True or False: High-speed diesel engines are only suitable to run No.1 and No.2 distillates.

High-speed diesel engines are specifically designed to operate effectively with lighter fuel oils, such as No.1 and No.2 distillates. These fuels are characterized by their low viscosity and improved ignition properties, which are suited for the combustion characteristics and operational requirements of high-speed engines.

High-speed engines, operating in the range of 900 to 1,800 RPM or more, require fuels that allow for rapid ignition and efficient combustion. No.1 and No.2 diesel fuels meet these criteria, as they provide the necessary flow characteristics and energy content for optimal performance. Fuels heavier than these, such as No.4 or No.6 fuels, have higher viscosities and require preheating or specially designed burners to ensure proper atomization and combustion, making them unsuitable for high-speed engines.

While the engine design could technically allow for burning various fuel types under specific conditions, the statement reflects the conventional suitability of high-speed diesel engines predominantly for No.1 and No.2 distillates. Thus, the assertion is considered true within the common operational scope for these engines.