mileage jumps 10%

I love when they end ethanol in gasoline in May.

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rick++ wrote:

When do they switch back?
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rick++ wrote:

I've found very little difference if you buy a reputable product such as Shell, etc.
Get your gas from the favorite local discount outfit? Yep, you'll see a big drop during ethanol season. Murphy Oil at Wallyworld can really suck...
BTDT
JT
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On Thu, 13 May 2010 20:35:38 -0500, Grumpy AuContraire

Would that be because they use crappy ethanol in discount stations, so removing the ethanol allows the mileage to jump? Or reputable gas is not much better than ethanol so removing the ethanol has little effect?
I don't notice much difference myself, but I don't keep very good stats. My 91 Accord gets around 21-22 in mostly local driving using Gulf or Citco mostly.
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wrote:

Like you, I've never seen much of a different between fuel blends. I do have a friend who claims that he can tell a difference between the North Carolina and Ohio gasoline blends (depending on the location different jurisdictions have different fuel requirements - see http://www.exxon.com/USA-English/Files/US%20Gasoline%20Map%20100102.pdf ) .
He claims that if he fills up in North Caroline that he can make it to his destination in Ohio on one tank of fuel, but that when he fills up in Ohio, he can't make it home without stopping for fuel around 70 miles from home. I've never been able to understand why this would be true, unless he buys gas in NC without ethanol and with ethanol in Ohio - but even then it doesn't seem the different would be so dramatic. It is a 500 mile trip. He claims to average 32 mpg on the trip to Ohio. The car has 18.5 gallon tank. So it seems that going on the trip to Ohio he arrives with around three gallons to spare. Assuming he refuels coming back with 1.5 gallons in the tank, it seems his return mileage must be around 25 mpg. This is a 20% decrease. It does not seem possible. Maybe when he gets to Ohio, he only has 0.5 gallons left and his actual to Ohio mileage is then around 28 mpg. And coming back, he knows he cannot make it home, so he stops early and really is getting 27 mpg. This might be consistent with changes in blends, but I still have a hard time reconciling his claim. I've always assumed other factors were involved - possibly caution. I would estimate, the difference in range between "pure" gasoline and a 10% ethanol blend would have been about 15 miles (500 miles with pure gasoline, 485 with the blend). Maybe a 15 mile difference is enough to trigger a stop.
In my opinion, no one should see much of a jump if they are driving a modern fuel injected car. Ethanol has 85% as much energy as typical gasoline. So it you have 10% ethanol in the gas you buy, at worst the mix (90% Gasoline + 10% Ethanol) will have 98.5% as much energy as typical "pure" gasoline. Modern cars with properly functioning feedback system can easily adjust to this mix, so at worst you should see a 3% decrease in mileage (again assuming a "modern" car). A 3% variation in fuel economy is in the noise range for anyone not doing carefully controlled economy measurements. It is overwhelmed by many other factors. People who do one tank averages have no chance of detecting the different. Even averaging fuel economy over multiple tanks of gas is unlikely to reliably detect the difference.
Of course all this goes out the window if you have an older car with a carburetor. The gasoline / ethanol blend can wreak havoc with the fuel economy on those vehicles (not to mention what it can do to fuel lines, fuel tanks, and other fuel system parts).
Ed
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On 05/14/2010 07:38 AM, C. E. White wrote:

no, it's 76,100 BTU/gal vs 114,000 BTU/gal.
http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent .

that's average. legal is between 5-15%.

it's about 2% average. but that's a bullshit 2% when the taxpayer pays to subsidize production, the taxpayer gives tax breaks to the oil companies for using it, pays more at the pump AND after all that, gets lower mpg's.

that is true. had to re-o-ring the injectors on my civic because of it. and mtbe prior to that.

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wrote:

I like wikipedia as well, however other sources list different values. Depending on where you look and whether you are looking at the lower or higher heating value, the Department of Energy claims the energy content of ethanol is as high as 83,333 British thermal units (Btu) per gallon (http://www.eia.doe.gov/oiaf/ethanol3.html ). I've seen other claim has high as 84,600 (http://en.wikipedia.org/wiki/Gasoline ). Quotes for energy content for gasoline are all over the place as well. A chart at http://www.afdc.energy.gov/afdc/pdfs/afv_info.pdf lists the energy content of gasoline as varying from 109,000, to 125,000. Depending on your prespective you can claim that ethonol has a little as 61% as much energy as gasoline or as much as 78%. Ive seen the 2/3 figure (this is 76,100/114,000) many times, but I think it is on the low side. The 85% number I used was just plaing wrong - sorry. I don't even recall where I got it (probably a mistake on my part). To be fair, it probably best to stick to one source for comparison. The Department of Energy has a Fuel Properties Comparison Web Page at http://www.afdc.energy.gov/afdc/fuels/properties.html . This site lists the lower heating value for gasoline as 116,090 BTU. For Ethanol they list 76,330. Both of these are close to the wikipedia article you cited, so I'll go with your numbers. This implies Ethanol has 66% as much energy as gasoline. This would imply that E10 (10% Ethanol blended into gasoline) should have around 96.6% as much energy as straight gasoline (instead of the 98.5% which I claimed).

I've never seen any indication that gas I by has more that 10% ethanol (well except for a couple of stations that sell E85). Is 15% ethanol common?

I was under the impression that at least in some areas, the ethanol was mandated to be used becasue of clean air regulations. In my area, it is not, but stations still carry it. I beleive they have to label the content - or do they? I buy gas at Costco and somethimes they have a sticker on the pumps that says the fuel may contain up to 10% ethanol and somethimes they peel the stickers off. The BP station doesn't have a sticker. The Murphy stations used to have a sticker, but I haven't bought any gas there in a long time. I keep a gas mileage log book, nad can't really see a difference in mileage related to brand. I quit worrying about ethanol, at least as long as they keep it to less than 10%. Both my Fords claim I should use gasoline blended with 10% ethanol or LESS. I'll have to keep my eye's out for that 15% ethanol fuel.

I saw a Jensen-Healey burn up becasue ethanol ate a natural rubber tee that connected the two carburettors to the fuel supply.....
Fortuatley modern cars seem to be able to handle ethanol without a problem.
Ed
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On 05/14/2010 11:34 AM, C. E. White wrote:

so let's say you're paying $2.75 a gallon. that means you're only getting $2.65's worth of gas for your $2.75. if you think that doesn't matter, you can personally pay me $2.75 for only $2.65's worth of gas if you like ed. i'll take checks and sell you as much as you can use.

i don't know if it's "common" ed, but from what i understand from spending hours reading through dupont's o-ring material data, 15% is the legal max spread for "10% blend". i guess they're interested in knowing that stuff since their product has to withstand it.
besides, what is "10%" anyway? it's certainly not 10.000%. and every little taxpayer-subsidized drop of extra ethanol keeps you buying just a little more gasoline. 2% of our average daily consumption of 386 million gallons is 7.7 million gallons. at $2.75 per gallon, that's $7.7 billion dollars a year extra sucked out of consumers wallets/purses - ignoring the additional tax/subsidy costs of course. like many producers of many materials, it only needs a fractional massage of the delivery tolerances to yield millions of extra dollars in annual revenue.

that is the bullshit fed to the proles [and maybe the idiot politicals that don't know what the heck they're doing with this stuff. maybe.], but it's a scam. it doesn't help combustion, or combustion cleanliness - all it does is "increase" measured "oxygen" on exit. and that is bullshit because the "oxygen" bound into the alcohol molecule does not yield energy in the combustion process.
ethane = 22,400 BTU/lb ethanol = 12,800 BTU/lb
that's the effect of adding one little oxygen atom.

why don't you look for the weights and measures sticker instead? it's more informative if you don't know what the ethanol stuff means.

no, you saw a poorly maintained vehicle burn. all hoses should be monitored for condition and replaced as they age. that hose didn't magically disintegrate instantly on first contact. and if they were natural rubber, they were the wrong material and not original.

for a while. it appears to be a real problem for seal polymers.

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On 05/14/10 10:38, C. E. White wrote:

Uphill vs downhill?
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dgk wrote:

Well, I'm currently driving an '82 Civic 1500 automatic and average in the mid 30 mpg range in mixed driving. A couple of times I went to the off brand stuff this winter and ended up in the low 30mpg range.
What really grinds my butt is the fact that here in the Austin, TX metro area, the local "authorities" have imposed the ethanol requirement, not the feds or state since air quality has never come close to violating federal standards. In fact, the worst air quality around here occurs every spring from agricultural burning in Yucatan, messyco...
JT
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On 5/13/2010 8:35 PM, Grumpy AuContraire wrote:

The physics of it are pretty plain. There is simply much more energy stored in gasoline than in ethanol. No amount of ethanol quality will change physics.
Michael
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On 5/13/2010 11:20 AM, rick++ wrote:

We have a single station in town that is independent. They sell ethanol free gas all year round. I just love getting the better mileage.
Michael
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