A Place For Fun With Old Engines
This subject spans many decades...
PRESENTING THE
DETROIT DIESEL INLINE 71 SERIES
In the late 1930s the brilliant design team at the
GM Research Laboratories, led by Charles Kettering, set out to
develop a versatile 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
shared with sister Electro-Motive Division.
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, a wide range
of engine mountings, and marine transmissions. Consequently the
engines could also be used for a wide 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 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 model was widely applied
as a refrigeration engine in railroad cars.
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 application.
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, and 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 widely used bus engine
for several decades. 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.
**********
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
time.
**********
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
launching.
**********
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.
**********
