: Improve gas mileage with water??? Stupid or Scientific?



JSMeloche
07-30-04, 02:34 PM
Ok now you must say "another guy who wants to improve gas mileage on the N* with stupid things" Well this is just a question...

A couple of years ago I came accross an article written by a automotive enthusiast writer. The way of improving gaz mileage is done by sucking humid air in the intake, and suposevly this can improve the gas mileage.

You get humid air by taking a bottle and inserting 2 lenths of tubing. One short tubing finished by a "bubbler rock"(small rock you put in a fish tank to aerate the water, which is connected to the air pump) so it creates small bubble in the bottle and humidify the air. And the other lenth of tubing not in the water and connected to T on the vacuum line, so it only sucks humid air, not water.

Im a bit worried about hydro lock... but i dont think humid air can hydro lock an engine.

Do you think this can help for gas mielage? or arm the N* engine in any way??? Im curious, it does not cost much to do this thing. And it would be interesting to see if this is just another "gimmic" or a real scientific way to improve gas mileage.

maydog
07-30-04, 05:30 PM
You are talking about water injection, with it you can effectively increase the octance rating of the gas air charge. This helps reduce detonation so you can run higher compression and more aggressive timing. I think it works well on supercharged and turboed cars without an intercooler (using a more sophisticated setup than a bubbler however). It will allow to tune for more power but I don't think it helps with mileage?

I found some old army papers on reasearch using it on aircraft engines - it think it was used on some planes long ago.

I did some playing with it for experimentation sake. Be careful to not let water accumulate in the intake, or it will get slurped up on the first WOT and cause problems.

-Its probably not worth the effort.

mcowden
07-30-04, 05:38 PM
Temperature affects mileage more significantly than humidity, and even its effects are offset by changes in friction properties between high and low temperatures. I'm trying to picture the device you described and all I can think is it will not affect humidity by a margin significant enough to have any effect on fuel economy. Not to mention the potential problems if there is an uncontrolled release from that water bottle into the intake. Do yourself a favor. Forget that idea and any other miracle gas mileage increase devices/additives/procedures/modifications. They serve no purpose other than to decrease your money mileage. On top of maintaining vehicles in good condition, here are some thoughts from a site I found by Googling for "gas mileage" + humidity:

An SAE (Society of Automotive Engineers) paper titled Nine Ways to Get Better Fuel Mileage offers the following suggestions: 1) use moderate speeds (the best cruising speed is between 30-40), 2) drive at a smooth, steady pace (as traffic permits), 3) accelerate slowly and allow automatic transmissions to upshift, 4) anticipate stops and minimize braking, 5) avoid prolonged warm-up idling, 6) limit extensive idling, 7) be sure parking brake is fully released, 8) minimize electrical loads and use of air conditioner, 9) consolidate short trips, plan routes in advance, and avoid heavy traffic.

So you asked the question "Stupid or scientific?" and I think the answer is overwhelmingly "stupid."

Ranger
07-30-04, 10:17 PM
I found some old army papers on reasearch using it on aircraft engines - it think it was used on some planes long ago.


The old DC8's aka "water wagons" used to use water injection to increase take off performance.

dkozloski
07-31-04, 02:28 AM
Water injection in and of itself does not increase power. If you inject water spray into the intake it allows you to use higher manifold pressure settings without detonation by cooling the intake charge. Usually the water is combined wtih alcohol as antifreeze to prevent freezing up the system at high altitude. This system is also referred to as "ADI", Anti-Detonate Injection. Engines develope less power under high humidity conditions because any water vapor introduced displaces some amount of oxygen in the intake charge. Any perceived power boost during a rainstorm or such is from the effects of cooling rather than water vapor or humidity.
As a side note, you can do a pretty good job of removing carbon from an engines combustion chambers by spraying water from a Windex sprayer or such in the intake with the engine running at a fast idle. The shock cooling from the water spray dislodges the carbon and out it comes from the tailpipe.

N0DIH
08-13-04, 02:40 PM
You get humid air by taking a bottle and inserting 2 lenths of tubing. One short tubing finished by a "bubbler rock"(small rock you put in a fish tank to aerate the water, which is connected to the air pump) so it creates small bubble in the bottle and humidify the air. And the other lenth of tubing not in the water and connected to T on the vacuum line, so it only sucks humid air, not water.

This is actually VAPOR injection, not water injection.

Difference? Water is injected under load conditions only, when needed. Vapor injector is full time, always coming in.

With Water Injection there is a significant amount of water being injested in the combustion chambers. This has some cooling effect (watch your MAT readings on your Cad) and allows higher ignition timing to be used, where you CAN get better fuel economy. Also will allow you to run lower octane fuel without the fear of detonation which will severely damage your engine. Remember, for every 11 degrees drop in intake temp, is 1% HP improvement. My 91 4.9 averages around 60-70 degrees C in 80-85 degrees F ambient temp. Lots of room to cool things down here.

Vapor injection (Edelbrock used to make a good version of this) was used in Canada WAY up north where they had to keep police cars, maintenance trucks, etc running 24/7 to keep them from freezing up. They used the vapor injection there (which alcohol) and when the engines were torn down they were INCREDIBLY clean, no deposits, no buildup whatsoever.

They are similar in effect, but delivered differently. Vapor Injector will have VERY little effect on your octane usage and fuel economy. It WILL keep a mild steam going all the time, primarily at idle or slow engine operation.

Water Injection (Edelbrock used to make a great system, "Varajection") which was rpm and load based. So you would not be dumping water in during load or no load conditions. It would vary higher water or less water depending on the load. Great system, but the vacuum port was very fragile and easily broke. $100 down the drain....

You can make a good system with ideas from http://www.highperformancepontiac.com/tech/0309pon_turbo/. He runs 11.80's on a stock 455 with a homebrew turbo and water injection. Blow through carb. The magazine had a good detail on the water injection setup, so look for back issues.

Just think, add upwards of 5 degrees more timing with 87 octane on your ride with water injection can lower operating costs and have power/economy benefits.

Stupid or Smart? Smart, if done right....

Thomas Martin