I May Be Wrong About Water Injection WRT Improving Fuel Economy

[freebeard]

...it depends how you inject it!! I'm looking at testing out bubbling the egr through water to cool it ...

That might be a good idea. Since you're casting a wide net, so long as it doesn't involve traveling flame fronts and such, you might be able to model it in software. Quoth Google "Boiling water at 100 degrees Celsius: 540 calories are needed to turn 1 gram (at 100 degrees Celsius) of water to steam." The energy to raise 40° to 100° would be 60 calories IIRC.

[teoman]

For it to be accurate you need microcontroller based injection with a fuel injector or pwm'd pump.

Also if you want to inject hot water that instantly vaporizes, it has to be 540 degs C or so.

Mayve an exhaust heated hotplate that instantly vaporizes the water injected on to it.

[freebeard]

it has to be 540 degs C or so.

[teoman]

Physics of it is working against us in this frontier. Whereas in others it is an advantage.


How about a heat pipe, from exhaust to a point in the air itake tract. It will be at exhaust temp, when you spray water on to it, it will instantly vaporize.



Or a pipe going all the way down to the exhaust, with the exhaust side sealed but touching the exhaust. You shoot water down, steam squits out. (This will have more delay). A y pipe closer to exhaust with injector attached could minimise the delay. Once you vaporise the water, it will be at 100 deg C plus. (Not exhaust temp) so during its journey to the engine it will not lose energy.

[freebeard]

Maybe I was wrong. 540°C is only 104°F. My conversion in my head went off the scale.

I had a Chrysler slant six that had a plate between the floor of the intake plenum and the top of the cast iron header.


http://www.allpar.com/slant6.html

"Aluminum block"!

Edit: It turns out the aluminum block wasn't successful, but...

Walt Ronk wrote about the Lean Burn (the world’s first such computer-controlled system, except the electronic fuel injection used on some 1958 Chryslers). He said that, according to the Mitchell guide, there was no difference between 1979’s Electronic Spark Control ignition (ESC) and Electronic Lean-Burn ignition. The ignition box is mounted on the air cleaner. There was an early style with two pickups in the distributor and a later version with a single pickup.

So, one could have a slant-six Valiant or Barracuda that Has lean burn like a Civic and gets 30mpg.

[t vago]

Originally Posted by ThermionicScott

I thought it was due to fewer oxygen molecules in the thinner air, so that the engine needed to inject less fuel for any given scenario, with the downside of less available horsepower at full throttle.

This is what I want to test. Nobody knows for certain why warm-air and hot-air intakes work. As you do now, I once thought this explanation was why WAIs work, but...

A few weeks back, I had noticed that I was getting insanely high trip economies (31 MPG for a 20 mile trip at an average speed of 45 MPH ?) and I also noticed that temperatures were a bit warmer (one day, it was actually 70 F) at the same time. So, I began thinking that maybe the gasoline being injected was being heated past the point where it would start to vaporize for cold-weather formulations, and that might could explain my higher-than-normal fuel economy.

So, this steam idea is my way of testing why a WAI works.

Originally Posted by teoman

For it to be accurate you need microcontroller based injection with a fuel injector or pwm'd pump.

This is the route I intend to travel. I am looking at Aquamist's solenoid valve - it's supposed to be operational up to about 250 Hz, or so. Pricy little devil, though.

Originally Posted by teoman

Also if you want to inject hot water that instantly vaporizes, it has to be 540 (sic) degs C or so.

I am only going to be using this system during part-throttle conditions, where the intake manifold has a vacuum. That being said, I don't need to heat the water to 100 C for it to vaporize. I am looking to heat the water to about 90 C, instead. For part-throttle conditions, this should be sufficient.

The process of evaporation will cool off the water droplets as they evaporate, which would normally limit the amount of water mist that actually turns into vapor. This is why heating the air is also necessary - the air will provide extra heat energy to allow the formation of more water vapor.

https://www.ohio.edu/mechanical/ther..._TempSat1.html

Originally Posted by teoman

Mayve an exhaust heated hotplate that instantly vaporizes the water injected on to it.

Hm... Maybe. Would like to place the water injectors as close to the intake ports as possible, though.

Also going to be using a liquid-to-liquid heat exchanger. Engine coolant goes in one loop, and it will heat up the water-ethanol mix in the other loop.

[oil pan 4]

I did this experiment once.
I took gas about the time they stop producing the winter formulation, put it in a sealed container waited a month or 2 till virginia summer time temperatures had arrived then burned it. I was able to pickup +2mpg the 2 times I was able to run the experiment.
I was expecting there to be no difference.
I was running a normal tune on my camaro's carb at the time.

[jakobnev]

FYI: 540⁰C if 1004⁰F

A thousand and four.

[teoman]

Originally Posted by oil pan 4

A gasoline engine seeing a benifet from water injection could work it's just not easy and usually doesn't work.

Any insights on what the trick would be?

[oil pan 4]

I think the trick is water injection actually doesn't do anything at all when you are trying to get increased fuel economy.
A dangerous mix of high compression, regular gas and lean burn for economy.
Then water or water and methanol injection to tame air fuel detonation under high load, so you don't have to burn aviation gas all the time, which is expensive and not economic at all.
Assembly line made gasoline engines are designed to be mild enough to not benefit from water injection. So power and possibly fuel economy suffer.