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Originally Posted by 534BC
Butane is a liquid (under pressure) and a gas at ambiant temp and pressure, like propane only the vapor pressure is less.
I suppose a distinction should be made about the two alcohols and also many different brands will change for various reasons.
Methanol is added in winter for fuel line anti-freeze. It way under 1% and will never be noticed for mpg or hp sake.
Ethanol is added at (up to) 10% and is used all year round, but may not be used from time to time, but not haveing anything to do with winter/summer. When ethanol blend fuel is used the methanol is not added even in winter.
I hear some people claiming lower mileage with ethanol, but I would be hard pressed to be able to tell you the difference if you filled my tank and made me guess which fuel you had used. I think I'd have better luck smelling it than one or two tanks of mpg tests. Theoretically the ethanol blend should have a few % lower mpg and 85% ethanol is claimed to get 10% less mpg. This I do believe,,,,
The truth is that over 99% of people probably have no idea what gas they're using and even if they do know, it doesn't make any difference anyways.
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If butane is only a liquid under pressure, than why are you saying it is the difference when you put in a non pressurized gas tank and it turns into a gas?
There is a difference in performance noted by several drivers and this is no fairy tale like you are making it out to be.
The heating value also varies by grade and by season. On average, the heating value of premium-grade gasoline is about 0.7 percent higher than regular-grade because premium-grade, in general, contains more aromatic hydrocarbons — the class of hydrocarbons with the highest densities. The heating value of winter gasoline is about 1.5 percent lower than summer gasoline because winter gasoline contains more volatile, less dense hydrocarbons.
Oxygenated gasolines, which are required in some areas of the U.S, have lower heating values because the heating values of the oxygenate components are lower than those of the hydrocarbons they displace. The percentage decrease in heating value is close to the mass percent oxygen in the gasoline. For example, gasoline in carbon monoxide nonattainment areas must be oxygenated to a minimum of 2.7 mass % oxygen during four or five winter months.6
Footnotes
6 Nonattainment area is an EPA designation for an area where an air pollutant, carbon monoxide in this case, exceeds the limit established by the National Ambient Air Quality Standards more often than allowed.
As a result, its heating value is about 2.7 percent lower than conventional gasoline. Federal reformulated gasoline and California Phase 3 reformulated gasoline in federal reformulated gasoline areas must be oxygenated year-round to an average oxygen content of about 2 mass %. As a result, their heating values are about 2 percent lower than that of conventional gasoline. In addition, California Phase 3 reformulated gasoline sets some limits on distillation temperatures and aromatics content, which have the secondary effect of lowering the density of the fuel compared to conventional gasoline. This reduces the heating value by about another 1 percent.
http://www.chevron.com/products/prod...rmance/pg4.asp
Ethanol has
not been the oxygenate of choice for summer RFGs because the volatility increase makes it more difficult to meet the very tight vapor pressure limits of these gasolines. Now, with many RFG areas banning MTBE, more volatile hydrocarbons will have to be removed at the refinery to make RBOB.
http://www.chevron.com/products/prod...ormance_issues
Oxygenates are fuel additives (alcohols and ethers) that contain oxygen which can boost gasoline's octane quality, enhance combustion, and reduce exhaust emissions. The term oxygenated gasoline most commonly refers to the wintertime program that reduces emissions of carbon monoxide (CO) from motor vehicles. Although required by the federal Clean Air Act, winter oxygenated gasoline programs are implemented by the states. This section provides information about oxygenated gasoline, winter oxygenated gasoline areas, oxygenates (such as ethanol and MTBE), and health effects testing of oxygenates.
http://www.epa.gov/otaq/oxygenate.htm
Affects on fuel economy
http://www.epa.gov/otaq/regs/fuels/ostp-3.pdf
Oxygenated Gasolines and Fuel Economy
http://www.chevron.com/products/prod...etin/oxy-fuel/
Oxygenated Gasoline
Chemistry
Oxygenated gasoline is a mixture of conventional hydrocarbon-based gasoline and one or more oxygenates. Oxygenates are combustible liquids made up of carbon, hydrogen, and oxygen. All the current oxygenates belong to one of two classes of organic molecules: alcohols and ethers.1
Footnotes
1 The word ether reminds many people of the anesthetic. Although the anesthetic commonly is called ether, its correct chemical name is diethyl ether (CH3CH2OCH2CH3). It is not used as a gasoline oxygenate because it is too volatile.
In alcohols, a hydrocarbon group and a hydrogen atom are bonded to an oxygen atom: R-O-H, where "R" represents the hydrocarbon group. All alcohols contain the "OH" atom pair. In ethers, two hydrocarbon groups are bonded to an oxygen atom; the groups may be the same or different: R-O-R or R-O-R'.
This is from Chevron themselves stating that they use alcohol as an oxygenate in the winter months which has less heat per unit and therefore more of it has to be used for the same power unit production.
If you want to argue with the gas manufacturers and the government, go right ahead. Butane is a gas at our operating temperatures and therefore has no bearing seeing it will evaporate out of the fuel during production, transportation and filling our tanks.
That is if it is even a constituent.