This paper presents an investigation into the optimization of cooling systems in large bore two-stroke cycle engines. Even though common operating knowledge suggests that cooling capacity will increase with an increase in the water flow rate, there are documented cases where engine cooling can be increased by adjusting the cooling water flow to something less than the maximum flow rate. As such, a need existed to explore the heat transfer mechanisms from the combusting gases to the cooling water and then from the cooling water to the environs. PRCI funded a project at the K-State National Gas Machinery Laboratory to collect OEM cooling system operating specifications, determine if there was, in fact, an optimal operating condition of the cooling system and to then explore the claims that the higher flow rate does not always lead to improved cooling. This paper reports on the latter portion of the study where an engineering model was developed to quantify the heat transfer rate from the combusting gases through the cylinder walls and then to the cooling water flowing through the engine block and head. The cooling system engineering model is physics-based and relies on the plethora of information in public-domain literature.