An engine assembly may include a fuel injector having a housing, an actuation mechanism, and a valve member. The housing may define a high pressure region, a low pressure region, a longitudinal bore, and a valve seat having an aperture extending therethrough. The actuation member may be disposed within the longitudinal bore and may include a first axial end surface. The valve mechanism may include a second axial end surface abutting the first axial end surface. The first and second axial end surfaces define an outer contact perimeter and a chamber within the outer contact perimeter. A radial surface area defined by the chamber formed by the first and second axial end surfaces may be at least 25 percent of a radial surface area defined within the outer contact perimeter.