To be fair that also happens, it’s just not the only reason to do it.
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In all of these case of real world water injection what happens is that post combustion there is hot expanded gas carrying away much otherwise wasted energy as heat. Injecting water pre-combustion to keep the engine cooler and permit overthrottlingpost combustion in a jet engine similar to an non-combustive afterburner, in a piston engine carefully timed post combustion to boost on the down stroke, it absorbs much this heat in both applications as a phase conversion to steam and big increase in volume.
There was also a program in the 70s where Israel was trying to match the Egyptian mach 3 capable(when stressed over the limit) Mig-25 recon overflights which they couldn’t touch or match. The plan was to mod a F-4 phantom as the F-4X or ‘Peace Jack’ and have water injection at the intake, to break up the intake shock waves before they hit the engine turbines and to cool compressed intake air to boost feed to the engine, way less elegant than the SR-71 with a turbojet bypass outer ramjet but apparently the concept worked. It was canceled by pressure from Macdonald-Douglas who didn’t want a hotrod fighter mod faster then their forthcoming Mc-D F-15 which could only do mach 2.5. https://en.wikipedia.org/wiki/F-4B_Phantom_II#Proposals
Thank you for sending me down that rabbit hole of obscure information. A city-boy like me loves to learn something new everyday!
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I believe that you’ll find that to be a myth (Google it) 
I never really understood the suppressed technologies conspiracy theory. There would have to be a global cabal that plays a endless game of Whac-A-Mole as these techs are rediscovered again and again.
The Wikipedia article is correct as far as it goes but water injection goes back a lot further than that. Its original use was to allow a higher compression ratio in gasoline engines by cooling the valves and spark plug and reducing detonation. With the low CRs in those days (1920s-1930s) this increased the efficiency, which was important during the Depression.
However, it needed a lot of soft or distilled water, which was expensive and needed large tanks. It was tried for a while on trucks and buses but the added weight and complexity meant the gain wasn’t worthwhile. Harry Ricardo did work on improving detonation performance with better head design, and this proved to be the way forward.
Water injection always runs into the same problem; it has no effect at low power, but large amounts of water are needed for high power. The oil companies and engine makers didn’t try to stamp it out; it just kept being tried and then failing to deliver.
I remember seeing it used on a supercharged Kawasaki bike engine to prevent detonation; in that case it would have been simpler, and probably much better, just to shim the cylinders and reduce the CR a little, but the owner didn’t want the trouble of lifting the top end, and thought that the plumbing into the air intake looked cool.
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The “suppressed technologies” is intended to explain to the gullible idiots who are being conned why this new wonder technology that they are being invited to invest in, has not yet been commercialised.
It is a weapon in the armoury of con men. One of the best was the one who demonstrated an engine running on water in a Chicago hotel - he had discovered that the cold water pipes to the sink ran downwards a considerable way so he could pump some gasoline back into the water pipe. Being less dense than water it floated on top and the water pressure did the rest. He is supposed to have taken a fair bit off investors before disappearing.
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I didn’t understand a word of that.
According to Carnot, the efficiency of an engine is related to the ratio of temperature of accepted heat to rejected heat. IC engines are complicated because of the inlet strokes in which air is compressed so absorbing energy, but water injection lowers the peak ignition temperature (accepted heat temperature) as well as the exhaust (rejected heat temperature).
If the CR can be raised either by supercharging or reducing the combustion chamber volume, then the original peak temperature can be restored, and the exhaust temperature will not be as high as without water injection, so the overall Carnot efficiency increases.
This is right up until your water injector throws a wobbly, too much water enters a combustion chamber, the air is compressed against a water lock and either the head comes loose or a con rod comes out the side of the engine, a disadvantage of water injection I forgot to mention above.
Sorry, wrote that before caffeine, my English writing has been pretty bad lately too.
1-spark fires, combusts the compressed fuel air mix
2-combustion chamber is now full of burned hot exhaust gas which pushes piston
3-water inject fires, temp drops drastically inside chamber/cylinder but pressure goes up from the steam phase change expansion using that heat for something more useful.
It is trading the expanded high temp gas for an even better expanding steam which replaces the formerly very high temp combustion gases to push the piston. After thinking it is actually a two stage hybrid internal combustion/steam engine. The water inject steam recovered much of the otherwise wasted heat of combustion and there is less thermodynamic loss in the conversion of flame to mechanical energy. Obviously this is not the goofy gadget in the OP but an injector in the cylinder timed to spray the water after the combustion is complete. I think the % of boost or better mileage was not worth having a second tank of water mix for normal automobiles.
Kind of related to the BMW? project where they ran a small steam engine off the waste engine heat to scavenge a bit more power. No idea if that went anywhere.
These actually work. You do need to get the water from fracking sites though.
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[quote=“dnebdal, post:32, topic:49066”]
ran a small steam engine off the waste engine heat
[/quote]pretty much, except doing the recovery inside the main engine a few milliseconds after the combustion happens and before any waste heat gets into the block or exhaust.
Of course you can’t.
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They make great stud-finders too.
(I’m talking construction here.)
I’m not absolutely sure that that’s true? Conceptually, “using engine power to modify the combustion process in a way that ends up wringing a bit more useful energy out of it” doesn’t seem to break any laws - it’s conceptually the same idea as, say, running at a higher compression.
As for the specific method, uhm - I do seem to remember something about Carnot cycles and higher efficiency at higher combustion temperatures, so it falls into “someone competent would have to take it apart to convince me either way”.
You’re not going to get that “3 - water inject fires” effect by mixing water in with the gasoline, though; you only get it if you have separate valves to let the water in. Otherwise you’ve injected the water in phase 1.
Can there be more efficient combustion processes? Of course it is possible. Is there such thing as “surplus engine elctrical power”? Not likely. The description makes it sound like electolysis of the hydrogen is “free” in terms of energy consumption. That’s the bit that doesn’t make sense.
AFAIK it was a completely separate injector. Mixing the two systems seems like a big mess to save some money.
