Bruce patented the 6 stroke engine in 1981.
<http://www.google.com/patents?id=gP02AAAAEBAJ&printsec=abstract&zoom=4&d q=Crower+stroke#PPA3,M1>
IF you are ADD and/or sleepy - DO NOT ATTEMPT to read this patent.
ABSTRACT
An internal combustion engine having at least one cylinder, the at least one cylinder having intake and exhaust ports, the engine comprising: a slidably and rotatably disposed camshaft; a cam and follower arrangement including cam lobes disposed on the camshaft, for controlling the intake and exhaust ports, each of the cam lobes having multiple lift surfaces which are shaped to provide at least two different periods of time during which the intake and exhaust ports are open; and, apparatus for axially displacing the camshaft during operation of the engine, whereby the different periods of time may be selected in accordance with engine or vehicle speed. 
...and this is just the opening paragraph. Counting drawings it is 12 pages L O N G.
In aviation past the J-79 jet engine on the KC-135 used demineralized water injection for 120 seconds/6000 gallons on takeoff to increase thrust. Demineralized to prevent mineral deposits. IMHO the water was converted into noise.
