An internal combustion engine can include a combustion volume within a cylinder of an internal combustion engine. The combustion volume can be defined at least by a cylinder wall and a first piston in the cylinder. A swirl port can deliver a fluid into the combustion volume via a swirl port outlet such that the delivered fluid is directed around a periphery of the cylinder with a fluid velocity disposed at a predetermined angle away from tangential to a curve of the cylinder wall to generate a swirling motion in the combustion volume.