A V20 engine is a V engine with 20 cylinders.
Engines of this number of cylinders are not common in automobiles, but this configuration is used in some diesel locomotives.
For example, the 1960s diesel locomotive EMD SD45 diesel-electric locomotive is fitted with a 20-cylinder EMD 645E3 two-stroke engine. The engine name is based on the displacement of each cylinder in cubic inches. In this case, it is 645 cubic inches (10.6 L) for each of 20 cylinders for a total of 211 L. Power output is 3,600 horsepower (2.7 MW), net for traction, with the maximum gross power output being closer to 5,000 HP when operated in self-test mode, with the generated output being dissipated by resistors.
EMD produced an upgraded/special version of SD45 later, EMD SD45-2 and EMD SD45T-2, still powered by 20-cylinder EMD 645E3, but EMD SD45-2 have some changes on the rear of the locomotive's long hood,while EMD SD45T-2 has a locomotive cooling system modifications, known as "tunnel motor". And 20-cylinder 710 series diesel engine was also built for the EMD SD80MAC locomotive. EMD still manufactures these engines, which are primarily used in the power production and marine industries. An EMD 20-710 can produce over 5,000 horsepower.
V20 diesel engines have also been used in marine applications: Mercedes-Benz has produced one such engine. Wärtsilä also currently produces a V20 engine for use in power plants that can produce 13,500 horsepower (10 MW).
MTU Friedrichshafen produces a 20-cylinder diesel engine called the 20V4000, used in marine and rail applications, such as the Brookville BL36PH locomotive.