Abstract: A four cycle, 12-cylinder engine includes four cylinder groups each having three cylinders located adjacent to each other. The cylinders in each cylinder group have intake strokes which are apart one from another by 240.degree. in terms of angle of rotation of the engine crankshaft. The cylinders in each cylinder group are connected through respective branch intake passages with a common intake passage. Means is provided for separating the common intake passage of one cylinder group from the common intake passage of another cylinder group.

Abstract: An engine construction which comprises a cylinder block having a series of bearing seats formed therein for the support of a crankshaft, a lower block having bearing caps formed integrally therewith and adapted to be secured from below to the cylinder block with the bearing caps aligned with the corresponding bearing seats for the support of the crankshaft, a balancer shaft, a drive transmitting unit for transmitting the drive of the crankshaft to the balancer shaft, and an oil pan adapted to be removably fitted from below to the lower block and positioned on one side of the lower block opposite to the cylinder block. A surface region of the cylinder block and a mating surface region of the lower block which is brought into contact with the surface region of the cylinder block when the cylinder block and the lower block are connected together are formed with respective pluralities of bearing recesses for the support of the balancer shaft.