A combustion engine can include an engine block having interior and exterior block surfaces and a combustion generating system connected thereto, with the inner block surface defining a cavity therein; an exhaust port between the inner and exterior block surfaces; a crankshaft rotatably fixed within the cavity and configured to rotate around an axis; and leading and trailing blades connected to the crankshaft. During a combustion event, the inner block surface is complementarily shaped to the leading and trailing blades, such that the inner block surface is outside the blades' ranges of travel. A combustion generating system can supply and ignite an air fuel composition to create a combustion force positioned closer to one of the blades, forcing the one of the blades to rotate away from the combustion force, which rotates the crankshaft around the axis.