Abstract: An engine includes cylinders using pressure differences to motivate the pistons. Each cylinder has a first outlet in its' first end, the first outlet being coupled to a vacuum chamber via a first valve and a first conduit, a second outlet in the cylinder's first end, the second outlet being coupled to an air pressure chamber via a second valve and a second conduit, a third outlet in the cylinder's second end, the third outlet being coupled to the vacuum chamber via a third valve and a third conduit, and a fourth outlet in the cylinder's second end, the fourth outlet being coupled to the air pressure chamber via a fourth valve and a fourth conduit. The valves are electrically controlled by a processor. When the first and fourth valves are turned on, the piston is pulled forward by a pressure difference created by the vacuum chamber and is at the same time pushed forward by a pressure difference created by the air pressure chamber.