B / FL413F series air-cooled diesel engine for high-speed four-stroke, V-type, 90 ° cylinder row angle, direct injection type ω (or inclined cylinder) combustion chamber and secondary combustion system. The use of gantry-type crankcase and each cylinder a cover structure. The crank connecting rod structure is a multi-bearing three-layer alloy sliding bearing intermediate thrust crankshaft. Parallel rods and oil-cooled pistons with three seals. B / FL513 series air-cooled diesel engine is in the succession of B / FL413 series of air-cooled diesel engine on the basis of the advantages of B / FL413 series of air-cooled diesel engine in the use of the problems found in the targeted improvement and timely increase in accordance with technological progress.