This manual covers the Mitsubishi 6A1 engine family, specifically the 6A12 and 6A13 variants. These V6 engines, known for their popularity in engine swaps, power a range of vehicles including the Galant, Diamante, and FTO. The 6A12 features a DOHC 24-valve system with a displacement of 1998cc, while the 6A13 offers SOHC 24 valves and a displacement of 2498cc. These engines represent a blend of performance and engineering characteristic of Mitsubishi vehicles. This comprehensive English service manual provides detailed information for the maintenance, repair, and overhaul of the 6A1 engine family. It includes essential sections on general information, technical specifications, and the use of special tools. Key maintenance procedures covered include drive belt and timing belt service, fuel and emission control systems, ignition, cooling, intake and exhaust manifolds, valvetrain components, lubrication systems, and bottom-end components such as pistons, connecting rods, crankshafts, and the cylinder block. This guide is an indispensable resource for owners, mechanics, and technicians seeking to ensure the optimal performance and longevity of their Mitsubishi vehicles.