A practical engineering guide to petrol-fuelled internal-combustion engines, presenting foundational thermodynamics, the Otto cycle, and detailed components such as cylinders, pistons, connecting rods, crankshafts, valves, camshafts, carburettors, ignition systems, lubrication, and cooling. Chapters explain two-stroke and four-stroke arrangements, a duplex air-scavenging two-stroke design, methods for measuring power with indicator diagrams, and properties of liquid fuels. Emphasis is on design, construction, maintenance, fault diagnosis, and practical illustrations and diagrams that support workshop application and understanding of engine operation and repair.