You mentioned jet pilots used water injection.
I also heard water injection had been available for many years. Dating to
W.W.II
when the Germans needed a way to make fuel go farther. They added water
injection to tanks, creating a modest but real increase in fuel availability.
I suppose when water expands in the combustion chamber, there is a
corresponding increase in horse power, if water's expansion into gas is
indeed greater than petrol's. At those amounts there should be a cleaning
affect as well and at such high temperatures shouldn't have posed much of a
problem for corrosion. Today, types of antifreeze can be added to alleviate
difficulties at high altitudes and cold temperatures for engines run on
water/petroleum mixes.