Air intake port for a lean-burn gasoline engine

A lean-burn gasoline engine comprising;

• at least one air intake port, the at least one air intake port comprising an air inlet, at least one air outlet, and an air channel connecting the air inlet to the at least one air outlet, the air channel comprising an air channel floor and an air channel ceiling, wherein the air channel floor is at least substantially flat in a direction of air flow in a region adjacent to the air outlet;
• a combustion chamber with at least one air inlet being connected to the at least one air outlet of the air intake port, the air inlet of the combustion chamber comprising a throat where the air outlet of the air intake port meets the air inlet of the combustion chamber;
• and
• a movable valve being arranged to move between a closed state for closing off the air inlet of the combustion chamber and an opened state wherein intake air can flow from the air intake port into the combustion chamber.