Abstract: An embodiment combustion chamber for an internal combustion engine includes a chamber body including a cylinder configured to receive fuel and air for carrying out an engine cycle including a combustion reaction of the fuel and a chamber roof including an injector tunnel opening disposed on an inner surface of the chamber roof, the injector tunnel opening being configured to guide the fuel injected in an injecting direction toward the cylinder, and the injector tunnel opening including a protrusion disposed on a path of the fuel along the injecting direction, the protrusion being configured to re-direct the path of the fuel along a re-directed path away from the inner surface of the chamber roof and a pair of grooves arranged on sides of the protrusion, respectively, the pair of grooves being configured to guide the fuel separated by the protrusion to the sides of the protrusion.