engine wear with e85?
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engine wear with e85?
"For ethanol contaminated with larger amounts of water (i.e., approximately 11% water, 89% ethanol, equivalent to 178 proof ethanol), considerable engine wear will occur, especially during times while the engine is heating up to normal operating temperatures. For example, just after starting the engine, low temperature partial combustion of the water-contaminated ethanol mixture takes place and causes engine wear. This wear, caused by water-contaminated E85, is the result of the combustion process of ethanol, water, and gasoline producing considerable amounts of formic acid (HCOOH, also known as methanoic acid and sometimes written as CH2O2). In addition to the production of formic acid occurring for water-contaminated E85, smaller amounts of acetaldehyde (CH3CHO) and acetic acid (C2H4O2) are also formed for water-contaminated ethanol combustion. Of these partial combustion products, formic acid is responsible for the majority of the rapid increase in engine wear."
is this a concern on normal warm up? or is there only a worry if the e85 gets contaminated?
is this a concern on normal warm up? or is there only a worry if the e85 gets contaminated?
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Don't forget about the moisture in the air as well.
As air temperature rises, air density goes down, but saturated vapor density goes up.
For example, dry air at 20C has a density of 1200g/m^3. At that same 20C, saturation density is 17.3 g/m^3. So, the air can be 1.44% water by weight.
At 30C, air density is about 1165g/m^3 and saturation density is 30.4g/m^3. So, now, the air can be 2.6 wt% water.
There is an exponential rise in saturated vapor density as the temperature rises, so if there is any moisture present in the air and heated air coming from the turbo, etc, the hotter it gets the more water it can be saturated with, which in turn will be brought into the combustion chamber.
Also, the PCV system is bringing any mositure that may accumulate in the crankcase back into the IM and into the combustion chamber as well.
Overall, though, I don't think it is anything to worry about, but it definitely is a real issue. Also ethanol is hygroscopic, so who knows how much water it can pick up sitting in the storage tanks as the gas station, being dispensed, etc. I've read that most OEMs actually put special coatings on the pistons and engine parts to resist possible acid contamination in flex fuel cars.
Eric
As air temperature rises, air density goes down, but saturated vapor density goes up.
For example, dry air at 20C has a density of 1200g/m^3. At that same 20C, saturation density is 17.3 g/m^3. So, the air can be 1.44% water by weight.
At 30C, air density is about 1165g/m^3 and saturation density is 30.4g/m^3. So, now, the air can be 2.6 wt% water.
There is an exponential rise in saturated vapor density as the temperature rises, so if there is any moisture present in the air and heated air coming from the turbo, etc, the hotter it gets the more water it can be saturated with, which in turn will be brought into the combustion chamber.
Also, the PCV system is bringing any mositure that may accumulate in the crankcase back into the IM and into the combustion chamber as well.
Overall, though, I don't think it is anything to worry about, but it definitely is a real issue. Also ethanol is hygroscopic, so who knows how much water it can pick up sitting in the storage tanks as the gas station, being dispensed, etc. I've read that most OEMs actually put special coatings on the pistons and engine parts to resist possible acid contamination in flex fuel cars.
Eric
Last edited by l2r99gst; May 24, 2008 at 07:32 PM.
I figured I would post a chart in this thread since I just linked to it in another thread in the ECUFlash forum for something else. My numbers above were correct for the percent of water that can be in the air, but in terms of % of water to fuel is even worse and at or over the 11% mentioned in the first post. I'm curious if anyone in hot, humid climates running E-85 has done any engine oil analyses to see if any of these acidic byproducts and engine wear is occuring.
If so, the TBN of the oil may be reduced more quickly and need to be changed more frequently.
For example, if you look at the following chart:
At 90*F (about 32*C) and 100% relative humidity, the air can hold 30 grams of water per kg (1000 g air) of air. At an A:F ratio of 14.7:1, during cruise or idle, that would mean you are using 1000/14.7 = 68 g of fuel.
So, that means for every 1000g of air, 30 g is water, and 68 g of fuel is being used. That is a ratio of water to fuel of 30/68 = 44%.
So, that is well above the 11% contamination level mentioned in post #1, where low-temperature partial combustion of ethanol can produce these acids.
Or does this not matter, because this is water that is being introduced to the combustion chamber rather than tp the E-85 beforehand, so this isn't considered contamination and the by-products don't have a chance to form?
Eric
If so, the TBN of the oil may be reduced more quickly and need to be changed more frequently.
For example, if you look at the following chart:
At 90*F (about 32*C) and 100% relative humidity, the air can hold 30 grams of water per kg (1000 g air) of air. At an A:F ratio of 14.7:1, during cruise or idle, that would mean you are using 1000/14.7 = 68 g of fuel.
So, that means for every 1000g of air, 30 g is water, and 68 g of fuel is being used. That is a ratio of water to fuel of 30/68 = 44%.
So, that is well above the 11% contamination level mentioned in post #1, where low-temperature partial combustion of ethanol can produce these acids.
Or does this not matter, because this is water that is being introduced to the combustion chamber rather than tp the E-85 beforehand, so this isn't considered contamination and the by-products don't have a chance to form?
Eric
Last edited by l2r99gst; Jun 13, 2008 at 08:34 AM.
All i can say is my O2 housing and DP bolts are rusty. FWIW. Maybe it's that acid, most likely regular alcohol + water corrosion. I wouldn't read into Wiki article too much....
Also at cruise it's 9.8 or so 1000/9.8= 102g of fuel
Which is 30/102=29% water in the mix.
By the way the OP didn't do a good job with the post, plucking a couple of sentences from the Wiki article. So even if you believe in Wiki, you'll see it says "The risk primarily comes in the rare event that the E85 fuel ever becomes contaminated with water". Obviously the author isn't even thinking about air and its water content for regular combustion.
Also at cruise it's 9.8 or so 1000/9.8= 102g of fuel
Which is 30/102=29% water in the mix.
By the way the OP didn't do a good job with the post, plucking a couple of sentences from the Wiki article. So even if you believe in Wiki, you'll see it says "The risk primarily comes in the rare event that the E85 fuel ever becomes contaminated with water". Obviously the author isn't even thinking about air and its water content for regular combustion.
Water contamination
In addition to corrosion, there is also a risk of increased engine wear for non-FFV engines that are not specifically designed for operation on high levels (i.e., for greater than 10%) of ethanol. The risk primarily comes in the rare event that the E85 fuel ever becomes contaminated with water. For water levels below approximately 0.5% to 1.0% contained in the ethanol, no phase separation of gasoline and ethanol occurs. For contamination with 1% or more water in the ethanol, phase separation occurs, and the ethanol-water mixture will separate from the gasoline. This can be observed by pouring a mixture of suspected water-contaminated E85 fuel in a clear glass tube, waiting roughly 30 minutes, and then inspecting the sample. If there is water contamination of above 1% water in the ethanol, a clear separation of ethanol-water from gasoline will be clearly visible, with the colored gasoline floating above the clear ethanol-water mixture.
For ethanol contaminated with larger amounts of water (i.e., approximately 11% water, 89% ethanol, equivalent to 178 proof ethanol), considerable engine wear will occur, especially during times while the engine is heating up to normal operating temperatures. For example, just after starting the engine, low temperature partial combustion of the water-contaminated ethanol mixture takes place and causes engine wear. This wear, caused by water-contaminated E85, is the result of the combustion process of ethanol, water, and gasoline producing considerable amounts of formic acid (HCOOH, also known as methanoic acid and sometimes written as CH2O2). In addition to the production of formic acid occurring for water-contaminated E85, smaller amounts of acetaldehyde (CH3CHO) and acetic acid (C2H4O2) are also formed for water-contaminated ethanol combustion. Of these partial combustion products, formic acid is responsible for the majority of the rapid increase in engine wear.
Engines specifically designed for FFVs employ soft nitride coatings on their internal metal parts to provide resistance to formic acid wear in the event of water contamination of E85 fuel. Also, the use of lubricant oil (motor oil) containing an acid neutralizer is necessary to prevent the damage of oil-lubricated engine parts in the event of water contamination of fuel. Such lubricant oil was required by at least one manufacturer of FFVs (Chrysler). This requirement was later removed.
For non-FFVs burning E85 in greater than 23.5% E85 mixtures (20% ethanol), the remedy for accidentally getting a tank of water-contaminated E85 (or gasoline) while preventing excessive engine wear is to change the motor oil as soon as possible after either burning the fuel and replacing it with non-contaminated fuel, or after immediately draining and replacing the water-contaminated fuel. The risk of burning slightly water-contaminated fuel with low percentages of water (less than 1%) on a long commute is minimal; after all, it is the low temperature combustion of water contaminated ethanol and gasoline that causes the bulk of the formic acid to form; burning a slightly-contaminated mix of water (less than 1%) and ethanol quickly, in one long commute, will not likely cause any appreciable engine wear past the first 15 miles of driving, especially once the engine warms up and high temperature combustion occurs exclusively.
For those making their own E85, the risk of introducing water unintentionally into their homemade fuel is relatively high unless adequate safety precautions and quality control procedures are taken. Ethanol and water form an azeotrope such that it is impossible to distill ethanol to higher than 95.6% ethanol purity by weight (roughly 190 proof); regardless of how many times distillation is repeated. Unfortunately, this proof ethanol contains too much water to prevent separation of a mixture of such proof ethanol with gasoline, or to prevent the formation of formic acid during low temperature combustion. Therefore, when making E85, it becomes necessary to remove this residual water. It is possible to break the ethanol and water azeotrope through adding benzene or another hydrocarbon prior to a final rectifying distillation. This takes another distillation (energy consuming) step. However, it is possible to remove the residual water more easily, using 3 angstrom (3A) synthetic zeolite pellets to absorb the water from the mix of ethanol and water, prior to mixing the now anhydrous ethanol with gasoline in an 85% to 15% by volume mixture to make E85. This absorption process is also known as a molecular sieve. The benefit of using synthetic zeolite pellets is that they are essentially comparable to using a catalyst, in being reusable and in not being consumed in the process, and the pellets require only re-heating (perhaps on a backyard grill, in a solar reflector furnace, or with heated carbon dioxide gas collected and saved from the fermentation process) to drive off the water molecules absorbed into the zeolite. Research has also been done at Purdue University on using corn grits as a desiccant. [3] Once the ground corn becomes water logged, the corn grits can be processed much as the zeolite pellets, at least for a number of drying cycles before the grits lose their effectiveness. Once this occurs, it is possible to run the now water-logged corn grits through the natural fermentation process and convert them into even more ethanol fuel.
In addition to corrosion, there is also a risk of increased engine wear for non-FFV engines that are not specifically designed for operation on high levels (i.e., for greater than 10%) of ethanol. The risk primarily comes in the rare event that the E85 fuel ever becomes contaminated with water. For water levels below approximately 0.5% to 1.0% contained in the ethanol, no phase separation of gasoline and ethanol occurs. For contamination with 1% or more water in the ethanol, phase separation occurs, and the ethanol-water mixture will separate from the gasoline. This can be observed by pouring a mixture of suspected water-contaminated E85 fuel in a clear glass tube, waiting roughly 30 minutes, and then inspecting the sample. If there is water contamination of above 1% water in the ethanol, a clear separation of ethanol-water from gasoline will be clearly visible, with the colored gasoline floating above the clear ethanol-water mixture.
For ethanol contaminated with larger amounts of water (i.e., approximately 11% water, 89% ethanol, equivalent to 178 proof ethanol), considerable engine wear will occur, especially during times while the engine is heating up to normal operating temperatures. For example, just after starting the engine, low temperature partial combustion of the water-contaminated ethanol mixture takes place and causes engine wear. This wear, caused by water-contaminated E85, is the result of the combustion process of ethanol, water, and gasoline producing considerable amounts of formic acid (HCOOH, also known as methanoic acid and sometimes written as CH2O2). In addition to the production of formic acid occurring for water-contaminated E85, smaller amounts of acetaldehyde (CH3CHO) and acetic acid (C2H4O2) are also formed for water-contaminated ethanol combustion. Of these partial combustion products, formic acid is responsible for the majority of the rapid increase in engine wear.
Engines specifically designed for FFVs employ soft nitride coatings on their internal metal parts to provide resistance to formic acid wear in the event of water contamination of E85 fuel. Also, the use of lubricant oil (motor oil) containing an acid neutralizer is necessary to prevent the damage of oil-lubricated engine parts in the event of water contamination of fuel. Such lubricant oil was required by at least one manufacturer of FFVs (Chrysler). This requirement was later removed.
For non-FFVs burning E85 in greater than 23.5% E85 mixtures (20% ethanol), the remedy for accidentally getting a tank of water-contaminated E85 (or gasoline) while preventing excessive engine wear is to change the motor oil as soon as possible after either burning the fuel and replacing it with non-contaminated fuel, or after immediately draining and replacing the water-contaminated fuel. The risk of burning slightly water-contaminated fuel with low percentages of water (less than 1%) on a long commute is minimal; after all, it is the low temperature combustion of water contaminated ethanol and gasoline that causes the bulk of the formic acid to form; burning a slightly-contaminated mix of water (less than 1%) and ethanol quickly, in one long commute, will not likely cause any appreciable engine wear past the first 15 miles of driving, especially once the engine warms up and high temperature combustion occurs exclusively.
For those making their own E85, the risk of introducing water unintentionally into their homemade fuel is relatively high unless adequate safety precautions and quality control procedures are taken. Ethanol and water form an azeotrope such that it is impossible to distill ethanol to higher than 95.6% ethanol purity by weight (roughly 190 proof); regardless of how many times distillation is repeated. Unfortunately, this proof ethanol contains too much water to prevent separation of a mixture of such proof ethanol with gasoline, or to prevent the formation of formic acid during low temperature combustion. Therefore, when making E85, it becomes necessary to remove this residual water. It is possible to break the ethanol and water azeotrope through adding benzene or another hydrocarbon prior to a final rectifying distillation. This takes another distillation (energy consuming) step. However, it is possible to remove the residual water more easily, using 3 angstrom (3A) synthetic zeolite pellets to absorb the water from the mix of ethanol and water, prior to mixing the now anhydrous ethanol with gasoline in an 85% to 15% by volume mixture to make E85. This absorption process is also known as a molecular sieve. The benefit of using synthetic zeolite pellets is that they are essentially comparable to using a catalyst, in being reusable and in not being consumed in the process, and the pellets require only re-heating (perhaps on a backyard grill, in a solar reflector furnace, or with heated carbon dioxide gas collected and saved from the fermentation process) to drive off the water molecules absorbed into the zeolite. Research has also been done at Purdue University on using corn grits as a desiccant. [3] Once the ground corn becomes water logged, the corn grits can be processed much as the zeolite pellets, at least for a number of drying cycles before the grits lose their effectiveness. Once this occurs, it is possible to run the now water-logged corn grits through the natural fermentation process and convert them into even more ethanol fuel.
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I'd say your concept and calculations are reasonable. The acids will form, but as mentioned, this is a low temperature issue. I think the degree to which acid forms will depend greatly on how efficiently the mixture burns just after a cold start.
mplspilot - Yes, sorry, I am always thinking about gas AFR instead of true E-85 AFR...thanks for the correction. However, it's still well above the 11% mentioned that can cause issues during warm-up and partial combustion.
mrfred - I agree with you, and I think it will be mostly a non-issue, but nevertheless, it may be something to keep in mind when running E-85 and possibly doing an engine oil analysis to see how it's affecting the life of the oil and/or potential engine wear.
I plan on converting to E-85 in the near future since I have it readily available where I live, but I would like to get as much info first. I'm really curious if anyone has done an engine oil analysis, epsecially in a hot, humid climate.
mrfred - I agree with you, and I think it will be mostly a non-issue, but nevertheless, it may be something to keep in mind when running E-85 and possibly doing an engine oil analysis to see how it's affecting the life of the oil and/or potential engine wear.
I plan on converting to E-85 in the near future since I have it readily available where I live, but I would like to get as much info first. I'm really curious if anyone has done an engine oil analysis, epsecially in a hot, humid climate.
Last edited by l2r99gst; Jun 13, 2008 at 10:38 AM.
