Internal combustion engine

An internal combustion engine comprising a cylinder block, the cylinder block defining a cylinder bore, the cylinder bore comprising an upper end that terminates within the cylinder block such that a cylinder bore top wall is defined, a piston capable of reciprocating within the cylinder bore between top dead center and bottom dead center, the piston being capable of being inserted into the cylinder bore from a bottom end of the cylinder bore, a first vertical plane extending along a first lateral side of the cylinder bore, a second vertical plane extending along a second lateral side of the cylinder bore, the first vertical plane and the second vertical plane being parallel to each other, a cylinder zone being defined between the first vertical plane and the second vertical plane, a crosshead coupled to the piston, the crosshead extending laterally outward from the piston and crossing the first vertical plane and the second vertical plane, a first crankshaft having a first crankshaft axis, the first crankshaft axis extending parallel to the first vertical plane and being positioned outside of the cylinder zone, a second crankshaft having a second crankshaft axis, the second crankshaft axis extending parallel to the second vertical plane and being positioned outside of the cylinder zone, the first crankshaft and the second crankshaft having synchronized and counter-rotating movement relative to each other, the first crankshaft coupled to the crosshead with a first connecting rod, and the second crankshaft coupled with the crosshead with a second connecting rod.