Let's continue to be Nerds and Geeks, and talk about liters, weight and mass.
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I am surprised nobody talked much about jet engines...
After all, what these machines do for power is
mass acceleration.
So, let us talk about the past century and jet engines.
Jet fuel is say, of a specific gravity of about .81 (call it 81% of weight of distilled water).
Of course, as mentioned, varies with temperature. Hot fuel is "lighter".
Now, let's talk about the old jet engines with
water injection There were the P&W JT3C-6 with water (called J-57 in the USAF/NAVY).
Some 707-120 and DC8-10 had these "wet engines".
Even the 747s... there were JT9D engines with water...
Last letter W in their designation, as JT9D-7AW, or -7FW
These 747 got some 2,000 lbs of thrust extra per engine using "water".
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Now, most "aviation experts" (many here) said "water... to keep engine cold".
When you go full power, put water ON, keeps EGT low...
Can I smile...?
What water did really, was to
increase accelerated mass flow.
Extra mass of water (specific gravity 1) to jet fuel (SG of .81)...
Result was more power... without increase in EGT, as water does not burn.
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Imagine an inventor finding way to have "Hg (mercury) injectors" SG of some 13.
Would be a bit of vitamins for our engines...!
Happy contrails