EMD 710

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EMD 710
A grayish EMD 710 engine on the upper center and a generator on the right. Engine and generator are mounted to a diesel locomotive. A silver ladder below contacting the locomotive. On the lower left, a rectangular instrument box with its upper surface in white and sides in blue.
An EMD 12-710G3B engine, installed in an Iarnród Éireann 201 class locomotive
ManufacturerElectro-Motive Diesel
Also calledG-Engine
ConfigurationV8, V12, V16, and V20
Displacement710 cubic inches (11,600 cm3) per cylinder
Cylinder bore9 116 in (230 mm)
Piston stroke11 in (280 mm)
Block materialFlat, formed and rolled structural steel members, and steel forgings, integrated into a weldment
Head materialCast iron, one per cylinder
Valvetrain4 Valves per cylinder, SOHC
Compression ratio15.3:1
RPM range
Redline904 (950 on G3C models)
TurbochargerHybrid turbocharger, below half throttle, clutch-driven blower takes over
Fuel typeDiesel
Oil systemWet sump
Cooling systemLiquid cooling
Power output203 kilowatts (272 hp) per cylinder
Dry weightup to 25.57 tonnes (25.17 long tons; 28.19 short tons)
PredecessorEMD 645
SuccessorEMD 1010 - the heavily redesigned and refined EMD 265H to meet Tier-4 emission standard

The EMD 710 is a line of diesel engines built by Electro-Motive Diesel (previously General Motors' Electro-Motive Division). The 710 series replaced the earlier EMD 645 series when the 645F series proved to be unreliable in the early 1980s 50-series locomotives which featured a maximum engine speed of 950 rpm.[1] The EMD 710 is a relatively large medium speed two-stroke diesel engine that has 710 cubic inches (11.6 liters) displacement per cylinder,[2] and a maximum engine speed of 900 rpm.[note 1]

In 1951, E. W. Kettering wrote a paper for the ASME entitled, History and Development of the 567 Series General Motors Locomotive Engine,[3] which goes into great detail about the technical obstacles that were encountered during the development of the 567 engine. These same considerations apply to the 645 and 710, as these engines were a logical extension of the 567C, by applying a cylinder bore increase (645), and a stroke increase (710), to achieve a greater power output, without changing the external size of the engines, or their weight, thereby achieving significant improvements in horsepower per unit volume and horsepower per unit weight.

Since its introduction, EMD has continually upgraded the 710G diesel engine. Power output has increased from 3,800 horsepower (2,800 kW) on 1984's 16-710G3A to 4,500 horsepower (3,400 kW) (as of 2012) on the 16-710G3C-T2, although most current examples are 4,300 horsepower (3,200 kW).

The 710 has proved to be exceptionally reliable, but the earlier 645 is still supported and most 645 service parts are still in new production, as many 645E-powered GP40-2 and SD40-2 locomotives are still operating after four decades of trouble-free service, and these often serve as a benchmark for engine reliability, which the 710 would meet and eventually exceed, and quite a number of non-SD40-2 locomotives (SD40, SD45, SD40T-2, and SD45T-2, for example, and even some SD50s), have been rebuilt to the equivalent of SD40-2s with new or remanufactured engines and other subsystems, using salvaged locomotives as a starting point. Some of these rebuilds have been made using new 12-cylinder 710 engines in place of the original 16-cylinder 645 engines.

Over the production span of certain locomotive models, upgraded engine models have been fitted when these became available. For example, an early 1994-built SD70MAC had a 16-710G3B, whereas a later 2003-built SD70MAC would have a 16-710G3C-T1.

The engine is made in V-8, V-12, V-16, and V-20 configurations, although most current locomotive production is the V-16 engine, whereas most current marine and stationary engine production is the V-20 engine.


All 710 engines are two-stroke 45 degree V-engines. The 710, and the earlier 645 and 567, are the only two-stroke engines commonly used today in locomotives. The 710 model was introduced in 1985 and has a 1-inch (25 mm) longer stroke (now 11 in or 279 mm) than the 645 (10 in or 254 mm stroke). The engine is a uniflow design with four poppet-type exhaust valves in the cylinder head. For maintenance, a power assembly, consisting of a cylinder head, cylinder liner, piston, piston carrier, and piston rod can be individually and relatively easily and quickly replaced. The block is made from flat, formed, and rolled structural steel members and steel forgings welded into a single structure (a "weldment"). Blocks may, therefore, be easily repaired, if required, using conventional shop tools. Each bank of cylinders has a camshaft which operates the exhaust valves and the Unit injectors.[4]

Pre-1995 engines have mechanically controlled unit injectors (UIs), patented in 1934 by General Motors, EMD's former owner. Post-1995 engines have electronically controlled unit injectors (EUIs) which fit within the same space as a unit injector.[5] An EUI is EMD's implementation of EFI on its large-displacement diesel engines.

See EMD 645 for general specifications common to all 567, 645, and 710 engines.

Unlike the two earlier engines, which could use either a Roots blower or a turbocharger, the 710 engine is offered only with turbocharging. The turbocharger (a combination turbo-compressor system) follows EMD's innovative design that uses a gear train and over-running clutch to drive the compressor rotor. This system acts as a centrifugal blower, during low engine speed, when exhaust gas temperature (and, correspondingly, heat energy) alone is insufficient to drive the turbine. At higher engine speeds, increased exhaust gas temperature is sufficient to drive the turbine, the clutch disengages, and acts as a true centrifugal turbocharger. The turbo-compressor can revert to compressor mode momentarily during demands for large increases in engine output power. While more expensive to maintain than Roots blowers, the turbocharger significantly reduces fuel consumption and emissions, while improving high-altitude performance. Additionally, EMD's turbo-compressor can provide a 50 percent increase in maximum rated horsepower over Roots-blown engines for the same engine displacement. But, unlike the earlier 645 and 567, which offered both Roots-blown and turbocharging, EMD's turbo-compressor is an integral part of all 710 models, therefore this 50 percent increase is already incorporated into the maximum rated power of all 710 models. The putative horsepower of an otherwise equivalent displacement but Roots-blown, that is, naturally aspirated, 710 may be approximated by multiplying the turbocharged horsepower by 0.67.

Horsepower for any naturally aspirated engine is usually derated 2.5 percent per 1,000 feet (300 m) above mean sea level, a tremendous penalty at the 10,000 feet (3,000 m) or greater elevations which several Western U.S. and Canada railroads operate, producing as much as a 25 percent power loss. Turbocharging effectively eliminates this derating.

Certain models have engine controls that permit lower fuel consumption (possibly at the expense of higher emissions) or lower emissions (possibly at the expense of higher fuel consumption).

Rail versions[edit]

ID Engine type Max RPM Power (hp) Power (MW) Introduced Locomotive(s)
8-710G3A-T2 V-8 900 2150 1.6 2007 GP22ECO, SD22ECO, GT38ACe EFI equipped. Romanian Class 63, Class 65, Class 66-2, Indonesian CC205 class.
12-710G3A V-12 900 3000 2.2 1985 GP59, F59PH, Australian National DL class, New South Wales 82 Class.
12-710G3B-T2 V-12 900 3150 2.3 2007 SD32ECO EFI equipped.
12-710G3C-U2 V-12 950 3150 2.3 2006 Euro 3000 EFI equipped.
12-710G3C-EC V-12 950 3200 2.3 1993 F59PHI EFI equipped.
12N-710G3B-EC V-12 900 3200 2.5 1998 British Rail Class 66, British Rail Class 67, Irish Rail 201 Class, RENFE Class 334, EMD DE/DM30AC
12N-710G3B-ES V-12 900 3200 2.5 1998 WAGR S class (diesel), Downer EDI Rail GT42CU AC, Downer EDI Rail JT42C-DC.
16-710G3A V-16 900 3800 2.8 1984 GP60, GP60M, GP60B, SD60, SD60M, SD60I, SD60F, Australian National AN Class, New South Wales 90 Class.
16-710G3B V-16 900 4000 3.0 1992 Early SD70, SD70M, SD70MAC and SD70I.
16-710G3B-EC V-16 900 4000 3.0 1997 SD70, SD70M, SD70MAC and SD70I models equipped with electronic fuel injection (EFI).
16-710G3B-ES V-16 900 4000 3.1 1997 Downer EDI Rail GT46C
16-710G3B-T1 V-16 900 4000-4200 3.0-3.1 2003 EPA Tier 1 Emissions compliant/EFI Equipped SD70M, SD70MAC, Alstom PL42AC EPA Tier I emissions compliant/EFI equipped.
16-710G3B-T2 V-16 900 4000 3.0 2005 SD70M-2 (Norfolk Southern), MP40PH-3C EPA Tier II emissions compliant/EFI equipped.
16-710G3C V-16 950 4300 3.2 1995 SD75M, SD75I.
16-710G3C-EC V-16 950 4300 3.2 1995 SD75M, SD75I, SD90/43MAC EFI equipped.
16-710G3C-ES V-16 950 4300 3.2 2007 Downer EDI Rail GT46C ACe
16-710G3C-T1 V-16 950 4300 3.2 2003 SD70M (late model), SD70MAC (late model)
16-710G3C-T2 V-16 950 4300-4500 3.2 2004 SD70ACe, SD70M-2, SD70ACS, SD70ACe/45, EPA Tier II emissions compliant/EFI equipped.
16-710G3C-U2 V-16 950 4300 3.2 2006 Euro 4000 EFI equipped.
20-710G3B-EC V-20 900 5000 3.7 1995 SD80MAC EFI equipped, GT50AC (Indian Railways WDG5)
20-710G3C-ES V-20 950 5300 3.9 2011 SD80ACe EPA Tier 1 Emissions compliant.

Stationary/Marine versions[edit]

EMD E23G[6]
ManufacturerProgress Rail
ConfigurationV8, V12, V16, and V20
Displacement710 cubic inches (11,600 cm3) per cylinder
Cylinder bore9 116 in (230 mm)
Piston stroke11 in (280 mm)
Block materialFlat, formed and rolled structural steel members, and steel forgings, integrated into a weldment
Head materialCast iron, one per cylinder
Valvetrain4 Valves per cylinder
Compression ratio16:1
RPM range
TurbochargerHybrid turbocharger, below half throttle, clutch-driven blower takes over
Fuel typeNatural gas
Oil systemWet sump
Cooling systemLiquid cooling
Power output193 kilowatts (259 hp) per cylinder
Dry weightup to 25.85 tonnes (25.44 long tons; 28.49 short tons)
Predecessornone, this variant is a conversion
SuccessorCaterpillar CG170

Like most EMD engines, the 710 is also sold for stationary and marine applications.

Stationary and marine installations are available with either a left or right-hand rotating engine.

Marine engines differ from railroad and stationary engines mainly in the shape and depth of the engine's oil sump, which has been altered to accommodate the rolling and pitching motions encountered in marine applications.

Engine Speed

  • Full . . . . . . . . . . . . . . 900 RPM
  • Idle . . . . . . . . . . . . . . 350 RPM

Compression Ratio . . 16:1

Brake Horsepower (ABS Rating)

  • Model 710G7 Engines
    • 8-cylinder: 1800
    • 12-cylinder: 2800
    • 16-cylinder: 3600
    • 20-cylinder: 4300

See also[edit]


  1. ^ Same parts suitable for 1000 rpm speed, yet rated lower because of earlier problems in EMD 645. Factory-fitted governor limits to 900 rpm.
  1. ^ 40-series versions of the 645, save the initial teething problems with the 20-645E, which were eventually resolved, proved to be exceptionally reliable.
  2. ^ "Progress Rail" (PDF). www.emdiesels.com.
  3. ^ Kettering, E.W. (29 November 1951). History and Development of the 567 Series General Motors Locomotive Engine (PDF). ASME 1951 Annual Meeting. Atlantic City, New Jersey: Electro-Motive Division, General Motors Corporation. Retrieved 6 January 2015.
  4. ^ Bernard Challen, Rodica Baranescu (ed.), Diesel Engine Reference Book Second Edition, Butterworth-Heinemann 1999 ISBN 0 7506 2176 1 pg 598
  5. ^ The camshaft still operates the unit injector's built-in plunger pump, as the pump's performance is unequaled in atomizing and injecting the fuel at great pressure; the electronics controls the timing of certain events within the unit injector, thereby achieving, variously, maximum horsepower, minimum emissions or minimum fuel consumption, as directed by the engine control system.
  6. ^ "Progress Rail-Natural Gas Solutions".

External links[edit]