For the refurbishment projects, one of the most important problems is to evaluate the economical efficiency of the project. It is difficult to estimate, with good accuracy, the hydraulic efficiency in situ for existing configurations and even more difficult to estimate the upgrading of the characteristics after refurbishment. The aim of this paper is to propose a procedure for performance measurement and for the analysis of a turbine characteristics applied on a refurbishment project. By comparative model tests, we propose a procedure to estimate, with good accuracy, the increasing of turbine performances in the refurbishment projects.