Abstract: A switch valve for an exhaust gas-driven turbocharger system comprises a valve body defining an inlet passage, an outlet passage, and a generally annular volute in fluid communication with the outlet passage via a plurality of openings extending generally radially inwardly from the volute. A valve seat is disposed adjacent the outlet passage. A movable valve member is slidable between an open position spaced from the valve seat and a closed position engaged with the valve seat. The volute is bounded on a radially outer side by an outer wall extending about the circumference of the volute. The inlet passage enters into the volute at a first circumferential location. At a second circumferential location diametrically opposite from the first circumferential location, the volute has a dam presenting a substantial impediment to circumferential flow.