quote:

Originally posted by welder:
... I was interested in finding out if water injection would steam away any coking left behind after single tank svo cold starts, that application would not need constant injection. ...

IMHO that is an assumption that would need to be supported by facts. Not saying your wrong just saying... that is a pretty strong assumption that you might want to rethink. Occasional H20 injection per 100 miles migh well do the trick just fine for the purpose you state.

Neither assumption we have any facts to support so it's only an educated guessing game we start with.

quote:

Originally posted by jeepin, moggin Jessup (coachgeo):
[QUOTE]
Neither assumption we have any facts to support so it's only an educated guessing game we start with.

I have been running the water injection system for about 4-6 weeks, I will be pulling my turbo to incorporate an intercooler in about 4 more weeks, I should get a fairly good idea about the effects of the water mist on the carbon build up in the intake manifold, if the intake isnt clean I doubt its clean further down the engine. Might give us a better idea.... but still wont prove anything...

Coach, I wasn't making an assumption. I used the words "interested in finding out". Isn't hypothesis part of the scientific process?

I admit I know very little of water injection systems, but since another forum member mentioned that water injection kinda steam cleans some engine areas, I thought it MIGHT help remove any residue from single tank svo cold starts. If so, that's good news and may make take the focus of svo tech away from 2-tank systems to single tank systems.

I hope that someone actually tests the hypothesis. My only fear is that unheated water injection may cool the flame front and actually cause more harm than good. Any single tank injection cleaning tests should be done with both heated and unheated water to compare results.

The main reason for water injection is to cool the intake charge and reduce exhaust gas temps. that will allow you to turn up your fuel and thereby increase power, without risking dangerous EGT'S..... IN THEORY! test on mercedes diesel's dont show those results.

I am not really following you on the heated Misting. The cold water misting is being directed into the intake, post turbo, this charged air has already been heated (exhaust spins the turbo) and the water is evaporating, and therefor cooling the charge, with some luck it will cool it enough to make it denser (more O2 to burn), and it will be cooler reducing internal engine temps. Im not sure what standard intake air temps are (anyone) but exhaust gas temps run from 500f-1200f, Is the theory that hot water will evaporate better than cold water. This is not something I know much about but.... Is there going to be a noticable difference in evaporation of water, hot versus cold, on an intake charge that is in the 400f-1000f Range?

quote:

Originally posted by Quinn8it:
... I have been running the water injection system for about 4-6 weeks, I will be pulling... intake manifold, if the intake isnt clean I doubt its clean further down the engine....

Look forward to your results. Most of what I've read about WI and cleaning things has to do with combustion chambers. Don't remember much being said about intake manifold but don't quote me on that.

quote:

Originally posted by jeepin, moggin Jessup (coachgeo):
Look forward to your results. Most of what I've read about WI and cleaning things has to do with combustion chambers. Don't remember much being said about intake manifold but don't quote me on that.

Im not really looking for a cleaning effect, but that seams to be on everyone elses mind... I was just offering that if I noticed a cleaning effect there... it might be cleaning elsewhere...

quote:

My only fear is that unheated water injection may cool the flame front and actually cause more harm than good.

So from this I can deduce that you think cold water will put the combustion fire out and hot water won't. Interesting!
If you did bother to read up on water injection you would know that it is well documented that it takes a LOT of water to make any Difference to EGT's.
I would be REALLY interested to know why you think hot water would not quench a flame, maybe a few thousand degrees in temprature and under significant pressure but a similar amount of cold water would?
I know you don't know much about water injection and are learning but as you have made the comment about hot water a few times, maybe you could explain why you think hot water would be benificial?

quote:

Any single tank injection cleaning tests should be done with both heated and unheated water to compare results.

Here we go, case in point.
Exactly WHY "SHOULD" tests be done with both heated and unheated water? What facts, scientific principal of even just general infomation do you base this assertion on??

You have made a statement here advising people how their tests should be conducted which is not a question or quiry, it is a plain and clear directive so PLEASE tell us exactly why you say heated water SHOULD be used?

Can you support this or any other statement with factual or accepted principal rather than just something you have dream up with no reason or substance.


I have been running water on my car for 5 months now and I have noticed the intake has been substantially cleaned. When I first put the water on, the manifold had a lot of oil in it from the breater and now it is almost shiny. I don't know what this has to do with what is in the combustion chamber, but as my car has improved dramatically in the way it runs since the water has been added, I have no doubt the water is cleaning and keeping the engine free of deposits.

Given the improvement in the cars performance, It is my firm belief that the rings or combustion chambers may have had deposits which lowered the cars performance and these have now been removed, restoring performance in line with what it should have been or would have been years earlier.

Hi Quinn8bit. The idea of heating water before injection was to reduce its ability to absorb heat as it would already be hot. Although this seems counterproductive on the surface of traditional diesel theory, because svo relies on heat to give a reasonable assurance of complete combustion, cooling the air charge post turbo will likely add power due to the relationship between air temp and air density, there is a theoretical potential to cool the air to the point that it doesn't combust the veggie oil completely.

I know that greasers are running svo even in cold climates like Alaska etc, but without testing, there is no real way to know for sure whether cold water injection will cause the compression ignition flame front to cool the veggie enough to cause coking. Perhaps it would only cause trouble in very cold climates, but not in moderate or hot climates. Perhaps the cooling effect of cold water being atomized into the air charge will only cancel heat introduced by the turbo and not cool the air enough to cause incomplete veggie combustion.

Without thorough testing of the effects of cold water injection on veggie combustion over different climatic extremes, we'll never know whether it has any bad effects or not. If unheated water (with alcohol added to prevent freezing) does cause coking in cold climates, then adding insulation and a gentle heat source to the water tank and a FPHE to the water line may prevent this potential coking effect. Of course after installing all that stuff, there wouldn't be any more need to add antifreeze to the water to prevent freezing.

Both MjrChode and Johno noticed the potential for cold water injection to cause problems. I'm only offering heating the water as a potential cure to a potential problem.

I went back and read those post again... My take:

quote:

mjrchode
It will also cool the combustion chamber so to much might not be a good thing.

The further from the intake the better as it gives the mist a chance to absorb the heat and mix with the air intake charge. I assume the MB does not have an intercooler so you can place it as close to the output of the turbo as possible.

Johno absolutely makes reference to overcooling the charge but I couldnt find any mention by mjrchode, the quote above by him was the closest i found.... I was not convinced that johno was speaking from experience, maybe theory..???...

I will lay out a little theory i have been knocking around...
If the WI system is set up like most, with a boost pressure activated pump. the mist will not turn on until at the lowest, 1/2 max boost, many people set that even higher like 3/4 full boost. at these boost levels you have raised your EGT's by minimum 300f and as much as 800f, I have a pyrometer and the temp rise is almost instant. I have heard claims of up to 200f reduction in EGT with the use of WI. I think that is vastly exagerated, at least for 5 cylinder Mercedes Diesels. But lets just say for this theory that it reduces your EGT by 100f. Standard Idle in one of these benz diesels is like 400-500f once its warmed up. Punch the gas and EGT's shoot up to 800f in a couple seconds. Based on those temps if you car can burn the fuel at idle or low load situations it sould be able to burn your fuel at high load situations even with a reduction in charge temp.

The Water Injection just cant lower the temp that much. It just dosent work that well! If you can develop a water injection system that can get you full load EGT's lower than your Lite load/boost EGT's then I think you are on to something!

Once again this is only theory and i am sure there could be something i dont understand......
Any thoughts??

Hi Welder,

I'm just wondering, Do you have any idea whatsoever on the principal behind how a diesel engine operates?

Hi DCS. Yes, I have some understanding of how a compression ignition engine operates. I know for example that ignition is derived from the heat caused by compressing a piston full of air. That's why I was concerned when Johno mentioned the concern that perhaps the injected water droplets may cool the air charge excessively as the water turns to steam. Although this would increase pressure (good thing), in extremely cold climates, this may cool the air enough to slow the flame front as it moves through the atomised veggie spray potentially leading to incomplete combustion(bad thing). Johno mentioned that veggie is a slower combusting fuel than diesel. I hope the concern is proven to be unnecessary.

As to your sentiment, this is a public forum. Basic courtesy and topical content seem to be the moderators main concern. However, if you feel that membership should be limited to experts only, then perhaps you should propose that to the moderator. I'm guessing that since the motive of this forum seems to be both the technical advancement and PUBLIC PROMOTION of biofuels (biodiesel specifically), she may decline your offer to alienate people with less knowledge and experience than yourself.

On this forum I have interacted with surgeons, chemists and professional engineers. They all had enough common sense and basic decency to interact with other members using tact and discretion. They didn't waste time ridiculing lesser members or butting heads with other experts.

If you find my posts that irritating, please feel free to put me on your ignore list.



Hi Quinn8bit. The qoute by Mjrchode that you provided is the one I was referring to. He misspelled the word "to". It was meant to read "too much", not "to much".

At any rate, the data you provided seems fairly compelling. Ultimately, I hope that the concern that Mjrchode, Johno and I seemed to share is proven unnecessary.

I know that a pyrometer measures EGT, but I'm not sure that EGTs necessarilly reflect the air temps inside a combustion chamber at full compression. I know that fuel ignition is caused by the heat of air compression, but doesn't the actual burning of the fuel add more heat than what is required to combust the fuel in the first place? If so, does anyone know what temps are common in the combustion chamber pre-ignition? If they are significantly lower than EGTs, then they are likely to be more relevant than EGTs.

If combustion chamber temps are NOT significantly lower than EGTs, then you are likely correct that injecting water while running on svo likely won't cause any problems.

I watched my Pyrometer closely on my 2mile commute today. While rolling along at city street cruising speeds 30-40mph i noticed that my EGT readings were in the 500f-700f range this was all under 5psi of boost, let off the gas slightly and it will settle down to close to 400f.

Except for a few takeoffs from stoplights my commute was constant. I was almost never in a 7psi or more boost situation, therefor my WI system never turned on. Those temps are a base reading, you will always be achieving those temps and the hope that WI will decrease EGT's would be directed at temps above that level. If your fuel can combust at those opperating temps there is no reason it wont combust at higher opperating temps, even if those temps are lowered by the WI system.

One other thing, All of my experience with WI and Diesel is based on the mercedes 617 engine. On another forum I frequent 3 other members with quite a bit more experience than me in this area(benz diesels) all installed WI systems on there Benz (2 617,1 603) None of them recorded any EGT drop. I plan on setting mine up so I can test EGT's with and without the WI but I dont really have much hope for large drops in temp. Point being that I dont think you need to wory about your intake charge being to cold!

Sounds good! I hope you are right. I know that people like Elsbett and others have done a lot to make a single tank svo system a practical reality. Everything from tank heaters, line heaters, injector heaters as well as battery and block heaters (for cold starts) can potentially help a single tank svo diesel perform well on grease, but there has still been a lingering hesitance to convert to single tank systems as opposed to two tank systems. Some braver folks do go the single tank route, but I think most trust the 2 tank conversion more. My concern for the use of water injection was mostly for the single tank svo people who lack the option of steam cleaning their combustion chambers while running on bio or petro rather than slower burning svo.

Someone mentioned that they thought water injection wouldn't be able to steam clean coking deposits from injectors. I think that DI injectors actually protrude into the combustion chamber don't they? If so, wouldn't the steam be able to clean the outer surfaces of the injectors? Does injector coking happen more internally or an externally? I can see that steam would likely have a harder time cleaning the inside of an injector than the outside, but if coking is more of an exterior problem, then maybe water injection will turn out to be a big preventative anti-coking measure for single tank svo owners.

Ill let you know how my injectors look in a couple months when I pull them. They will have over a year and 8000 miles on single tank WVO, I added the water injection 2 months ago and just switched to Biodiesel(1 tank so far). At some point I added injection line heaters and a vegetherm pre IP. You wont be able to draw any real conclusions from the mishmosh of systems i have run but it will be interesting to see if the injectors are coked.

DI injectors have a little bit of room in the tip, just before the spray orifices. This is called the Sac. Modern injectors are designed to minimize the Sac volume, almost to zero, but older ones had a significant Sac volume. Residual fuel (after the injection event was done) sat in the Sac and cooked there. Some fuels (SVO especially) would build-up a thich deposit in the Sac after a few zillion repeated cycles (ie: engine running). The injector tips weren't hot enough to cleanly burn off that residue (they'd have to be nearly incandescent to do so!!!). Water/steal can't reach inside the injector to blast off those deposits, but they probably aren't a concern to most of us with "modern" engines, with their minimal Sac volume injectors.
Both DI and IDI injectors can develop deposits on the outside. I've read them referred to as "trumpeting", becasue they resemble a miniatrure carbon trumpet. They form at the periphery of the spray pattern, sort of the way coral grows. Water/steam would be an effective way to remove those deposits.
Ring/land coking is not likely to be cleanable with steam or water. Engine manufacturers have been looking for a way to do that for about 100 years. Their "solution" so far has been to only use clean-burning fuels that don't leave deposits on cylinder walls, and combustion chamber designs that insure complete combustion before the droplets reach the cylinder walls.

To address Quinn8it's question: I don't have direct experience with water spray, only what I've read, plus some working knowledge of water phase changes and the effect on temperature and pressure of compressed gas charges (I'm a test engineer, but not of diesel engines). I've worked around diesel engines most of my life, but the newest ones I've worked on were made in the 1980's, before common-rail and electronic controls. We ran a lot of different engines on test stands in school (heat engines lab), and I've performed heat balances on most types, which were very instructive. None of they used water spray, so again, I can only speak from what I've read.
Cheers,
JohnO

Just learned of this thread today. Have not read it myself yet but was told it was a good thread in RE to MB's

MB 603 Water Injection Topic

That was a big source of information for me before I did my WI install.
Things to note about this article: the author noticed zero EGT reduction. and the install was on a Mercedes 603 engine. I have a 617 engine and was assuming that I could also place my nozzle in my EGR block plate (as he did). This was not the case on my engine, once i removed the block plate it became obvious that there was not a straight shot for the mist into the intake. This meant my quick little install of putting the pump and reservoir in the trunk, running the tubing to the engine compartment and tapping the nozzle into a 1/8" thick piece of easy to remove metal turned into removing the turbo and the intake manifold and having to drill and thread the intake.... I also, and would recomend everybody else do this, pulled the exhaust manifold and installed a Pyrometer probe at this time and change out all gaskets.

Also Im not sure if it is mentioned in that thread but the author has said in other postings that he now has the system on a toggle switch and does not use it 95% of the time he is driving. But he was soley looking for EGT reduction so he could turn up his full load, and the system never accomplished that.

I did some reading at one of the TD truck sites, and people are claiming 200 degree drops using the SNOW kit.

quote:

Originally posted by Shaman:
I did some reading at one of the TD truck sites, and people are claiming 200 degree drops using the SNOW kit.

The guy that wrote the post that the link in jeepins post linked back to the Snow Kit web site. He was expecting those results and got Zero EGT reduction. There are two other members on another forum I frequent that showed Zero EGT drop... I havent done a real test of my system, but I have turned it before off and it is not a noticible temp change on the Pyrometer. These were all on Mercedes 617 and 603 engines... maybe the diesel truck engines are different... Anyone know?

May just have to up the water amount, i.e. bigger pump or more nozzle