S (stall position): in this point the turbine velocity is zero and the impeller is rotating; the efficiency in the stall stage is minimum amount, about 50%, which implies that half of the facility coming within the engine is lost as a result of friction and dissipated as warmth; at https://fernandoddwqh.topbloghub.com/40320942/the-2-minute-rule-for-torque-converter-clutch