An exhaust gas turbine portion of a vehicle engine turbocharger is provided with at least one variable guide-blade cascade with guide blades in a nozzle opening to the turbocharger rotor for effectively changing the cross section of the exhaust flow to the rotor wherein the angle of the guide blades is selectively settable by an adjusting device. The width dimension of the gap between the ends of the guide-blade cascade and the casing wall defining the nozzle is adjustable between a substantially zero gap dimension and a maximum gap dimension.