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Post alcohol / water injection ?

Has anyone done any testing with alcohol / water injection into there intake. I've read several clips to say it raises octane, burns fuel cleaner, raises performance and economy. WOW! Before I get too excited, I'd like to hear if anyone has any experience or opinion on this matter. The common mix seems to be 80% alcohol / 20% water. The following systems are pressurized by pumps, but I would think even a simpler system using the vacuum pull would be effective and proportional to demand.
http://home.att.net/~stevemon/AlcoholInjMod.html
http://www.dawesdevices.com/howto.html

Old 06-01-2001, 05:10 PM
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I know that the large pulling tractors that run staged turbos do this. Im not sure that you would see any real gains by doing this, because of the size of the turbo. It cant hurt to look into it though.
Old 06-06-2001, 12:35 AM
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I dont know about water/alcohol, but i have seen just water injection. I believe all of the WRC rally cars use it,it seems to be most effective on turbo cars, and sport compact car magazine installed a system on one of there cars and saw a reasonable gain because it dropped intake temp around 10 degrees resulting in between 5-10hp, and it also reduced cylinder temp allowing them to run a few more pounds of boost before experiencing any detenation. I assume by adding alcohol to the mixtue you would further inhance this effect.
Old 06-06-2001, 05:40 AM
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There's really no benefit to a naturally aspirated car. Water injection reduces the charge pressure, allowing more boost (hence power) in turbo/supercharged/nitrous engines before detonation occurs. Unless something is seriously wrong with it, an NA car won't need this extra cooling to prevent detonation.
Old 06-06-2001, 06:48 AM
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Whoops, meant to say "...charge temperature...".
Old 06-06-2001, 09:48 AM
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yah it allows you to up things, and you have to "up" the things enough to make it worthwile. The only way i would see it working on an NA car is if you were running say 13:1 compression pistons or something akin, where the temperatures are getting hot hot hot baby.
Old 06-06-2001, 10:29 AM
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Water injection can help a NA car you have to advacnce the timing and I belive you adjust the air fuel mixture a little lean.
Old 06-06-2001, 10:42 AM
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I have never heard of anyone using water injection on an N/A motor (including the all-motor drag Hondas) - but I guess you could do it although it would probably hurt performance.

Erick
Old 06-06-2001, 10:45 AM
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Using vacuum to pull the water/alcohol mixture is not proportional to load. It is inversely proportional to load.

You will dump a butload of alcohol into the intake on decels, and hardly any at all when at wide open throttle.

There is almost no vacuum at all in the intake when at WOT (unless you've got an extremely dirty air filter).
Old 06-06-2001, 02:53 PM
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Quote:
Originally posted by Kaos:
Using vacuum to pull the water/alcohol mixture is not proportional to load. It is inversely proportional to load.

You will dump a butload of alcohol into the intake on decels, and hardly any at all when at wide open throttle.

There is almost no vacuum at all in the intake when at WOT (unless you've got an extremely dirty air filter).
Use ported vacuum it increases with throttle opening.

wolfrpi: It would increase power because it allows you to advace timing more before detonation starts. The water will be a liquid when it enters the combustion chamber and turns to steam as the air heats up on the compression stroke asorbing alot of heat cooling the cylinder and allowing the timing to be advanced more.

Old 06-06-2001, 05:45 PM
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Quote:
Originally posted by kaffine krazed:
Use ported vacuum it increases with throttle opening.

wolfrpi: It would increase power because it allows you to advace timing more before detonation starts. The water will be a liquid when it enters the combustion chamber and turns to steam as the air heats up on the compression stroke asorbing alot of heat cooling the cylinder and allowing the timing to be advanced more.

you lose low end when you advance the timing, and then your not gaining very much maybe 2 HP by advancing the timing so the water kills what you have gained, right?

Old 06-06-2001, 05:54 PM
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Water injection works on the same principle as an intercooler. The water vapor cools the intake charge a bit, thereby making denser and getting more into the cylinder. This is assuming that it is water vapor. Ever notice that your car runs stronger on a cool, foggy morning? In addition, it does allow you to advance the timing a bit, producing a bit more power. We played with it 25 years ago on V8s, it does work to a point but you won't see hugh hp gains from it. (Speed costs money, how fast do you want to go?) The major downside is potential hydrolock and corrosion to the internal engine components. Water IS a polar solvent. If it were my car, I would look other places for hp gains, flow and cc the head, blueprint the engine (with special attention to align boring), knife edge the crank, bump the compression a bit, change the cam, and chip it. Like I said, speed=bucks. I think you would be much happier with a nitrous system if you want instant 951 power. Or better (and more cost effective) yet, get a 951 .

Dave951M

[This message has been edited by Dave951M (edited 06-06-2001).]
Old 06-06-2001, 06:05 PM
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OK - six days later and all of a sudden some good input... I think. This debate will probably only be settled when good test data is provided. I've read applications for both turbo's and na's.
So I'm one of those modest 944na'ers. Knowing that I'll never win any races what say I install the the injection system and drop from 92+ octane to tractor juice. Since the H20 injection in effect raises octane, I should run equally well with lower octane fuil - wella, suddenly I've got enough spare change to send my kids to college.
Old 06-06-2001, 06:14 PM
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World War 2 fighters used to use this for "war time power". It would give them a little extra power if they needed to out climb someone for instance.
Old 06-06-2001, 07:07 PM
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yah but if all the planes had it they would all be doing the same thing right, whoever thought of it first had it for maybe a day and won a battle or two that day but then the next day all the planes had it or am i wrong

[This message has been edited by AMCPorsche924Powerhaus! (edited 06-06-2001).]
Old 06-06-2001, 08:04 PM
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True, but all of the planes had different performance and the injection only lasted for a few minutes before it ran out, so it was more of a matter of when to use it.
Old 06-07-2001, 12:14 AM
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Yes, water injection was used in WWII fighters. The purpose was to increase the density of air (higher altitudes = lower density), hence maintaining proper air / fuel ratios.
Old 06-07-2001, 07:33 AM
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The FW-190 had a methanol injection system for "boosts" of power.

I would recommend staying away from this water/alcohol system and just keeping it in tune, good repair, and the foot off of the firewall. If you must try it, do it on something other than a Porsche, like a ford escort or chevy chevette maybe. This way, if you puke it, there's no loss to the automotive world.

Dave951M
Old 06-07-2001, 02:51 PM
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The BF 109 as well I believe. Good to know we have some aviation knowledge here.
Old 06-08-2001, 01:04 PM
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As a matter of interest, the Republic P47 Thunderbolt, Grumman F6F Hellcat, and Vought F4u Corsair all used water/methanol injection for "war emergency power". They all used the Pratt & Whitney R-2800 (2,800 cu inch) Double Wasp 18 cylider radial engine with turbo/supercharging.

The turbo pressure was regulated by a conventional wastegate which the pilot had no control over, but the supercharger could be adjusted by the pilot. When emergency power was needed, the supercharger pressure was maxed and the water/meth injected to control the combustion temperatures. The extra power could only be used for short bursts because it would cause undue stress and eventual engine failure otherwise. This would up the overall output to 2,500hp from the normal max of 2,100. An experimental version running on 115 octane even hit 2,800hp.

Old 06-08-2001, 02:14 PM
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