Abstract: A steam turbine of the type which incorporates a turbine case defining a plurality of passages having outlets opening through an inside end wall of the turbine case in a direction generally parallel to the turbine shaft, with nozzles positioned over the outlets to direct steam against the periphery of the turbine wheel, can be modified to a higher efficiency design. To perform the modification, the nozzles are removed, an arcuately shaped housing is positioned in covering relationship with the outlets, and an arcuately shaped louver is positioned so as to form an end wall of the housing. The louver has a plurality of vanes to direct the steam against the periphery of the turbine wheel to cause rotation of the turbine shaft and the housing forms a confined steam flow path from the outlets to the louver. The downstream turbine blading can be modified if desired.