Six-Stroke Engine

A six-stroke engine is an internal combustion engine design that adds extra strokes beyond the conventional four-stroke cycle in an attempt to improve fuel efficiency, reduce complexity or lower emissions. Some designs use a single piston that captures waste combustion heat and uses steam or air as a working fluid for an additional power stroke, while others split the six strokes across two pistons running at different rates, with the second piston sometimes replacing conventional valve gear or increasing the expansion ratio beyond the compression ratio. Early examples include Samuel Griffin 1883 engine, built to work around Otto cycle patents and later sold as the Kilmarnock, and later prototypes such as Bruce Crower 2006 water injection design and the 1989 Bajulaz engine with supplementary combustion chambers. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/