A couple of questions about water injection.

[phord]

I read somewhere that best place for water/methanol injection will be through egr tube?(when leaning out the mixture)
Would water injection cause oil dillution?
Do I have to install a wideband oxygen censor on fuel injected engine when tuning for leaner mixtures? Do I need an egt gage and manually control methanol/water flow?

[Andyman]

I don't agree that the EGR tube is a good place for a water injector. I don't think there is enough air flow there. The EGR usually doesn't work at all near full throttle.

Water injection could dilute the oil with some water. To prevent that, you could turn it off when the engine or the intake air is cold. It might help to heat the water before it gets to the water injector. Also, the system should put a reasonable limit on the water flow. I think I've read that the water flow rate should be about 5% of the fuel flow rate when the water injection is working. That way you would use a maximum of one gallon of water when you use 20 gallons of gasoline.

I don't think you have to get a wideband oxygen sensor to run a lean mixture. If you use one, it might help you to figure out what your fuel mixture is while you drive. You would have a voltmeter monitoring its voltage mounted so you could see it while you drive.

If you lower the voltage of the MAP (manifold absolute pressure) sensor signal with some electronics between the MAP sensor and the ECU (computer) you will lean out the mixture. It would be a good idea to switch off any lean mixture during high load conditions so you don't overheat the pistons or lose engine power. The check engine light will probably go on if you lean out the mixture unless you also send a different voltage signal from the coolant temperature sensor to indicate to the computer that the engine is cold even when it is really warm. Some fuel injection systems use an air flow sensor instead of a MAP sensor so the modifications would be different.

I don't know any reason why you would need an EGT (exhaust gas temperature) gauge. I suppose the amount of water injection will affect the exhaust temperature. I don't know much about that. I just know that a low exhaust temperature is an indicator of high efficiency.

I don't think you should have manual control of the water flow rate. It would be too much of a distraction while driving. The control system should control the flow rate according to the speed and load of the engine. I guess it could be as simple as a relay connected to a tachometer circuit and a vacuum switch. The water injection could turn on whenever the engine speed and load exceed a certain level. It would be much better to have a variable water flow rate.

[naturalextraction]

Unless you have an externally driven atmosphere acquisition and compression system (yea, probably didn't need to say that), ie; turbo, belt driven supercharger and want to use water as an anti-detonate, it will not provide any mileage or combustion efficiency benefits. Yes it may clean up your exhausting gases to some degree, but can absorb a significant amount of the heat energy your engine needs in making the conversion to mechanical energy through the force on the piston that transfers that motion/energy to your crank. In effect making the transfer of chemically derived heat energy, in this case, less efficient. It will clean your piston tops nicely however. Also if not metered correctly, and granted it would take a lot of water, some have hydra-locked their engines (with ill advised/lacking appropriate information) with attempts at water injection. Make sure that what you hear or are reading regarding W.I. is from credible, tried and tested sources, preferably entities with real backing, labs, accredited authors etc. If your engine is naturally aspirated with F.I. or with old school carburetor (analog A/F metering device) then water injection is not for your power plant.

[Andyman]

According to an article in the Mother Earth News, water injection is also useful with a normally aspirated high compression engine. You can read the story here:

WATER INJECTION WIZARDRY

[naturalextraction]

Hi Andman, first that article was from 1979. Meaning that todays E.F.I. systems allow and control the I.C.E. to run at optimal performance levels without detonation. Basic E.F.I. system out perform any Analog carburetor unit from those days for sure.
In high static compression engines, which is different from dynamic compression ratios (incorporating actual ratios from atmospheric conditions, elevation etc.) detonation was more prominent before E.F.I. systems were introduced. Whereby reducing ignition timing was necessary or utilizing high octane fuels to compensate. Water injection on naturally aspirated, high compression (11:1 or better in an I.C.E), especially at sea level, could benefit, again primarily in power, by keeping timing advance on loweroctane fuel. This was utilized on drag strips all over the country. Cars in the day utilizing water injection in Bakersfield didn't racing in Denver.
Also understanding the basics to the thermal dynamic transfer of heat energy and heat absorbed by the water in an Isochoric (constant volume as in I.C.E.) or as in Isobaric (higher compression like diesels) efficiencies drop unless the volumetric efficiency of the chamber is brought up by external influences. The details to all of this has been written in volumes from many bonified research institutes and from credible private sector sources for many years now. Again the source of the information is critical before accepting it's content.
Second, as I said above, unless there is credible referencing to the story ie: well defined testing methods, third party referencing to the testing and methodology, it resides in the phenomenon of pseudoscience. Which in most cases is having only some of the information.
This is a big issue amongst scientist and engineers. Here you can understand it's cause and effect from the experience of others. There are many well thought out comments here:
CR4 - Thread: Curbing the Spread of Pseudoscience
Also the fact that he claims 20-25% gains in mileage, and that would depend on the methodology in how he made that determination, could be attributed to many, many other factors, especially with that type of induction, timing and ignition system. Just my thoughts. This thread posted here in Ecomodder alone provides some good suggestions for testing mileage: http://ecomodder.com/forum/showthrea...ery-11445.html

[NiHaoMike]

I remember reading that water injection can allow for leaner mixtures, which can increase fuel economy.

[naturalextraction]

Reading where, from what? What tests were they running? If you absorb heat energy that is needed to push your piston, how can you run less fuel and maintain usable power? You have whats called a drive-ability problem. Power drops immensely. Again with out expanding heat from the chemical energy, there is NO mechanical conversion of power/the expending energy called heat. Plain and Simple. The thought with water is still for anti-detonation. Leaner conditions can and will create pre-detonation. Especially with older analog systems, with water you CAN run leaner conditions by absorbing excess latent heat. (valves, piston tops, any carbon spot retaining heat) But you will have POOR performance at best. (and by poor, I mean hardly usable) Running 18:1 or leaner, without a turbo or any other forced air system, the results will be really poor power especially depending on the displacement and method of fuel delivery (management).