The first article presents the results of an experimental study of the effect of the magnitude of the combustion chamber displacers on the engine cooling performance when operating at full and partial loads and changing the temperature of the combustion chamber walls in a wide range. The second article presents the results of studies of the operation of the ZIL-120 engine in high-altitude conditions without supercharging and with supercharging with the help of a volumetric supercharger of the YaAZ type . The experimental and theoretical dependences of a number of indicators of the engine operation of altitude change are established and the possibilities in the sense of increasing the engine power when applying supercharging. are shown. The third article describes the experimental installation, equipment and sequence of the experimental study of the transient processes of motor-tractor diesel engines, as well as some results of the study of the transient processes of the YAMZ-238N diesel engine . Dynamic characteristics and evaluation parameters are proposed for the evaluation of dynamic qualities of engines. According to these characteristics, the features of the work of the diesel engine YAMZ-238N on uninstalled modes. The article uses the international measurement system SI.