This document discusses six-stroke engines as a more efficient alternative to four-stroke engines. It describes two main types of six-stroke engine designs: single piston and opposed piston. Several single piston engine examples are provided, including the Griffin engine which uses a heated vaporizer to improve fuel efficiency. The Bajulaz engine is also described, which uses two additional chambers above each cylinder for combustion and air preheating. Benefits over four-stroke engines include increased power and torque, lower emissions, and simpler design. However, six-stroke engines also have increased complexity and cost compared to four-stroke engines. The document suggests they may be best suited for applications like racing vehicles, heavy machinery, and stationary engines.