[hotrod]

Is it possible to have a picture about how he install the whole thing?
I guess it'd be pretty similar to Richard's proposal above.

I've never seen the installation but it is explained in some detail in another forum : (posts are about 2 years old)

http://www.eng-tips.com/viewthread.cfm?qid=72284

Look for the posts made by " turbododge " --- I haven't figured out a way to invite this guy over here yet, as I don't see any sort of a private messaging system on the eng-tips forum --- maybe I'm missing something, but I would like to see him join this thread if he happens to browse this forum under a different username.


================== quick summary of his key posts ======

turbododge (Automotive)
30 Oct 03 19:51
I just got referred to this thread by a friend and being a long time user of water injection thought you all may be interested in what I have personally seen over the years. I run a twin turbo, now EFI (was carb), twin turbo 340 Mopar in a 70 Cahllenger, strictly street, 14 psi boost, intercooled.

I use an old Edelbrock Varijection system that has been altered for instant on under boost conditions at 7 psi. It varies the amount of water based on rpm and absolute manifold pressure. It does not have adequate pressure to spray directly into a pressurized intake manifold, so I spray directly on the turbine blades. The turbos are lower than the inlet ducting to the throttle body, so even if I have a valve failure, I cannot water slug the engine. I have run this system for over 15 years on carbed and EFI turbo engines, and would not go without water injection. I can run 8 to 1 compression at 14 psi on 92 octane all day without worrying about detonation.

I find the talk about atomization, hummidty, where the water evaporates, etc to be very interesting, as I have watched my system extensively over the years. When I spray on the turbine blades, the water (with 50% isopropyl) vaporizes instantly, before it even touches the blades. I have 50K mile turbos that show no erosion at all, and even the intercooler does not get any significant amount of moisture in it. The ductwork all stays dry. The low pressure area at the turbine inlet easliy evaporates the water spray. I found no difference with EFI or blow thru carb in this respect.

When I was running a suck through carb setup, I was spraying directly into the carb throat with the water, and found that the carb venturi would vaporize the water right along with the fuel from the venturi. Subsequent running through the turbo also further atomized both elements. All was good unless the inlet ducting was cold enough to condense out the fuel and slug the engine.

In an N/A engine, you would spray straight into the carb with most systems like a Spearco. An Aquamist you could go into the manifold below the carb as they atomize better, but most folks don't do that. Unless you are dumping very large amounts of water into the carb, it will atomize, if it did not, it would build up in the intake and give a big slug to the engine when you turned, etc, and probably thermal shock or hydraulic the engine to distruction. I think it would be a very risky business to try to get, or count on getting unvaporized water into the cylinder.

As far as the power is concerned. As I mentioned before, my setup is instant on, off a pressure switch, or an override switch in the cockpit. I have done lots of testing at boost levels to 12 psi (max without detonation without water) with the water on and off. I give people rides and turn the water on and off, then off and on to see if they can feel the accelleration rate change. I can tell you that no one has ever not been able to tell that the water came on and the accelleration rate increased. It is very significant. I would be surprised, however, if you would be able to readily feel the difference in an N/A engine, as when I turn the water on and off while holding the boost down with the throttle, I cannot feel a difference at all, in my low compression engine.

My net conclusion is that on a boosted car above 10 psi, water injection is necessary if you want to be able to run decent compression, timing, and mixtures, plus you will get more power do to charge cooling, even if you are intercooled. On an N/A car, I would use water only if you need it to kill detonation because of high compression, bad gas, etc. I don't believe it would give you enough more power to notice.

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turbododge (Automotive)
31 Oct 03 0:18
Turboice: You are absolutely correct in that one big factor with water injection is killing the detonation to allow you optimize other conditions. It is very common in the turbo crowd to try to drown the detonation with extra fuel, even down to 10 to 1 A/F. All it does is cost power and give minimal results. The is a very good chart in the Hugh MacInnis book Turbochargers on the affects of water on detonation, boost level and air fuel ratio. One look at the chart and you can become a water booster for life.

Concerning the non erosion of my blades, it may have to do with the fact that my water only comes on when I really need it, so it is on a very small % of the time, but I am also very carefull to send the nozzle stream (it is not atomized) at the CENTER of the compressor shaft so that any impact is on a slower speed, less critical area, and the water flow moves out the blade rather than impacting it. Also, with Varijection, there is less water at lower rpms and boost levels and more at higher speeds and boost. A single output volume, set to deliver enough water at full load, like a Spearco, can easily overwhelm a turbo spinning at lower rpm and impact the blades harder. With the EFI controlling spark and A/F (12.5 A/F under boost)and careful tuning of the water we normally will only use a gallon of water per 1 to 2K miles of street driving, as we are good to 10 psi very safely without any water, (and 12 if the gas is good). So putting is enough water to get to 14 psi is pretty easy.

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turbododge (Automotive)
31 Oct 03 12:40

...

The erosion of the blades discussion is very interesting, and may apply to others differently than me. I am running plain old T04, oil cooled turbos, and have been for many years. The newer turbos with the aforementioned lighter blades and perhaps more brittle alloys may be more of a problem. With those I have no experience. There was a post that mentioned someone who had a friend who did get blade erosion (post probably gotted whacked because it referenced another site). Was this person, by any chance, running a water/methanol mix in his system? From what I have seen and heard, methanol will take out turbine blades, throttle body plates and bearings, and can even corrode the tips of fuel injectors enough to cause pattern problems. That is why I use Isopropyl in mine.

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In thread http://www.eng-tips.com/viewthread.cfm?qid=82878


turbododge (Automotive)
5 Jan 04 18:51
I have been injecting water/isopropyl alcohol on the turbine blades of my twin turbo 340 Mopar for 15 years now. This kind of system was very popular in the past, as it was much more difficult then to inject into the boost stream because of the high pressure. The blade erosion issue has always come up in discussion, but the only ones I have seen that had problems were either on stationary units that ran the injection constantly, instead of only under boost like in a street car, or if they used methanol in the injected liquid. Methanol is much more corrosive than isopropyl. My turbos have over 40K miles on them with no signs of erosion at all. I use about 1 gallon of water/isopropyl mix per 1000 miles. My system is also variable with speed and boost, so I don't overload the airstream with too much liquid at any time. It also atomizes better if you aim a single spray nozzle directly at the shaft of the turbine, the liquid usually is totally vaporized by the time it is 1/4" from the nut on my setup.

I can run with or without the water very easily, and if I am holding a boost level and turn on the water, you feel a very positive increase in accelleration. I am also running an intercooler, so this is beyond the intercooling affects.

If you do a good job of setting up the system, I would not be afraid to inject ahead of the turbo, as I have seen very good results that way.


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turbododge (Automotive)
7 Jan 04 0:01
Yes definitely on the compressor wheel, poor phraseology on my part.

I am not up on the viscosity/vapor pressure etc with methanol vs isopropyl, but I know I have seen methanol systems corrode the compressor wheel, but never an isopropyl setup do the same. Downstream corrosion is even more of a problem with with methanol, and I have even seen corroded throttle shafts stick in the carb base. Intercoolers will also sometimes condense out a small amount of water or alcohol in cold weather and the methanol will also go work on the intercooler. I would guess that the compressor gets wet enough with the methanol someplace along the line, either at cold start, cold idle or such. The corrosion I have seen covered more of the depth of the blade than impingement damage which tended to be very close to the entrance edges of the blades.

The other thing that goes with this is that all the other systems that had problems with corrosion also were on/off, non variable, systems, which can heavily overload the compressor at low rpms, cool air conditions. I have literally seen liquid drip from the compressor housing hose connections after a run.

I am sure there are lots of folks that have successfully run methanol in their setups, but for me the isopropyl makes it much easier and more reliable, with very little downside.

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turbododge (Automotive)
7 Jan 04 20:36
Overrange: We drive the car a lot, but spend a very, very small percent of the time at throttle positions that would turn on the water. If we do a 500 mile "cruise" through the countryside, it is very possible that we will not use any water at all. My system does not come on until 8 psi of boost, (out of 14psi maximum),and since the system matches water flow to boost and rpm, water flow at that point is quite low. I can tell you that a 340 CID V8 will accellerate very quickly at 7 psi, and it is easy to stay within that range by controlling the throttle. To use the full 14 psi on the street requires a very good road in a remote area as the tires can go loose at any time, in any of the first 3 of 5 gears, depending on the traction. Even if the water does come on, it is only on for 10 or so seconds per use (maximum) before you are way over 100 mph. If I am testing and tuning, I have used a much as a quart in a day.

Although I did not mention it earlier, as the question I was addressing was the feasibility of injecting into the compressor, is that my system is not primarily used for inlet charge cooling, as I have an intercooler for that. My system is to allow me to run decent boost, without detonating, on 92 octane pump gas. Without the water I will get detonation at 10 to 12 psi, depending on the gas and weather conditions. It takes much less water to reduce detonation (as long as you have an intercooler to cool the air) than it does to cool the air enough to make power. That said, if I run up to 10 psi with the water turned off, and then turn it on, you can feel the car pull harder, so I am either gaining from cooling of the air further, or because of a better combustion process in the cyliders. I don't know what it is, but you sure can tell if the water is on or off.

The car also has a very good cold air system on it that takes air in through the boxed wheelwells that a fed from spoiler ducts, with only 6" of ducting before the turbos, after the large K & N filters.

===============

As you can see by the above he sprays a solid stream directly on the compressor shaft nut, and allows the spinning compressor nut to beat the stream into a microfine mist moving radially outward. His system is in my estimation an ideal case of wet compression as there is no time for the water mist to evaporatively cool the air stream before it arrives at the compressor, but it will modify the compression due to the high presence of water in the air flow.

I on the other hand needed to maximize the density increase due to air charge cooling pre-compressor to get the most out of my undersized turbo.


I might add that I am not too concerned with his observations about methanol corrosion as he was obviously talking about setups that grossly over injected fluid and kept the intake tract wet all the time. Any system like mine that only comes on intermittently at high air flow demands will quickly dry out any condensate in the intercooler etc. That is one of the reasons I turn my system off in cold weather. I don't need the detonation suppression when the weather is cold ( I don't run high boost when its snowy and icy out ).

Perhaps a little of both would be best one very small spray jet well back from the compressor with some sort of a dropplet trap to keep any but smallest dropplets from passing into the compressor, and a hub injection setup to get the advantages of wet compression.

The other obvious question is are some of us willing to consider the turbo compressor a wear part and to plan on replacing it on a regular basis? I know many of the hard core performance nuts upgrade turbos on a very frequent basis, and for them replacing a $40 compressor wheel (or what ever they cost) every 2 years would not be a big deal in exchange for the performance advantages. I'm sure the WRC folks or people that compete in similar levels of competition would have no problems at all with that sort of replacement cycle. Serious drag racers might go through several clutches, a couple rear ends and a motor or two every year. A little R&R on the turbo compressor is not that big a deal in the grand scheme of things.



Larry