Valve seat insert for high power and high speed diesel engines

A valve seat insert 138 for a combustion engine comprising a annular insert body 140 having first and second axial end surfaces 48', 50', an inner and outer peripheral surface, and a valve seating surface 159 for contacting the exhaust valve 25 extending between the first axial end and the inner peripheral surface. The valve seating surface including an outer curved segment 162 forming a first wear crown 164 for contacting the valve 25 at an early wear state, and an inner curved segment 168 forming a second wear crown 170 for contacting at a later wear state, with a linear segment 166 extending between the out and inner curved segments. An inner peripheral surface segment extends down from the second axial end , with a sloping segment 171 extending between this and the valve seating surface. The sloping segment extends radially outward from the inner peripheral surface segment toward the seating surface at an acute angle 177 of 6° or greater relative to central axis of the valve seat. The angle may be from 7° to 9°. A transitional curved segment 173 may connect the inner peripheral surface segment to the sloping segment.