Okay, so now the next question I have is similar to the one that Muleears asked, but worded slightly different:

Is there any real risk of causing damage if I just leave the water injection system on ALL the time when the truck is running? I'd like to be able to just wire up a shur-flo constant duty pump so that when the ignition circuit is on, the pump is on also. I'd wire in a cheap 10 minute delay so the engine would be warmer when the water started flowing.

I'd like to have a variable flow injection system, but I'm not sure how to do so cheaply, reliably, simply and safely. A rheostat on the throttle cable would be able to vay power to the pump as the motor opens up, but increasing and decreasing power to the pump doesn't necesarilly vary the water flow in proportion to the engine activity. Maybe some sort of motor or solenoid controlled valve would be able to vary water flow to match the engines activity.

It's either a variable draw injection system or else I'll cheap out and just go with a one flow fits all system.

Any other ideas?

I really think you are trying to over complicate things Welder. There are no real advantages I can think of to running the water all the time but it would seem to me there are a lot of drawbacks and Dangers. If you wired the injection to the ignition and someone turned it on for some reason without the engine running, you could fill a cylinder with water and do some serious damage. You could probably tap into a signal that would trip the water only when the engine was running but why bother?

If you set the WI up to just come on at a certain boost pressure or throttle setting, you will still have a clean engine and a simple, easy to set up system.

I guess I was just trying to get the water flow into the air intake to follow the increase and decrease of normal engine RPM fluctuations. Can one water flow rate effectively do its job over a wide range of RPMs? There's a big difference between 7.3 litres of displacement at 1000 RPM versus 2500 RPM.

Perhaps it's not very important that water flow rate follow engine RPM. I just didn't want to have a single flow rate system that is excessive while at low RPM while also being inadequate at higher RPM.

I'm sure someone will come up with a cheap, effective solution. Then again, maybe there's no significant problem.

I'm with welder, I'd like all the time accept idle. My van does not have inter-cooler. I was hoping for a little performance plus milage & safer temps for any big towing. Throttle position should be a good place for signal.(now, just a way to figure out & reglate flow)
Or better yet, a boost signal for turning on & off. That way when engine not running, no signal or danger of pumping.

I forgot to ask, What is meth? methanol alcohol? Is it cheap & I thought it was semi -dangerous when handling, & storage of highly flamable juice. Also if it is this, isn't the flame produced almost invisable?

If I could figure out how to get the thing to come on at about 1000 or 1200 RPM I'd be happy. That way, it wouldn't pump water while idling.

Since SVO kit companies have a little warning device called a "forgot-to-purge buzzer", I can't help but think the same thing might help with water injection systems. Start driving and after a decent warm up, turn on the water injection pump. When shutting down, shut off the pump. If I forgot to shut the water pump off for parking, the buzzer would remind me so I don't fill a cylinder with water like DCS warned me about.

Sound sensible?

I also couldn't help wondering if it would make any sense to have some sort of power switch wired up to the water pump circuit, so that by reading a power sensor that monitors alternator output, the water pump could be left on always. When the alternator is putting out power, the pump circuit is energised. When the alternator is dormant, the pump circuit is broken. Of course, I'd have a second switch under the dashboard so I could shut off the water pump if I wanted to (like when there's no water in the injection tank). A system like this would likely eliminate the need for a pump-left-on warning buzzer.

I wish Tim Cook, Dana, Johno or Crossbones would come in and offer some advice on how to best control the water pump. I've got a guy at work who seems to know everything, but he's not a forum member. I'll have to run the scenario past him on monday and see what he can add.

Does anyone know why there isn't rust formed in the combustion chambers when the engines shut down with water mist in the cylinders? I mean, I know the water gets vapourized and exhaused after combustion, but unless I shut the water pump off before the engine, there should still be a little mist sucked into the engine and left to rust right?

The rusting might not happen overnight, but over a weekend, or while going away for a week long holiday on a jet the engine might suffer some significant corrosion.

I know that water and oil don't like to mix much, so I can see how a coating of oil can protect ferrous metals fron rusting, but why wouldn't the oil be burned away just like water gets steamed away?

Remember that at shutdown, there will be some partially compressed cylinders with water in there with the air. They may have had the water and oil cooked off at the previous combustion event, but now they are post post air/water intake, but pre fuel injection and may not have enough oil residue present to protect against rust.

Knowing nothing about water injection systems, I'm assuming that people must shut off the water a few minutes before shutdown to cook off all injected water mist.

Am I being paranoid, or is it even an issue at all?

quote:

Originally posted by welder:
I wish Tim Cook, Dana, Johno or Crossbones would come in and offer some advice on how to best control the water pump.

So do I because they would tell you the same thing I am in that you are complicating something simple that will have no benifit or effect.

The reason the bores don't rust is because no one runs water all the time! This is where you are making problems that never existed before because no one ever did it this way for reasons exactly like this!!

With all respect, I strongly suggest you gentlemen leave your cars alone because your lack of understanding of the principals and practicalities involved and compulsion to go down the track of always having the water on is going to cause you to do some significant and expensive damage to your engines.

What you do is your choice but if you find yourselves walking, don't blame the water injection or say IT caused your engines to be damaged because the blame will lie a lot closer to home.

your mental picture is off. These dont run all the time. Most common arrangement would be with somethng like a brake light switch or a passing gear switch. If you put the pedal to the metal it contacts the spring loaded switch and the water blend gets sprayed into the intake. When you back your foot off the spring returns the switch to the off position. There is tons of other ways to do it from pedal, finger buttons etc.

For extra safey you can wire it thru a oil pressure activated switch (Hobbs switch) so that when engine drops below your desired oil pressure it can switch off any power from being able to get to the injection unit.

Im not an expert on Hobbs switches (hobs?) switches but you can search on them.

I will relay my experiences with water/water-alcohol injection on turbocharged gasoline engines over the years.

I used water injection ONLY as a detonation supressant so that in some instances, I could run the lowest octane fuel available at the pump.

While I water injected many turbocharged gasoline engines, the application that I learned the most from is one of my trucks with a turbocharged 454 that was used for hauling a trailer up and down the east coast.

This is what I found:

1) water indeed decarbonizes the combustion chamber and piston top.

2) water injection lowers exhaust temperatures. (100 degrees F on this particular application)

3) water injected ahead of the turbocharger will indeed cause compressor blade erosion, although in this particular case, very light. The turbocharger is still on the engine.

I see no reason to believe that on a diesel engine, the results would not be the same.

The final system I built used boost pressure to inject the water. Waterflow was pretty much proportional to boost and with a bleed orfice in the water tank, once boost was gone, the pressure leaked off within a few seconds and water stopped flowing. The system had no moving parts.

Sometime during the summer, I hope to install a water injection system on a '95 E350 van with a Powerstroke. I have made 4 trips back and forth to Florida (3000 miles each trip) with this vehicle on various blends of WVO in a non heated system.

I have several other vehicles on the blends as well, but so far have not encountered any problems that have forced me to tear into the engines to see what the insides look like. One of my Oldsmobile diesels is in need of head gaskets, but only had about 1000 miles on blends so I'm not expecting to find anything out of the ordinary as far as deposits are concerned.

DCS, this thread was actually started by Bork. I don't see why you are so insistant that trying to automate a water injection system is a bad idea.

The reason I wanted some input from those other members I mentioned is that they are knowledgeable AND constructive. You have given advice on other threads that was excellent and much appreciated. This thread isn't any different only I don't see what you have against somebody installing a auto controlled water system.

A PROPERLY designed automatic control system would eliminate forgeting to turn the water pump on or off. How is that useless?

Are automatic transmissions a waste of time too?

"The reason the bores don't rust is that no one runs water all the time!" An automatic water injection control system would be designed to reflect this fact.

Muleears, Bork and myself have all seen the advantage of some sort of automatic control system. Aardvark even added a litle advice on this topic.

The fact is that by having only manual control of a water injection system, a person might forget to shut it off and return to find a cylinder full of water, as you already warned about. Perhaps turning the pump on manually would be best, but I personally would want a fail safe system to be SURE I didn't accidently leave the pump on overnight or while at work.

You've already pointed out the danger of leaving the pump running while the engine is off. It appears you are arguing against yourself by suggesting that a control system is a waste of time and effort.

I don't have any real operating experiance with a water injection setup but have been reading about them for years. I don't recall anyone running a water spray full time, there are propane fumigation setups that DO run full-time, mainly to reduce diesel fuel use, but at todays propane prices I don't know if this is economical or not. The more expensive propane fumigation setups use a pressure controlable vapor regulator to adjust the amount of propane based on the boost pressure, more boost equils more propane. works for propane as it is a vapor when passing through the pressure regulator and these pressure-compinsated regulators are a standard industrial product. I have not researched to see if there is any sort of pressure controled liquid regulator available to veriably control water pressure. This is likely to be less effective with liquid water as you have to increase the input pressure 4 times to double the flow through a fixed spray nozzle orifice.

For progressive water injection setups I have read about use one pump to create the pressure but they use more than one spray nozzle, the seperate nozzles are turned on progressivly, as the boost pressure increases, by using a seperate solenoid valve for each spray nozzle.

From reading about water injection on diesel engines i'm still not sure just what is accomplished other than cylinder cleaning, I thought it was to reduce the exhaust temps under heavy load, but, as has been stated in other posts here, it apparently takes a LOT of water to effect the exhaust temps to any amount. One guy on another web discussion said he was pushing upwards of 10 G/H of water through his severly hopped-up ford before the exhaust temps dropped appreciably but the engine was not running as well as hoped with this much water.

If you are adding a large excess of fuel (smoking like hell under full throttle) I assume you are passing a lot of burning fuel past the exhaust valve, maybe not ?. the water steam is taking up room in the cylinder, the water vapor or fine spray went in "cool" and is flash converted to superheated steam in the cylinder, superheated steam still has to fit into the fixed size of the cylinder so the pressure has to increase, it would seem that the pressure in the cylinder has to be greater with water than without it, may be sort of like increasing the compression ratio without actually mechanically doing it, don't know.

Controls -- All the water injection setups I have read about inject the water when the engine is under load, either controled using a pressure switch that turns the water on above some amount of turbo boost pressure, or simpler, by a microswitch on the accelerator linkage someplace, boost is probably better as it insures the engine is being fed more fuel and the turbo is spooled up before adding the water.

Reading manufacturers web pages (several advertise systems on ebay, good referances) a shurflo type pump setup uses the pumps built-in pressure switch to control the spray pressure, not the best, as the pump will cycle on/off when spraying. From my own experiance there is usually a 40 pound pressure differance between the pumps internal on/off setting, this pressure change causes veriations in the fineness of the spray fog. this also causes the spray nozzle to shift from spraying to dribbling as the pressure drops to "0" when the pump is turned off completely. The more elaborate setups add a solenoid valve between the pump and the spray head, this valve eliminates the dribbling. They turn the pump on using the "ignition" power line from the vehicle key, through a "system armed" manual switch, this applies power to the pump so it makes output pressure against the solenoil valve and then the pump turns off from it's internal pressure switch, the actual spray is controled by opening the solenoid valve at the appropriate time based on throttle linkage position or boost pressure or whatever, this gives a cleaner spray as there is pressure at the instant the valve is opened and when the valve turns off the pressure drops very quickly to the spray head. From the posts in this discussion, from the folks actually testing this, it appears thet the concern about spray consistancy and dribbles may not actually be a problem with a diesel ?

Welder,

I think you are missing my point.
I am not against an automated system per se, I just have no idea why you would go to the trouble of making one when I cannot see what good it would do to have water spraying into the engine full time such as when it is under light load for instance.

I certainly don't think I know everything so maybe you could explain to me with reasonable detail, why you want to have a constant type WI system?
Specificaly I would like to learn what problems you think a full time system would fix or prevent that a normal on/off constant rate system dosent and what benifits it would provide to the engine to make it worthwhile.

I can't see any point to the sort of system you are suggesting but if you could explain to me what the practical advantages are that you see and would justify the trouble and expense of a variable rate system on a Diesel, I am always ready to learn and change my mind.

Look, I sincerely apologise if I came on like a jerk, it's just that I often carry a lot on my mind and although I'm very impressed water injection, I'm just concerned that one day I might accidently leave the thing on and come out of the grocery store to a find a couple cylinders full of water. Idiot-proofing the system would help me sleep better, that's all.

I understand that usually, nobody runs their water injection systems constantly while the vehicle is running. As I said before, having a manual start switch with an automatic off switch would be cheap insurance against disaster. Of course, the auto-off switch would only engage if the water pump was left on and the engine were shut off. Hopefully, I would remember to turn the water off at least 5 minutes from home and thereby allow the engine heat to thoroughly drive out any water residue. If not, the system would automatically shut off the water and sound a buzzer to remind me to re-start the engine for a few minutes to dry things out inside.

What really exites me about water injection is that I'm hoping that just maybe it will make single tank svo a more safe and trustworthy proposition. My big old 7.3 is an IDI so theoretically it's fairly tolerant, but for someone with a TDI diesel single tank svo vehicle, maybe a water injection system would be just the thing for steam cleaning any coked veggie residue left behind after those cold starts.

The reason I was thinking of a little more fulltime injection is; My van has no intercooler & thought I could get a few more ponies.(thus slight increase in milage?) This would be only if I went thru the trouble of putting one on for the questionable carbon build up. Thats why I posted the ? in the 1st place, to learn more & enlighten me. I know about the use on gassers but wasn't sure about diesel affects. This thread got much more response that I thought it would, But this is good for learning. Keep it coming.

In thinking more about water injection and what the guys that burn diesel use it for. I don't see any advantage using it at part throttle other than possibly for carbon cleaning. A small amount of water would likely cool the intake air charge (make it denser so more air fits in the same space), more air is input into the cylinder but this is errelevant at part throttle, as there is more than enough air even without the water to burn the part-throttler amount of fuel that is injected. Cooling the air to increase it's density MAY make sense with the throttle wide open, depends on how your fuel system is set up. My 92 Cummins does not smoke even at wide open throttle as the factory fuel settings are not injecting more fuel than can be burnt with the amount of air going into the cylinder, this is basically the same condition as at part throttle, so the only thing the water injection will likely be doing in my case is decarboning. If the vehicle is being overfueld, either due to no turbo or having been tweeked to increase the power, it will be smoking at full throttle because there is not enough air getting to the cylinder to completely burn the fuel, under these conditions the water injection should help a LOT by cooling the incoming air thus increasing it's density, now more air can be packed into the same spac so there is more air in the cylinder to burn more of the fuel. I think this is the reason some of the hop-up guys are injecting a LOT of water, more air burns more fuel means more power..

A water spray might cool the intake charge, but would displace air at the same time, decreaseing the O2 available to burn. It would be a race between denser charge/more O2 from the cooling effect and less dense/O2 from the displacement effect.
The quenching effect of water vapor in the cylinder can be dramatic. Again, this can be good or bad, depending on which effect you're looking at. Compressing water vapor raises the temperature at which it will turn back into liquid droplets, absorbing a bunch of heat in the process. This heat absorbtion helps prevent preignition in a gas engine, but has the potential of delaying diesel ignition, or slowing flame propagation. Those are bad. To a certain extent our diesel engines need heat, especially to efficiently burn slow fuels like SVO. Water can moderate the temperatures of some engine components. That would be good. Those conditions only happen during really hard use, not steady cruising. Over-cooling the charge during combustion might increase the amount of unburned fuel reaching the cylinder walls, leading to ring gumming. That would be bad.
I would conclude that I don't know enough about the effect of water injection to give a general "good" or "bad" opinion. It's an experiment, so it would only be a failure if we don't learn something. Survival of the engine may not be a requirement for that kind of success.
A simple control system would disable the water injection when the vehicle isn't moving. This brings to mind using the neutral safety switch to disable it. Also the parking brake. Maybe a sensor in the speedometer, if so equipped (my Mazda keeps the glow-plugs partially on below 20mph with just such a sensor, for example). As for water purging, I believe the water spray would only need to be turned off moments before shutting off the engine. There's no cool place for the water to condense while it's running.
This is an interesting thread.
Cheers,
JohnO

Good info Johno. I also had concerns about the side effect spin offs of the cooling effect that water spray injection might have in a diesel. That's why I thought about having the water heated by a heat exchanger.

I have no idea how much power is reclaimed by intercooling a turbo, but if it's not that huge, then perhaps pre-heating the intake air won't be such a bad idea after all.

As you say, compressing the water vapour changes how much heat it will absorb, but if it's already hot, then it might not matter so much.

Advancing the injection timing by 2 or 3 degrees, running lean on the fuel supply and preheating incoming air might just add enough to the usual single tank svo mods to provide a very clean burning, single fuel svo system.

By pre-heating the water injection system also, the flame front cooling effect of water injection may be negated enough that regularly steam cleaning the carbon and gum coking out of the combustion area just might make single tank svo systems more of a mainstream proposition.

Many people who go svo would like to go single tank, but choose a two tank approach for reliable longevity. Steam cleaning any deposits away may change that.

I'll have to check with a guy that makes chip programs & see if he's ever done any water injection systems & was able to make changes to timing/injection peramiters thus affecting efficiency that normally would not be obtainable without water. Inter coolers do make a difference, other wise factory would not go thru the trouble & expense.The turbo raises temps. A buddy that rebuilds turbos, has a lot of specs reguarding temps. I have a scan guage which shows intake temp right before filter. ON a 75degree day, on highway, it will read 75, but at idle, engine heat rising must get sucked in & temp goes over 100. At idle it is OK(no wet stacking)

I was talking to a member of another mercedes forum who uses this kit: http://www.alcohol-injection.com/bas...n-kit-p-8.html He doesn't burn WVO but has had good results with the WI. Is this the type of system you guys are talking about?