Opposed piston engine

A two strokes per cycle, internal combustion, direct injected, opposed piston engine comprising:

• at least two crankshafts rotationally coupled;
• at least two pistons traveling in opposite directions;
• at least one cylinder with intake ports toward one end of the cylinder and exhaust ports toward an opposite end of the cylinder, the intake and exhaust ports located so that the intake ports are opened first when the pistons are moving apart, and the intake ports are closed last as the pistons move inward;
• and
• an intake manifold covering the intake ports and having an internal shape comprising a circular gas hook region inside the intake manifold circling the cylinder and radially bordered by a concave gas hook wall, and laterally bordered by a gas hook reaching in from a manifold outer wall towards the intake ports and configured to reverse a direction of the flow of exhaust gases back towards the intake ports, for reducing exhaust gases flowing into the intake manifold;
• wherein the intake ports in the intake manifold are in fluid communication with ambient air at ambient air pressure.