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Thread: Flex Fuel engines

  1. #1

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    Flex Fuel engines

    I know thw Rotax 912 will burn up to 10% Eth are there any others? Is anyone with a o-200 or o-235 burning up to 10% Eth?

  2. #2
    steveinindy's Avatar
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    Not that I'm aware but you might try finding a sales rep for the various engine manufacturers you are considering and ask them. That would be your best source of information rather than going off of hearsay, vitriol and anecdotal reports on an internet forum. If a stock engine is going to tolerate the presence of alcohol without serious issue, the manufacturer will be the one to know about it first in most cases.


    That said, I will point out that mentioning any tolerance or acceptance of ethanol in fuel tends to produce a very marked reaction around here. Put on your asbestos undies and buckle up my friend. This might get pretty rough.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



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    FlyingRon's Avatar
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    Well the engine manufacturers don't even admit to wanting you to be able to run auto gas in them.
    If you're in a certificated bird, neither of the STCs for auto fuel allow any amount of ethanol.

    If you are talking the academic exercise of putting it in your experimental aircraft, then it's up to you to be the engineer and test pilot. I only have passing interest in this in the Aviation area but I'm a boater so I can tell you what I've learned there. E10 while taking blame for a lot of ills really doesn't seem to be that big of a problem especially in an area where you can expect a lot of hydroscopic pickup like in a boat. E85 however is another story entirely. There's definitely issues with corrosion and such (which is why even the cars the stuff is designed for need to be specifically "Flex Fuel" vehicles.

    I'm not even going to get started on the ecological and economic disaster that ethanol currently is. Suffice it to say, the only ones really benefiting from the current system is Archer Daniels Midland.

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    10% really isn't properly considered "flex fuel"; it's just an additive (many would say contaminant). E85, now that's a different fuel requiring a flex fuel engine.

    The big problem is compatibility of ethanol with the rubber parts in the engine and fuel system, i.e. seals, hoses, etc. Rotax uses ethanol resistant rubber compounds in their newer engines, but the older engines don't... and because they're certificated, it's difficult for the manufacturer to change them.

    Corrosion is another issue, but not so much on an engine that's run frequently.

  5. #5
    steveinindy's Avatar
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    Well the engine manufacturers don't even admit to wanting you to be able to run auto gas in them.
    If you're in a certificated bird, neither of the STCs for auto fuel allow any amount of ethanol.
    If it's not supposed to have auto gas run through it, why are you trying to use it then? That's my biggest question to the folks who point at the word "certificated" and go "See! That doesn't apply to us".

    If you are talking the academic exercise of putting it in your experimental aircraft, then it's up to you to be the engineer and test pilot.
    The problem is that most homebuilders aren't exactly the best qualified to be doing such testing since a lot of us get so excited that our creation is airborne that even the basic flight testing gets put aside in place of a glorified solo joyride.

    There's definitely issues with corrosion and such (which is why even the cars the stuff is designed for need to be specifically "Flex Fuel" vehicles.
    No offense intended but...

    Imagine that, a vehicle designed for the fuel it will be using. I never really thought of that being a good idea.


    I'm not even going to get started on the ecological and economic disaster that ethanol currently is. Suffice it to say, the only ones really benefiting from the current system is Archer Daniels Midland.
    Thanks for leaving it at that. It's the political BS that gets dragged in whenever this gets brought up that makes these threads more or less pointless because it turns into a big circle jerk.

    Corrosion is another issue, but not so much on an engine that's run frequently.
    Which is to say that it's a significant problem for most GA aircraft because of the infrequency with which people fly. I often wonder how many of these problems could be averted simply by pulling the plane out of the hangar every (or every other) weekend and running it for a few minutes to get the oil circulated through the engine.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  6. #6

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    . Put on your asbestos undies and buckle up my friend. This might get pretty rough.[/QUOTE]

    ooooppppppsssss! was just a passing thought that slipped out.

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    Quote Originally Posted by FlyingRon View Post
    Well the engine manufacturers don't even admit to wanting you to be able to run auto gas in them.
    well, not QUITE true any more: Lycoming Service Instruction No. 1070Q

    http://www.google.com/url?sa=t&rct=j...htt0kw&cad=rja

    see also:

    http://www.fuelandfiber.com/Archive/...E85/age85.html

    http://www.google.com/url?sa=t&rct=j...gx113A&cad=rja

    http://www.google.com/url?sa=t&rct=j...92BXNw&cad=rja

    http://www.txskyways.com/about_us.htm

    your mileage may vary.

  8. #8
    FlyingRon's Avatar
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    Quote Originally Posted by steveinindy View Post
    If it's not supposed to have auto gas run through it, why are you trying to use it then? That's my biggest question to the folks who point at the word "certificated" and go "See! That doesn't apply to us".
    I don't know what point you're trying to make. People have been running AutoFuel in airplanes for years now even though Lycoming and Continental do not recommend it. The FAA approves it and it is arguably better for those planes that were designed for 80 octane than trying to run them on 100LL avgas. Similarly the manufacturers wouldn't probalby admit that you can run non-factory parts on the engine, yet the FAA approves them and people have been flying legally and safely for 60-70 years with aftermark stuff.

    Which is to say that it's a significant problem for most GA aircraft because of the infrequency with which people fly. I often wonder how many of these problems could be averted simply by pulling the plane out of the hangar every (or every other) weekend and running it for a few minutes to get the oil circulated through the engine.
    While I agree with you that inactivity is an issue (and this is certainly a problem with autofuel versus avgas, avgas is designed for this). It's n ot going to help with E85. Running the engine isn't going to keep the fuel tanks and other components from corroding. There's no "oil" running through any of those parts. The only place there is likely to be oil and fuel mixing togother ought not to have fuel "sitting" in it while parked.

  9. #9
    steveinindy's Avatar
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    The FAA approves it and it is arguably better for those planes that were designed for 80 octane than trying to run them on 100LL avgas
    This is technically correct. I always forget about the 80 octane engines because they had been phased out of production before I was born (or at least for the most part) so they aren't something that jumps to mind.

    The point was that if you have an engine (and as you pointed out, a fuel system) designed for one fuel and you're most likely parked somewhere where that fuel is generally more readily available than the alternatives, I can't see anything (other than a flimsy "economic" argument which falls apart when you really examine it; there's also a general "screw you" attitude that motivates some because they simply can "get away with it" but that's thankfully the minority of pilots and that tree tends to be somewhat self-pruning due to other activities that attitude tends to predispose towards) that justifies tankering in automotive gas.

    As for the FAA giving it their blessing, I don't know if that's really the best argument to use either since most of the time people on here are grousing about how the FAA doesn't have a clue. They approve all sorts of things that are pretty questionable when it comes to safety or reliability so long as the paperwork is in the right order.

    Running the engine isn't going to keep the fuel tanks and other components from corroding. There's no "oil" running through any of those parts. The only place there is likely to be oil and fuel mixing togother ought not to have fuel "sitting" in it while parked.
    Point taken but the comment was made about the engine. I was simply looking at that end of it. The other point I would make given that this forum caters to the experimental community is that if someone really wants to run autogas through their system, why don't they take the time and effort to switch (or build in the first place) the tanks and other parts in a way that can handle it. I have a good idea as to the answers to this but it's not socially acceptable to point them out on here.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  10. #10
    FlyingRon's Avatar
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    Quote Originally Posted by steveinindy View Post
    This is technically correct. I always forget about the 80 octane engines because they had been phased out of production before I was born (or at least for the most part) so they aren't something that jumps to mind.
    Darn younsters.
    The point was that if you have an engine (and as you pointed out, a fuel system) designed for one fuel and you're most likely parked somewhere where that fuel is generally more readily available than the alternatives, I can't see anything (other than a flimsy "economic" argument which falls apart when you really examine it; there's also a general "screw you" attitude that motivates some because they simply can "get away with it" but that's thankfully the minority of pilots and that tree tends to be somewhat self-pruning due to other activities that attitude tends to predispose towards) that justifies tankering in automotive gas.
    Not everybody has to tanker in auto gas and since when is wanting to spend less money a "screw you" attitude? Even premium autogas is still running over a buck cheaper than the cheapest 100LL I can find around here. If my plane would run on auto fuel, I'd definitely give it consideration. You haven't made any technical reason that autofuel is a bad idea other than you believe that 100LL is some sort of magical potion. This is EXPERIMENAL aviation after all. What you call a "screw you" and "get away with it" attitude is the the experimental aviation idea of innovation and independence.

    You haven't made the least bit of technical explanation as to why people should NOT deviate form 100LL.

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