Fast shock heating in a toroidal belt pinch produces a highly elongated, weakly compressed high-β plasma with electron and ion temperatures in the keV range. Electron heating is attributed to ion-sound turbulence. The effective drift velocity is increased above instability threshold by a distortion of the electron distribution related to strong density and temperature gradients. Quenching of the instability is related to ion-tail formation. Reflection of ions by the piston, however, is mainly responsible for ion heating and increases with increasing initial density.