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  1. #1
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    Default proper leaning, premiun auto gas in an emergency

    I had an interesting flight today. A 260 mile trip into a 15 mph headwind (I saw some 78 mph ground speeds).
    I leaned the old SWAG way; pulled the mixture out till the engine almost died, then pushed the mixture in till it smoothed out. I got to thinking about running too lean while I was just setting there trying to hold a heading and altitude (its was about 5:30 and bumpy). That's my first question: can I run too lean when I'm only generating 80 hp and do i need to worry about detonation?
    Now for question 2: 24 Miles fron my destination airport I chickened out and diverted to another airport to buy gas. When I got on the ground the airport was closed (Garmin database was wrong again), I called the emergency number and ended up waiting almost two hours for the attendant to show up and sell me some 100 low lead. The first guy I called was long gone and far away but he offered to call one of his buddies and have him come over and sell me a little premium car gas to get me to my destination. I declined, but kept thinking about it till I finally got fueled up. That's question 2: Would a few gallons of premuim car gas have worked or would it hurt the engine? One final note: It only took 17 gal to fill her up. I could have made it to my destination easily. But I don't feel bed about that. Live coward, dead hero and all that stuff!

  2. #2
    Senior Member randylervold's Avatar
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    Default Re: proper leaning, premiun auto gas in an emergency

    First question: if you're running at low horsepower (really anything below 75%, but especially below 65%) then no, you can't possibly run too lean and hurt anything. I do it all the time... pull the power way down, lean the bajezzus out of it, and watch with great joy as the fuel flow shows 4.5 gph or some such frugal figure. Of course this is keeping your engine cooler and cleaner inside as well. Be sure and richen it up though when it's time to climb.

    Second question: We will not approve the CC340 for auto fuel because virtually all auto fuel now has ethanol it which creates all sorts of problems, plus fuel quality can vary from country to country and you never know for sure what you're getting. That said the engine should run just fine in a pinch on PREMIUM auto fuel without detonation.

    Lastly, good job Rick on the fuel management judgment call -- better safe than in a mountain canyon dead somewhere because you "thought you could make it". With time you'll judgment will improve in forecasting range.
    Randy Lervold

  3. #3
    Senior Member chipallen's Avatar
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    Default Re: proper leaning, premiun auto gas in an emergency

    This whole thread falls into the same category as "wheel landing or "3-point"; everyone has an opinion. I'm a huge proponent of LOP operation in the Baron and in the Carbon Cub. Several years ago, I attended the Advanced Pilot Seminar in Ada, OK, put on by some real experts in the area of engine operation. One of the instructors, John Deakin published an article last month as a "rebuttal" to the Lycoming publication listed in a previous post. For those interested in really getting into the "nuts & bolts" of LOP Operation, you can read the entire article in the following link, or to make it easier, I've attached as a PDF. I'm certainly not an expert in this field, but my personal experience has been outstanding with both large and small block, fuel injected and carbureted engines; operated LOP they run cool, they save a LOT of fuel, minimal sacrifice in airspeed, and easily reach TBO with no cylinder problems.

    http://www.advancedpilot.com/article...articleid=1838
    Attached Files Attached Files

    Chip Allen

    SWT Aviation, Inc.
    Cubcrafters Southeast Sales Center
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  4. #4
    Senior Member Steve Y's Avatar
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    Default Re: proper leaning, premiun auto gas in an emergency

    Quote Originally Posted by chipallen View Post
    This whole thread falls into the same category as "wheel landing or "3-point"; everyone has an opinion. I'm a huge proponent of LOP operation in the Baron and in the Carbon Cub. Several years ago, I attended the Advanced Pilot Seminar in Ada, OK, put on by some real experts in the area of engine operation. One of the instructors, John Deakin published an article last month as a "rebuttal" to the Lycoming publication listed in a previous post. For those interested in really getting into the "nuts & bolts" of LOP Operation, you can read the entire article in the following link, or to make it easier, I've attached as a PDF. I'm certainly not an expert in this field, but my personal experience has been outstanding with both large and small block, fuel injected and carbureted engines; operated LOP they run cool, they save a LOT of fuel, minimal sacrifice in airspeed, and easily reach TBO with no cylinder problems.

    http://www.advancedpilot.com/article...articleid=1838
    What is your thinking of LOP operation of the CC in reference to the statement: "Bottom line is that because of limitations of the carburetor and induction system, in my airplane you can only run half the engine LOP without it getting pretty rough." ? Not being knowledgable about this engine and soon to own one, I am interested in what these "limitations" in this engine are?
    I would tend to be swayed to LOP operation for the CC if it indeed was feasible ?
    Thanks-Steve
    Last edited by Steve Y; 07-25-2013 at 09:07 AM.

  5. #5
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    Default Re: proper leaning, premiun auto gas in an emergency

    Quote Originally Posted by randylervold View Post
    ...Lastly, good job Rick on the fuel management judgment call -- better safe than in a mountain canyon dead somewhere because you "thought you could make it". With time you'll judgment will improve in forecasting range...
    Amen. Most pilots I know think that the FAA minimum fuel reserve of 30 minutes at cruise power day and 45 minutes night is not enough. It is legal, once having taken off with the 30 minute daytime reserve, to watch it dwindle to nothing due to unexpected conditions. Right.

    Three of my experiences. . .

    Shortly after getting my commercial, I flew a Cessna 150 4.1 hours and landed with about three gallons left, half a gallon of which was usable in all flight attitudes. I was holding my breath the last thirty minutes. I realized that wasn't too bright. After some consideration, my personal rule is an hour reserve day and night. If flight conditions, unexpected winds, etc., drop it to 30 minutes, it is time to stop and get more fuel to bring my reserve back up to at least one hour.

    One go-around at full power can use a bunch of cruise power fuel. I once did two go-arounds trying to get into an airport with one paved runway after a frontal passage. The wind was a varying 90 degree gusty, burbling over the ridge, cross wind. The dirt crosswind runway was unusable due to rain preceding the frontal passage. I went to a nearby airport which was downwind with several runways.

    Another time, I was headed for an airport with weather which required the ILS for landing. About an hour out, I was given holding instructions; there was a disabled airplane on the runway and the airport was closed until it got cleared.

    Bottom line, things can cause unexpected delays in landing. Reserve fuel on board provides alternatives. As the number of alternatives decreases, one can find oneself painted into a corner.

    FWIW and YMMV. Have fun, with the shiny side up, and the engine making power.
    Last edited by RobHill; 05-14-2014 at 07:06 PM.

  6. #6
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    Default Re: proper leaning, premiun auto gas in an emergency

    Quote Originally Posted by randylervold View Post
    First question: if you're running at low horsepower (really anything below 75%, but especially below 65%) then no, you can't possibly run too lean and hurt anything. I do it all the time... pull the power way down, lean the bajezzus out of it, and watch with great joy as the fuel flow shows 4.5 gph or some such frugal figure. Of course this is keeping your engine cooler and cleaner inside as well. Be sure and richen it up though when it's time to climb.

    Second question: We will not approve the CC340 for auto fuel because virtually all auto fuel now has ethanol it which creates all sorts of problems, plus fuel quality can vary from country to country and you never know for sure what you're getting. That said the engine should run just fine in a pinch on PREMIUM auto fuel without detonation.

    Lastly, good job Rick on the fuel management judgment call -- better safe than in a mountain canyon dead somewhere because you "thought you could make it". With time you'll judgment will improve in forecasting range.
    I agree completely with Randy’s comments. The only thing I would add to all of this is.
    Any time the engine is running rough when leaning, it’s usually an indication of a cylinder not performing at the same level as the rest. Most of the time, this is caused by differences in air distribution inside the engine, whether its fuel injected or carbureted.
    It can be compared to a team of four horses pulling a wagon; if one of them is not working very hard it increases the stress and load on the rest and shortens their endurance. What I’m trying to say is no matter what the power level is or the amount you lean, you should always use the combination that allows the team to work together and share the load as equal as possible. Smooth engine operation is better than rough engine operation

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  7. #7
    Senior Member Dan L's Avatar
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    Default Re: proper leaning, premiun auto gas in an emergency

    I've used Premium ethanol-free car gas a few times in a pinch. No noticeable change in egt or cht temps. And it is always diluted to some extent with remaining 100LL.

    Not sure why that got underlined. I probably touched something on the iPad.
    Flying Carbon Cub EX #11 since 2011

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    Default Re: proper leaning, premiun auto gas in an emergency

    Is anyone out there running there cc340 LOP using the Dynon d180 for information? I have been doing this a little at 55% power or less and its interesting not only do you burn lots less gas but the 3,4 cyl. Temps go down by 60 degrees and the front,1,2 cylinders go up by 50 degrees!! Haven't really figured that one out . Any ideas? Royce

  9. #9
    Senior Member randylervold's Avatar
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    Default Re: proper leaning, premiun auto gas in an emergency

    Yes, I've been flying LOP at low power settings ever since setting foot inside CC over 4 years ago, wouldn't cruise any other way. ;-)
    Randy Lervold

  10. #10
    Senior Member cityrancher's Avatar
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    Default Re: proper leaning, premiun auto gas in an emergency

    I will step in with my experience on LOP.I have had very good luck on Continental fuel injected engines with GAMI balanced injectors. I have managed to successfully run LOP in a Turbo carbureted 182 with an O-540. The problem with other carbureted engines (like my 0-200) is the induction system does not supply fuel in a critically balanced amount to each cylinder. That cause some cylinders to lean at too extreme a range for successful LOP operations. Fuel injected with balance injectors is easy, most carb engines (Continental especially) will not run smoothly LOP. You really should have full engine monitoring (EGT all cylinders) to attempt this.
    Last edited by cityrancher; 07-25-2013 at 10:21 AM.

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