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Big news out of Florida, as Piper Aircraft has announced that they successfully completed the first flight of one of its Archer aircraft using 93 octane premium unleaded automotive gasoline. Here is a link to the official announcement: http://tinyurl.com/ls74hv4
Does your closest FBO offer 93 octane already? Check it out here: http://www.globalair.com/airport/
Doesn't seem like it should be a big surprise here.
I've been running on auto fuel for 20 years. These 1930 technology engines don't really care what they burn.
We used to have an old tractor that started on gas and then chugged away all day on diesel fuel. Low compression and spark plugs.
Heres the funny part. In the non-aviation engine design world, we wish that all gasoline was along the lines of 100LL or slightly lower octane UL version, and that we werent stuck with this variable garbage called auto-fuel. All the constantly varying chemistry that may be fine one month, but next month is destroying fuel system parts, or knocking a high output engine to death. In all seriousness, the GA community has no idea how LUCKY they are to have something as nice as 100LL.
Yea... How lucky we are to pay $6.00+ a gallon for AV gas, vs. $3-4+ a gallon...
It adds up really quick, for those of us with shallow pockets, trying to escape the bonds of earth, once in a while.
Yea, how lucky we all are...
Damage costs from cheap automotive fuel also add up. Many non aviation engine manufacturers will test run their engines on 100ll or some other specialty fuel before shipment, just to avoid the failures caused by mo-gas. It is a constant battle, and is only getting worse. Im not even talking about ethanol here...Quote:
Originally Posted by I_FLY_LOW
Interesting reads:
Part 1:
http://www.eaa.org/autofuel/autogas/...vs%20Avgas.pdf
Part 2:
http://www.eaa.org/autofuel/autogas/...20Part%202.pdf
I remember them from a while ago. If memory serves most of that information is at least 10 years old. Unfortunately things have changed in the auto-fuel world. I would love to see a tightly controlled unleaded fuel made available, but I doubt the price would be any lower than 100LL. Auto fuel is something non-aviation engine manufacturers struggle with to this day, its just not nice.Quote:
Originally Posted by I_FLY_LOW
Quote:
Originally Posted by rayatglobalair
Ray, that webpage lists "mogas" but does not tell the octane rating. The closest airport to me with "mogas" is GIF with $5 100LL and $5 "mogas" of unpublished octane or ethanol content. The next closest is SEF with $5.30 100LL and $5.75 for whatever their "mogas" is. Why fly all the way there expecting to pay the same or even more and not be sure if what they have for sale is adequate? Don't bother replying "phone first" because I've found a phone promise often doesn't meet the pump label.
Put another way, I've been burned on crosscountry trips by expecting to get what i needed and finding it was not really as indicated. and that was when i had an airplane that only needed 80 octane. now that i NEED 91, flight planning to a place listing generic "mogas" is not an option unless they back it up with 100LL at a competitive price. which, thankfully, SEF and GIF can do. but there is no $ savings there unless flying a rotax and trying to use longer oil change intervals. big whoopee.
For local flying, try pure-gas.org
My Lyc O-320, per the manual, said to use 87 octane, unleaded.
We usually used the then $1.89 / gallon 100LL, but always ran TCP (lead scavenger) in every fillup.
We did do some bulk auto fuel for a while, until we got tired of the handling of it.
The plane ran fine, on either fuel, and saw no change in fuel economy between the two.
If I were going to use auto gas now, which I may very well do so, when the time comes, it will be non-ethanol.
We have several stations scattered around where I live, that sell the non-e fuel.
The rest, so far, are 10%E.
I ride motorcycles, also, and avoid the stuff in my bikes, and lawn mowers, at all costs.
There's no mystical, magical aircraft engine only elixir to it.
Yes different branded stations have their own additive packages that are added usually right at delivery time, but very little else is different.
The only variable, is the onsite storage, like mentioned before, with the allowance of moisture in the fuel tanks, and any other trash that may be in there.
With the exception of the excessive water content, usually fuel filters catch the majority of whatever other contaminants may be.
I've never in all my years of driving, or flying, wound up with a bad batch of fuel.
I'm pretty cautious about where I purchase fuel, and feel that may be a reflection of the quality of the fuel I've purchased over the years.
Interesting reading, very informative.
I have a 300 gal tank in my hanger which a bulk dealer fills for me, I use high octane and test for ethanol each time. So far nothing has appeared. I also fire sleeved all my fuel lines and have never had a problem. I live in the north where we seldom get above 80f so I don't believe vapor lock is an issue.
What I take from what I have read is that auto gas has higher volatility, it evaporates quicker which would make it "better" fuel as only gasoline vapors burn so the easier it evaporates the easier it will burn?
Incorrect,Quote:
Originally Posted by raytoews
Engines dont run on "vapor", they run on atomized liquid droplets for the most part. There are "light ends" in the fuel that will vaporize, and this is to help cold ignition. With auto fuel the vapor pressure varies with the season, meaning that in winter the fuel has more light ends to help cold start, in the summer less to avoid vapor issues. Here lies much of he issue, the ever changing chemistry and the random addition of various light solvents like toluene. Part of it changes in the pipeline, part of it is up to the individual station. From a design standpoint, trying to design and calibrate an engine for auto-fuel is like hitting a moving target in the dark. From the outside to people that dont know engine design, it does not seem like a big deal though, and I think this is where a lot of arguments come from. Either you understand it, and know what will be required to deal with it, or you dont understand it and think everything will work just fine all the time.
What manual is that, I Fly? Are you referring to the Lycoming Service Instruction on acceptable fuels, and specifically 87 AKI mogas?Quote:
Originally Posted by I_FLY_LOW
Octane numbers without a frame of reference can be misleading... 87 AKI mogas is comparable to 82 motor octane avgas... for instance, as you probably know...
Piper's ethanol-free 93 PUL (premium unleaded) demonstration isn't a very universal solution, given that west of the Great Plains, 91 octane alcohol-containing premium is more the norm...
I used to visit Gonzales quite frequently... we have a styrene plant in Donaldsonville...
Paul
What were you saying about AKI, OICU812, C3-PO and all that?
Notice the lower portion of the second pic... "Approved by F.A.A".
Also notice the limitation of lead content in the third pic.
This is a repro, and when I run across it, I'll post the original.
http://i29.photobucket.com/albums/c2...psf94f53af.jpg
http://i29.photobucket.com/albums/c2...ps0da055ce.jpg
http://i29.photobucket.com/albums/c2...ps984c35f7.jpg
Ok I must not see what you are seeing. In none of the pages above does it mention unleaded Mo-gas. It is calling for 80/87 AKI "aviation grade fuel". It also most certainly does not specify 87 (r+m)/2 octage automotive fuel. I could see where you might be confused though since the av and automotive world both use the word "octane", though measured differently.Quote:
Originally Posted by I_FLY_LOW
AvGas vs Auto Fuel:Quote:
Originally Posted by Aaron Novak
http://en.wikipedia.org/wiki/Avgas#Grades
Octane rating:
http://en.wikipedia.org/wiki/Researc...rement_methods
AKI:
Anti-Knock Index (AKI)[edit source | edit]
In most countries, including Australia and all of those in Europe, the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI, and often written on pumps as (R+M)/2). It may also sometimes be called the Pump Octane Number (PON).
So, what's wrong with running auto gas in the lower compression O-320's if Auto fuel has the correct anti knock ratings?
Here in the US a auto fuel can have a higher Ron, and lower Mon ( or the other way around ) and still be a legal 87 ( or other ) octane. Yet they can act completely differently in an engine. This is a hard thing for people outside the engine industry to understand. Literally I can go buy 2 batches of auto fuel that have the same pump (r+M)/2 rating, and they can have significantly different knock margins ( degrees of spark timing to knock ) on a higher output engine. Thats why in the auto and powersports engine world, we are spending huge ammounts of effort on knock control systems, and it is nowhere near easy. Aviation fuel is rated on a different research engine, and does not vary due to the nature of the testing. 100 octane aviation fuel will be the same from batch to batch, year to year. The auto fuel industry has a lot of ability to blend in whatever stock are cheap today, dope it up to just meet the sloppy standards and call it a day. Thats why you end up running 93 (ish) auto fuel in your 80/87 rated engine, as the worst cast auto 93 will probably have knock margins close enough to 80/87 to be safe for the most part.Quote:
Originally Posted by I_FLY_LOW
Along with that, I'm surprised 100LL has lasted as long as it has, with all the removal of lead in everything else.
http://www.flyingmag.com/blogs/fly-wire/avgas-pain-pump
Im not. It has lasted as long as it has, because auto fuel as we know it, is not a direct replacement in many ways. The issue with replacing 100LL has less to do with the lead, and more to do with the chemical make up of the fuel itself that affects everything from fuel system materials to long term corrosion to vapor lock to who knows what else. Some engines may need to have their valve and seat materials adjusted for longer life. Sure some higer output engines need the extra knock margin the lead gives, but most do not. The best alternative I see, is a 94UL aviation specific fuel, with engines that have had their materials adjusted accordingly. Anything else is like rolling the dice.Quote:
Originally Posted by I_FLY_LOW
You're not?
They sure had no problem shoving 10%, and now 15% ethenol down our throats.
Older engines and even gast stations are being affected by it.
No Im not. Aviation is fortunate enough to have a regulatory body that provides a checks and balances system against other regulatory bodies. This does not allow one or more groups ( the EPA/oil companies, whose objective is questionable ) to force anything without the aggreement of the FAA ( whose objective is safety ). The automotive and small engine world does not have this and we are at the mercy of whatever foolishness the EPA/oil companies hand down, even though we travel to washington to lobby against it. This is why I keep saying that the aviation world is actually very fortunate. There are thousands of fuel related engine failures yearly in the auto and powersports markets, yet they have no ability to prevent the EPA and oil companies from doing whatever they wish. No regulation+no control=no predictability, and predictability is exactly what you want when your life is on the line.Quote:
Originally Posted by I_FLY_LOW
A lot of really interesting technical talk, but experience has taught me, it works just fine.
Test for alcohol on each tank fuel and go fly.
Ray
Recently my auto shop reminded me of the "Top Tier" gasoline retailing organization. http://www.toptiergas.com/index.html
As consumers, we need to look at more than the price when purchasing fuel.
Thanks for sharing your source material, I Fly... yeah, you did mistate the gasoline octane.Quote:
Originally Posted by I_FLY_LOW
Your O320 is approved for use with 80 octane avgas... that is 80 Motor Octane Number (MON).
That equates, roughly, to a mogas AKI (pump octane) of 85... so as you know from the EAA and Petersen STCs, you can operate your aircraft on conventional regular mogas, without ethanol, as long as you have the STC and have complied with any conditions (some low wing airplanes need additional fuel pumps, etc)
You were calling that 87... but the 87 in 80/87 is the rich supercharge rating, which operationally doesn't affect your normally aspirated engine. That 87 number comes from an F4 octane engine, and doesn't correlate well to any other octane numbers, like the MON+RON/2 or AKI that you see at the gasoline station... so it's misleading and technically invalid to refer to that number in deciding what fuel you want.
I believe the Piper of the thread title has a Lycoming engine certified on the no-longer-available 91/96 octane (or 91/98 octane) aviation gasoline. The 91 MON, motor octane number, correlates to a mogas octane of 96, which you won't find anyplace but a gasoline station that sells racing fuel. However, Petersen Aviation has an STC for those Lycoming 91 octane engines to run on premium unleaded ethanol-free mogas. I don't recall the minimum octane they specify, but I think it's 93 AKI, pump octane, which brings us back to my original comment... it's difficult to find that stuff ethanol free. It's nearly impossible to find that stuff in the West.
Ignorance isn't bliss when it comes to engine octane numbers. People who just shrug and say, "gasoline is gasoline" can end up off airport in a field somewhere, with a hole burned in a piston.
Paul
When in doubt, look it up. don't need 93AKI for Petersen STCs:Quote:
Originally Posted by PaulMillner
http://www.autofuelstc.com/stc_specs.phtml
http://www.autofuelstc.com/
but cost savings? around here we can get 100ll avgas at the airport for as low as $4.87, octane-unspecified-on-the-web mogas at the airport for $4.90, or ethanol-free 90(?) octane boat gas at the local stop&rob for $5.00. name yer poison, pilgrim. your mileage may vary.
Unfortunately past experience with auto fuel does not mean squat in the future. Mogas is ever changing, ASTM testing methods change, and there is no way of knowing for sure that the fuel you bought at the local gas station meets ANY specs. Heck we have had 93 octane pump fuel measure in at 89. 30 years ago when the STCS first came out, Mogas was a better fuel......times have changed, and not for the better as far as MOgas for aviation is concerned.
Around here, 100LL is $5.50. Ethanol-free Mogas is $3.90.
What happened to the big push for using ethanol in planes?
Seems like in 09'Airventure, IIRC, that they had a couple airshow pilots, plus a few other exhibition planes that were pushing the E85 fuel.
I wasn't interested then in the idea, but wondered now, because I haven't heard much about it, lately.
Did it get quietly swept under the rug?
I owned a Cherokee 140 with a 0320 for over 25 years. During that time it consumed a lot of 'mo-gas' with absolutely no problems. I had more trouble with 100LL fouling the spark plugs no matter how many different techniques I tried. Using 100LL was OK for longer trips but doing any amount of 'airport hopping' (short and any amount of taxing) was sure to cause plug fouling. When we pulled the plugs on annual they were always filled with balls of lead that resembled solder. Never had vapor lock either but then was consistant about using the electric fuel pump on take off and landing and it has a fuel pressure gauge. That engine now has over 1500 hours on it since overhaul and still performing well. I will agree there might be some concern with detonation with the higher compression engines but the 0320 is only 7:1. Ethanol is another story at this point in time due to possible breakdown of fuel system components.
Let's see... it says, "91 Octane Minimum"Quote:
Originally Posted by cdrmuetzel@juno.com
But then... note the thread title, "Piper completes flight tests of Archer fueld by 93 Octane"
It seems we have a disconnect here...
Of course, in parts of the mountanous west, even 91 UL is difficult to find... RUL is 85... MUL is 87, PUL is 89...
Paul
Paul, Lycoming requires 93 aki minimum for autogas. That is probably why Piper used 93. But Petersen's STCs require 91. Disconnect? Mebbe, but that might be why. Lycoming SI 1070S.Quote:
Originally Posted by PaulMillner