Why EMD 710 Was Banned: The Engine That Was Too Powerful
The engine that saved EMD’s reputation.
By the early 1980s, General Motors electrotive division faced a crisis that threatened four decades of locomotive dominance.
Their latest 645F engines were failing in service, suffering reliability problems that shocked an industry accustomed to bulletproof EMD quality.
Railroads that had trusted EMD for generations were suddenly looking at General Electric’s locomotives with serious interest.
The EMD 710 diesel engine introduced in 1984 wasn’t just an update.
It was a rescue mission.
This engine had to fix the 645F’s problems while delivering more power, better fuel economy, and modern electronic controls, all while maintaining the legendary reliability that had built EMD’s reputation.
Failure wasn’t an option.
The company’s future depended on getting this righT.
The 710 succeeded brilliantly with 710 cubic in of displacement per cylinder achieved through a 1 in longer stroke than the 645.
The new engine delivered up to 4,500 horsepower in later versions while proving even more reliable than the legendary 645E that had powered the iconic SD40-2.
The 710 became the foundation for EMD’s modern locomotive lineup, powering thousands of SD60, SD70 MAC, SD70M, and SD70 ACES that continue hauling freight across North America and around the world.
For over 30 years, the 710 has been EMD’s workhorse, proving that when your reputation is on the line, solid engineering and relentless attention to reliability can turn a crisis into triumph.
Historical context and developmenT.
The story of the EMD710 begins with the hubris of succesS.
After dominating the locomotive market for decades with their reliable 645 engine, EMD engineers pushed too hard for more power.
The 645F series, introduced in the late 1970s for 50 series locomotives, increased maximum engine speed from 900 RPM to 950 RPM to boost horsepower outpuT.
This seemingly minor change proved disastrouS.
The higher RPM stressed components beyond their design limitS.
Engines suffered from vibration issues, increased wear rates, and unexpected failures that were completely uncharacteristic of EMD productS.
Railroads that had operated thousands of 645e powered SD42s for hundreds of thousands of miles without major issues suddenly faced locomotives requiring extensive maintenance after relatively short service liveS.
The GP50, GP60, SD50, and SD60 models equipped with 645F engines developed poor reputations that persist today.
EMD’s engineering teams went back to fundamentalS.
Rather than continuing to extract more power from the 645 through higher speeds, they returned to the proven approach that had served the company since the 1930S.
Increase displacement, maintain conservative operating speeds, and prioritize reliability over peak performance numberS.
The solution was eleganT.
Lengthen the stroke by 1 in from 10 in to 11 in.
While maintaining the same 9.0625 inch bore as the 645.
This created exactly 710 cubic inches per cylinder, a 10% displacement increase that could deliver more power at the proven 900 RPM engine speed that had worked so well in millions of service hourS.
Development moved quickly, driven by the urgent need to restore EMD’s reputation and competitive position.
The golden age.
The EMD710 entered production in 1984 with the SD60 and immediately began rebuilding EMD’s damaged reputation.
The first 16710G 3A engines produced 3,800 horsepower, more than the troublesome 645F, but at the safer 900 RPM speed.
Railroads that had been burned by 645 degrees Fahrenheit reliability problems approached the new engine cautiously, but the 710 quickly proved itself through flawless performance.
The breakthrough came with the 1990s introduction of AC traction technology.
The SD70 MAC powered by a 16710G3B producing 4,000 horsepower revolutionized heavy hall railroading.
Burlington Northern Santa Fe and Union Pacific ordered over 1,000 SD70 Max each.
And these locomotives transformed mountain railroading by providing unprecedented tractive effort without wheel sliP.
The 710’s smooth power delivery proved perfect for AC Traction’s precise control requirementS.
Union Pacific’s 1999 order for 1,000 SD70M locomotives, the largest single locomotive order in North American railroad history, validated the 710’s succesS.
These locomotives, along with hundreds more SD70M purchased by other railroads, became the backbone of modern freight operationS.
The 710 had not only restored EMD’s reputation, but exceeded the legendary reliability of the 645E.
The SD70ACE, introduced in 2004 to meet EPA tier 2 emissions standards, represented the 710’s maturity.
The 16-710 G3C-T2 engine delivered 4,300 horsepower with improved fuel efficiency and lower emissions than earlier versionS.
Major railroads including CSX, Norfolk Southern, Union Pacific, and Canadian Pacific ordered thousands of SD7AES, making it one of the most successful modern locomotive designs and cementing the 710’s position as the industry standard.
Technical brilliance.
The EMD 710’s technical sophistication built upon seven decades of two-stroke diesel engine developmenT.
Like its 567 and 645 predecessors, the 710 featured a 45°ree V configuration with Uniflow scavenging exhaust valves in the cylinder head, intake ports in the cylinder liner.
This design ensured complete combustion and excellent fuel efficiency while maintaining the two-stroke cycles advantage of twice the power pulses per revolution compared to four-stroke engineS.
The critical innovation was the turbocharger system.
Unlike the 645, which could use either roots blowers or turbochargers, the 710 was designed exclusively for turbocharging.
The gardriven turbocharger featured an overrunning clutch that allowed it to function as a centrifugal supercharger at low engine speeds, providing adequate air flow for starting and low-speed operation.
At higher speeds, exhaust energy took over, creating an efficient turbocharger that eliminated the altitude related power losses plaguing naturally aspirated engineS.
Electronic unit injectors introduced in 1995 represented the biggest advance in fuel delivery since mechanical unit injectors were patented in 1934.
The EUI system provided precise fuel metering across all operating conditions, improving fuel economy by up to 5% while reducing emissions and enhancing throttle response.
Each injector featured electronic control that allowed optimization of injection timing and duration for every cylinder under all load conditionS.
The 710’s modular power assembly design continued EMD’s tradition of field serviceability.
Individual cylinders could be replaced without major engine disassembly and components were designed for rebuild rather than replacemenT.
This philosophy meant 710 engines regularly operated for 3 years or more between major maintenance events, setting industry benchmarks for reliability that competitors struggled to match.
Challenges rise by the 2000S.
The EMD710 faced challenges that engineering excellence alone couldn’t solve.
The EPA’s progressively stricter emission standards were approaching levels that would fundamentally challenge the two-stroke diesel engines architecture.
While EMD successfully met tier 0 through tier 2 standards with the 710, the looming tier 4 requirements set to take effect January 1st, 2015 presented a seemingly insurmountable obstacle.
General Electric had been steadily improving their four-stroke FDL engine family and had captured the majority of the North American locomotive market by the late 1980S.
While the 710 helped EMD regain ground during the 1990s and early 2000s, GE’s continuous improvements and aggressive pricing maintained their market leadershiP.
By 2010, GE held approximately 70% market share compared to EMD’s 30%.
The corporate ownership changes complicated matterS.
In 2005, GM sold EMD to Greenbryer Equity Group and Berkshire PartnerS.
5 years later, Progress Rail, a Caterpillar subsidiary, purchased EMD.
While these changes brought fresh capital and management, they also created uncertainty about the company’s direction and commitment to locomotive manufacturing.
EMD initially believed the 710 could be modified to meet tier 4 standards through advanced after treatment systems and electronic controlS.
Extensive testing proved otherwise.
The two-stroke architecture’s fundamental characteristics made achieving tier 4 compliance while maintaining performance and reliability in realworld railroad conditions extremely difficulT.
The engine that had saved EMD in 1984 had reached the limits of what regulations would permiT.
This crisis forced EMD to make the most significant engine architecture change since abandoning the Winton 201A in 1938.
The transition.
The transition away from the 710 for domestic production marked the end of an erA.
When EPA tier 4 standards took effect on January 1st, 2015, EMD could no longer build 710 powered locomotives for use in the contiguous United StateS.
The SD70ACE, EMD’s primary road switcher model, was immediately shelved for domestic production, creating a crisis similar to what the 645F had caused three decades earlier.
EMD’s response was the SD70 ACE-T4 unveiled in October 2015 and powered by the new 1010J engine, a four-stroke design derived from the earlier 265H engine.
The 12cylinder 1010J produced 4500 horsepower while meeting tier 4 standards, but represented a fundamental break from EMD’s 8 decade commitment to two-stroke technology.
Testing began in spring 2016 with first deliveries to Union Pacific in December 2016.
However, the 710 story didn’t end.
The engine remained in production for export markets where tier 4 standards didn’t apply and EMD continued offering 710 powered locomotives to railroads in Canada, Mexico, and overseas marketS.
The proven reliability and extensive parts availability of the 710 made it attractive for international customers who prioritized dependability over the latest emissions technology.
Perhaps more significantly, the 710 found new life in locomotive rebuilding prograMs.
EMD’s 710ECO repower packages allowed railroads to replace aging 645 or earlier 710 engines with modern 710G3C engines, extending locomotive life by up to 40 years, while improving fuel efficiency by 10 to 25%.
Thousands of older locomotives received 710 repowers, creating a thriving business that sustained EMD through the domestic production hiatuS.
Legacy and modern impacT.
The EMD710’s legacy is measured not just in locomotives built, but in crisis averted and reputation restored.
When the engine entered production in 1984, EMD faced an existential threat from their own engineering mistakes with the 645F.
The 710 didn’t just fix those probleMs.
It exceeded the legendary reliability of the 645E, setting new benchmarks for diesel locomotive engine performance that competitors still struggle to match.
Over 30 years of production, the 710 powered some of the most successful locomotive designs in railroad history.
The SD70 MAC revolutionized mountain railroading with AC traction.
The SD70M became the backbone of major railroad fleetS.
The SD70 ACE proved that emissions compliance didn’t require sacrificing performance or reliability.
Collectively, thousands of 710 powered locomotives continue moving the world’s freight, many approaching or exceeding 2 million miles of service.
The 710’s influence extends beyond EMD.
The engine proved that evolutionary improvement of proven technology often succeeds where revolutionary change failS.
General Electric studied 710 reliability extensively, incorporating lessons learned into their own designS.
The two-stroke diesel engines efficiency and power density continue influencing modern locomotive development, even as four-stroke designs dominate new production.
Today, Progress Rail continues supporting the 710 through parts production, remanufacturing programs, and export locomotive production.
The engine that saved EMD in 1984 continues serving railroads worldwide, proving that when engineering is done right, longevity isn’t just possible, it’s inevitable.
The 710 stands as testament to what can be achieved when crisis forces return to fundamental engineering principleS.
Build it strong, keep it simple, and make it laSt.
The engine that rescued a legend and became one itselF.
The EMD710 proved that when your back’s against the wall, solid engineering winS.
