The implementation of the so-called "sliding-gate" dynamic method to measure in a faster way (up to ten times) the efficiency characteristics on hydraulic turbomachinery is presented. The new model testing measurement method is successfully applied on two different cases dedicated to recover the energy lost in release valves of water supply networks: a 2.65 kW double-regulated laboratory prototype of an in-line axial microturbine with two independent variable speed counter-rotating runners; a 11kW multi-stage centrifugal pump as turbine (PAT) with varaible speed. The universal test rig of the HES-SO Valais/Wallis, Switzerland, dedicated to asses hydraulic performances of small-power turbomachines, has been employed. The applied procedure consists, in a first step, on measuring the 3D hill-chart of a given testing model (turbine or pump) by the classical static point-by-point method. Then, a second digitizer is added to acquire synchronized dynamic signals of the sensors in parallel with the existing acquisition/control system of the test rig. The dynamic measurements of efficiency are performed at different constant speeds of the test rig recirculating pumps while increasing and/or decreasing the speed of the testing model runner(s) from zero to maximum, and vice versa, slowly enough in order to keep a steady-state operation. In the end, the resulting 3D efficiency hill-charts of the two tested machines obtained by the dynamic and by the classical static point-by-point measurement methods are compared, with the measurement precision and repeatability particularly emphasized.