This paper presents results of the instrumentation of 373 blows from two SPT deployments performed in the Sarapuí­ II Test Site, located in Duque de Caxias, Rio de Janeiro. In these blows the hammer drop height, its velocity at impact, the rate of blows and also the energy transferred to the rod stem have been measured. It is therefore possible to know the loss of energy for the SPT process (and the corresponding efficiency factors), since the hammer is delivered at zero velocity up to the time the transmitted energy reaches the rod stem.