The object of the research is a combine harvester the design of which allows to use the heat of engine exhaust gases for grain pre-drying. The purpose of the work is to develop the design of such a combine harvester. The authors carried out the theoretical research on the justification of the optimal design solutions and design calculations. The possibility of using the heat of the combine engine for drying grain during direct combine processing is considered. The possible options for supplying the drying agent to the grain mass flow are analyzed. The analysis of known solutions allowed to identify the options for using engine heat for drying grain which are the most optimal in terms of drying efficiency and ease of execution. It is revealed that the most optimal method is to supply the drying agent to the fan that supplies air to the sieve, and to supply the heated air to the hopper. The design scheme of the modernized combine is grounded. Thermal calculation of the heat exchanger is performed. The required surface area of the heat exchanger for Vector-410 combine harvester is 4.57 sq. m