An internal combustion engine includes a cylinder case forming a cylinder bore having a centerline and an inner bore surface. A piston disposed within the cylinder bore forms a crown surface. A region defined between the piston and the cylinder bore in a radial direction has an annularly shaped mouth opening surrounding the crown surface. A cylinder head is disposed to cover an open end of the cylinder bore such that a variable volume is defined within the cylinder bore between the cylinder head and the piston. The cylinder head also forms a flame deck in fluid contact with the variable volume. A deflector structure forms a portion of the inner bore surface adjacent the flame deck surface, and is disposed between the flame deck and a topmost ring seal groove of the piston when the piston is at a TDC position.