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Old 01-20-2010, 07:50 PM   #1
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ETOH and gas

On my way back or to Vegas this past weekend, I was reading about Porsche and ETOH additive in gas. The "expert" wrote something about how it makes water form in the gas tank and how porsche says in thier manual that the car should never be run past 1/8 of a tank because it will suck up the water and hydrlock the motor.

I can not find the magazine so can someone explain to me what they are saying and if it is true.

All gas in the Austin TX area has 10% ETOH.

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Old 01-20-2010, 08:29 PM   #2
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I've been told I shouldn't run below 1/8th of a tank because the fuel pump is cooled by surrounding fuel (it resides within the tank itself) and it will overheat and seize if you always run the car on an empty tank.

I never heard anything about the ethanol percentage being anything more than a nuisance on performance and rough idle when the motor is cold.
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Old 01-21-2010, 06:30 AM   #3
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I found the magazine...

It is Feb 2010 issue of Excellence. They state that the ETOH turns into water when sitting in the tank and that there is a layer of water in the bottom.

The concern is that when you run low on gas, and turn corners, the water will slop around and get picked up into the intake and end up in the motor.

They state that older cars can ruin the injectors but newer cars should be ok.

Any truth to this?
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Old 01-21-2010, 06:47 AM   #4
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Boys, boys...

Ethanol is the same chemical as Vodka.

Does vodka turn into water if it sits in the bottle? no

Ethanol is hygroscopic however which means it will absorb water from the atmosphere and if a tank full of 100% ethanol was left in a fuel tank with no fuel cap for a long time in a humid climate, then it would absorb some water which could be a problem.

Fuel in the US contains no more than 10% ethanol unless it is E85 which contains 85% ethanol.

Modern fuel systems are very tight and humidity from the atmosphere is not a concern especially when only 10% of the fuel is ethanol. This is a non issue.

What is more concerning however is that the caloric content of ethanol is 15% less than that of gasoline. So 10% of your fuel is 15% less energetic than the gasoline.

Also mpg using ethanol is 15% lower than mpg from gasoline.

When spread across every auto in the US that is a significant drop in overall fuel economy.

Ethanol is an oxygenate for fuel that helps it burn more thouroughly and reduce emissions. It is far far better for the environment than MTBE which is known for polluting large amounts of ground water with very small amounts of contamination.

Economically ethanol is produced in the US and that is good for the economy.

In the long run ethanol is worth its drawbacks but it does not "turn to water".

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Old 01-21-2010, 07:10 AM   #5
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Quote:
Originally Posted by landrovered
Boys, boys...

Ethanol is the same chemical as Vodka.

Does vodka turn into water if it sits in the bottle? no

Ethanol is hygroscopic however which means it will absorb water from the atmosphere and if a tank full of 100% ethanol was left in a fuel tank with no fuel cap for a long time in a humid climate, then it would absorb some water which could be a problem.

Fuel in the US contains no more than 10% ethanol unless it is E85 which contains 85% ethanol.

Modern fuel systems are very tight and humidity from the atmosphere is not a concern especially when only 10% of the fuel is ethanol. This is a non issue.

What is more concerning however is that the caloric content of ethanol is 15% less than that of gasoline. So 10% of your fuel is 15% less energetic than the gasoline.

Also mpg using ethanol is 15% lower than mpg from gasoline.

When spread across every auto in the US that is a significant drop in overall fuel economy.

Ethanol is an oxygenate for fuel that helps it burn more thouroughly and reduce emissions. It is far far better for the environment than MTBE which is known for polluting large amounts of ground water with very small amounts of contamination.

Economically ethanol is produced in the US and that is good for the economy.

In the long run ethanol is worth its drawbacks but it does not "turn to water".
Actually, the ethanol in gas picks up water during manufacture, transportation and storage. When it sits in your tank, it can separate and form acidic compounds with other additives in the fuel, and attack a wide variety of surfaces such as the mild steel fuel lines, pump components and the injectors. This is why E85 vehicles have all stainless fuel systems, special injectors and other components; making a true conversion from normal gas to E85 price prohibitive.

We recently had a Z06 Vette in the shop that the owner (on a 9-month assignment in China) put into storage with a full tank of gas, but no stabilizer. A mere couple of grand or so later, we replaced all the parts screwed up by the water that separated from the 10% ethanol gas and he was on his way again.

Use fuel stabilizers if you let the car sit, it is cheap insurance, and now even recommended by a lot of the OEM’s………..
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Old 01-21-2010, 07:13 AM   #6
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Also to clarify... hydrolocking a motor is something I happen to know about being a Land Rover affecianado.

Hydrolocking occurs when the air intake is submerged in water like in a river crossing. Since liquids are not compressible then the motor can hydrolock when the quantity of water ingested exceeds the available space at the top of the cylinder between the piston and the head on the compression stroke.

Water in the fuel system is delivered by the fuel injectors and is atomized and cannot hydrolock the motor. It can inhibit combustion but it will not hydrolock the motor.
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Old 01-21-2010, 07:27 AM   #7
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Quote:
Originally Posted by JFP in PA
Actually, the ethanol in gas picks up water during manufacture, transportation and storage. When it sits in your tank, it can separate and form acidic compounds with other additives in the fuel, and attack a wide variety of surfaces such as the mild steel fuel lines, pump components and the injectors. This is why E85 vehicles have all stainless fuel systems, special injectors and other components; making a true conversion from normal gas to E85 price prohibitive.

We recently had a Z06 Vette in the shop that the owner (on a 9-month assignment in China) put into storage with a full tank of gas, but no stabilizer. A mere couple of grand or so later, we replaced all the parts screwed up by the water that separated from the 10% ethanol gas and he was on his way again.

Use fuel stabilizers if you let the car sit, it is cheap insurance, and now even recommended by a lot of the OEM’s………..
I happen to be in the biofuels business and am well aware of the proper manufacture, storage, transport, distribution and use of many biofuels including ethanol.

Yes, being a hygroscopic chemical, it has the property of absorbing water from the atmoshphere and yes, fuels have a shelf life that most people don't really realize.

Gasoline is degrading from the moment that is is manufactured just like ethanol and many other compounds.

Yes, modern fuel systems have eliminated problem areas through materials selection to deal with the solvent nature of ethanol.

The primary difference in the combustion of ethanol, CNG and LPG from gasoline is ignition timing. Since the caloric value of these fuels is less, the timing must be advanced much more than normal.

Modern flex fuel vehicles have different fuel curves for E85 and E10 that accomodate the needs of the engine to handle the difference.

Whether the Vette suffered from water in the fuel or old gasoline is really moot, either could have caused a problem and fuel stabilizers are a good way to prevent problems of this nature.

The fact is that you cannot buy gasoline without ethanol in it in the US. So we have to deal with it. If you buy gas from a high volume gas station and use your vehicle on a regular basis, and have a good gas cap on your car, you will not have a problem.

If your car sits up, then some Stabil is a good investment.

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