The report describes the first attempt to dynamically simulate the effects of internal heat sources for signature prediction of ground vehicles. The two vehicles examined are the MT-LB and the T72. The simulations are made in RadThermIRT without any results imported from CFD calculations. The results are validated versus earlier field trial measurements. The geometry and mesh of the vehicles have been imported from ANSYS ICEM CFD and were partly based on laser scannings of the vehicles. Most of the internal geometry was done in RadThermIRT. The main focus of the report is:  To develop a general code for internal heat distribution and air mass flow rates.  Do setup and connection of geometrical and non geometrical (fluid) parts in RadThermIRT.  Simulation of the heating and cooling phase for the two vehicles. The main characteristics, i.e. the air intake grill and the exhaust outlet, are well simulated compared to the validation data both for the heating and cooling phase. The validation versus thermocouple loggings also showed a good agreement, especially for the cooling phase where the measured engine block temperature from the field trial was more representative. The code can be used for modelling and simulation of vehicles during different modes of operation, for EW simulations and building signature libraries. To calculate the plume and its convective effects a CFD computation is necessary and which with advantage could be used together with the here described code for internal heat sources.