In internal combustion (IC) engines, fuel combustion generates extremely high-pressure and high-temperature gases, reaching temperatures between 2000°C and 2500°C. Effective thermal managements is critical to maintain optimal engine performance, as excessive heat can lead to lubricant degradation, component wear, and potential engine seizure. Conversely, overcooling reduces thermal efficiency, thereby limiting engine performance. Cylinder fins play a crucial role in balancing these requirements by dissipating unwanted heat while retaining sufficient thermal energy to enhance engine efficiency. This study investigates the influence of cylinder fin thickness and slot placement on the thermal performance of IC engine cylinders. Using numerical simulations, the study analyzes heat transfer characteristics, identifying optimal fin geometries that maintain engine temperature within the target range of 100–200°C. The results provide insight into how fin design parameters can be optimized to enhance heat dissipation without compromising thermal efficiency, contributing to improved engine reliability and performance.