I was a bit amazed to see that someone was claiming to have a prototype up and running. The idea came to me in an auto-tech class I took in '96, when the instructor mentioned water injection. I was thinking WTF? He didn't elaborate on it, I forget why he even mentioned it but I started thinking about what it might mean. I was pretty sure I'd have heard about a 6 stroke hybrid system if one existed and then I found out it was as you mentioned, to help with low octane fuel and I believe I recall there was some emissions benefit.

It seemed like an intriguing possibility, I mean it's well known that waste heat is big in the IC engine. But I kept thinking of reasons why it couldn't possibly work, one being the fact that the water in the pipe waiting to be injected would be pretty hot just from being in close proximity to the block. It would stay liquid under pressure of course but by the time it was injected, it would be near steam already.

As for corrosion, I can imagine there would be problems there but then again, water vapor is already present after combustion so who knows. Maybe some sort of stainless steel surface on the piston. The water would have to be aggressively filtered, some sort of carbon filter no doubt.

I dunno, it's out of my hands in a big way at this point anyway.

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1986 300SDL, 362K
1984 300D, 138K