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  #21  
Old 12-02-2010, 12:22 PM
RICE RACING RICE RACING is offline
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Default Re: Injecting water into a rich a/f mixture is not a good id

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Originally Posted by Richard L
Not so long ago, a user of our WI system has lost some 40+ WRHP during a dyno tuning session, not surprise to know that he was quite disappointed. Only after a few months later and have discovered that his engine is tuned to run an a/f ratio of around 10.5:1.

I would really like to hear from anyone if they have suffered the same experience?
Great thread Richard !

I have seen this in my own current car, but I put it down to non audible misfires. When I have had a super strong ignition system on various other cars I have done I have not seen losses in that magnitude but they def do exist.
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  #22  
Old 12-02-2010, 11:19 PM
Richard L Richard L is offline
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Spark power has a great deal to do with how much fuel and water cam jam into the comnustion chamber. Too much fuel produce partial oxidation of carbon. Carbon monoxide only produces a 1/3 power of Carbon dioxide.
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  #23  
Old 20-07-2010, 12:35 PM
stevebez stevebez is offline
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Default Re: Injecting water into a rich a/f mixture is not a good idea

I have a slight problem with my pending install - and after reading this it seems I may struggle to get success without a retune ....

Basically the car runs very rich (sub 11:1) - typically because its oversafe position and also for IAT cooling... motor has a hoplessly small I/C which cannot cope and ECU pulls timing once IAT's reach 60C, and starts to pile in fuel from there on up ... at 90C the blower shuts down...

I am curious how the ECU map is configured for lower IAT's in terms of AFR's/fuel flow ... so guess I will only know this once the system is up and running...
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  #24  
Old 20-07-2010, 02:47 PM
Howerton Engineering Howerton Engineering is offline
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Default Re: Injecting water into a rich a/f mixture is not a good idea

There are few variables in the equation. Where is the IAT sensor in the inlet track. Will you be injecting before it so it is wetted? If so, you will just need to lean the fuel maps for whatever mixture you are sparying to bring the AFR's back to a reasonable level. If you have a rough idea of the heat compensation curve for your car(how much timing it pulls at what temp thresholds) you will get an idea of what can be gained even without changing the timing maps.

If practice, the right amount of methanol sprayed in the inlet track will provide substantial cooling. This is the type of application where I really like using methanol, as it will flash off and cool better. Straight water will not cool (according to the sensor ) as well as methanol. Each application is always a bit different so it will take a testing to find what works for you.
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  #25  
Old 22-07-2010, 03:08 PM
stevebez stevebez is offline
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Default Re: Injecting water into a rich a/f mixture is not a good idea

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Originally Posted by Howerton Engineering View Post
Where is the IAT sensor in the inlet track. Will you be injecting before it so it is wetted? If so, you will just need to lean the fuel maps for whatever mixture you are sparying to bring the AFR's back to a reasonable level.
Can you elborate on this a bit ... why would a wet bulb read lead to more rich conditions? all else equal. The IAT and MAP are a few inches from the I/C exit. The intercooler is a long narrow water/air type.

Either jet location option will result in a wet bulb read.
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  #26  
Old 22-07-2010, 03:22 PM
Howerton Engineering Howerton Engineering is offline
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Default Re: Injecting water into a rich a/f mixture is not a good idea

Some people spray after the sensor to avoid "tricking" the ECU. I see it as a tool, that when used right works well without tuning of the ECU. Some cars like the STI, run on a MAF with built in IAT before the turbo so in that case, no cooling effect is transmitted to the ECU.

May comment was to say that is you use methanol to cool the IAT sensor, more so than water will, that methanol is fuel and if the car is already at an optimum AFR the methanol will move the motor to a richer mixture.
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  #27  
Old 11-06-2011, 02:51 AM
dsmtuned dsmtuned is offline
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Default Re: Injecting water into a rich a/f mixture is not a good idea

Quote:
Originally Posted by Richard L View Post
Not so long ago, a user of our WI system has lost some 40+ WRHP during a dyno tuning session, not surprise to know that he was quite disappointed. Only after a few months later and have discovered that his engine is tuned to run an a/f ratio of around 10.5:1.

I would really like to hear from anyone if they have suffered the same experience?
I thought I would dig this thread up from the grave after experiencing this phenomenon on the dyno last week.

My turbo DSM made about 15AWHP more without WI on the dyno. This was on 91 octane pump gas. I am new to the tuning software ECMLink and had a base tune with 11.1:1 AFR as the target in the WOT load maps for safety while I was getting used to the software. The timing was very aggressive at 21* near the top of the RPM range. The boost was set to 22psi with about 35lbs/min. The WI mixture consisted of 50% methanol and 50% distilled water. Since I have the time now, I went to the dyno to get a baseline so I have something to compare with when I get the car really well tuned.

I attached a dyno plot of all 4 runs for reference, although it is a little hard to decipher the individual runs. I really wanted some WI data, so the 1st run (002) was without WI. It was also a calibration run, so the data is not totally pertinent. There was obvious knock with the ECU taking 3.2* of timing away due to knock.

The 2nd run (003) was with my second nozzle only (larger nozzle). This run made about 288WHP. There was no knock, but the AFR went down to 10.8:1 on my log and even lower than the dyno wideband O2 sensor would read. This run maintained the power further into the RPM range because of knock control.

The 3rd run (004) was with both nozzles (WI at ~15% of total fuel injected). This run had the lowest HP (~282WHP) and lowest TQ. It, of course, also had the richest AFR at about 10.5:1 on my wideband. There was no knock, but power was not maintained into redline, I think, because the mixture was just too rich.

The 4th run (005) was again with no WI and made the most power at 295.8WHP. This one knocked like crazy (ECU took 6* of timing away), causing the power to peak and then drop off quickly.

I know this engine can handle a lean AFR with the WI. My previous tuning method was an air-flow converter, which modified the airflow signal from the MAS throughout the RPM range. I had a custom burned chip, which defined the timing and fuel tables in the ECU, but I fine tuned the AFR and timing with the air-flow converter. It was a constant trade-off, timing vs AFR. I found a sweet spot and ran a 12.8@109 in the quarter mile at about 12.9:1 AFR and 20* of timing on 91 octane gas and the 2 nozzle WI set-up with water/methanol 50/50. So I know with the proper tuning (leaning of the AFR), I can get an even better quarter mile time, and dyno.

So what I learned from this is that there IS such thing as too rich a mixture for WI.

-Craig

Last edited by dsmtuned; 23-04-2019 at 03:48 AM.
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