EMD 645

The EMD 645 engine is a vast popular 2 stroke cycle medium speed diesel engine used in locomotive, marine, and stationary applications. The cylinders are arranged in a V-shape at 45 degrees. It is arguably one of the most successful engines ever produced by General Motors. This engine can be found at the heart of locomotives, pump houses, boats, power generators, etc all over the world. I'll try to make this post as high-level and not as boring as I can.

An EMD 645 at the heart of the Irish CIÉ 071 Class
Of course the F40PH uses the EMD 645

The 645 engine is based on the previously successful EMD 567 engine with an increase in bore from 8-1/2 to 9-1/16 inches.The stroke of the engine remained the same as the 567 engine at 10 inches. The number 645 denotes the cylinder displacement of the engine, at 645 cubic inches. Both engines employ a fabricated steel block of identical key dimensions. The change in displacement of the engine was done through a new power assembly where the cylinders were housed (props to the designers of the 567 for their vision for the engine's future evolution). The number 645, of course, denotes the engine displacement of 645 cubic inches per cylinder of the engine (the car guys still think your tiny little 450s or what not are big?). The engine came in roots blown (think supercharger) for lower or turbocharged for higher horsepower versions. The turbocharger has an ingenious overrunning clutch and only disengages when the engine is running at a sufficient speed to spin the turbo with its exhaust gas (in other words, the turbocharger acts as a supercharger at low rpm). The engine also comes in assorted numbers of cylinders, 8, 12, 16, or 20. Being a medium speed the engine runs at a maximum of 900 rpm.

The Australian G Class also has the 645
The engine had been through a vast number of iterations which maximized its efficiency. This engine is no longer in mass production but is still available from EMD (now part of Caterpillar) on a by-request basis. And because it is such a versatile, reliable, and durable workhorse, the 645 engine is also available in refreshed form from various sources.


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