The article deals with issues related to the development of the high-temperature evaporative cooling (HTEC) systems of internal combustion engines (ICE). These systems can transfer the proportion of heat that flows to the ICE into the cooling system. HTEC systems are usually part of the integrated heat recovery (IHR) systems based on large-piston ICEs. It is proposed to improve the efficiency of the operation of the HTEC systems, as well the IHR systems on their basis, by a significant increase in the temperature of the cooling body in the cooling jacket up to 200°C and even 350°C. The increased coolant temperature causes a decrease in the power of the heat fluxes from the heated surfaces thus causing the engine overheat. This reduction can be compensated by increasing the area of the cooled surfaces of the sleeves and cylinder heads. To test the theoretical proposals, a working ICE model equipped with the HTEC-based IHR system was developed. The results of its bed tests are provided. During the experiments, the temperature of the coolant in the cooling jacket reached 204°C, with the engine performance remaining stable. © Published under licence by IOP Publishing Ltd.