Future of 100LL AvGas

[DevDad]

What about the availability of Mogas? Obviously, if 100LL disappears, airports would need to accomodate the new fuel source. Right now, however, Mogas at airfields appears to be tough to find. Obviously, you can lug it from gas stations, but not while you're flying away from home.

Mike

[jmartinez443]

Originally Posted by DevDad

What about the availability of Mogas? Obviously, if 100LL disappears, airports would need to accomodate the new fuel source. Right now, however, Mogas at airfields appears to be tough to find. Obviously, you can lug it from gas stations, but not while you're flying away from home.

Mike

My guess is that FBO's will start stocking 82UL - which is mogas straight off the pipe bofore they brand it and add all of the additives, detergents, and octane bumping junk.

Those running unleaded tolerant engines should be ok. One reason the FBO's don't do it now is lack of demand. That will change once 100LL goes away.

[erich weaver]

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Since conventional knowledge says that the lead is for valve stem lubrication, I don't understand what an ignition system can do about that. Is there more to it?
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Im no expert, but.....my understanding is that the primary purpose of lead in gasoline is as an octane booster, meaning its used as an anti-knock agent, presumably by slowing the controlled explosion going on in the cylinders, which affects the position of the cylinder relative to the power pulse. The timing of the spark plug firing is obviously also of critical importance to the timing of the power pulse, hence the ignition system is very relevant. I believe the GAMI PRISM system attempts to sort out all these timing issues by monitoring temperatures/pressures in the cylinder.

Maybe Ross or others more knowledgable than me can correct or augment this?

erich

[TomAniello]

Jet-A is going to continue to be around to meet the demand of airliners and business aircraft. While Thielert doesn't yet sell to the homebuilt market, I hope that Van's is talking to them and other diesel manufacturers about doing an OEM deal. Turbo-diesels have their own set of limitations, but they could be a good option for us.

Not to start an engine war, but I'm also going to take a closer look at the Subaru conversions.

While I also agree that it would seem criminal to leave 100,000+ aircraft owners without a fuel option, I fear that the refiners really don't give a darn. It's insignificant business for them, regardless of how much pressure our industry tries to put on them. The fuel may go away, but I have faith that some enterprising individual will see the opportunity and come up with a solution.

At my current build rate of 2 hours per week, I'm still about 20 years away from first flight. Maybe by then Marty McFly and Dr. Emmett Brown will have their Mr. Fusion listed in Van's accessory catalog.

[David-aviator]

Originally Posted by rv6ejguy

They're not going to orphan 100,000+ piston aircraft in North America. There will be an unleaded avgas replacement. What that might cost would be the concern.

The auto engined experimentals won't worry much about the demise of 100LL and I suspect most aircraft engines with a properly calibrated EI won't care much either. Hopefully they cover the octane requirements of some of the older turbocharged and supercharged certified engines.

I'm still going with 10 to 1 pistons in my turbo Subaru. Got programmable fuel and spark control with knock sensing if required as well.

My H6 is running at 10.7:1 and I've pushed 87 mogas through it while observing the timing, it does retard somewhat hopefully at the behest of the knock sensor. This was comparing with 100LL. But no more. It's 91 mogas now unless away from home and then its 100LL. I heard that one 2.5 engine burned up with 87 mogas while running at much high power. (maybe the knock sensor died?)

!00LL is great fuel. It's vapor pressure is never a problem and it is standard everywhere. Mogas is neither anywhere. Its vapor pressure has to be checked before flight and the fuel more than likely is laced with political ethanol. All of the mogas I've used has had ethanol - so far no problems with it. Vapor pressure is vapor pressure, whatever it checks at, whether it has ethanol or not. The plumbing system, including the aluminum tanks, aluminum fuel lines and high pressure auto fuel hoses are OK to this point. (about 4 years)

For at least the past 10 years there have been doom and gloom presentations at OSH on 100LL, but its still here. Every year I come away with a feeling, well this could be it. That is one reason I went with the Subaru engine. It likes mogas. It does not like 100LL without some serious effort to get the lead out.

Stuff to think about.....be sure to check with Jan Eggenfellner on the latest engines and mogas if that is your fuel of choice. Last I heard the recommendation was 100LL probably because the new ECU did not have a proven knock sensor - but they've been doing much flight testing recently with huge software changes and that issue may have been put to bed. I don't much think about it as my ECU is stock Suburu.

[Ron Lee]

Why worry about spending $7000 - 10,000 for avionics that do nothing for the GA pilot when tens of thousands may be grounded?

[rv6ejguy]

There are some pretty cool ignition systems out there which can measure cylinder pressure through plug ionization voltage and such plus the older type knock sensor technology to fix the next cycle if the previous one knocks. These have both been used for some time on certain automotive applications.

The Subaru has a very well developed combustion chamber compared to most aviation ones plus have knock control and of course variable ignition and valve timing based on load and rpm. Low octane fuel mainly causes a slight loss in power due to retarded ignition timing. Some newer engines are running over 10 to 1 on 87 octane and 11.25 on 91-92.

The aftermarket ECU solution has proven knock sensing capability.

I've run many race engines on leaded avgas and never saw any difference in valve seat or stem wear rates, mainly just more deposits on the chambers and valves. As long as you have proper valves and hard seats, operation on unleaded fuel should pose no big problems in my experience.

I think the vapor pressure of standard mogas is a possible concern when used in aircraft so one has to be careful here as David points out. I'd prefer that some properly blended 98 octane unleaded avgas replaces 100LL when the time comes. Someone will step up to the plate to supply if the big guys pull out I think. It might be a small market for Shell, Exxon or Esso but there are still hundreds of millions to be made by someone to refine and distribute avgas for a long time to come.

[roadrunner20]

Originally Posted by hevansrv7a

Superior's 8.5:1 compression ratio 360 CU engine is OK on premium auto gas. That's official from Superior. =

I'm also running premium 93 in my IO-XP360. At $3/gl vs $4.50-5.25/gl for 100LL, I'm looking forward to the day when airports begin supplying it. This is why I went with Superior. At times, I've considered bringing gas cans enroute to refuel vs paying $5.25/gl as I did when I refueled at Pine Mt GA.

[Ironflight]

I used to run MOGAS exclusively in one of my airplanes for ten years....of course, it was a J-3 Cub, we never took it anywhere farther than 25 miles from the home, and we filled it with Jerry cans from the Texaco down the street from the airport.

I actually have no fundamental objection to MOGAS, but I don't run it in the RV for one major reason - I am concerned about the alcohol deteriorating the seals in th fuel system. And quite frankly, I am not confident that I can always find MOGAS without alcohol (or EVER find it these days....). The bottom line is that I use my airplane to travel - a LOT. And most airports I stop at have 100LL, not MOGAS. I don't want to constrain my fuel stops to only places that advertise MOGAS, and I rarely see it. I also wouldn't want to take the time to test the fuel for Alcohol at each and every stop - my time is worth more than that, and I love the flexibility of RV speed and range. For local flyers with a tank in their pickup, I concede that it makes sense. But flying 300 hours per year, much of it away from home....I have to stick with what is commonly and safely available. No disrespect for those that burn MOGAS - I can see that point of view if it is appropriate for your type of flying.

That said, if 100LL goes away (and I seriously doubt that will happen in a market-driven economy without a viable substitute coming along), I would find a way to burn what WAS available.

Paul

[asav8tor]

http://www.age85.org/


Someone quick! We need to inform these guys about the dangers of Ethanol in their avgas.....

Oh my they have been burning it over 10 years.

Someone tell them to stop!

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When 100LL goes away a paradigm shift will occur in our thinking.