Abstract:
An internal combustion engine includes an arrangement of cylinders each having a reciprocating piston operatively linked to a crankshaft. The cycle for each cylinder includes an intake stroke, a compression stroke, a power stroke, an exhaust stroke, and two free strokes during which the exhaust valve or a separate clean air valve is left open. The power stroke of each cylinder fires simultaneously with the free stroke of another cylinder. The engine and method of operation provides a six stroke cycle for each power stroke to yield three revolutions of the crankshaft per cycle, thereby increasing fuel efficiency.