Water Production In An Engine?

[Geico266]

I heard this info about internal combustion engines at SnF and thought I would test the knowledge of the VAF.

Answer to come in a few days.

[John Clark]

Look something like this for each 100 gallons of gasoline burned:

90-120 gallons of water
3 to 10 gallons of unburned gasoline
? to 2 pounds of soot
? to 1 pound of resins and varnishes
1 to 4 pounds of nitrogen and sulfur acids
6 to 10 ounces of insoluble lead salts (if leaded gasoline is used)
1 to 2 ounces of hydrochloric and hydrobromic acids.

John Clark
RV8 N18U "Sunshine"
KSBA

[Rivethead]

John are you sure about those numbers? I don't know what the numbers are but I do know muffler shops make a lot of money replacing mufflers that rust out from the inside.

[gasman]

The question was..... How Much Water Is Produced By A Gallon Of Gas In An Internal Combustion Engine?

NONE!......... pole 1... 5.88% at this time.

Gas does not produce water. The combustion process produces water by leaving it behind when the oxygen is consumed in the fire. Gas will not burn without AIR. And AIR has moisture in it.

So should the question have been.... How Much Water Is Produced By burning A Gallon Of Gas In An Internal Combustion Engine?

Water is produced any time there is a fire. There is more moisture in the air at your gas range due to the fire of the burner. A gas oven is much more humid than an electric oven.

[tacaruth]

The basic chemical reaction that occurs when gasoline burns is the combination of a carbon-hydrogen molecule with the oxygen in the air. This produces carbon dioxide and water molecules in a perfect reaction. This is where the water produced by the combustion comes from.

Tom
RV-7A N175TJ Flying

[DrHolling]

Originally Posted by gasman

,<snip>
Water is produced any time there is a fire.

This statement is true when the 'fuel' contains hydrogen and the 'oxidizer' contains oxygen. Burning magnesium makes a very intense fire but doesn't produce water as a by-product (no hydrogen). Clorine makes a very good oxidizer but won't produce water as part of the oxidation process.

I had 'assumed' your question was in regards to the water produced by the combustion process. The correct answer to the question, as stated, would be ZERO. You know what they say about 'assuming'

dave

[tacaruth]

Try this calculation:

Carbon molecular weight = 12
Hydrogen molecular weight = 1

Basic gasoline molecule = C8H18 (octane in this example)

Carbon % = (8 * 12) / (8 * 12 + 18 * 1) = 96 / 114 = 84.2%
Hydrogen % = (18 * 1) / (8 * 12 + 18 * 1) = 18 / 114 = 15.8%

Gas = 6 lbs / gallon * 15.8% = .948 lbs hydrogen

Oxygen molecular weight = 16

Basic water molecule = H2O

Oxygen % = (16 * 1) / (1 * 2 + 16 * 1) = 16 / 18 = 88.9%
Hydrogen % = (1*2) / (1 * 2 + 16 * 1) = 2 / 18 = 11.1%

Water produced = .948 / .111 = 8.54 lbs / 8.33 lbs/gallon = 1.02 gallons

Tom
RV-7A N175TJ Flying

[John Clark]

Thanks Tom! I was sitting here trying to remember the math. The thing that we forget is that at the "ideal" mixture, the average engine has an air/fuel ratio of 14.7:1 by weight so, for every gallon of gasoline we use something around 8000 gallons of air.

John Clark
RV8 N18U "Sunshine"
KSBA

[Geico266]

Originally Posted by tacaruth

Water produced = .948 / .111 = 8.54 lbs / 8.33 lbs/gallon = 1.02 gallons

Tom
RV-7A N175TJ Flying

We have a winner! See DR for your totally cool and very expensive prize!

Now isn't it a wonder why these engines need to get oil temps up to 200F each flight? This helps "burn off" the water out of the oil. In talking with the lubrication engineer from Phillips Aviation Oil I got a lot of questions answered and myths busted.

1. After each flight remove the dip stick for 10-15 mins to allow water vapor to escape from the crankcase oil. You can actually see water vapor coming out.

2. Oil temps of 200 - 220F are totally normal and in fact good for the oil & engine. Temps to 240F on climb out are nothing to worry about at all. No need to "step" the climb out to allow the oil to cool.

3. Engine oil will suspend water so getting the temps up is a really good idea considering the amount of water the engine produces.

4. Oil changes at the end of the season is really important for any engine in that the "corrosive additive package" only last 3-4 months in an engine being used so letting an engine sit all winter with the old oil is a bad idea.

5. Semi-synthetic aviation oil is semi good at suspending lead. If you burn alot of 100LL you should not use semi- synthetics. (JMHO)

6. Anything you can do to preheat an engine before start up (during cold weather) is a good thing. Idling below 1,000 for the 1st 2-3 mins is not a good thing either. Get that oil to the bearings ASAP.

7. I know oil has been beat to death, but it was nice to hear from an expert and I thought I would pass along the info.

Lets not start a flaming war over oil, I just thought I would pass on what I heard.

[hevansrv7a]

Originally Posted by Geico266

We have a winner! See DR for your totally cool and very expensive prize!

Now isn't it a wonder why these engines need to get oil temps up to 200F each flight? This helps "burn off" the water out of the oil. In talking with the lubrication engineer from Phillips Aviation Oil I got a lot of questions answered and myths busted.

1. After each flight remove the dip stick for 10-15 mins to allow water vapor to escape from the crankcase oil. You can actually see water vapor coming out.

2. Oil temps of 200 - 220F are totally normal and in fact good for the oil & engine. Temps to 240F on climb out are nothing to worry about at all. No need to "step" the climb out to allow the oil to cool.

3. Engine oil will suspend water so getting the temps up is a really good idea considering the amount of water the engine produces.

4. Oil changes at the end of the season is really important for any engine in that the "corrosive additive package" only last 3-4 months in an engine being used so letting an engine sit all winter with the old oil is a bad idea.

5. Semi-synthetic aviation oil is semi good at suspending lead. If you burn alot of 100LL you should not use semi- synthetics. (JMHO)

6. Anything you can do to preheat an engine before start up (during cold weather) is a good thing. Idling below 1,000 for the 1st 2-3 mins is not a good thing either. Get that oil to the bearings ASAP.

7. I know oil has been beat to death, but it was nice to hear from an expert and I thought I would pass along the info.

Lets not start a flaming war over oil, I just thought I would pass on what I heard.

I'm not going to flame anyone, but it should now be apparent to all that you produce a lot of water vapor when you run your engine. Much of it blows by the rings. Consequently, the hot air in the crankcase contains a lot of moisture. When the engine cools the water must condense because cool air cannot hold as much moisture as hot air. Your engine is a rain forest each time you shut down. For me, the answer is some version of an engine dehydrator. I use it religiously when the engine is not running. Just making the oil hot to remove the water that's there accomplished nothing because you are putting more in. Further, the absence of moisture will help with less acid formation, I suspect.