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ETHINOL GAS


DARKSTAR

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I was riding to work this morning and heard a news announcer read a story about gas prices and a possible solution. The solution being considered in my state is to add ethinol to the gas sold here. How would ethinol gas affect my RT?

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Joe Frickin' Friday
How would ethinol gas affect my RT?

 

You'll get slightly lower fuel economy (MPG), but that's pretty much it.

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Until you get past 10% concentration.

 

Many vehicles can safely burn 85% ethanol (E85) fuel. But there are issues there too. Not only lower MPG, but also cold starts weren't as smooth. You can't burn E85 in a normal vehicle like your RT.

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Joe Frickin' Friday
Until you get past 10% concentration.

 

Many vehicles can safely burn 85% ethanol (E85) fuel. But there are issues there too. Not only lower MPG, but also cold starts weren't as smooth. You can't burn E85 in a normal vehicle like your RT.

 

Not clear what sort of concentrations Darkstar was talking about, but for E85, that's not about adding ethanol to gas, it's about adding gasoline to ethanol. And yeah, you'd need a FFV to burn that stuff.

 

But I think it's pretty common to get up to 10% ethanol blended into ordinary pump fuel, yes? Especially in places like California?

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One thing I've been pondering... since E85 fuels don't seem to provide significant cost savings and do incur a definite fuel mileage hit, why would one expect them to be a commercially viable alternative at any time in the reasonably near future? (And that's even including the rash of tax breaks recently enacted to assist the ethanol industry.) I suppose there is of course a petro fuel price point where E85 would eventually develop a cost advantage but right now E85 is available at only a few thousand stations across the country and per a report I saw last night the number of stations is shrinking rather than growing due to lack of sales. Until there is another significant spike in oil costs I don't see ethanol-based fuels as capable of achieving a the 'critical mass' desirability that will be necessary to change that.

 

And then there are the considerations as to exactly how energy-efficient ethanol fuels really are, but those are difficult to gauge since the data supplied by the Sierra Club and Archer Daniels Midland seem to be at polar opposites (although it's pretty obvious which arguments have the government's ear.) smirk.gif

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As an owner of a FFV since 2000 and a big proponent and user of E85, I'll have to jump into this hijack for a second.

 

Until late last fall E85 did have a cost advantage over gasoline, even given the reduction in mileage with E85. But then the refiners caught onto using it more as an additive and have been buying up the market, and the price of it too has skyrocketed.

 

Why I don't believe E85 (or any combustion fuel) is the end-all answer to our energy problems (only changes in our consumption habits will do that), I do think it offers useful advantages over petroleum based products for two main reasons: It is a product produced in its native consumption markets. It is significantly less polluting.

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It is likely that you have been using gasoline with oxygenates added already (for years, in fact). The popular oxygenate used to be MTBE until it was discovered in groundwater and determined to be a health risk. Oxygenates promote cleaner burning of the fuel in your engine, the reason they are added.

 

So, now blenders are adding ethanol (not ethinol) as the oxygenate in place of the banned MTBE. Most autos will NOT run well on high levels of ethanol (E85 for example) due to the Lambda system’s inability to tolerate high levels of oxygen in the exhaust. A FFV has a fuel system that is able to detect the level of ethanol in the fuel and adjust the ECU accordingly to provide correct fuel/air ratios.

 

As for 10% ethanol, it will not affect your vehicle to the extent that you will be able to detect it.

 

Why use ethanol? Because US farmers can grow it……….ethanol comes from corn and other crops which are renewable……..what a concept………grow fuel for your car instead of paying OPEC countries $70.00/bbl for their crude.

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How would ethinol gas affect my RT?

 

You'll get slightly lower fuel economy (MPG), but that's pretty much it.

There was an issue where higher concentrations of either methanol or ethanol caused failures of rubber parts in the fuel system, but as I recall this has been eliminated in new cars. Come to think about it, considering the chemical properties of each, the problem was probably with methanol.

 

Bob.

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There was an issue where higher concentrations of either methanol or ethanol caused failures of rubber parts in the fuel system, but as I recall this has been eliminated in new cars. Come to think about it, considering the chemical properties of each, the problem was probably with methanol.

 

Where's Shawn when you need him?

 

He mentioned to me once that most all seals are now E85 friendly.

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Joe Frickin' Friday
Most autos will NOT run well on high levels of ethanol (E85 for example) due to the Lambda system’s inability to tolerate high levels of oxygen in the exhaust. A FFV has a fuel system that is able to detect the level of ethanol in the fuel and adjust the ECU accordingly to provide correct fuel/air ratios.

 

At a stoichiometric mixture - whether of gasoline, ethanol, or a blend of the two - all of the available oxygen (including any provided by the fuel itself) is consumed in the combustion reaction. So no matter what fuel you're dealing with, the O2 sensor "knows" how much fuel is needed. If there's O2 left in the exhaust, the sensor says "too lean;" if there's no O2 left, the sensor says "too rich."

 

Apart from materials compatibility, the fuel system needs to be sized to deliver the greater quantity of ethanol required to produce a stoichiometric mixture. For gasoline, the stoich. A/F ratio is about 14.6 to 1; for ethanol, it's more like 9 to 1, meaning that on pure ethanol, the fuel system has to deliver about 60% more fuel than when running on gasoline. It needs bigger injectors, and fuel delivery maps that are calibrated for ethanol.

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At a stoichiometric mixture - whether of gasoline, ethanol, or a blend of the two - all of the available oxygen (including any provided by the fuel itself) is consumed in the combustion reaction. So no matter what fuel you're dealing with, the O2 sensor "knows" how much fuel is needed. If there's O2 left in the exhaust, the sensor says "too lean;" if there's no O2 left, the sensor says "too rich."

Yes, providing there is enough "adjustment range" in the system for the Lamba sensor to "pull" the system to stoichiometric. There is a limit to how much the Lamda sensor can correct the basic fuel map, so it is possible that in some systems it may not be able to fully correct a mixture problem caused by using a fuel other than pure gasoline.

 

My old BMW320i that I used to have (with a KE-Jetronic system), came with a warning not to use gasohol, primarly because its Lamda sensor had only a very narrow range of correction of the basic mixture.

 

Maybe newer cars can correct over a broader range.

 

Bob.

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Joe Frickin' Friday
Yes, providing there is enough "adjustment range" in the system for the Lamba sensor to "pull" the system to stoichiometric. There is a limit to how much the Lamda sensor can correct the basic fuel map, so it is possible that in some systems it may not be able to fully correct a mixture problem caused by using a fuel other than pure gasoline.

 

I think that apart from injector capacity, that's the key difference between a FFV and a non-FFV: the FFV is smart enough so that when the O2 sensor is calling for huge departures from the standard fuel map, it realizes that the fuel composition has changed and it should switch to a different fuel map, or tweak some variable that represents fuel composition (however it's implemented in the software; Knappy?).

 

One of the error codes that the early oilhead Motronic (on the 1100's) can put out is something to do with excessively large correction factors being called for by the O2 sensor.

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While not much of a tree hugger, I hate being controlled by overseas interests with gas. Therein lies my hope that E85 gets bigger: So it's grown here, renewable, and I doubt we'll have to go to war with a corn farmer in Kansas over it's supply!

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At a stoichiometric mixture - whether of gasoline, ethanol, or a blend of the two - all of the available oxygen (including any provided by the fuel itself) is consumed in the combustion reaction. So no matter what fuel you're dealing with, the O2 sensor "knows" how much fuel is needed. If there's O2 left in the exhaust, the sensor says "too lean;" if there's no O2 left, the sensor says "too rich."

 

Apart from materials compatibility, the fuel system needs to be sized to deliver the greater quantity of ethanol required to produce a stoichiometric mixture. For gasoline, the stoich. A/F ratio is about 14.6 to 1; for ethanol, it's more like 9 to 1, meaning that on pure ethanol, the fuel system has to deliver about 60% more fuel than when running on gasoline. It needs bigger injectors, and fuel delivery maps that are calibrated for ethanol.

 

Mitch,

 

My understanding is that if excess oxygen shows up in the exhaust, the mixture is too rich (due to oxygenates in the fuel) and the opposite for lean. But the system would have to “calibrated” to the fuel so as to make corrections at the right proportions otherwise the dreaded surging or hunting might occur.

 

Am I wrong?

 

I agree that more fuel is required to maintain correct stoichiometry for fuels with high proportions of ethanol. But, most FI systems would be able to handle E85 without changing injectors to provide higher fuel delivery capabilities, no?

 

Help me understand here….I’m still in FI kindergarten.

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WOW!! eek.gif You guys are REALLY thorough and it sounds to me like the stuff is more trouble than it's worth. dopeslap.gif It also sounds like it's only in it's infancy and in the future could be a very positive thing. Right now it sounds like something I should avoid.

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Paul Mihalka

Here in Mid-Atlantic it is official to switch from MTBE to ethanol and make the gas E10. It is already announced that that change by itself will INCREASE gas prices 10 to 15c a gal, because there is not enough ethanol available. Go figure... frown.gif

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My understanding is that if excess oxygen shows up in the exhaust, the mixture is too rich (due to oxygenates in the fuel) and the opposite for lean. But the system would have to “calibrated” to the fuel so as to make corrections at the right proportions otherwise the dreaded surging or hunting might occur.

 

It is not "oxygenates" that supply extra oxygen. It is simply the single oxygen atom that is part of the hydroxyl radical in ethanol (formula: C2H5OH).

 

Note also that it is not JUST the presence of the single oxygen atom that upsets the FI system calibration. A significant contributor to the problem is that there is different ratio of carbon atoms compared to hydrogen atoms in ethanol, than there is in gasoline. One carbon atom requires 2 oxygen atoms for combustion to CO2, whereas for hydrogen, 2 hydrogen atoms require only one oxygen for combustion to H2O.

 

If the ratio of carbon to hydrogen in a fuel is different than for gasoline (nominally iso-octane, C8H18), then the fuel-oxygen ratio needs to change.

 

Bob.

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Here in Mid-Atlantic it is official to switch from MTBE to ethanol and make the gas E10. It is already announced that that change by itself will INCREASE gas prices 10 to 15c a gal, because there is not enough ethanol available. Go figure... frown.gif

 

Agreed. Here in NJ, my local BP station has a sticker on the pump for as long as I can remember which states "May contain up to 10% Ethanol". Cost for super unleaded 93 octane is $2.99 today, I expect that to go up again and again over the summer. I'm happy my bike is getting 45mpg and my 20mpg Audi is sitting in the driveway alot these days.

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I think that apart from injector capacity, that's the key difference between a FFV and a non-FFV: the FFV is smart enough so that when the O2 sensor is calling for huge departures from the standard fuel map, it realizes that the fuel composition has changed and it should switch to a different fuel map, or tweak some variable that represents fuel composition
Our FFV (2000 Ranger PU) also has some type of sensor in the fuel line that senses the % of alcohol in the fuel and sends that info to the engine mgmt. computer also.
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