Water injection

[user-23911]

There's only so much water CAN evaporate in the port. Once the RH is 100% there's no more evaporation, inject more water and it'll evaporate in the cylinder when the temp goes up.

[Circlotron]

Having worked on a few steam engines and power plants most people don't know that going from liquid water to steam increases the volume by 1700% ... there is a lot of power in steam .... not sure I want to convert but just saying

Way more than that even!
The old rule of thumb was that a cubic inch of water makes a cubic foot of steam.
That's 1728 times as big, say 1700 times.
1700% is only 17X as big.

[Circlotron]

the water does take up space, that otherwise could be occupied by air and fuel. but does contribute to piston push some on the power stroke as steam expands.

That's an interesting point for discussion.
If all the water has *already* turned to vapour before combustion begins then when the water VAPOUR is heated by combustion it will expand just the same as the 80% nitrogen also in the cylinder. Provided the water vapour doesn't get so hot that hydrogen/oxygen dissociation occurs then there will be no real difference between water vapour and normal atmospheric air for a working fluid as regards pressure/volume/temperature AFAICT. If however there are still liquid droplets of water present when combustion begins then it takes a buttload of heat energy to vaporise them, latent heat of evaporation, before the temperature begins to rise. This heat needed to vaporise the water droplets without increasing their temperature is provided by the flame and so is not subsequently available for producing power. https://en.wikipedia.org/wiki/Latent_heat

[Circlotron]

It's already Saturday here ....you're still stuck on yesterday........that'll never change.
You'll never catch up.

Wait till it's Monday at your place and only Sunday in 'murica.

[Schurkey]

So if the water was direct-injected you'd have an IC semi-steam engine?

the water does take up space, that otherwise could be occupied by air and fuel. but does contribute to piston push some on the power stroke as steam expands.

That's an interesting point for discussion.
If all the water has *already* turned to vapour before combustion begins then when the water VAPOUR is heated by combustion it will expand just the same as the 80% nitrogen also in the cylinder. Provided the water vapour doesn't get so hot that hydrogen/oxygen dissociation occurs then there will be no real difference between water vapour and normal atmospheric air for a working fluid as regards pressure/volume/temperature AFAICT. If however there are still liquid droplets of water present when combustion begins then it takes a buttload of heat energy to vaporise them, latent heat of evaporation, before the temperature begins to rise. This heat needed to vaporise the water droplets without increasing their temperature is provided by the flame and so is not subsequently available for producing power. https://en.wikipedia.org/wiki/Latent_heat

All this gets us back to Bruce Crower (I think it was Bruce) who made some headlines with his "six-stroke" engine. The final two strokes were another expansion and exhaust cycle, with water injected towards TDC. The water would flash to steam from residual heat, the 1700x expansion pushed the piston down and made power.

I could never figure out why he added two strokes when he could just push the water in near TDC of the regular burn. But then, I'm not as smart as BC.

Edit: http://autoweek.com/article/car-news/in ... oke-engine

[Truckedup]

the water does take up space, that otherwise could be occupied by air and fuel. but does contribute to piston push some on the power stroke as steam expands.

That's an interesting point for discussion.
If all the water has *already* turned to vapour before combustion begins then when the water VAPOUR is heated by combustion it will expand just the same as the 80% nitrogen also in the cylinder. Provided the water vapour doesn't get so hot that hydrogen/oxygen dissociation occurs then there will be no real difference between water vapour and normal atmospheric air for a working fluid as regards pressure/volume/temperature AFAICT. If however there are still liquid droplets of water present when combustion begins then it takes a buttload of heat energy to vaporise them, latent heat of evaporation, before the temperature begins to rise. This heat needed to vaporise the water droplets without increasing their temperature is provided by the flame and so is not subsequently available for producing power. https://en.wikipedia.org/wiki/Latent_heat

I'm not the smartest... but/// The water must enter the cylinder as soon as the intake valve opens...Then some must vaporize when it hits the somewhat hot valve and combustion chamber surface....Then the spark plug ignites the fuel air mixture....At this time ,is the water vapor taking heat from the combustion process? That would mean less heat and less pressure? Than the water vapor become a high pressure steam and helps push down the piston?

[mike hohnstein]

Tell you this, 645" diesel V-8 turbo, charge air cooler, propane injection and shooting windshield washer fluid in with a two jet system @ the cac outlet. Boost goes up 3# with the water on. EGT's 200 degree's cooler, only down side had to add 40 gallon tank for the system.
This one, sold to me after a sales chat, works pretty damn good in my world.
https://www.snowperformance.net/

[gruntguru]

going from liquid water to steam increases the volume by 1700% ...

...and if it's vaporizing in the intake system (not in the cylinder) think of how much fuel/air mix is displaced!

When water vaporises in the intake, it cools the charge and shrinks it by more than the extra volume occupied by water vapor. So the net effect is an increase in air mass to the engine.

[gruntguru]

So if the water was direct-injected you'd have an IC semi-steam engine?

When water vaporises during combustion, it cools the charge and reduces pressure. Yes, OTOH the creation of steam increases pressure. I haven't done the calcs to state categorically but I suspect the result is similar to what happens in the manifold, the cooling effect is more significant than the "steam" effect.

[gruntguru]

You need to do less reading and more actual hot rodding.
Use the stuff in real world situations, like roots supercharging a street motor. Especially the lil B&M blowers.

I've been using water injection in various forms as long as I've been playing with turbos and that's since about 1982.

In that case I am surprised you haven't had the experience of progressively increasing the boost on an engine (petrol fuelled) and increasing WI to control detonation to the point where you are injecting too much water (fire going out, water in crankcase etc) then tried 50:50 water methanol and discovered:
1. Better detonation control at the same boost and WI flow rate.
2. Better tolerance to injection quantity. (you can inject more of the stuff).
3. Better intercooling effect despite the lower latent heat value (methanol evaporates more readily in the manifold)

[user-23911]

In that case I am surprised you haven't had the experience of progressively increasing the boost on an engine (petrol fuelled) and increasing WI to control detonation to the point where you are injecting too much water (fire going out, water in crankcase etc) then tried 50:50 water methanol and discovered:
1. Better detonation control at the same boost and WI flow rate.
2. Better tolerance to injection quantity. (you can inject more of the stuff).
3. Better intercooling effect despite the lower latent heat value (methanol evaporates more readily in the manifold)

You're making it all up.(did you study the 2 links on the first page?)

I've used straight water, straight methanol, ethanol and everything in between.
The fire doesn't go out but you find the limitation of the ignition system (which I've fixed).
Nor does the crankcase fill with water when you have a proper working PCV system.
BUT
If you're one of the usual ricers and don't understand PCV you'll delete it, fit a catchcan and you'll have problems.

[Fireonthemountain]

Turbo-Rocket Fluid and steam engines what will they think of next....

[Geoff2]

Plus water has oxygen in it....

[Circlotron]

Plus water has oxygen in it....

That oxygen is not available to help combustion though. It is tightly bound to pairs of friendly local hydrogen atoms. Takes about 3000 deg C to separate on average 50% of those happy marriages.

[user-23911]

Carbon reacts with water at high temp (at a lot less than 3000)to give CO and H2.
It's an endothermic reaction, it uses energy. You get the energy back with the combustion of CO and H2.


Maybe as low as 706 deg C?

http://www.madsci.org/posts/archives/20 ... .Ch.r.html