dubulup

-CxHy + (x + (y/4))O2 -> xCO2 + (y/2)H2O

no H2O on the left so how would it effect (or is it affect???) AIR : FUEL ???

adding H2O on the left moves the reaction further from the right (which is good, because too much to the right, and we all know what happens)

any chemistry geeks care to correct me if I'm wrong?!?!?

(I'm an idiot, so don't take geek the wrong way)

FDNewbie

iTrader: (10)

I understand what you're saying...I'm not saying in terms of water playing a role in the combustion process. I'm thinking in terms of relative concentrations of the reactants for the combustion process.

You have air, and you have fuel. Lets say they're in a 1:1 ratio (for the sake of example). If you add water, water will ultimately displace one of the two components to an extent, effectively decreasing it's (relative) concentration. The result: me assuming that the amount of fuel is static, I'd think it would displace a bit of air/decrease it's concentration, effectively making you run a bit rich?

On that note, decreasing both air and fuel concentrations in an equal fashion wouldn't be a problem, because the ratio would remain the same, so you're not running rich or lean. So it's only when one of the components is affected (or one considerably moreso than the other).

If my basic chem logic is off, or its application doesn't work, plz feel free to correct me. Irrespective of all the explanations, however, I'd still like to know if anyone's done any actual testing to verify the effect of WI on AFRs (if any)

HobbeZ

you might want to check some other forums like the mr2 club forum and so forth. they probably have alot more information since they don't have the luxury of having a front mount etc, so they have to turn to other alternitives for cooling etc.

Kento

The volume of air ingested by the motor at full throttle/boost versus the actual amount of water injected is so lopsided (any amount that would have an effect on the a/f ratio would be great enough to cause problems with combustion) that there is no basis for concern.

dubulup

Vaporize my man! The energy of heat exchange is FAR more taxing than the displacement of water in the combustion chamber.

More dense air, you can fit more inside the money spot. If fuel was the same, you'd run lean(er), the exact opposite of your thinking. But that's why we have air temp fuel correction maps...but you said fuel was static, so you've got a leaner (not to the danger point) mixture, that is harder to ignite...you've got almost a balance.

But even a stock ECU has a air temp correction map...but the stock temp sensor might not be fast reacting?!?!?

There is no "lock" fuel map that I'm aware of (why would you want it)...so in closing, I see no NEED to test A:F ratio; but yes I'm also curious to the actual facts.

I'm yet to hear someone blow a motor due to WI, yes while tuning one might bog a motor with too much water...not hydrolock a motor. Too little water...not as cool of an intake temp, no big deal...

NOW running insane boost only allowable with water mapping...run out of water, BOOM. Fawk or run lean on water...BOOM!!!

Kento

WI has little effect on the actual density of the air already in the intake tract, so it has no real effect on a/f ratios. Its real effect is dropping combustion chamber temps, which is what enables the tuning to take advantage of that and make more power. You don't suddenly run lean by running WI, nor do you get a magical power boost by just running WI; you need to tune for it to get power benefits. Using WI as a safeguard against detonation is the only reason to install it with no other mods.

boostedrotor

i have the aquamist system in my car, it runs off injector duty cycle and boost pressure....no tuning required...we run 50/50 water and methanol or alchohol...it drastically reduces intake temps, it does not lean out....we ran a wideband on this car for a while and checked afr's with and without the water injection and noticed no significant differences in the afr's...

pianoprodigy

If one is seeing ridiculous intake temps, (e.g. 60+C at the drag strip) and feeling a SIGNIFICANT power loss, would one then see power benefits without tuning just by the shear fact that the intake temps are drastically lower?

Kento

Any power gains would be the result of the ECU reacting to colder intake temp readings because again, all WI does is reduce combustion chamber temps. It doesn't make the air inside the intake tract or combustion chamber any more dense (and contain more oxygen for the combustion process).

fastcarfreak

if you tune for water injection you will definately see increases in power. If you dont tune for water injection you get the benifit of peace of mind. im buying it so i dont blow another damn motor.
adam

FDNewbie

iTrader: (10)

Kento, if I understand correctly then, WI is good because it lowers intake and thus combustion chamber temps, and lower temps = less chance for predetonation, correct? I don't understand how something can decrease air temps but not affect density? PV = nRT, and solving for density (n/V) gives you density = P/RT, so higher temps = less dense air, or greater density = lower temps. My point: I'd think that if you drop the temps, you'd HAVE to end up w/ an increase in air density, which would yield more power, no? I thought this was the whole bases of NO2 injection too...drop temps drastically, increased air density = greater combustion = more hp? (I have a feeling I'm in for a "no, dumbass, that's not how it works" response lol)

Lastly, how exactly does WI decrease temps? Is it simply because it's hotter than it's surroundings, so the heat (energy) around it is used to vaporize it, dropping temps? Because if that's the case, and we're talking about a tiny mist of air, I don't see how that would significantly reduce air temps overall of a super hot combustion chamber...

ROTARYFDTT

iTrader: (4)

Great information. However, I have a couple more questions.

Since the main consensus is running WI without tuning, as a motor insurance policy. What are you guys using for activation points, seems as though something around 10psi would be optimal. Also, are you guys always running it whenever you drive, or only on occasions in which you’re driving hard? I was thinking about only having it running WI on cruising nights and at the drag strip, or basically any other time I know I am going to beat on the car.

Furthermore, based on your driving characteristics. Under heavy boosting and basic driving, how much water consumption are you seeing, and how often must you "fill up?" I was thinking about using my washer fluid reservoir for simplistic reasons but I am unsure it’s large enough.

Kento

Well...
Well, first there's no such thing as "predetonation". There's detonation and preignition; two different things.
There's not a whole lot of evaporation that goes on in the intake tract when the water is injected. Much of the temp drop that is measured is due to condensation/evaporation by airflow over the sensor itself. It's when the intake mixture is ignited in the combustion chamber where the water really makes a difference by truly evaporating at that point and absorbing huge amounts of heat, excessive combustion heat that could cause detonation.
Read above.
No, nitrous oxide injection works by introducing additional oxygen molecules into the combustion chamber. And you don't just add nitrous and get horsepower; you have to add extra fuel to react with that oxygen, because otherwise you're leaning out the mixture terribly with all the additional oxygen.
Turning water into vapor absorbs a tremendous amount of heat energy, even more than methanol and fuel. You only visualize a "tiny mist", but remember that a large volume of intake mixture is crammed into the combustion chamber before it ignites.

Make like your medical studies. Buy some books and start reading.

dubulup

Here are a couple pics of my set-up. Activation - I've still been tweeking it but currently, I like ON @ 5800rpms OR > 8psi; OFF 5600rpms AND < 6psi.

https://www.rx7club.com/showpost.php...2&postcount=78

If I'm in a 7, I'm beating on it

My reservoir is 2.5qts...I'd say I have about 5 hours of driving on it (on this fill up) and it doesn't look like I'll need to fill it up anytime soon.

J_J

I deplete the water tank after I go through about a full tank of gas. It all depends on how you drive your car but filling up the tank shouldn't be a chore if you have the the external reservoir that Cooling Mist sells with their kits.

The main reason I purchased it is because it's an additional safety layer for my engine. If I were to get a bad tank of gas or somehow experience a lean-running condition, I'd have something to help ward off detonation and possibly prevent a 3k rebuild. Basically it's like insurance for my engine--for added piece of mind.

mad_7tist

i think it was volvo or sabb released a paper saying that after torque peak they found they could start replacing as much as ~40% of the fuel injected with water and found no power loss or excessive exhaust temps. as the main purpose of the heavy a/f ratio after rthe peak is mainly to keep the temp down and stave off any preignition.

FDNewbie

iTrader: (10)

Well I guess I just don't expect to get a "read some books" response when asking technical questions beyond my scope, since that's what the forum's all about IMO. This isn't a "READ NOOB" situation, and I think every question/problem could prob. be answered by reading the service manual and simply taking things apart and inspecting for wear/damage. But I don't see ppl saying "READ THE SERVICE MANUAL" and don't think people want to go thru that trouble. We wanna capitalize on the info others already have, that's all.

To keep this as short as possible, you can't fathom the amount of reading that's required just to pass as it is. There certainly isn't any time left for leisure reading. The forum kills so much of my time as it is, and I usually only check it during breaks (or at least I try to lol). Try doing 45+ credit hours and finding "lesiure time."

Yea my fault. You're right. I was speaking of preingition, which could lead to detonation.

Gotcha. So minimal change in the intake temps, thus minimal change in air density. And the presence of water in itself isn't what's lowering the temps, it's when energy (in the form of heat) is used to evaporate the water in the combustion chamber that causes the drop in temps. Good stuff

Oops...excuse me if I was incorrect. I thought the NO2 was just causing temp changes that increased air density...I didn't know it directly added O2 to the combustion process. Not quite sure what the chemical formula would be either. But I now understand. Oh, and I know that w/ increased O2, you have to increase your fuel mixture, because the increased O2 obviously changes the AFR, making you run lean.

I got you except for the last part. "Tiny mist" (small amount of water) in what you refer to as "a large volume of intake mixture" sounds like it's supporting my guess that the larger the intake volume, the smaller the effect of a tiny mist of water, unless you increase the amount of water injected accordingly...

Kento

OK, Ramy, look: first, you'll have to pardon the acidic nature of some of my responses. It's just a little frustrating to read some of your posts; they signify that you're trying to ski down a black diamond trail before even learning to ski down a bunny slope first...

What I meant by "buy some books and start reading" is that I don't want you to think you'll learn everything from an internet forum, or even the internet for that matter. Don't get so defensive. All I'm saying is that you often post what you consider to be fact without knowing whether it actually is beforehand. And that often leads to the spread of misinformation.

Sorry Ramy, but this is what I meant about trying to learn something based on tidbits you grab from the internet. I guess I made the mistake of taking it for granted that the majority of people who have already modded cars know what the concept of spraying nitrous is...
And who cares what the chemical formula is? In this case, if you know the basic concept, all that type of stuff is basically just an ego exercise.

Your previous post was basically asking the question of how a "tiny mist of water" could make a difference in combustion chamber temps. I was only stating that what you termed "a tiny mist of water" in relative terms to using WI at full throttle can be extremely influential on combustion temps.

Kento

Pre-ignition doesn't lead to detonation. Detonation is an uncontrolled ignition of the intake charge caused by that charge in the combustion chamber achieving a high enough temperature (through overly high intake and combustion chamber temps, then being compressed, which raises temps even more) to ignite without a spark. Pre-ignition is ignition of the intake charge before the actual spark by other means, such as combustion chamber "hotspots" glowing hot enough to act like a glow plug in a miniature RC engine.

FDNewbie

iTrader: (10)

I can appreciate that. And while your point is 100% valid, I guess (at least in my mind) I think it's still ok to learn as you go along rather than do it the correct way, which would really mean leave the car alone until you know how it works, and don't modify it until you know what the modifications you're doing truly entail. That's def. the way to go about it, but I know that's just not going to happen anytime soon. So I try and grab what I can here and there to fill in the gaps as I move along, plus sometimes I just want information on a certain subject matter, even tho I may be missing the whole, because I trust that if you guys stand behind the concept of doing/using something, it's prob solid. I just wanna see if I can understand the mechanism behind it. You'd be surprised how much trust I have in ppl like yourself, Jim, Tyler, and a few others

Understood. This specific example was from another thread I had posted in months ago, and I got that explanation, and no one corrected it, so I assumed it as true. But obviously, no one can scour ALL the threads and ensure they're all 100% accurate. I know this isn't the utmost and complete source of knowledge, but for now, it's gonna have to do - at least for me. And I'll try and stay off posting about what I don't know for sure...which basically means I should pretty much stop posting LOL Feel free to point it out to me, on the thread or via PM, whatever. I'll make an earnest effort to work at it. Just kinda hard when again, most of the info I get is FROM the forum, and when I don't see it disputed, I assume it's true.

Gotcha. I don't know much about NO2 or anything else that isn't mainstream/common w/ FDs, cuz pretty much all I know is FDs (although it may not be much). I don't ever plan on running NO2, so it wasn't anything I looked into either. Always came across to me as being a cheap way to get power (cheap ie cheesy), not to mention dangerous and too "Fast and Furious"ish for me lol

Gotcha. Thanks

FDNewbie

iTrader: (10)

So basically both entail igniting w/o a spark from the plug, but in detonation it's due to the increased heat of the charge itself, while pre-ignition is from other means such as increased heat of a certain areas of the chamber itself (hotspots), right?

Kento

Yes. Do you know how a diesel engine works?

FDNewbie

iTrader: (10)

You tryin to make a fool outta me? LOL. If it's not an FD, I don't know jack about it. And if it's an FD, there's still a hella lot more left for me to know about it. In short, save for the fact that I've been very responsible in modding and maintaining my FD, I'm prob the exact person you WOULDN'T want owning one

In short, no I don't know how it works. Care to share?

Kento

No, not trying to make a fool out of you. Just trying to get you to research and learn some basic internal combustion engine principles. A simplistic view on diesel engines:
http://auto.howstuffworks.com/diesel1.htm
In very basic terms, it uses detonation to ignite the mixture.

FDNewbie

iTrader: (10)

Kento, I know you weren't. I was just j/k. Thanks for the link. I really appreciate it. Checking it out now...