"Charlie+" wrote: (clip) Surely with modern electronic injector controls
the same effect could be
produced by metered atomised water injection a fraction after the oil/air
flame
front has started in a 4 stroke cycle. (clip)
^^^^^^^^^^^^^^^^^^^^
This may be possible, but it culd be tricky. You don't want to cool the
burning gases excessively, because that would cause a loss in pressure, with
a resulting loss in power. OTOH, it's possible that the vaporizing water
could even out the cylinder pressure on the downstroke, resulting in a
longer sustained power stroke. This would be sort of like a steam Diesel
stroke. (The Diesel injects fuel evenly as the piston descends.)