Calculating the heat transfer rate of the engine is very difficult due to the complex geometry design of the engine and the periodic flow of air and fuel during engine operation for full cycles. Various theories hypothesize that about 25% of the energy contained in the fuel is converted into useful work and the remaining 75% is released into the environment by the engine. The main objective of the present work is to improve the heat transfer rate of existing constructions of the engine cylinder block by modifying its construction and also with new materials. To this end, two CAD models were created using CATIA software, then a transient thermal analysis with ANSYS at ambient temperature for the summer season of 45oC for the real one and the proposed internal combustion engine design was performed one after the other. Other to optimize the geometric parameters and improve the heat transfer rate. From the results of the transient thermal analysis, it was found that the proposed engine cylinder block design has better performance and heat transfer rates than the actual engine cylinder block design.