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Thread: Running on Auto...fuel that is

  1. #1
    Senior Member RanRan's Avatar
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    Default Running on Auto...fuel that is

    What's the problem with running these engines (forever) on auto fuel, i.e. lead-free? Lead was always a funky, cheap way of adding a little 'lubrication' and octane (pinging), before synthetic oils were invented. When I purchase my CC, I'm going to run it on auto gas after break-in. What do you think about that?

    Is anyone running auto gas? I assume then, that you are also running a good synthetic oil. What are your oil temps like? When you pull your plugs, what do they look like?

    Thanks to Randy L (the GM here), for some excellent articles on oil (on another thread), I have come to understand this: If you are running on Autogas you must use a synthetic oil. And if you wish to use synthetic oil you must run Autogas.

    If you must use that nasty leaded stuff (now and then) with synthetic oil - there's no harm done - you'll just have to change the oil more often. By their current design, synthetics don't like lead.

    There you go. Have at it. Tell me where I'm wrong. (And can't fly for a third of the cost of what is commonly paid) ;-)

    Ran
    Last edited by RanRan; 01-26-2011 at 05:50 PM.

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    Senior Member randylervold's Avatar
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    Default Re: Running on Auto...fuel that is

    Ran, there is one reason that CC will likely never approve mogas for our aircraft... ETHANOL.
    Randy Lervold

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    Default Re: Running on Auto...fuel that is

    And.....with auto gas now going to 15% ethanol, it is going to get rapidly worse. At the current 10% ethanol, I sometimes have trouble in my motorcycle and in my 86 Chevy pickup with moisture. Also ethanol will eventually eat a fuel system not designed for it. Think of the additives in auto fuel that have no place in the function of an aero engine, they contribute to build up and pre-ignition in an aircraft engine which will shorten life cycle.

    Ethanol is a magnet for water. Buying fuel is a major cost, but buying fuel that additionally attracts water by design is not good to say the least.

    Aviation may be forced to abide by this line of thinking (ethanol), but in the long run it will introduce additional costs that will smite the population of GA aviation in general. I see no good things for me in its future.
    Last edited by Frank; 01-27-2011 at 10:46 AM.

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    Senior Member randylervold's Avatar
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    Default Re: Running on Auto...fuel that is

    I'm not so concerned with our fuel system materials compatibility, I believe they are, but here's the dealbreaker scenario....

    Your plane is filled with mogas/ethanol and sits outside for a month or so. Condensation accumulates every day in your half full tanks as they heat up and cool down. After a month or so a fair amount of water has accumulated. The ethanol absorbs it up to a point and you don't see it when you diligently sump your tanks. But your plane has now passed that point where the ethanol can hold the water and it is separating, "phase separation" it's called. It's 40° outside and you takeoff over the mountains. The OAT quickly falls below freezing and the now-separated water that has now been sucked into the fuel line freezes. Your engine quits over nasty mountains and though you're a superb pilot you just can't make a survivable landing on the side of a mountain and you are killed. The NTSB determines the cause and your widow now sues CC for approving autofuel when this is a known failure mode. We are now out of business, the fleet is orphaned, and we can't make great airplanes anymore. So, where's the upside in CC approving auto fuel in the CC340?
    Randy Lervold

  5. #5
    Senior Member RanRan's Avatar
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    Default Re: Running on Auto...fuel that is

    Quote Originally Posted by Frank View Post
    And.....with auto gas now going to 15% ethanol, it is going to get rapidly worse. At the current 10% ethanol, I sometimes have trouble in my motorcycle and in my 86 Chevy pickup with moisture. Also ethanol will eventually eat a fuel system not designed for it. Think of the additives in auto fuel that have no place in the function of an aero engine, they contribute to build up and pre-ignition in an aircraft engine which will shorten life cycle.

    Ethanol is a magnet for water. Buying fuel is a major cost, but buying fuel that additionally attracts water by design is not good to say the least.

    Aviation may be forced to abide by this line of thinking (ethanol), but in the long run it will introduce additional costs that will smite the population of GA aviation in general. I see no good things for me in its future.
    They run mogas in Europe with no problem. All modern aircraft engines and fuel systems are made for ethanol - that's why CC planes are STCed for mogas. Lastly, ethanol does mix with whatever water condenses in the fuel tank (it ain't much) - and makes the water BURNABLE. That's a beautiful thing.

  6. #6
    Senior Member RanRan's Avatar
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    Default Re: Running on Auto...fuel that is

    Quote Originally Posted by randylervold View Post
    Your plane is filled with mogas/ethanol and sits outside for a month or so. Condensation accumulates every day in your half full tanks as they heat up and cool down.
    Playing devil's advocate here. ;-)

    So you fill the tanks up before you take off - that takes care of phase separation with the mogas. If you're running avgas, you still have to worry about the water.

    To be fair, I did have your scenario happen to me with my car (1/8 tank on a frigid day following warm day/s) - but I couldn't even get to warm-up temps before conking out. Filling it up solved the problem. But it kept pumping - even if it was phase separation slush.

    There's caveats for either fuel. And good habits to follow for both.

    So I don't see it as a safety issue - the avgas guy could top off and forget to check for water or do an inadequate job of checking.

    Ran
    Last edited by RanRan; 01-27-2011 at 12:43 PM.

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    Default Re: Running on Auto...fuel that is

    AOPA ePILOT special report dated 26 Jan. 2011:

    "FAA's approach and engagement on unleaded avgas".

    http://tinyurl.com/5uudv8r

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    Senior Member RanRan's Avatar
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    Default Re: Running on Auto...fuel that is

    Quote Originally Posted by Frank View Post
    AOPA ePILOT special report dated 26 Jan. 2011:

    "FAA's approach and engagement on unleaded avgas".

    http://tinyurl.com/5uudv8r
    Thanks Frank. The LSA idea was to make aviation more affordable and easy. The old idea that if you can afford an airplane, you can afford $6-7 dollars a gallon for fuel does not hold true any more. The LSA market will die out if fuel costs add another 200 to 300 dollars per WEEK to the cost of ownership.

    Mogas runs a high-performance Corvette engine just fine. Add one little thing to an Airplane engine and you can fly with the same piece of mind. Can you guess what it is?

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    Default Re: Running on Auto...fuel that is

    Quote Originally Posted by RanRan View Post
    Thanks Frank. The LSA idea was to make aviation more affordable and easy. The old idea that if you can afford an airplane, you can afford $6-7 dollars a gallon for fuel does not hold true any more. The LSA market will die out if fuel costs add another 200 to 300 dollars per WEEK to the cost of ownership.

    Mogas runs a high-performance Corvette engine just fine. Add one little thing to an Airplane engine and you can fly with the same piece of mind. Can you guess what it is?
    I really have not a clue.....but let's wait on the answer ...and see if others might know.

  10. #10
    Senior Member RanRan's Avatar
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    Default Re: Running on Auto...fuel that is

    Quote Originally Posted by Frank View Post
    I really have not a clue.....but let's wait on the answer ...and see if others might know.
    That sounds like fun. I could give you a hint: it performs the same vitally important task for either fuel. But this is aviation - so don't look there.

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