The focus on engine thermal management is rapidly increasing due to the significant effect of heat losses on fuel consumption, engine performance and emissions. This work presents a time resolved, high resolution 3D engine heat balance model, including all relevant components. Notably, the model calculates the conjugated heat transfer between the solid engine components, the coolant and the oil. Both coolant and oil circuits are simultaneously resolved with a CFD solver in the same finite volume model as the entire engine solid parts.The model includes external convection and radiation. The necessary boundary conditions of the thermodynamic cycle (gas side) are mapped from a calibrated 1D gas exchange model of the same engine. The boundary conditions for the coolant and at the oil circuits are estimated with 1D models of the systems. The model is calibrated and verified with measurement data from the same engine as modeled. The simulation results are also compared with other measurements of similar engines.Experiments give information on the absolute energy flows in the engine system (fuel input, mechanical power and heat flows). This is used to calibrate and verify the overall accuracy of the numerical model. The model gives high-resolution space-time temperature distribution of all modeled components. Therefore, it can be used to study in detail the difference between alternative thermal management strategies. Furthermore, the model can give information about critical local temperatures for durability. These types of information are important for the optimal design of the complete vehicle cooling system, the engine-bay thermal management and the structural reliability of the engine.