Water injection works when you actually inject water. I'm not so sure how already evaporated water will work.

The basic way a heat(combustion) engine works based on gases and temperatures. A rapid increase in temperature creates a rapid increase in pressure. The bigger the difference in temperatures before and after combustion, the greater the change in pressures. So, a lower initial temperature will give you more power.

Fine droplets of water easily absorb heat and evaporate. Injecting water mist does this - lowering the initial temperature of the fuel/air mixture. It's not magic, it's science :D

Lower pre-combustion temps will also help to prevent knocking and preignition (they're not the same thing), so you can run with more advanced timing and possibly with cheaper gas. Also, supposedly the added water keeps carbon deposits from forming in the combustion chamber and on the valves.

I'm a skeptic in general, but especially hard to convince when anyone touts a 5-dollar device that could drastically improve mileage. I'm not saying that's what you're doing, I'm just talking about in general. A real injection setup definitely could. Simply hooking up a 5th injector and running it off the existing injector setup (you'd need more wiring) would even give you a variable amount of water. Yeehaw!
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1990 740 Turbo, on its way to stock specs, maybe beyond

dont know if this thread is still active...

i am thinking of this for my brick. but looking at the cheap setup from the "journey to forever" link you posted. what if you hit a bump and water splashes up to the outlet hose from the bottle? isn't the idea that you want water vapor not the liquid? i feel that a bump in the road would cause liquid to get sucked into the vacc line and thus into your engine causing issues...
i dont really know much about the concept but it was my understanding that you want just he vapor for the cooling and increased density, not the actual liquid. correct me if i'm wrong...

The idea looks simple and good . I checked turbo bricks, there it is crazy world , people are using cold start injectors,washer pumps etc or 250-500$ kits , defeats the whole purpose for me.

I have few questions though.
So it will be like a vaccume leak through water . Does not it throw the computer into thinking about unmetered air and set error code etc.

Volvo itself has built in system which leaks vaccume through charcoal canister or sucks the fuel fumes from charcoal canister. So may be it is alright to set it up like that and I am thinking too much.

I was thinking of using one of the hose from charcoal canister as it is on the throttle body as well.

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DD-1990 240 DL SW M47II FI 3.1 220 K miles Turbo Sways,Custom headlight circuit ,Insulated roof,Tinted Glass,

This is interesting. I had almost exactly the same setup back in 1979.
An older fellow told me about it. Perhaps he got it from Mother Earth news.

I was driving a Fiat 128 coupe at the time which was a blast but had no a/c. This car was carburated of course.

I had one of those big glass Orange Juice bottles tucked under the hood and I had an aquarium stone (made from sintered metal from K mart) connected to a vacuum port on the inlet manifold with aquarium plastic tubing. Air could enter the bottle but had to leave after bubbling through the water so I effectively had a moist vacuum leak.

The principle was that if your car seemed to go better on a wet day it would do the same with this setup. I recollect that I got 1 mpg more with it than without it, around 30 mpg.
I could always tell when the bottle was out of water!
I never put it on another car and that was close to 30 years ago. I would put it on a car today but I drive a VW diesel or a Volvo diesel mostly.
It works....not a lot, but yes it works.

cheers, Steve

I designed and built a similiar system for my hot rodded B18 in a 144S years ago. I used a ported vacuum inlet for the water "injection" and put a manifold vacuum operated heater valve (Plymouth)in the water line. When cruising along with high manifold vacuum the valve stayed shut--open the throttle, vacuum dropped, valve opened, water (metered through a carb jet) gets sucked into ported vaccuum port(s). It worked great with my 11 to 1 compression motor, kept the combustion chamber spotless and used about 1 and half gallons (washer fluid)per 15 gallon tank of gas. I was running twin Weber carbs at the time--similiar to 32/36's but they were from Renault LeCars with 30/30 throttles and lots of vacuum ports (also electric idle valves to insure no run-on)--and mounted on a pair of manifolds meant to mount 32/36's to a carbureted 164. This set-up ran great, got 22/23 around town and 27/28 on the road.

It seems very cool... however, I'm wondering about the long-term effects of MORE water in our fuel today, especially in these older engines that we're toying with.

I really don't know; I'm just wondering.