My thoughts on Bruce Crower’s six-stroke engine

If you don’t know what I’m talking about, read this first.

Briefly,
Four Stroke:

• Piston moves down, drawing air and fuel into cylinder
• Piston moves up, compressing air and fuel
• Spark plug fires, causing mixture to explode, pushing piston down
• Piston moves up, expelling exhaust gasses.
• Cycle repeats

Six Stroke:

• Piston moves down, drawing air and fuel into cylinder
• Piston moves up, compressing air and fuel
• Spark plug fires, causing mixture to explode, pushing piston down
• Piston moves up, recompressing exhaust gasses
• Water is squirted into cylinder, flashing to steam, pushing piston down
• Piston moves up, expelling exhaust gasses and steam.
• Cycle repeats

While I haven’t done any calculations as to the amount of energy that can be gained by utilizing exhaust heat in this manner, I am confident that it will result in greater efficiency gains than BMW’s method.

I also know just the engine to use as a test mule for this project. The Honda CVCC engine. The test engine needs (at least) three valves – fuel intake, water intake, and exhaust. Most three-valve engines operate both intake valves from the same camshaft lobe. Not the CVCC. It has three cam lobes for each cylinder – intake, aux intake, and exhaust. All that would be needed to convert this engine to six-stroke is a new camshaft and timing belt pulleys (to slow the cam down to 1/3 engine speed). The carburetor even has a separate section for the aux intake. I haven’t looked closely at it, but it shouldn’t be too difficult to convert it to atomize water in that venturi and fuel in the main venturi.