Every company in the automotive industry has been researching methods to enhance the
thermal efficiency of gasoline engines such as Miller cycle technology, EGR technology, and lean
burn technology. To apply these technologies, further improvement in supercharging efficiency is
required and the adoption of a variable geometry turbocharger is being considered. Because the
exhaust gas temperature of a gasoline engine is higher than that of a diesel engine, however, it is
necessary to significantly enhance the durability of high-temperature components including the
variable mechanism. Mitsubishi Heavy Industries Engine & Turbocharger, Ltd. developed a
variable geometry turbocharger for gasoline engines that has sufficient durability at an exhaust
gas temperature of 950°C and started supplying prototypes to automobile manufacturers.
