Mitsubishi 4B1 Engine

The Mitsubishi 4B1 engine is a range of all-alloy straight-4 engines built at Mitsubishi's Japanese "World Engine" powertrain plant in Shiga on the basis of the Global Engine Manufacturing Alliance (GEMA). Although the basic designs of the various engines are the same, their exact specifications are individually tailored for each partner (Chrysler, Mitsubishi, and Hyundai). The cylinder block and other basic structural parts of the engine were jointly developed by the GEMA companies, but the intake and exhaust manifolds, the cylinder head’s intake and exhaust ports, and other elements related to engine tuning were independently developed by Mitsubishi.

All engines developed within this family have aluminium cylinder block and head, four valves per cylinder, double overhead camshaft layouts, and MIVEC continuous variable valve timing. All variations of 4B1 engine share the same short block. The difference in displacement is achieved by variance in bore and stroke.

The 4B1 engine family is the first to have the continuously variable valve timing MIVEC system applied not only to its intake valves but also to its exhaust valves. The intake and exhaust cam timing is continuously independently controlled and provide four optimized engine operating modes.