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Discussion Starter · #1 · (Edited)
I thought there was another thread where this discussion had begun but I have not been able to locate it, so I will continue from here.

Sir Ricardo's testing shows very well the results of a properly implemented water injection system with no caveats as to necessary limitations for it to be beneficial.



As can be seen in his research fuel dumping alone can only in suppress detonation to a certain point and after that point you will get detonation and lose power. Fuel only tuners have done a great job bringing people to this point. However they leave a lot on the table that could otherwise be obtained. As you can see the knock threshhold can be pushed even further back with water injection while continuing to increase BMEP even while maximum cylinder pressures begin to fall. The only draw back of his work was that he did not work with water injection until fuel was no longer effective. Empirical results from years of water injection use in almost every form of competition have shown that you can begin using water as soon as knock suppression is needed and that water injection is more effective at suppression than fuel dumping at every point. The results in application have shown you can continue with a specific fuel consumption of .4 along the entire illustrated spectrum of BMEP and replace it with water more effectively and efficiently.

The basis of this is well established in chemistry, consider Glassman's work:

...thus one can conclude - correctly - that hydrocarbons inhibit the oxidation of CO.

It is apparent that in any hydrocarbon oxidation process CO is the primary product and forms in substantial amounts. However, substantial experimental evidence indicates the oxidation of CO to CO2 comes late in the reaction scheme. The conversion to CO2 is retarded until all the original fuel and intermediate hydrocarbon fragments have been consumed.
* Source: Combustion, Third Edition, Glassman, p. 76

FYI - the point where the conversion to CO2 begins to become retarded is as soon as you are richer than your engine's maximum power AFR or ~12.5:1 AFR (somewhere between 12:1 and 13:1 anyway depending on engine efficiency) Richer than 12:1 and you certainly are experiencing retarded CO2 reactions to the point of it occuring in the exhaust pipe and cats.

Clearly fuel dumping is undesirable for cooling due to gasoline's low specific heat and as further shown by Glassman it is inhibiting the very reaction that releases the most energy in combustion the completed conversion to CO2. Besides the negative aspects of fuel dumping that are only over come by increased boost, Glassman's work also goes on to prove that water actually plays a very active, critical and necessary role in the completed conversion to CO2. Keep in mind that water is a by product of combustion - the conversion to CO2 in combustion occurs primarily as a result of the water made available during combustion. Additional water actually further encourages this otherwise slow reaction that occurs late in combustion but releases most of its energy to occur much more rapidly and powerfully right when it is needed towards the end of the combustion process right when BMEP is arrived at.

The results have been undeniable to all that have properly implemented water injection - it is the next level of tuning.

To be announced at SEMA, be sure to stop by the Aquamist booth and visit:



Ed.
www.turboice.net
 

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Water injection has been around forever it seems... I just noticed WRX people finding out about it this year.. I do not like it. People just dont realize how much cylinder pressure they are putting on the motor... Granted they arent getting any detonation, but failure is very possible... I would try to stay away from it, or just use it to prevent detonation rather than as a tuning crutch.

-mike
 

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Discussion Starter · #3 ·
Please expand upon exactly how water injection is a tuning crutch rather than a tuning enhancer? It makes a nice sound bite but I have yet to see any research against it or any indication that it is anything but beneficial. Filling the cylinder with excess hydrocarbons that not only will not burn but will inhibit the proper completion of combustion and ultimately rob power would appear to be the true crutch.

Just use it to prevent detonation? That is all it is used for, in the same way that excess fuel dumping is being used only to prevent detonation. The only thing is water is much better at preventing detonation and as a result overly rich fuel settings are no longer needed.

I think we are very aware of how much cylinder pressure is being put on the motor - Ricardo's work shows us - see the link above the graph illustrates very well that the maximum cylinder pressure reached goes up relatively little while BMEP continues to improve to the point where max pressures even start to drop.

The shortest and least well substantiated posts are always the ones that use sound bites - its a band-aid, its a crutch, it is a poor man's intercooler. Why has noone ever stepped up to support the sound bite with hard research, data or evidence? There are dozens of SAE and NACA documents supporting the benefits of water injection - I have yet to find any that would indicate that it is deterimental. I have been begging people to provide any hard evidence other than quoting Corky who provided no support and is not subjected to peer review the way that proper engineering papers are. As for poor mans intercooler I always love that one - it seems to me that spending $500 on water injection rather than $1500 on the "recommended" supporting mods for a VF-30 upgrade would contribute much more to making its user a lot less poor than the one who was drawn in by a profit method rather than a tuning method.

I really do have an open mind but I have asked time and again for support backing up that it is detrimental and noone has ever brought it forward. I think sound bites and cliches are much more indicative of being closed minded about it. There simply is no chemical or thermodynamic principle to suggest that using fuel to suppress knock is anywhere close to even equaling water injection less likely being preferable.

Ed.
www.turboice.net
 

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OK, when people are blowing up stroker motors b/c they are running 30 degrees of timing and are leaning it out so much... Doesnt that sound like a crutch for tuning rather than an aid?

Now on turbo BMW M3s people are only running low low boost, and using water injection to prevent an detonation. Whereas WRX owners think they can add 5 degrees of timing everywhere and lean it out to 12.5-13.0 :1 AFR. That i think is wrong, eventually the motor will fail.

I think it should be used as a backup preventative measure, not as 'race gas'

-mike
 

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Discussion Starter · #5 ·
You hit the nail on the head but are blaming the wrong part. Just because water injection will suppress knock even on a tune that is inappropriate to the motor - does not mean the tuner should do so. The technology is not at fault in that case the user is. I have always qualified the benefits and success of water injection as being based on a properly implemented system.

Is that to say that with fuel dumping 30 degrees is appropriate advance but with water injection it isn't?

Assuming you are talking about the stroker recently lost on the return from PA, that motor saw water injection only at the end of its life - he was tuning without it for most of its life. To imply that water injection or anything water injection enabled him to do that he otherwise couldn't is a misrepresentation. And even when he did implement water injection he only used it as you suggested it should be used in you note above as an extra margin of knock suppression he didn't tune anymore aggressively than he did with fuel dumping as a matter of fact I believe he was even still dumping fuel. He said the motor would run fine with its tune if water injection was completely removed that it was just additional knock margin.

If the issue with his motor is that he is generating too much pressure, this tells me that it is the tuning technique in general that did so because he ran the same pressures without water injection. If people are running too much advance - point to that. Faulting water injection technology for a users actions is like blaming the weapon for murder.
 

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This is slightly off topic from what you guys are talking about, but there was someone on an RX7 forum who built an extremely effective water injection kit for his car. He uses it as a safeguard against high intake temps rather than what you guys describe it as. His thread on clubrx7 should still be up and I could link to it if you guys wanted to.
 

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Discussion Starter · #7 ·
All part of the whole picture. Cars that are intercooler challenged benefit even more so than ones that have good intercooling. Water does a great job of intercooling. As a result of his intended use to intercool I am sure he is running leaner and with more advance than he was before.

This page from my paper attempts to cover all the things that WI is affecting: http://www.turboice.net/documents/turbowhitepaper/waterinjection.htm
 

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Those that have tried water injection on the WRX have had tuning issues. I'm not willing to pioneer this one, but I am looking into another detonation suppression technique.

-Jim
 

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Discussion Starter · #9 ·
There is only one that I am aware of that had a tuning issue. Certainly mine didn't have any tuning issues along with many over at NASIOC. AKWRX pioneered this on the WRX quite some time ago.

EcuTek has partnered with Aquamist to offer an integrated product.

In markets outside of the US, Aquamist has also partnered with ChipTorque to provide a joint integrated product called AquaXede.

Works is talking about offering water injection soon (I know not WRX but still).

There are many knock suppresion techniques available, this is the one that I have had the most success with over the years.

By any chance did you happen by the Aquamist booth at SEMA?
 

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Well, the point is, WI has a very specific appeal.

A good quote was from a guy on s2ki when asked why he doesn't care about detonation: "Well, cause I can afford to put 100 octane in my tank every day"

IMHO WI's niche in tuning in America is to be found in supporting jdm engines which ECU's have far more aggressive timing due to the few more points of octane over there.

well of course that totally discounts the GN folks but whatever.

But WI still isn't as good as C16 and that's that. So why would use WI when you got race gas? The answer is b/c water is dirt cheap right? but if you can afford a 25-30 thousand dollar car, IE the WRX, why would you be skimping out on gas money?
 

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verc said:
But WI still isn't as good as C16 and that's that. So why would use WI when you got race gas? The answer is b/c water is dirt cheap right? but if you can afford a 25-30 thousand dollar car, IE the WRX, why would you be skimping out on gas money?
Because some people scraped together cash to buy it.

You should really be saying "If you can afford a 250-300 thousand dollar car..." because I know quite a few people who bought a WRX because it was the sportiest thing at the price range.

Last time I saw unleaded race gas, it was pretty damn expensive...
 

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Well yeah exactly. I happen to be a full time college student who myself scraped together cash, and am dropping my GPA, to own this car.

Which is why my car is practically STOCK b/c I am poor lol :D

Well ok maybe not C16, but cool blue 100 is like what, 4-5 dollars a gallon?
 

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I would feel much "safer" running propane injection on a turbo car than water injection. The propane adds the octane that race gas offers, so that you have the added knock safty margin...however with propane, your not running the risk of putting a non-compressable substance into your engine. Guys with VR4's have done it for a long time. I think it costs more to implement, but not MUCH more.

-jason
 

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Discussion Starter · #14 ·
The compressibility issue isn't one. You didn't say it but hydrolocking from water injection (unless you have siphoning due to an improper application) is a myth. The amount of water being injected at 15% water to fuel is only around 1% of the total induction charge into the cylinder. And liquid gasoline doesn't compress either - since it takes more gasoline than water to suppress knock you add more noncompressible using fuel dumping than water/methonal injection. While you are absolutely correct that propane compresses and water does not the relatvie quantities just don't matter much. Also propane injection much like many methanol injection applications (rather than a mix) is generally utilized in a manner which is replacing gasoline as a fuel. My application, use and discussion on water injection is replacing gasoline or any fuel which is being used for cooling/knock suppression with water. This is an application which ceases at the point where fuel that would have actually been burned is being removed. Alternative fuel applications are totally different than what I am getting at and even further beyond many enthusiasts willingness to consider than water injection.
 

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I didn't mean using propane injection as an "alternative fuel". It is used in turbo applications as a fuel enhancer and is injected in almost the same identical way as water is injected in that application. I'm not talking about converting the entire car to propane.

Propane is controlled by boost level, and the propane is injected before the throttle body at measured levels (just like the water would be). Propane is slightly higher than 100octane. Injecting 100oct. propane and 91-93oct. gas = 96-98oct levels.

-jason
 

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Discussion Starter · #17 ·
jmussetter - I did understand that you weren't talking about a full conversion - but introduction of an alternative fuel is a mixed fuel application. The few implementations I have been involved with using propane the amount of gasoline pulled from the mixture with the injection of propane pulled was much higher than with just water in the same way that a water/methanol mix pulls more gasoline than just water.

Water is the best substitute for the excess fuel that is dumped for cooling anti-knock purposes. Use of another fuel only for this purpose would remain less effective since their specific and latent heats are lower than water and excess hydrocarbons continue to remain inhibiting the oxidation of CO. When introducing another fuel to the mix it is best used to replace gasoline that would have been actually consumed in combustion, there is no reason to continue to introduce additional hydrocarbons if they will not be used in combustion.

Just my opinion from my use and research - there certainly are dozens of applications and levels of use for alternative induction mixtures to air and straight gasoline dumping.
 

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verc said:

But WI still isn't as good as C16 and that's that. So why would use WI when you got race gas? The answer is b/c water is dirt cheap right? but if you can afford a 25-30 thousand dollar car, IE the WRX, why would you be skimping out on gas money?
Someone added nitromethane to his methanol / water WI mix and claimed better results than C16. Any thoughts on this?
 

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Discussion Starter · #19 ·
I would not be surprised by the outcome.

Every engine's maximum performance AFR is different - and it is different for different fuel mixes.

Anytime you can run a fuel mix knock free at that maximum power AFR (i.e. no excess hydrocarbons to inhibit combustion) - you are golden and water injection is not only unneccesary but undesirable.

To the extent any fuel mixture you are using, including methanol or other "fuel" in a water injection mix, is richer than its maximum power point there are excess hydrocarbons inhibiting combustion through the interference of the oxidation of CO. Water injection will suppress knock and permit the removal of these excess hydrocarbons - it should not be extended beyond that application.

There are many substitutes to 92, 93 and 94 octane pump gasoline that are better fuels for engine combustion they have higher octane ratings and also release more energy or have a better energy release profile than gasoline - using them to lean to maximum power AFR will alwys be preferable. However, even they have their limits and they are not feasible for everyone. Water injection isn't even feasible for everyone.

To the extent you want the maximum tune for your engine, you have to get rid of those excess hydrocarbons and lean to the max power AFR, whether by using super high octane fuels or water.

If I were building a race dedicated car - I would build it to use fuel that would be knock free at maximum power AFR. It would only be run on that mix. Although if you want really high boost you likely couldn't mix a fuel to run that way and if permitted in the class I would use water injection over it in that case. Although few of us could afford to build, run or maintain a race dedicated car running over 25psi.

90% of the moderately increased hp WRXs that are on the street and also daily drivers could run knock free at 12.5 AFR on race fuel - but most of us couldn't afford that bill on a car that also is a daily driver. This is where the application of water injection on a street car permits tuning to be advanced beyond the pump gas maps and it does so affordably. The cost is additional complexity in the operation of the car, additional monitoring and additional maintenance also become necessary. Some of us have more time than money and want that additional power - this is where it works for those that desire it.
 

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The few implementations I have been involved with using propane the amount of gasoline pulled from the mixture with the injection of propane pulled was much higher than with just water in the same way that a water/methanol mix pulls more gasoline than just water.
This is probably true because the Propane burns as fuel does where-as water does not, so with water, you would still need enough gas to cause complete compustion, with propane you would too, but it would be less fuel since the propane will burn also. No arguments there...

Use of another fuel only for this purpose would remain less effective since their specific and latent heats are lower than water and excess hydrocarbons continue to remain inhibiting the oxidation of CO.
Probably true again. Water would have better cooling effects than propane would because it's specific heat is higher and thus removes MORE heat during the evaporation process. No arguments there either....

However, there are 2 different means by with to suppress knock. 1) is to reduce the heat of the intake charge and cylinder heat to prevent a premature explosion (what water injection does, AND what intercoolers do).
- OR -
2) Raise the octane of the fuel so that cyliners heat doesn't pre-det the fuel (what C16 does, AND what propane inj. does.)

If you are experiencing knock with 91 octane on a specific tune, you can reduce knock by implementing either of the two methods. Water inj. is closer to method 1, whereas propane inj. is closer to method 2. It CAN'T be argued though, that EITHER of those methods would have the same result (one might be more effective than the other depending on the specific tune).

I'm not trying to start a flame or anything, just posting an 'alternative' to water that is VERY alive in other car circles, such as the 3000GT/Stealth guys who are running 700-900HP on 91oct and propane inj. on a daily basis.


-jason
 
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