Water Injection

Submitted: Saturday, Mar 22, 2008 at 19:14
ThreadID: 55812 Views:5399 Replies:5 FollowUps:6
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Really just an out of interest type question, but has anyone fitted a water injection system to their 4x4. Have found lots of examples of use in high boost scoobys etc to prevent knock running higher boost. I have read about claimed big advantages with a turbo diesel (lower combustion temps, more torque) but have never come across anyone in the real world that has done it... anyone?
cheers,
Gil
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Reply By: Member - Kiwi Kia - Saturday, Mar 22, 2008 at 20:16

Saturday, Mar 22, 2008 at 20:16
Sort of defeats the purpose of water filters/traps dosen't it ?
AnswerID: 294138

Follow Up By: Dion - Saturday, Mar 22, 2008 at 21:06

Saturday, Mar 22, 2008 at 21:06
Kiwi,
not really. Filters and water traps are for keeping water and moisture out of fuel injection systems, where it can cause lots of expensive damage to injection pumps and injectors.
The water injection being discussed here is injecting water into the inlet manifold, therefore the first time the fuel and water meet, is in the cylinder when both are atomised.

Cheers,
Dion.
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Reply By: obee - Saturday, Mar 22, 2008 at 20:25

Saturday, Mar 22, 2008 at 20:25
I am old enough to remember when water injection was promoted but it never took off much. I imagine the effect of a bit of water would increase compression substantially. When water turns steam it expands dramatically and this property is what made steam engines what they were. Very efficient in it's time. No more.

Fighter aircraft in World war two used water injection (at least some did) and I reckon it over came the difference in ambient atmospheric pressure whe they were stretching the ceiling. But fighter aircraft were not expected to survive long so any damage to the engines was not so relevant.

In an Automobile that is expected to go for years and sits in the garage for periods with residue of injected water sitting in the cylinders the scenario might be different. I dont know.

I would be interested to learn the history of water injection.

Owen
AnswerID: 294140

Follow Up By: gilghana - Saturday, Mar 22, 2008 at 21:31

Saturday, Mar 22, 2008 at 21:31
Fair bit of info here:
http://en.wikipedia.org/wiki/Water_injection_(engines)

The residual water I reckon would not be a problem - the system I am thinking about would only inject (before inlet manifold) according to boost, so as you park up there would be no water going into the cylinders, so I reckon there would be a minimal chance of things going rusty! From forum searches there is a little bit of feedback on WI, but not much and seems to be quite old? Whole concept is quite intriguing...

From Aquamist web site:


"Hello, I enjoyed reading your web page. I researched what the Army studies in the 70's on the subject ICE (In-cylinder Engine Cooling) cooling as found in your references. I have obtained copies of the reports.

In 1970, W.D. Weatherford, Jr. and R.D. Quillian presented to ASE a paper, Total Cooling of Piston Engines by Direct Water Injection (Trans. 700886). This study looked at performance of a spark-ignition engine and found that engine cooling can be achieved without adverse effects on combustion or engine performance by injecting water on the compression stroke. Also, NOx are reduced. BSFC was not significantly reduced.

In 1974, S.J. Lestz, R.B. Melton, Jr., and E.J. Rambie took the above authors' work further and reported similar conclusions in Feasibility of Cooling Diesel Engines by Introducing Water Into the Combustion Chamber (US Army Report 750129). Conclusions highlighted that the BSFC improved 5 - 20%. The best improvement was achieved by spraying water into the chamber during the compression stroke. NOx decreased and HC and CO tended to increase. Direct water injection was not recommended for ground mobile applications because full water recovery was not feasible above 100 deg. F. ambient temperature.

I was intrigued by the statements found in the paper about diesel. By injecting water into the cylinder late in the compression stroke, power was increased by 20.8% (with a corresponding reduction in BSFC). The exhaust had a gain of 17.5% in available energy due to generation of steam and coincidentally, a reduced temperature by several hundred degrees. Also, the indicator diagram shows higher pressure late in the power stroke. "

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Reply By: Member - David P (VIC) - Saturday, Mar 22, 2008 at 21:23

Saturday, Mar 22, 2008 at 21:23
Hi Gil, Old carby cars used to be able to gain a benefit some owners claimed, but the modern electronically controlled engines with all there sensors reporting to an ECU not to mention anti pollution equipment eg oxygen sensor....the time has long passed for fiddling beyond chipping the computer......the only way you could use water would be to arrange a spraying system on to the air to air turbo intercooler but is it worth the trouble?....silverback
AnswerID: 294147

Follow Up By: gilghana - Saturday, Mar 22, 2008 at 21:41

Saturday, Mar 22, 2008 at 21:41
Thanks David,
luckily my turbocharged 1HZ has no electronics beyond the fuel cut-off solenoid :-)

I do not as yet have an intercooler, and for sure a water spray system over the intercooler would drop charge temperatures (I used to have a WRX with such a set up). I am currently considering both intercooling and WI, so trying to get as much feedback as possible. What is interesting is that the WI would provide cooling when most needed (i.e. high boost) but on the other hand one of my concerns is that further torque would further stress engine components...
Gil
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FollowupID: 559955

Follow Up By: Member - David P (VIC) - Saturday, Mar 22, 2008 at 22:15

Saturday, Mar 22, 2008 at 22:15
Have you clicked on "technical" to the left ?....silverback
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Follow Up By: Stu & "Bob" - Sunday, Mar 23, 2008 at 11:32

Sunday, Mar 23, 2008 at 11:32
Thinking back, the F27 Fokker (as used by TAA) used to use water injection to boost power on takeoff, but was limited to a 30 second period only.
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FollowupID: 560007

Follow Up By: Member - David P (VIC) - Sunday, Mar 23, 2008 at 23:41

Sunday, Mar 23, 2008 at 23:41
Yea, I seem to remember a water/ethanol mix.....silverback
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FollowupID: 560117

Reply By: nickb - Sunday, Mar 23, 2008 at 22:13

Sunday, Mar 23, 2008 at 22:13
My old mechanic (he retired when EFI became common) used to pour a bit of water down the throat of carbies on older petrol cars whilst revving the engine. He reckons it used to clean excess carbon build up and make the engine run smoother. That may be another benefit of water injection.
AnswerID: 294296

Reply By: _gmd_pps - Monday, Mar 24, 2008 at 18:21

Monday, Mar 24, 2008 at 18:21
http://www.kennedydiesel.com/detail.cfm?ID=460

I have ordered mine .. just for fun ....
I get higher EGT when I run a +85 or +120 tune
or when I am fully loaded and tow the boat with a +40 tune
and put the foot down. Just want to see how much I can lower
the EGT. I do not intend to inject Methan (I am not a drag racer)
just the water component.

Will take a moment to build it in (still have lots of other things to add). I know a couple of US boys who have done it but they
mostly run Methan on the track which brings the Duramax to some 600+ horsepower (but only with transmission mods) ... on
a low volume engine its probably pretty much a waste, but I could be wrong.

have fun
gmd

AnswerID: 294460

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