Here's how the radical new engine concept is designed to work. This is basically a four-cylinder, opposed-piston engine, similar in basic concept to the EcoMotors OPOC and Achates Power opposed ...

4-stroke engine; a hypothetical 3-cylinder opposed-piston 4-stroke engine; and a three-cylinder opposed-piston two-stroke engine (the Achates engine). Opposed piston Engine renaissance (By Achates ...

H4 engines are horizontally opposed four-cylinder engines also commonly known ... The air-cooled flat-4 VW Beetle owes its origins to a Ferdinand Porsche design from the 1930s.