Shrouding the inlet valve increases the swirl intensities. The extent of shrouding the inlet valve alters the velocity distribution considerably and a shroud angle of 90 degrees is found to be satisfactory when it is used in conjunction with a specially designed passage. Distortion and valve rotation were the inherent problems associated with the shroud and in the present work these problems have been overcome by proper heat treatment and the provision of an arrangement to prevent rotation of the valve. Lower level of exhaust emissions are achieved by shrouding. Even though there is a slight decrease in power output from the engine the advantage of lowering the emission level achieved through shrouded valve provides the basis for trade off between power and emissions. (from Authors)