Symptoms of too much Water Injection

[TurboGTi]

I'm just wondering what are the symptoms of too much water injection.

Also what are the limits of water injection, can too much be injected?

suppose i increase timing on my engine and the boost to an absurd level and run two 1.0mm jets ... What are the consequences?


I know it is a strange question but what i really want to know is what is the most intense water injection Set up that you have or have come accross?

[SaabTuner]

NACA ran a WI with just water rate of 1/2 lb for every lb of fuel all the way to 10:1 A/F ratios or so. That's a pretty good amount of water.

Most modern cars have ignition systems designed with the exact voltage required to ignite the mixture in mind. So if you make it too hard to ignite the ECU has trouble. Also the NACA engine was 7:1 compression, higher compression engines will be even harder to ignite. Theoretically I'm not sure what the limit is. Diesels often run more water than fuel.

I guess the limit is wherever you end up when you can't get any more power by adding more, no matter how you tune/upgrade, and I'm not sure that point has been reached.

Adrian~

[TurboGTi]

hmmm good point adrain.

Well the reason i was asking is that i would want to run a twin jet setup with more boost .... but the catch is i would want one jet to run at 8 psi and the other jet to start at say 15 psi ......
... i belive that the only way to do this is to use a 2D system from aquamist, with the HSV used as the secondary jet ...

.. Do you think this is possible. :?:

[Slump]

This is a dyno of my car.

The blue line is "too much water", and the red line is a more correct amount of water.

The only difference between the two dyno runs is the adjustment of the quantity of water injected using the Aquamist MF2 controller (part of the System 2S).

http://cobweb.ibsys.com/~smith/miataweb/tuning/dyno2.gif

[Gelf]

This is a dyno of my car.

The blue line is "too much water", and the red line is a more correct amount of water.

The only difference between the two dyno runs is the adjustment of the quantity of water injected using the Aquamist MF2 controller (part of the System 2S).

http://cobweb.ibsys.com/~smith/miataweb/tuning/dyno2.gif

Do you mean you changed jets or reduced the amount with the same jet ?

If you changed jets, which size did your change from and too ?

[TurboGTi]

Hmm nice post Slump, it s almost like your engine was drowning in water,
That a big jump in power bny just proper tuning.

I don't like how the power curve gets a bit jagged at the higer RPMs like from 5500 RPM onwards ..

Are you running a high timing advance on your engine? or maybe too little water injection at that point... Also are you injecting pure water or are you mixing ......

I noticed a big difference when i used a 0.9mm jet versus the .5mm jet on my set up. The engine wouldn't bog as much and it didn't feel strong enuff.

I'll be dynoing sometime this month so i'll be checking my water injection system to see my gains ..

[PuntoRex]

Dyno is surely good, but too much water can be easily felt.

I'd used 1S system for a couple of years, in some cold winter days, the "summer jet" could be felt obiously. Engine output was clearly softened & faded. Swapped to a smaller jet immediately livened it up.

The other example is once the manifold pressure switch failed, the water was continuously injected (in a rush hour traffic jam) until I could find a place to pull over & unplugged the fuse. I barely managed to do that because when low rpm/off boost/idle, full flow of 0.7mm jet really made the engine stumble. I could only kangarooed along weakly. By this, the water for a whole week was injected within several minutes.

Fortunately there's no permanent damage.

[Richard L]

Dyno is surely good, but too much water can be easily felt.

I'd used 1S system for a couple of years, in some cold winter days, the "summer jet" could be felt obiously. Engine output was clearly softened & faded. Swapped to a smaller jet immediately livened it up.

The other example is once the manifold pressure switch failed, the water was continuously injected (in a rush hour traffic jam) until I could find a place to pull over & unplugged the fuse. I barely managed to do that because when low rpm/off boost/idle, full flow of 0.7mm jet really made the engine stumble. I could only kangarooed along weakly. By this, the water for a whole week was injected within several minutes.

Fortunately there's no permanent damage.


Interestingly, we have a few nervious users putting two pressure switches in parallel (806-157) electrically. Being normaly closed switching configuration, both of the switch has to be open-circuited in order for the WI to activate.

[PuntoRex]

That seems overkill.

Anyway, now I'm running on 2D, so the pressure SW failure would not be so dramatic. :smile:

[Richard L]

Hmm nice post Slump, it s almost like your engine was drowning in water,
That a big jump in power bny just proper tuning.

I don't like how the power curve gets a bit jagged at the higer RPMs like from 5500 RPM onwards ..

Are you running a high timing advance on your engine? or maybe too little water injection at that point... Also are you injecting pure water or are you mixing ......

I noticed a big difference when i used a 0.9mm jet versus the .5mm jet on my set up. The engine wouldn't bog as much and it didn't feel strong enuff.

I'll be dynoing sometime this month so i'll be checking my water injection system to see my gains ..

I think the limiting factor of "over water" is governed by the ignition system. On diesel engine, I have injected 600% !!! of water top fuel and the engine carrieds on running, not very nicely though - it was like a steam engine watching the exhaust puffing out white smoke (steam)

[JohnA]

This is a dyno of my car.

The blue line is "too much water", and the red line is a more correct amount of water.

The only difference between the two dyno runs is the adjustment of the quantity of water injected using the Aquamist MF2 controller (part of the System 2S).

http://cobweb.ibsys.com/~smith/miataweb/tuning/dyno2.gif

Interestingly, the blue 'drowning' run also appears to be much richer in fuel.
Did the extra water fool the oxygen sensor, or did you also change the fuelling as well?

[Richard L]

This is a dyno of my car.

The blue line is "too much water", and the red line is a more correct amount of water.

The only difference between the two dyno runs is the adjustment of the quantity of water injected using the Aquamist MF2 controller (part of the System 2S).

http://cobweb.ibsys.com/~smith/miataweb/tuning/dyno2.gif


What jet size were you using for this chart?

[Richard L]

This is a dyno of my car.

The blue line is "too much water", and the red line is a more correct amount of water.

The only difference between the two dyno runs is the adjustment of the quantity of water injected using the Aquamist MF2 controller (part of the System 2S).

http://cobweb.ibsys.com/~smith/miataweb/tuning/dyno2.gif

Interestingly, the blue 'drowning' run also appears to be much richer in fuel.
Did the extra water fool the oxygen sensor, or did you also change the fuelling as well?

I am also interested...

[Gelf]

Yes, we need info on the effects of WI on the oxygen sensor :!:

[DuMaurier 7]

You can feel the effects of over injection and if you have an exhaust tem. gauge you'll see it there too . I've meen over injecting for a little while , my exhaust temps moved from 1400 deg. F to 1000 deg.F , there was also a slight reduction in the "harsheness " of the car 's power.
My a/f ratios were also fairly rich 10-10.5 : 1 without any ignition breakup or bogging ! , Thats because I have an MSD 6 A on each of my leading plugs. :!:

[hamton]

I want to start WI for my car, but I noticed in the dyno below, a user that used WI, he lost power from 3500RPM and higher. Under 3500 RPM there is a huge gain. Is this the result of too much water or the ECU being too sensitive? Now he has other mods along with a custom tune.

http://forums.swedespeed.com/zerothread?id=42148

Info about the car at the time.
2005 Volvo S40 T5 with custom catback exhaust. At stock, the car produces 218HP / 236 ft-lbs torque. The 2.5liter inline 5 engine uses a small low pressure turbo that produces a max of 10psi.

In the forum he specifies he was using an aquamist is 1S system. triggered 0.5 bar. 0.6mm injector.

I have basicly the same car with a few other mods: BSR Stage 1, K&N, EuroSport catback. The BSR raises the psi to 15 and I'm guessing more fuel delivery. I was planning on using Aquamist 1s with .5mm injector and 100% distilled water but after seeing this, I'm a little discouraged. BSR does not do custom programming. I'm just curious if the same power loss will happen to me.

[hotrod]

The Buick GN folks frequently would tune by "feel" and discribe the effect of too much water injection as the car begins to "feel soggy". The throttle response gets softer, and it just feels a bit sluggish.

In that dyno plot I suspect what you are seeing is the result of improved air density at lower rpms. The cooling effect due to evaporation would likely increase your VE significantly especially in the lower rpm ranges where the mixture spends enough time in the manifold for some evaporation to take place. WI tends to slow down the burn speed slightly so it in effect would retard the ignition timing slightly. At low rpm that is not too big a deal but the combination of excess cooling lowering cylinder pressures at high rpm and not enough ignition timing would effect top end more I suspect.

If he could lean out his fuel mixture at high rpm he would probably get his power back for two reasons. Combustion temperatures would increase due to the leaner mixtures and he would get a slightly faster burn.

What the Buick GN guys would do is keep increasing injection rate until they felt that soggy feeling in the engine response, then they would lean it out, add boost or increase timing advance until they started to see signs of detonation or the car slowed down. Then repeat the cycle until the car no longer gets quicker.

Each car is unique in its needs so you can only extend someone elses dyno experience in a general way. Just give the car what it wants. If you make small incremental changes and monitor how the car responds it will tell you what it likes.

Larry