Water injection & gas economy on NA & FI

[ViksMSP]

Hi all, so I'v been away for a long time from this forum since I no longer have a mazda in my driveway, but I had a question and since I know that there are a few knowledgable gearheads on this forum I wanted to ask it here.
This whole deal about water injection got me interested and if it would be possible to actually have some good things come out not only on the hp end but also on the mpg end. Here's my thought:

On a FI car it's pretty simple, you need water to cool off the car cause you don't want to run high octane and you don't have good compression ratio for a turbo, so you cool off your chamber with some water and good to go.

But on an NA car, let's say your stock AF ratio is 11.5 to 12.5 and somewhere around 13.7 on idle on a honda, nissan and mazda not sure... So all of you are welcome to correct my assumptions. My first assumption is that you have maximum power at around 13-14.0 af ratio, and af ratio goes down in order to protect the engine, and protecting it from higher temperatures during load??? Ok, next assumption is that if you have some sort of a piggy back and a wideband and you are able to control the fuel entering the engine, what would happen if you tried to keep it at the leanest possible operation and add some water to keep it cool???
Wouldn't it in affect have much better gas mileage???

What am I missing? I read some articles on this but they were all kind of dumb, they were adding water to a motor and relying on knock sensor not to pull any timing and thus not stealing any power, but they were not improving the engines best, they were just trying to keep it.

So??? Anyone?

[Speedy3]

Hi all, so I'v been away for a long time from this forum since I no longer have a mazda in my driveway, but I had a question and since I know that there are a few knowledgable gearheads on this forum I wanted to ask it here.
This whole deal about water injection got me interested and if it would be possible to actually have some good things come out not only on the hp end but also on the mpg end. Here's my thought:

On a FI car it's pretty simple, you need water to cool off the car cause you don't want to run high octane and you don't have good compression ratio for a turbo, so you cool off your chamber with some water and good to go.

But on an NA car, let's say your stock AF ratio is 11.5 to 12.5 and somewhere around 13.7 on idle on a honda, nissan and mazda not sure... So all of you are welcome to correct my assumptions. My first assumption is that you have maximum power at around 13-14.0 af ratio, and af ratio goes down in order to protect the engine, and protecting it from higher temperatures during load??? Ok, next assumption is that if you have some sort of a piggy back and a wideband and you are able to control the fuel entering the engine, what would happen if you tried to keep it at the leanest possible operation and add some water to keep it cool???
Wouldn't it in affect have much better gas mileage???

What am I missing? I read some articles on this but they were all kind of dumb, they were adding water to a motor and relying on knock sensor not to pull any timing and thus not stealing any power, but they were not improving the engines best, they were just trying to keep it.

So??? Anyone?

It does make sense since going from liquid to steam, water expands 1600 times it's initial volume. The only problem is precisely controling the volume of water. Also, you have the oxidation side-effects. Anyways, AV-8 Harriers do this for an extra boost in the turbine engines while landing vertically which has a side effect of cooling the massive engine. The last thing though is the increase of the flash-point of the fuel/water ingested. The water would probably have an effect on the combustion like really, really high-octane gas, but in a really wierd way because of the intantaneous phase transition boundary from liquid to steam.

I'm sure Exxon-Mobile owns the patent.

[jdmls88]

they issue here is the water methanol kits are used like nitrous in short sprays. This mist cools the air and evaporates (more alcohol than water) as it enters the motor leaving cool DENSE air, more air going in= more fuel going in = worse fuel economy. If you tried to keep it really lean and add water, you would not only lose power but the cool air would make detonation easier. I have personal experience of cold air detonating and destroying motors. The water injection actually uses windshield washer fluid which is a methanol water mix where there is only a little bit of water. I think i answered your question best i could lol

[Rotus8]

Spray the water on the intercooler. It will do more for you.

[Speedy3]

Spray the water on the intercooler. It will do more for you.

ROFL!!! Couldn't have been stated better!

[ViksMSP]

they issue here is the water methanol kits are used like nitrous in short sprays. This mist cools the air and evaporates (more alcohol than water) as it enters the motor leaving cool DENSE air, more air going in= more fuel going in = worse fuel economy. If you tried to keep it really lean and add water, you would not only lose power but the cool air would make detonation easier. I have personal experience of cold air detonating and destroying motors. The water injection actually uses windshield washer fluid which is a methanol water mix where there is only a little bit of water. I think i answered your question best i could lol

I think you're talking about a different deal here. Cold air can potentially knock your motor if you don't have the gas to back it up, but cold air works different from water, and I'm not talking about any kind of hybrid mixtures, alcohol, methanol and so on. Just a good high pressure water mist that is activated per load and per rpm.
See, as I understand water will cool off the chamber after combustion and can potentially let the engine run at it's ultimate performance.
If you can potentially control gas & water perfectly, what would be the possible result?

[jdmls88]

I think you're talking about a different deal here. Cold air can potentially knock your motor if you don't have the gas to back it up, but cold air works different from water, and I'm not talking about any kind of hybrid mixtures, alcohol, methanol and so on. Just a good high pressure water mist that is activated per load and per rpm.
See, as I understand water will cool off the chamber after combustion and can potentially let the engine run at it's ultimate performance.
If you can potentially control gas & water perfectly, what would be the possible result?

this new 10% ethanol gas crap they sell at the gas stations lol j/k i couldnt tell you but i wouldnt do it

[Little Beavis]

Under light load you can run substantially leaner than the environmentally friendly 14.7:1. The issue is that you will not produce the same amount of power (less fuel obviously), which means that you will have to give more throttle to make up the difference. I would have to dig around to find the exact number but the most powerful burn is below stoich burn and is somewhere around 13-13.5:1 if I remember correctly. Anyway, just for shits and giggles I ran 17:1 one day cruising on the highway (last month) for a long trip filled up and ran 15.5:1 on the way back. Both trips yielded roughly the same mpg (not that great of a controlled test unfortunately). I may have just wanted to see the 17:1 being better, but nonetheless 15.5:1 is certainly better than 14.7 when cruising down the highway under very light load. Now keep in mind I have a Microtech, a wideband, all sorts of other gauges, and a J&S. . .so I wasn't doing anything unsafe, but I don't recommend trying it since there is the potential to do something stupid.

[ViksMSP]

Under light load you can run substantially leaner than the environmentally friendly 14.7:1. The issue is that you will not produce the same amount of power (less fuel obviously), which means that you will have to give more throttle to make up the difference. I would have to dig around to find the exact number but the most powerful burn is below stoich burn and is somewhere around 13-13.5:1 if I remember correctly. Anyway, just for shits and giggles I ran 17:1 one day cruising on the highway (last month) for a long trip filled up and ran 15.5:1 on the way back. Both trips yielded roughly the same mpg (not that great of a controlled test unfortunately). I may have just wanted to see the 17:1 being better, but nonetheless 15.5:1 is certainly better than 14.7 when cruising down the highway under very light load. Now keep in mind I have a Microtech, a wideband, all sorts of other gauges, and a J&S. . .so I wasn't doing anything unsafe, but I don't recommend trying it since there is the potential to do something stupid.
I wouldn't try anything like this without getting all the protective things first. Anyone know if there's a calculator that calculates mpg by load/engine size/weight & afr ratio?

[Speedy3]

I think some of you missed his point. He is talking about injecting water in with the fuel and adjusting the A/F ratio to obtain an optimum MPG by harnessing the energy in the phase transition of water from liquid to vapor orchestrated with a A/F ratio that compliments the water ingestion.

Correct me if I am wrong Viks.

[Little Beavis]

It mentions adding water "to keep it cool", I don't believe the intention was to create a steam engine or harness any power from a phase change.

And I did say I didn't recommend that people duplicate what I had tried. The risk for those without all the crap I have is too great for a minimal return.

[Speedy3]

It mentions adding water "to keep it cool", I don't believe the intention was to create a steam engine or harness any power from a phase change.

And I did say I didn't recommend that people duplicate what I had tried. The risk for those without all the crap I have is too great for a minimal return.

The energy that converted the water to steam came from the heat of the combustion of the gasoline. There will be 2 effects that will greatly increase power. Compression and cooling. So, if the intent was to just keep it cool, not gonna work because you're gonna get a ton of expansion.

[ZoomVT]

subbin for a cool topic.

[ViksMSP]

Ok, can someone clarify to me what really happens to a NA motor when you tune afr ratio to about 13.5:1? Does it get hot? does it start detonating? why? and so on. and as the afr increases I understand you will loose power because you have less gas that you're burning, but other than that, what else is happening?