English English http://en.wikipedia.org/wiki/Six-stroke_engine English http://en.wikipedia.org/wiki/Six-stroke_engine English six-stroke engine so we don't throw away so much excess heat Six-stroke_engine English English English http://en.wikipedia.org/wiki/Six-stroke_engine English six-stroke engines English English English English http://en.wikipedia.org/wiki/Six-stroke_engine English English English Six-stroke_engine