Water Injection Questions???
07-29-2005, 09:21 AM
#1
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Water Injection Questions???
I think Rich (RKrause) may be able to help, but I'm just wondering how you tune for water/akly injection? Less fuel, less/more timing versus a safe non sprayed tune? How do you know what size nozzle(s) to use? And what mixture is decent to run? This is using a basic aquamist kit, spraying a low boost (6-8psi) vortech LT1. Knock is rare and if ever, and always low (1-3 degrees at most) if it does occur during the run but I'm not sure if I'm spraying too much or could be cooling the intake more. Just looking for alittle more specific info/guidelines tuning via LT-1_Edit. Any info, links or help is greatly appreciated.
07-31-2005, 12:11 AM
#2
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Re: Water Injection Questions???
I have wondered this also and have never seen a good answer to this question. I did a search on the web for water injection and found several good sites, but this one seemed the best. It is lengthy, but not difficult to read and follow.
http://www.aquamist.co.uk/info/docum...rinjection.htm
From what I understand you want:
1. 12.5/1 a/f ratio
2. 10-15% water to fuel
3. 50/50 water/alcohol mix
My car is at the tuner right now and I am going to get him to figure fuel volume used and then measure the output of my water/alcohol system to see if I am in that 10-15% range.
Happy reading. Tell me if I am wrong.
http://www.aquamist.co.uk/info/docum...rinjection.htm
From what I understand you want:
1. 12.5/1 a/f ratio
2. 10-15% water to fuel
3. 50/50 water/alcohol mix
My car is at the tuner right now and I am going to get him to figure fuel volume used and then measure the output of my water/alcohol system to see if I am in that 10-15% range.
Happy reading. Tell me if I am wrong.
Last edited by David94TA; 07-31-2005 at 02:40 PM.
08-01-2005, 04:28 PM
#4
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Re: Water Injection Questions???
You should adjust the AFR ratio using water alone because alcohol will change the wideband reading.
I started with less timing and only water. When the AFR is ok switch to 50% alcohol.
I started with less timing and only water. When the AFR is ok switch to 50% alcohol.
08-01-2005, 06:36 PM
#5
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Re: Water Injection Questions???
The wideband does not care what fuel you are using. It measures lambda. If you are tuning for 12.5 on gas that is lambda .85. If you run water injection with alcohol you will still tune for lambda .85 (12.5 with the meter calibrated to display for gasoline).
08-01-2005, 08:04 PM
#6
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Re: Water Injection Questions???
If you tune it for water, then it will run rich with 50/50. Also, straight Methanol works better than 50/50. You generally will cut out 15% fuel (as much as 50% and as little as 0%), then supplement with Methanol. Aim for 12.5/1 and you'll be fine.
Mike
Mike
08-01-2005, 09:47 PM
#7
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Re: Water Injection Questions???
A 50/50 mix works best. The AF ratio is read the same way. 12.5:1 is a good start but it isn't any kind of rule. You may get away a little leaner with the water/alky as you don't need as much excess fuel to cool the charge. You want to sneak up on it, start rich. Ditto with timing - start without much timing and advance it slowly. You also need to experiment with the amount of injection fluid. Add it until it slows down/makes less power and then back off.
Hope this helps.
Rich
Hope this helps.
Rich
08-01-2005, 10:03 PM
#8
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Re: Water Injection Questions???
Don't want to start a pissing contest, but this guy's done alot more testing than I have:
Originally Posted by RAZOR
Reason to not use straight alcohol with the aquamist setup is that it will kill their pump.
Design to blow straight alcohol, run mix and compare knock readings vs running straight. Every platform tested using a knock sensor has responded better with straight alcohol when the real squeeze has been done.
If the car runs 15 PSI cleanly.. all you want is 17 PSI.. straight water/mix will quench the detonation. The deal I get into is run 15 PSI cleanly and want to run 25 PSI cleanly.. thats when you get into 30-40% fuel replacement and get the job done. Some cars run upwards of 40-50% replacement and get away with murder on 93 octane.
Jerry's car here in Tampa runs 35 PSI on 93 octane. 1997 Mirage, 2700 lbs + driver, full interior car, on kumo 18 inch street radials, 1.8 60 foot, ran 6.60 @108 1/8 and a 10.4 at 132 off the rev limiter. His car with the aquamist setup fastest it ever went was an 11.3. Switching from mix to straight.. it immediately dropped him to 10.8. Bigger turbo, more boost + AEM.. 10.4's..
Leave ya with this, ECS shot straight alcohol through a MAF back in Sept last year.. kinda barbaric.. car picked up 15 HP 25 TQ zero changes. Doug has easy over 800+ Dyno pulls on an injection kit.. as you saw the link above.. proof is in the pudding. With any water/mix system, there is no power gain on a non detonating tuned engine unless something else is changed. Like timing or boost. With alcohol.. the forced induction car runs like winter in the summer.
As much as I've messed with mixes.. no way the same power can be had running straight VP M1 methanol.
So I have Buicks, DSM's, Vette's, Supra's.. run on stock computers, AEM's, FAST, BS3.. all with zero issues running straight methanol.
Design to blow straight alcohol, run mix and compare knock readings vs running straight. Every platform tested using a knock sensor has responded better with straight alcohol when the real squeeze has been done.
If the car runs 15 PSI cleanly.. all you want is 17 PSI.. straight water/mix will quench the detonation. The deal I get into is run 15 PSI cleanly and want to run 25 PSI cleanly.. thats when you get into 30-40% fuel replacement and get the job done. Some cars run upwards of 40-50% replacement and get away with murder on 93 octane.
Jerry's car here in Tampa runs 35 PSI on 93 octane. 1997 Mirage, 2700 lbs + driver, full interior car, on kumo 18 inch street radials, 1.8 60 foot, ran 6.60 @108 1/8 and a 10.4 at 132 off the rev limiter. His car with the aquamist setup fastest it ever went was an 11.3. Switching from mix to straight.. it immediately dropped him to 10.8. Bigger turbo, more boost + AEM.. 10.4's..
Leave ya with this, ECS shot straight alcohol through a MAF back in Sept last year.. kinda barbaric.. car picked up 15 HP 25 TQ zero changes. Doug has easy over 800+ Dyno pulls on an injection kit.. as you saw the link above.. proof is in the pudding. With any water/mix system, there is no power gain on a non detonating tuned engine unless something else is changed. Like timing or boost. With alcohol.. the forced induction car runs like winter in the summer.
As much as I've messed with mixes.. no way the same power can be had running straight VP M1 methanol.
So I have Buicks, DSM's, Vette's, Supra's.. run on stock computers, AEM's, FAST, BS3.. all with zero issues running straight methanol.
08-01-2005, 10:10 PM
#9
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Re: Water Injection Questions???
My experience is different than his. You can't run one of these to max hp with a knock sensor active, so I am on a very different page there anyway. Design it and tune it not to knock and turn off the KS, it's next to impossible to eliminate false knock with the rest of the stuff needed. headers, NSA roller rockers with guide plates, blower, etc. Methanol has a much lower heat of vaporization than water. I'd run straight water before I'd run straight methanol.
Rich
Rich
08-02-2005, 06:36 AM
#11
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Re: Water Injection Questions???
Originally Posted by rskrause
Methanol has a much lower heat of vaporization than water...
Mike
08-02-2005, 07:06 AM
#12
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Re: Water Injection Questions???
Thanks for all the great posts. I will try and work on the tune, it's a little lazy right now (approx 11.7:1 or 11.8:1 on the WB @ WOT). Timing is mellow as well and I do plan to take it a little at a time (all great advice, thanks). I'm waiting for it to cool off before I get back to dyno/track tuning. I did lose a little mph adding the injection but I expected it due to the previous tune being safe (without water/alky), it just made things a little softer. Plus the warmer weather tends to do that since my previous best was run on one of those perfect cool dry fall nights. So 12.5:1 is pretty safe on pump gas (93 only for me)? It's strong enough internally, just wondered. Thanks again and keep it coming.
Eric
Eric
08-02-2005, 07:46 AM
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Re: Water Injection Questions???
As far as I recall from college, the latent heat of vaporization is the amount of heat needed to vaporize a substance. Therfore, if water has a higher latent heat of vporization...it needs more energy to vaporize. This means running straight alky will give you better cooling...since it has a much lower latent heat of vaporization. Feel free to correct me if i am wrong.
08-02-2005, 08:46 AM
#14
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Re: Water Injection Questions???
Originally Posted by engineermike
This has been a real mystery to me lately. Water has twice the latent heat of vaporization of Methanol. So, when it vaporizes, water should have twice the cooling effect on the air. Why, then, does my pipe form ice crystals just downstream of the Meth injection nozzles when water won't do that??? I'm seriously confused about that. Everytime I think I got Thermodynamics down good, something like this happens and I realize there are still things I don't know.
Mike
Mike
Rich
Last edited by rskrause; 08-02-2005 at 08:48 AM.
08-02-2005, 11:03 AM
#15
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Re: Water Injection Questions???
Originally Posted by RealQuick
As far as I recall from college, the latent heat of vaporization is the amount of heat needed to vaporize a substance. Therfore, if water has a higher latent heat of vporization...it needs more energy to vaporize. This means running straight alky will give you better cooling...since it has a much lower latent heat of vaporization. Feel free to correct me if i am wrong.
Depending on the boiling point and on the vapour pressure it will take a different time to evaporate (already before the TB, in the manifold or in the cylinder).
Also the droplets size makes a difference.
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