Dimensioning components regarding their behavior as part of a thermal system is a frequent issue in automotive projects. Sophisticated finite element softwares are necessary for the design of such parts due to the transient nature of the thermal event or due to the complexity of the geometry.The aim of this work is to develop a model for transient heat transfer with generation, conduction and convection heat transfer mechanisms, which is able to be processed by a simple workstation eliminating the need of expensive licenses or external simulation.The proposed model is based on the Finite Difference Method to linearize the derivatives with respect to time and space. The resulting linear system is solved to each time step and its dimension can be reduced significantly for thin bodies, where the temperature gradient is small along the thickness. The model is also capable of calculating the thermal behavior of non symmetric split bodies (e.g. fork shaped) with different boundary conditions for each segment.