, ships' boats, and
shore based power generating plants. Following the war the two
cylinder 71 was often used as a refrigeration engine in railroad
The 71 series served as the design
model for a number of other engines, both larger and smaller.
In 1945 GM introduced the larger but very similar 110 series uniflow
scavenged engine, which proved successful in many marine and railcar
applications. There were both Roots and centrifugal blower versions
of the 110 engines. Around the same time they introduced the smaller
51 series valveless cross flow scavenged engines. The 51 series
was built in small numbers, primarily as a marine and industrial
engine, and today they are very rare and eagerly sought by engine
collectors. The 51 series was replaced in the product line by
the more conventional 53 series uniflow scavenged engines in the
1950s, which was used in a wide range of marine, railroad and
industrial applications as well as in trucks. Vee versions of
the 71 series were also developed in this time period, and became
a very common bus, marine, and power generating engine for several
decades. The Vee 71 series eventually included six, eight, twelve,
and sixteen cylinder models. The product line was further supplemented
by the very similar but more powerful 92 series engines, basically
a larger bore version of the 71s, which remained in production
until very recently.
Article and page design by Preston Cook, ©2009
Above: A longitudinally sectioned view of the
Detroit Diesel 3-71 engine shows the view in the air box (left
to right) of the outside of the liner on cylinder #3, a section
through the piston and rod on cylinder #2, and an outside view
of the piston, rod, and rings on cylinder #3. Top three illustrations
by GM Diesel Power.
Above: The Detroit Diesel 71 series was stunningly
successful right from its introduction, and engine #100,000 was
produced by the middle of World War Two. The production life of
the 71 series was from the 1930s into the 1990s, making it one
of the longest manufactured and successful diesel engines of all
Above: The engine room of a newly completed tugboat
photographed in the early 1950s shows the typical application
of Detroit Diesel 71s along the port side as ships service engines,
with a Cleveland 12-278A main engine. From the 1930s into the
1950s, GM Diesel Power served as the marine and industrial sales
agency for all the GM divisions building diesel engines, including
Detroit Diesel, Cleveland Diesel, and Electro-Motive Division.
Under this arrangement, vessel sets of engines were often sold
and installed as a single order. This photo is from a Cleveland
Diesel Engine Division publicity package issued at the vessel
Above: A pair of Detroit Diesel 71s are shown
in the engine room of a Lehigh Valley Railroad tug at Jakobson
Shipyard in the late 1940s. The electrical switchboard is aft
of the two engines behind the access ladder to the main deck.
Photo from a Cleveland Diesel Engine Division press package.