US Patent 7690336 Adaptive miller cycle engine

A Miller cycle combustion engine capable of operating on multiple fuel types, and a method of operating the engine, is provided. The engine includes a fuel type determiner to determine the fuel type, and a compression adjustor to adjust the compression of a first cylinder of the engine to match the requirement of the determined fuel type. The compression adjustor is a variable valve timing system that provides a maximum compression when a fuel type requiring maximum compression is determined, and that advances or retards the opening of the intake valve to provide lower compression when a fuel type requiring lower compression is determined.