The paper presents the characteristics to determine the effect of elevated temperature coolant in the cooling system on engine useful parameters, the torque, power, specific fuel consumption and efficiency as a function of the effective engine speed and specific fuel consumption, hourly fuel consumption and air consumption as a function of engine load. The most popular and widely used method of cooling is liquid cooling, which ensures uniformity of temperature around the combustion chamber and easy acquisition and transfer of heat, although the properties of water are limited to a maximum temperature of the coolant. Increase the efficiency of modern internal combustion piston engines is done by modern control systems units of each engine according to its operating conditions, reducing heat loss in engine cooling and recovering energy from exhaust gases (e.g.: turbine air compressors). The results of tests confirmed the benefits of increased coolant temperature. The set of characteristics that applies the pressure of the cooling system affect the fuel consumption, especially at high speed, which contributes to increase effective efficiency of the engine

This paper deals with experimental selection of a cooling system of a brushless synchronous generator with permanent magnets and an additional excitation, designed and built in Department of Ship Electrical Power Engineering in Gdynia Maritime University. Three cooling system were tested: with an aluminium radiator and natural cooling with the aluminium radiator and an external fan and the aluminium radiator and two external fans. Results of thermal tests are presented for a machine with built-in thermocouples. The selection of cooling system for the investigated machine is based on the experimental results