To miniaturize an engine and make it compact by forming bosses accepting fasteners for fixing cylinder heads in part of a plurality of intake and exhaust passages formed on the cylinder heads fixed to a cylinder block.

This diesel engine 10 is provided with a cast block 12 having a pair of cylinder banks arranged in a V-shape and each aligned with a plurality of cylinders 24, and a piston is inserted into each cylinder 24. A cylinder head 34 is fixed to each bank, at least four intake and exhaust passages 46, 48 are formed for each cylinder 24 on each cylinder head 34, and at least one of the intake passages 46 is formed into an S-shape displaced with an inlet 50 and an outlet 54 in the radial direction. Bosses 76 are formed at positions aligned with the inlets 50 on the intake passages 46 to accept fasteners 74 for clamping the cylinder heads 34 to an engine block 12.