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How Diesel Two-Stroke Engines Work

General Motors EMD Engines

The General Motors EMD engine line is typical of the two-stroke diesel breed. These engines were introduced in the 1930s and power a large number of the diesel locomotives found in the United States. There have been three successive series in the EMD line: the 567 series, the 645 series, and the 710 series. The numbers refer to the number of cubic inches per cylinder, with a typical­ engine having 16 cylinders (for a total displacement on the order of 10,000 cubic inches!). When you consider that a 5-liter (305-cubic-inch) engine is considered to be very large in an automobile, you can see that one of these EMD engines is massive!

Here are some of the specifications for the EMD 645E3 engine:

Cylinder diameter - 9-1/16 inches

Piston stroke - 10 inches

Displacement per cylinder - 654 cubic inches

Number of cylinders - 16 or 20

Compression ratio - 14.5:1

Exhaust valves per cylinder - 4

Engine weight -

  • 16 cylinders: 34,526 pounds / 15,661 kg
  • 20 cylinders: 40,144 pounds / 18,209 kg (The oil pan alone weighs over a ton!)

Idle speed - 315 rotations per minute (rpm)

Full speed - 900 rpm

A typical horsepower rating for one of these engines is 4,300 hp!

For more information on the diesel two-stroke and other engines, check out the links on the next page!