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What about fuel types & gas mileage?

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  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,957
    I would think you'd need to also advance engine timing at altitude to maintain the same fuel mileage. But perhaps the re-calibration of the fuel mixture negates that necessity?

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  • shiposhipo Posts: 9,152
    General aviation engines have fixed timing and zero ability to adjust it one bit from where the factory set it and where the FAA certified it.

    That said, stoichiometric is stoichiometric is stoichiometric. Given the proper air and fuel ratio, the mixture will burn exactly the same regardless of whether the aircraft is at a density altitude of sea-level or 17,000 feet. ;-)

    Best Regards,
    Shipo
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,957
    I think that pre-computer, automobiles required a bump in timing (timing advance) to compensate for the carburator's inability to adjust proper fuel mixture at altitude.

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  • shiposhipo Posts: 9,152
    Hmmm, thinking back to the 1970s (when I turned a wrench to make a living), I don't remember tweaking the timing to help cars deal with altitude, that said, I do remember rejetting any number of carburetors.

    Best Regards,
    Shipo
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,957
    Well the bump in timing was great for cars that were going up 5,000 feet for a few days--you wouldn't want to re-jet just for that.

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  • shiposhipo Posts: 9,152
    Ahhh, got it. If one of the cars I worked on in San Diego was only heading up to the 5,000 foot mark for a few days, I wouldn't bother touching the car, however, the bump in timing doesn't sound like such a bad idea. The only cars I rejetted were the ones that were heading up into the Rockies or the Sierras to stay (or at least to stay for a considerable length of time).

    Best Regards,
    Shipo
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,957
    Oh advancing the timing definitely works--dramatic improvement in fact.

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  • dchen2003dchen2003 Posts: 34
    I heard some people say some of the gas is not 100% gasoline but with 10% alcohol. Because alcohol has lower energy density that cause lower MPG. Does any one know What brand of gas station use this kind of blend fuel? And what gas station has the best fuel based on your experience.

    Thank You
  • shiposhipo Posts: 9,152
    Typically the areas that mandate oxygenated fuels (i.e. most metropolitan areas) also mandate E10 (gasoline with 10% ethanol). If you live in such an area you're out of luck as 100% gasoline cannot be had for love nor money. ;-)

    Best Regards,
    Shipo
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,528
    Is alcohol being used in lots of areas now? I thought after he Katrina mess the gov advocated using as much ethanol as possible.
  • shiposhipo Posts: 9,152
    The proper name for "Ethanol" is "Ethyl Alcohol". Same same.

    Best Regards,
    Shipo
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,528
    >The proper name for "Ethanol" is "Ethyl Alcohol". Same same.

    Ethanol and ethyl alcohol are the same chemical, C2H5OH.

    Are you thinking you are correcting me on something? I don't understand the purpose of your post.
  • shiposhipo Posts: 9,152
    Hmmm, maybe I misunderstood the language of your first post:

    "Is alcohol being used in lots of areas now? I thought after he Katrina mess the gov advocated using as much ethanol as possible."

    My bad if I got the incorrect impression, but my reading of the above suggests that your language indicated that you were drawing a line between Alcohol and Ethanol. Please accept my apology if I read you incorrectly. :blush:

    Best Regards,
    Shipo
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,528
    I didn't word the first post well to say what I had in my mind. You're right that it's not clear.

    I thought after the Katrina fiasco they encouraged putting alcohol (ethanol) into more and more of the fuel across the country to increase the usage of ethanol (read: improve profit for big companies manufacturing ethanol from corn). I noticed that our pumps used to have a sticker indicating the content COULD contain up to 10% ethanol from some companies who included the ethanol in previous years. Those disappeared. I've not yet tested the name brands for ethanol in our area. I avoid those brands who include ethanol as a technique for reducing quality.

    I heard a tanker driver say that only 5 Shell stations used pure gasoline in his delivery area. It used to be Speedway, Clark, and other off brands that had ethanol disclaimers on their pumps in this area of Ohio. The use of ethanol reduced the cost per galloon so these stations sold ethanol gas at a price equal to the regular gasoline and made a higher profit per gallon because the ethanol doesn't pay state tax and maybe federal tax.

    I believe the ethanol gasoline gives lower miles per gallon.
  • shiposhipo Posts: 9,152
    Hmmm, I'm not sure of the politics regarding national usage of ethanol (I know they're there I just haven't gotten involved), however, I do know that the EPA has mandated oxygenated fuel in most if not all metropolitan areas around the country, and since MTBE has been found to be particularly nasty stuff, ethanol is now the preferred oxygenate.

    Here in the Boston area we had no ethanol infrastructure for a long time and as such we were allowed to get away with non ethanol fuels until about a year ago. When they hit, both of our cars immediately started returning about 5% fewer miles per gallon. Grrr.

    Best Regards,
    Shipo
  • imidazol97imidazol97 Crossroads of America: I70 & I75Posts: 18,528
    Hawaii legislation

    This states that 50% of fuel in US contains alcohol.

    governors' conference

    This states a minimum amount of renewable fuels (ethanol) that will be used. Maybe this was the required ethanol use that I was recalling. Rather than percent of fuel needing to be alcohol (ethanol) it states a quantity of ethanol to be used.
  • shiposhipo Posts: 9,152
    Good stuff, thanks for the links. ;-)

    An interesting point. None of the New England states sent a representative, not one. Hmmmm...

    Best Regards,
    Shipo
  • What about Chevron/Texaco gas stations that use Techron concentrate
    I noticed that i get better Gas Mileage than from Ethanol Based Gas.

    Does anyone agree or disagree?
  • shiposhipo Posts: 9,152
    You're mixing your additives so to speak.

    A few points:
    - Ethanol is an blending agent that is used as an oxygenate
    - Techron is Chevron's additive package to help keep fuel systems and the upper end of the engine clean
    - The two are not mutually exclusive
    - If you find fuel that is not an Ethanol blend it is almost a sure bet that your car will get better mileage with it (Techron or no) as compared to when you are running E10 (Techron or no).

    Best Regards,
    Shipo
  • jl49jl49 Posts: 33
    I bought a 2007 Jeep Compass just recently. I'm getting around 14 to 15 mpg's which is not the 23 to 26 mpg's advertised on the window sticker. Dealer claims it's the oil companies putting more ethanol in gas which is lowering the mpg's. What can I do?
  • kiawahkiawah Posts: 3,666
    Hope that when your vehicle breaks in with additional mileage, that it will loosen up and you'll get better mileage.
  • First use up all the gas in your tank until empty.
    Then I suggest switching to chevron/Texaco instead
    Keep away from no-brand gas station. I learnt the hard way (from buying bad gas)
  • jl49jl49 Posts: 33
    I have 400 miles on it right now. At what mileage is it officially broken in?
  • kiawahkiawah Posts: 3,666
    Should call that out in your owners manual. Everyone has a different opinion on this, as well. Personally, I believe by 1500 miles the vehicle is pretty well there, I consider it done by the first regular oil change.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,957
    Yeah I think the engine is "broken in" fairly quickly but your mileage may continue to improve even up to 10,000 miles. After 10K though, your mileage is pretty much carved in stone.

    Be sure to check tire pressure; also, if you regularly drive at over 70 mph, you aren't going to get the advertised MPG.

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  • Missouri has required 10% Ethanol in all grades since January 2008, although some gas stations were offering it in at least one grade a couple of years before the mandate kicked it. I've seen a noticeable (~3 MPG) drop in mileage on my 2004 Isuzu Axiom since then. So I'm wondering if direct injection engines are more sensitive to E10 than other engine types.
  • miccellmiccell Posts: 1
    Sorry to change the conversation, however my casual reading tells me that Ethanol in all grades is the least efficient bio-fuel thus far tested, and is in direct competition with humans for a ready available food source. Ethanol as fuel source should be removed our Lexicon. One day we all will regret the use of corn in this way.
  • shiposhipo Posts: 9,152
    I quit reading that dissertation after a couiple of paragraphs due to incorrect language and incorrect information. :P
  • vrmvrm Posts: 303
    I believe Acura recommeds premium gasoline for the MDX.
    However, I would like to use regular gasoline.

    I need feedback form other owners who are doing this or may haev done this in the past. Any degradation in engine performance or pinging?

    Thanks!
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