Detroit Diesel Series 71
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The Detroit Diesel Series 71 is a
two-stroke diesel engine A two-stroke diesel engine is an internal combustion engine that uses compression ignition, with a two-stroke combustion cycle. It was invented by Hugo Güldner in 1899.Mau (1984) p.7 In compression ignition, air is first compressed and heated ...
series, available in both inline and V configurations, manufactured by Detroit Diesel. The number 71 refers to the nominal displacement per cylinder in cubic inches, a rounding off of . Inline models included one, two, three, four and six cylinders, and the V-types six, eight, 12, 16 and 24 cylinders. The two largest V units used multiple cylinder heads per bank to keep the head size and weight to manageable proportions, the V-16 using four heads from the four-cylinder inline model and the V-24 using four heads from the inline six-cylinder model. This feature also assisted in keeping down the overall cost of these large engines by maintaining parts commonality with the smaller models.


History

The inline six-cylinder 71 series engine was introduced as the initial flagship product of the Detroit Diesel Engine Division of
General Motors The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...
in 1938. The V-type first appeared in 1957. Sales of The 71 Series ceased in the summer of 1995, with the four stroke Detroit Diesel engine introduced as a replacement.


Design

Bore and stroke are the same across all units, at . Inline models were famously "symmetrical", meaning that blower, exhaust, water manifold, starter, and other components could be mounted on either side of the basic block to fit a particular application. A number of models could also run with the crankshaft turning either clockwise or counter-clockwise, called "Right Hand" or "Left Hand" rotation engines (as viewed from the front of the engine). The less-common Left Hand engines were typically used in buses, because the rotation matched rear-engined
transverse Transverse may refer to: *Transverse engine, an engine in which the crankshaft is oriented side-to-side relative to the wheels of the vehicle *Transverse flute, a flute that is held horizontally * Transverse force (or ''Euler force''), the tangen ...
installations. Boats equipped with two engines would typically use one Left Hand and one Right Hand, so that the torque from the
propellers A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...
would cancel each other out, without the need for a complex reversing gear on one side. As a two-stroke
diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
that does not use crankcase aspiration cannot naturally draw in combustion air, the blower is inherently necessary to charge the cylinders with air for combustion. The blower also assists in
scavenging Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding ...
spent combustion gasses at the end of the power stroke. All Series 71 engines use
uniflow scavenging A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a Thermodynamic power cycle, power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being comple ...
, in which a
gear A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic pr ...
-driven
Roots blower The Roots-type blower is a positive displacement lobe pump which operates by pumping a fluid with a pair of meshing lobes resembling a set of stretched gears. Fluid is trapped in pockets surrounding the lobes and carried from the intake si ...
mounted to the exterior of the engine provides intake air through cored passages in the engine block and ports in the cylinder walls at slightly greater than atmospheric pressure. The engine exhausts through
pushrod A valvetrain or valve train is a mechanical system that controls the operation of the intake and exhaust valves in an internal combustion engine. The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) ...
-operated
poppet valve A poppet valve (also called mushroom valve) is a valve typically used to control the timing and quantity of gas or vapor flow into an engine. It consists of a hole or open-ended chamber, usually round or oval in cross-section, and a plug, usual ...
s in the cylinder head(s), with either two or four valves per cylinder. Unit fuel injection is employed, one
injector An injector is a system of ducting and nozzles used to direct the flow of a high-pressure fluid in such a way that a lower pressure fluid is entrained in the jet and carried through a duct to a region of higher pressure. It is a fluid-dynamic ...
per cylinder, with no high fuel pressure outside of the injector body. The injectors are cycled from the same
camshaft A camshaft is a shaft that contains a row of pointed cams, in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines (to operate the intake and exhaust valves), mechanically controlled ignition systems ...
responsible for opening the
exhaust valve A poppet valve (also called mushroom valve) is a valve typically used to control the timing and quantity of gas or vapor flow into an engine. It consists of a hole or open-ended chamber, usually round or oval in cross-section, and a plug, usual ...
s.


Nomenclature

The first number refers to the number of cylinders in the engine, followed by a hyphen or "V", indicating inline or vee, respectively, then 71 for the Series designation, referring the nominal displacement per cylinder in cubic inches (rounding up ). Like most Detroit Diesel two-cycle engines, the 71 Series are equipped with a blower yet still referred to as "
naturally aspirated Naturally may refer to: ;Albums * ''Naturally!'', an album by Nat Adderley * ''Naturally'' (Houston Person album) * ''Naturally'' (J. J. Cale album) * ''Naturally'' (John Pizzarelli album) * ''Naturally'' (Sharon Jones album) * ''Naturally'' ...
" ( SAE designation). These do not have a model suffix identifier: 6-71 is an
inline 6 The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine bal ...
. When the model number includes a suffix, it denotes additional features. Engines equipped with needle unit fuel injectors and commonly four exhaust valves per cylinder are indicated by the suffix "N", so for the V8, 8V-71N. Later versions were available with
turbocharger In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...
s, which discharged directly into the Roots blower intake; these have a "T" suffix, and with aftercooling, a "TA", so 8V-71T or 8V-71TA. "TT" indicates Tailored Torque and "TTA" Tailored Torque Aftercooled. These models are designated for economy (Fuel Squeezer) and constant horsepower ratings.


Applications

The most popular incarnations of the series 71 engine as used for highway vehicle applications included the inline 6-71, the V-block 6V-71 (both widely used in
transit bus Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...
es) and the 8V-71 V-8. In addition to
motorcoach A coach (or coach bus/motorcoach) is a type of bus built for longer-distance service, in contrast to transit buses that are typically used within a single metropolitan region. Often used for touring, intercity, and international bus service ...
propulsion, both inline and V types have found extensive usage in
school buses A school bus is any type of bus owned, leased, contracted to, or operated by a school or school district. It is regularly used to transport students to and from school or school-related activities, but not including a charter bus or transit bus ...
,
truck A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...
s,
fire apparatus A firefighting apparatus describes any vehicle that has been customized for use during firefighting operations. These vehicles are highly customized depending on their needs and the duty they will be performing. These duties can include firefighti ...
,
motor home A motorhome (or motor coach) is a type of self-propelled recreational vehicle (RV) which offers mobile living accommodation. Features Motorhomes usually have sleeping spaces for two to eight people. Each sleeping space is either fixed or conv ...
s,
construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...
and industrial machinery, a few farm tractors, commercial
fishing vessels A fishing vessel is a boat or ship used to catch fish in the sea, or on a lake or river. Many different kinds of vessels are used in commercial, artisanal and recreational fishing. The total number of fishing vessels in the world in 2016 was es ...
, and
military vehicle A military vehicle is any vehicle for land-based military transport and activity, including combat vehicles; both specifically designed for, or significantly used by military and armed forces. Most military vehicles require off-road capabiliti ...
s and equipment. The 71 series is very popular in marine applications, not only as a propulsion engine in small craft ( Gray Marine 6-71) but as auxiliary power to drive generators, winches and other heavy shipboard machinery. The Detroit inline 6-71 engine, in all of its variations, was also available as a 'pancake engine' (here variably called either 6L-71 or 6N-71) for horizontal (underfloor) mount applications, such as on larger
Crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...
and
Gillig Gillig (formerly Gillig Brothers) is an American designer and manufacturer of buses. The company headquarters, along with its manufacturing operations, is located in Livermore, California (in the East Bay region of the San Francisco Bay Area) ...
school bus A school bus is any type of bus owned, leased, contracted to, or operated by a school or school district. It is regularly used to transport students to and from school or school-related activities, but not including a charter bus or transit bus ...
es and
articulated An articulated vehicle is a vehicle which has a permanent or semi-permanent pivot joint in its construction, allowing it to turn more sharply. There are many kinds, from heavy equipment to buses, trams and trains. Steam locomotives were someti ...
puller transit buses (such as the
Crown-Ikarus 286 The Crown-Ikarus 286 is a type of transit bus that was manufactured for the U.S. market from 1980 until 1986, under a joint venture between the Ikarus Body and Coach Works (Ikarus), of Budapest, Hungary, and Crown Coach Corporation from Los Ange ...
). Many 4-71 engines were used in various types of construction equipment, such as
Galion Galion is a city in Crawford, Morrow, and Richland counties in the U.S. state of Ohio. The population was 10,453 at the 2020 census. Galion is the second-largest city in Crawford County after Bucyrus. The Crawford County portion of Galion is ...
highway graders. The 6-cylinder version was also used in the Victorian Railways
DERM The Diesel Electric Rail Motor (DERM) was a railmotor operated by the Victorian Railways of Australia. History Originally built as a petrol electric rail motor (PERM), they were the longest-lived rail motor on the Victorian Railways, wi ...
railmotor.


Variants



Model numbers


Further developments


WWII General Motors 6004/6046 engine

The inline 6-71 was adapted to British requirements as the power plant for Canadian (and later British) built
Valentine tank The Tank, Infantry, Mk III, Valentine was an infantry tank produced in the United Kingdom during World War II. More than 8,000 of the type were produced in eleven marks, plus various specialised variants, accounting for approximately a quarter ...
s where it was known as the GMC 6004, orders being placed in late September 1940. The 6046 Diesel was a twin engine setup used by US and British tanks and tank destroyers. *The M3A3 (Lee IV/Lee V) and M3A5 (Grant II) variants of the M3 tank *M4A2 variant of the
M4 Sherman tank } The M4 Sherman, officially Medium Tank, M4, was the most widely used medium tank by the United States and Western Allies in World War II. The M4 Sherman proved to be reliable, relatively cheap to produce, and available in great numbers. It w ...
*
M10 tank destroyer The M10 tank destroyer was an American tank destroyer of World War II. After US entry into World War II and the formation of the Tank Destroyer Force, a suitable vehicle was needed to equip the new battalions. By November 1941, the Army requeste ...
and the re-gunned British variant the 17pdr SP Achilles * M36B2 variant of the M36 tank destroyer


Detroit diesel 6051 quad-71

The
Detroit diesel 6051 quad-71 The GM Diesel/Detroit Diesel model 6051 Quad power pack consists of four inline 2-stroke diesel 6-71 engines mounted to one gearbox, usually with one shaft coming out of the power unit. The power units were fitted on landing craft and ships duri ...
was a Detroit Diesel Series 6-71 side by side tandem engine setup of two banks of four engines each driving two propeller shafts in Landing Craft Infantry
LCI(L) The Landing Craft Infantry (LCI) were several classes of landing craft used to land large numbers of infantry directly onto beaches during the Second World War. They were developed in response to a British request for seagoing amphibious assault s ...
. The eight engines produced a total of .


Soviet/Russian copies

In the
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
/ Russia, various versions of this engine-type were produced at the YaAZ automobile factory in
Yaroslavl Yaroslavl ( rus, Ярослáвль, p=jɪrɐˈsɫavlʲ) is a city and the administrative center of Yaroslavl Oblast, Russia, located northeast of Moscow. The historic part of the city is a World Heritage Site, and is located at the confluence ...
. Throughout
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, the 4-71 engine both in locally assembled form (built by
Lend-Lease Lend-Lease, formally the Lend-Lease Act and introduced as An Act to Promote the Defense of the United States (), was a policy under which the United States supplied the United Kingdom, the Soviet Union and other Allied nations with food, oil, ...
provided American industrial equipment) and from USA-supplied kits had been used for Ya-12 light
artillery tractor An artillery tractor, also referred to as a gun tractor, is a specialized heavy-duty form of tractor unit used to tow artillery pieces of varying weights and calibres. It may be 6x6, wheeled, continuous track, tracked, or half-tracked. Trac ...
s. After 1945, the 4-71 engine entered production in a slightly modified configuration (deuniversalization, conversion to metric units, a more powerful preheater) to suit the conditions of the
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
branded "YaAZ-204". After 1947 the factory used a copy of the 6-71 engine branded "YaAZ-206" in the heavy trucks YaAZ-210 and YaAZ-214 built from 1951 to 1959. The vehicle production was transferred to
KrAZ KrAZ ( uk, Кременчуцький автомобільний завод, ''Kremenchutskyi Avtomobilnyi Zavod'', Kremenchuk Automobile Plant, АвтоКрА́З or AvtoKrAZ) is a Ukrainian factory that produces trucks and other special-purpos ...
in
Kremenchuk Kremenchuk (; uk, Кременчу́к, Kremenchuk ) is an industrial city in central Ukraine which stands on the banks of the Dnipro River. The city serves as the administrative center of the Kremenchuk Raion (district) in Poltava Oblast (pr ...
,
Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...
in 1959, where trucks with newer versions of the YaAZ-206 stood in production until the appearance of the
four-stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...
V8-engined KrAZ-255 in 1967.


See also

* List of Detroit Diesel products


References

{{Commons category, Detroit Diesel series 71 engines


Sources

*Shelton, Chris. "Then, Now, and Forever" in ''Hot Rod'', March 2017, pp.16-29. 71 Two-stroke diesel engines Straight-twin engines Straight-three engines Straight-four engines Straight-six engines V6 engines V8 engines V12 engines V16 engines Diesel engines by model