T

TomAniello

Member
I work for a major aircraft OEM, and was given a presentation yesterday by the CEO of one of the largest aviation fuel distributors in the US. The topic was the future cost and availability of 100LL AvGas.

To make a long story short, refineries have little if any incentive to keep producing 100LL. It's an insignificant part of their business, it's expensive, and they can make greater margins using their capacity to make premium auto gas. He went so far to say that that there could be a very serious supply problem by as early as 2011. The price for 100LL will be much higher, if it is even available at all. Look to Europe, Africa, and South America for examples of this today.

I'm still several years away from mounting a powerplant on my RV-8, and had planned on just going the traditional Lycoming route. However, given the serious doubts about the future of 100LL, I'm going to give this decision much more careful thought.

My questions to my fellow VAF posters are:

1) What options do we have?
and
2) What do you plan to do?

I'd appreciate your thoughts.
 
Great Questions

I have been of the opinion that 100LL would be around for a long time. Now, I?m not so sure. I have two birds with auto gas STCs, a Cub and a 170. Even that may be a problem if the Ethanol trend continues.

My thoughts are that Jet A is our only shot. I think that the development of good 2 cycle diesel engines will be the fix for the 150hp to the 250hp range. Hopefully we will see some viable engines within the next couple of years.

As for me, I?m waiting for the RV-12. Initially, I was planning to try to re-engine it to get away from the Rotax. Now, I?m not so sure. The word is that 10% ethanol is not a problem in these engines. So, maybe Van did his homework and has found the perfect combination for us economy-minded pilots. Then again, perhaps there will be an alternative engine that will use Jet A by the time that I am ready for it. I certainly hope so.

Tom
 
TomAniello said:
I'm still several years away from mounting a powerplant on my RV-8, and had planned on just going the traditional Lycoming route. However, given the serious doubts about the future of 100LL, I'm going to give this decision much more careful thought.

My questions to my fellow VAF posters are:

1) What options do we have?
and
2) What do you plan to do?

I'd appreciate your thoughts.
Click to expand...

I read somewhere that there is only one manufacturer in the world that makes TEL (tetraethyl lead) - the additive that puts the LL in 100LL. So I agree with you 100LL will soon go the way of the Dodo.

There have been rumblings about 100LL going away for some time now, and that is why I intend to use a low compression (8.5:1), unleaded-fuel-friendly engine on my 8A. The future of low lead is also what steered me away from using an ECI 340 - its high compression pistons aren't compatible with unleaded fuels.

Read this very interesting article from AvWeb: http://www.avweb.com/news/maint/187232-1.html
 
very big concern for me as well... I expect to see a steep spike in price per gallon for 100LL way before 2011 hits. Granted I am far far away from choosing an engine, but I want to know what im going to do before I get there... $30k on an engine is something I want to be sure about... and not regret!
 
One Company - In England

jmartinez443 said:
I read somewhere that there is only one manufacturer in the world that makes TEL (tetraethyl lead) - the additive that puts the LL in 100LL. So I agree with you 100LL will soon go the way of the Dodo.
.....
Click to expand...

This is the one and only company....

http://pubs.acs.org/cen/business/84/8417bus2.html

Interestingly enough, it's in England across the river (Ferry across the Mersey) from my birthplace...

Given the "nanny-state" mentality in England, I'm surprised they are still allowed to make it....:) ...perhaps they haven't caught on yet....

gil A
 
The folks at GAMI have claimed that their PRISM ignition system will allow wide use of unleaded gasoline in aviation engines. Time will tell.

erich
 
TomAniello said:
I'm still several years away from mounting a powerplant on my RV-8, and had planned on just going the traditional Lycoming route. However, given the serious doubts about the future of 100LL, I'm going to give this decision much more careful thought.

My questions to my fellow VAF posters are:

1) What options do we have? ...
Click to expand...

Superior's 8.5:1 compression ratio 360 CU engine is OK on premium auto gas. That's official from Superior. Of course, with ethanol being added to auto gas, that could be a problem. Some states are exempting premium auto gas from the ethanol requirement.
erich weaver said:
The folks at GAMI have claimed that their PRISM ignition system will allow wide use of unleaded gasoline in aviation engines. Time will tell.

erich
Click to expand...

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?
 
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.:)
 
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
 
DevDad said:
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
Click to expand...

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.
 
[/FONT]

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?
[/QUOTE]

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
 
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. ;)
 
rv6ejguy said:
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.:)
Click to expand...

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.
 
I guess the ADS-B Out NPRM mandate is no concern

Why worry about spending $7000 - 10,000 for avionics that do nothing for the GA pilot when tens of thousands may be grounded?
 
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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.
 
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hevansrv7a said:
Superior's 8.5:1 compression ratio 360 CU engine is OK on premium auto gas. That's official from Superior. =
Click to expand...

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.
 
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
 
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!

--------------------------------------------------

When 100LL goes away a paradigm shift will occur in our thinking.
 
I find it hard to belive that 10% Ethanol in unleaded is so bad. If all of the horrible things that are supposed to happen are true, Interstate 90 should be littered with dead cars all winter. I wish someone smarter than me would seriously evaluate the effects of E-10 fuel in airplanes. I know higher concetrations of ethanol or metanol in concentration can cause problems but I really wonder about 10% ethanol.
 
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
Click to expand...
!

Well that's interesting! The REALLY interesting thing is that they have STCs. So what's all the doom and gloom about ethanol in mogas? Is this just an urban/aviation myth? Are there limitations on the STCs? They say opinions are like...well, you know... But does anyone KNOW the implications of 10% ethanol/90% mogas in an O/IO-320/360?

I suspect (opinion alert!!!) that the replacement for 100LL will be premium mogas without the ethanol chaser, and the STC paperwork will then be worthwhile to someone.
 
Lead in the Hogwash

If they'd just leave out the lead, avgas would be 95 octane, and would work just fine for 95% of the fleet.
This would give us cheaper gas and also solve the problem for the oil companies, since it would basically be just extra-high-quality premium unlead, which would be legal to transport by pipeline.

The only planes that NEED 100LL today are:
1) High-performance piston workhorses that ought to be upgraded to a turbine anyway.
2) Antique warbirds that could be derated to run on lower octane.
3) Hot-rodded experimentals who could easily take it down a notch (or buy their racing fuel the same way Nascar does).

The WORST solution is for us to do nothing and discover that the oil companies have decided on their own to quit making avgas. That would force the same changes as above, except now we'd all be running even lower octane car-gas, with all its problems: low vapor pressure, ethenol (and water) contamination, poor stability, irratic quality, etc, etc...

The oil companies can't make 95UL unless the government tells them to. And as long as we keep our mouths shut, that's not going to happen -- the government would just love to let GA die a slow death for lack of a fuel to burn. They know full well that the oil companies will eventually quit making avgas on their own if nobody says anything.

Aren't we just about sick of paying at least $1/gallon more for a poisonous additive that sticks valves, fouls plugs, and forces frequent $5/qt oil changes? Why are we willing to let the convenience of the tiny few who actually need the nasty stuff ruin it for everybody?

Read this:

Pelican's Perch #55 Lead in the Hogwash
 
Here is the problem: If the refineries said no more 100LL tomorrow, here is your alt fuel, a bunch of little things would happen. All could be addressed but many would be unknown without testing and would end up happening in the field. So many variables, fuel tanks, lines, valves, temps, pressures, carbs, injectors, engines, and on the list goes. Who is going to pay for all that study? Who is going to scream SUE! When an electric fuel pump diaphragm rips? A valve packing leaks? Fuel line weeps? An O-ring dissolves? Tank sealer falls off and plugs a fuel inlet?

Problem is no one wants to pay to figure this stuff out so we are stuck with 100LL. For now.....
 
asav8tor said:
Here is the problem: If the refineries said no more 100LL tomorrow, here is your alt fuel, a bunch of little things would happen. All could be addressed but many would be unknown without testing and would end up happening in the field. So many variables, fuel tanks, lines, valves, temps, pressures, carbs, injectors, engines, and on the list goes. Who is going to pay for all that study? Who is going to scream SUE! When an electric fuel pump diaphragm rips? A valve packing leaks? Fuel line weeps? An O-ring dissolves? Tank sealer falls off and plugs a fuel inlet?

Problem is no one wants to pay to figure this stuff out so we are stuck with 100LL. For now.....
Click to expand...

The only "little thing" that can happen if the fuel is exactly the same (except for the lead) is detonation. And that is only likely if you're running an engine with 10.5:1 compression and stock timing.

Yes, Lycoming and Continental would need to test their engines and declare which would work and which one's wouldn't. But frankly, if they don't already know, they need to hire an engineer.

What's the alternative? The oil companies simply quit making the stuff and we're stuck with cargas. That's puts us in the same boat with regards to testing, but with worse fuel and no factory support. And we get to lug highly explosive fuel in gas cans to the airport whenever we want to fly.

It's like anything else. Until the change comes, everybody will claim there's no solution. Then the change will happen anyway, and the things that have to be done to make it work will get done. And, as usual, the result will be worse than it could have been if the people who said it was impossible had got on-board in time to effect the outcome.

We can have cheap unleaded avgas that doesn't mess up our engines and threaten our safety. Or we can be learn to live with car gas. If we don't say anything, we get option 2.
 
What happens with 9.5:1 pistons?

Supposedly 8.5 was the max for auto fuel.

BTW, ethanol is a scam.
 
Car makers claimed engines would self destruct if the lead was removed from car gas. That was until the feds mandated no more lead. It was a miracle, all of a sudden car engines could run with no lead.
 
Gary R. said:
Is adding lead the only way to boost the octane in gasoline?
Click to expand...
No. However, it is (currently) the cheapest way. TEL (tetraethyl lead) is a great octane booster. Unfortunately, it is a "great" environmental pollutant - it doesn't degrade.

Otherwise, it must be blended. "Gasoline" is a mixture of several different streams in a refinery, and this mix is always changing to optimize the yield from the type of crude, product mix and season (vapor pressure of gasoline must be adjusted seasonally). Octane can be boosted by adding reformate, which is basically a low-octane that has been converted ("reformed") in an expensive process.

Someone mentioned NASCAR and leaded fuel. Lots of non-NASCAR race cars run on unleaded fuel and a growing number on diesel (particularly in endurance racing).

TODR
 
Randy Walls said:
I find it hard to belive that 10% Ethanol in unleaded is so bad. If all of the horrible things that are supposed to happen are true, Interstate 90 should be littered with dead cars all winter. I wish someone smarter than me would seriously evaluate the effects of E-10 fuel in airplanes. I know higher concetrations of ethanol or metanol in concentration can cause problems but I really wonder about 10% ethanol.
Click to expand...

The problem with that arguement is that cars are not subjected to temperature and pressure changes the same way that aircraft are.

Also, ethanol absorbs water which is released under the right circumstances. Not sure you'd like iced over fule lines at 10K.

I was watching a history channel show on Pikes Peak racers yesterday, and yes those cars were running special fluids to prevent breakdowns. For instance, normal break fluids would boil at the ambient pressure at 14k feet.

You can find some interesting articles about ethanol in airplanes at http://www.aviationfuel.org/autogas/articles/. This site is run by the EAA.
 
jmartinez443 said:
The problem with that arguement is that cars are not subjected to temperature and pressure changes the same way that aircraft are.

Also, ethanol absorbs water which is released under the right circumstances. Not sure you'd like iced over fule lines at 10K.
Click to expand...

Seems like in our society, anyone who gets an article published is an expert on the subject and we then use that information as gospel for the rest of eternity.

If ethanol absorbs water why don't fuel systems freeze up when the temperature is below 32F? When's the last time your auto fuel system froze up? If it doesn't freeze up in an auto, why would it in an airplane?

I just don't buy into boogy man information that gets restated and restated and meanwhile some of us are out flying around OK with the stuff. If you've had a problem with it, report it. But lets stop reporting what has not been proven or backed up by experience.
 
David-aviator said:
If ethanol absorbs water why don't fuel systems freeze up when the temperature is below 32F? When's the last time your auto fuel system froze up? If it doesn't freeze up in an auto, why would it in an airplane?
Click to expand...
Basically, because the freezing point of the gasoline/water/EtOH mixture is less than 32F. Adding EtOH to water is like adding antifreeze to water - it depresses the freezing point. 50/50 water / antifreeze mixtures don't freeze at 32F, right? EtOH tends to keep water in solution rather than letting it separate out into a separate phase. EtOH can be like Prist - it keeps the water in solution rather than letting it separate out and form ice in the fuel system (generally regarded as Bad).

Mogas is formulated for specific climatic conditions. This means changing the vapor pressure among other things. This blend is frequently updated at the refinery and/or gasoline terminal where trucks fill up to take gasoline to stations.

I suspect that during colder conditions, some amount of additive is used to keep water in solution (like Prist with jet fuel). If you took Mogas that wasn't blended for cold conditions, added water and then cooled it to, say 10F, you might get ice formation as the fuel is atomized or even out of bulk solution.

TODR
 
David-aviator said:

I just don't buy into boogy man information that gets restated and restated and meanwhile some of us are out flying around OK with the stuff. If you've had a problem with it, report it. But lets stop reporting what has not been proven or backed up by experience.
Click to expand...

David, it is true that I have not personally had experience with ethanol-laced fuel in an aircraft. And from your accounts, it seems that everything is fine and you feel comfortable with it. However, that does not invalidate the information in the available literature. Below please find an excerpt from one of the articles I referenced. Take it for what it's worth.

"Now we come to the really hard part: The fuel distribution system in all of the older aircraft. When
the fuel man mistakenly delivered some ethanol-containing fuel to my farm, I had three stalled
tractors and an old pickup that never ran right again. The ethanol fuel ruined all of the fuel hoses,
caused numerous leaks and necessitated the replacement of two fuel pumps and 11 fuel filters.
Now if you think your old aircraft will handle ethanol better than my old tractors, guess again.
Several years ago, another state tried ethanol in one of its Cessna aircraft. In a flight of less than
900 miles, the mechanic claimed that they had to change the composite carburetor float seven
times. There were also leaks and problems from other fuel system components."
 
Valve Seats, again

from:http://www.bp.com/sectiongenericarticle.do?categoryId=4503701&contentId=57723
Some engines benefit from the use of lead to help protect vulnerable engine valve seats. These could otherwise rapidly wear away, leading to loss of compression/engine failure. However, it must be said the use of lead can also give rise to problems such as spark plug fouling and attack on certain valve metallurgies.

And from:http://en.wikipedia.org/wiki/Avgas
Many general aviation aircraft engines were designed to run on 80/87 octane, roughly the standard for automobiles today. Direct conversions to run on automotive fuel are fairly common and applied via the supplemental type certificate (STC) process. However, the alloys used in aviation engine construction are rather outdated, and engine wear in the valves is a potential problem on automotive gasoline conversions. Fortunately, significant history of mogas-converted engines has shown that very few engine problems are actually caused by automotive gasoline.

And from TC:http://www.tcmlink.com/visitors/carenfeed/engoperhdr.cfm
Current aircraft engines feature valve gear components which are designed for compatibility with the leaded ASTM D910 fuels. In such fuels, the lead acts as a lubricant, coating the contact areas between the valve, guide, and seat. The use of unleaded auto fuels with engines designed for leaded fuels can result in excessive exhaust valve seat wear due to the lack of lead. The result can be remarkable, with cylinder performance deteriorating to unacceptable levels in under 10 hours.
 
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jmartinez443 said:
David, it is true that I have not personally had experience with ethanol-laced fuel in an aircraft. And from your accounts, it seems that everything is fine and you feel comfortable with it. However, that does not invalidate the information in the available literature. Below please find an excerpt from one of the articles I referenced. Take it for what it's worth.

"Now we come to the really hard part: The fuel distribution system in all of the older aircraft. When
the fuel man mistakenly delivered some ethanol-containing fuel to my farm, I had three stalled
tractors and an old pickup that never ran right again. The ethanol fuel ruined all of the fuel hoses,
caused numerous leaks and necessitated the replacement of two fuel pumps and 11 fuel filters.
Now if you think your old aircraft will handle ethanol better than my old tractors, guess again.
Several years ago, another state tried ethanol in one of its Cessna aircraft. In a flight of less than
900 miles, the mechanic claimed that they had to change the composite carburetor float seven
times. There were also leaks and problems from other fuel system components."
Click to expand...

Well, I guess its a good idea not to use it in old equipment. I've heard farmers don't like the stuff but they sure are not shy about producing it for everyone else...:)
 
And yet my Harley has 30 year old valve seats

hevansrv7a said:
from:http://www.bp.com/sectiongenericarticle.do?categoryId=4503701&contentId=57723
Some engines benefit from the use of lead to help protect vulnerable engine valve seats. These could otherwise rapidly wear away, leading to loss of compression/engine failure. However, it must be said the use of lead can also give rise to problems such as spark plug fouling and attack on certain valve metallurgies.

And from:http://en.wikipedia.org/wiki/Avgas
Many general aviation aircraft engines were designed to run on 80/87 octane, roughly the standard for automobiles today. Direct conversions to run on automotive fuel are fairly common and applied via the supplemental type certificate (STC) process. However, the alloys used in aviation engine construction are rather outdated, and engine wear in the valves is a potential problem on automotive gasoline conversions. Fortunately, significant history of mogas-converted engines has shown that very few engine problems are actually caused by automotive gasoline.

And from TC:http://www.tcmlink.com/visitors/carenfeed/engoperhdr.cfm
Current aircraft engines feature valve gear components which are designed for compatibility with the leaded ASTM D910 fuels. In such fuels, the lead acts as a lubricant, coating the contact areas between the valve, guide, and seat. The use of unleaded auto fuels with engines designed for leaded fuels can result in excessive exhaust valve seat wear due to the lack of lead. The result can be remarkable, with cylinder performance deteriorating to unacceptable levels in under 10 hours.
Click to expand...

I recently completed what was probably the fourth top-end overhaul on a 1974 Harley Sportster that I bought last year. With 9.5:1 compression and hemi heads, it was designed to run on 97 Octane leaded premium, but it's obviously been run on unlead for at least 30 years. The stock valve seats on this engine are merely ground out of the raw cast-iron heads -- they aren't even steel inserts. Although you can buy "no-lead" hardened valves and seat inserts for it, most people don't bother.

So what did I find when I pulled the heads? The factory original valve seats were still perfectly servicable after normal grinding for a new set of valves. The valves I replaced were NOT hardened "no-lead" valves, and I didn't waste my money on hardened replacements.

So much for "Valve Recession" theory.
 
Alcohol/Water in Fuel

Someone mentioned earlier that alcohol in fuel can hold water in solution to be released later and potentially cause problems in flight.

Hopefully one of you is a chemistry guru and can explain this to me. I'm confused because I thought the test for alcohol was to put a certain amount of water in a container, add the fuel, wait a few minutes and if the water content appeared to INCREASE then you have alcohol? The fuel tester I have is graduated in a way that supports this.
 
bjustus said:
Someone mentioned earlier that alcohol in fuel can hold water in solution to be released later and potentially cause problems in flight.

Hopefully one of you is a chemistry guru and can explain this to me. I'm confused because I thought the test for alcohol was to put a certain amount of water in a container, add the fuel, wait a few minutes and if the water content appeared to INCREASE then you have alcohol? The fuel tester I have is graduated in a way that supports this.
Click to expand...

From one of the articles at www.aviationfuel.org:

"There is an easy way to check for
alcohol in the fuel you buy with an
inexpensive, simple test kit available
from Petersen Aviation at (308) 832-
2050, www.webworksltd.com/petersen
or Sporty?s pilot shop (800) 543-8633.
They offer improved test kits for octane
range and alcohol presence.
Alternatively, another graduated
cylinder method with instructions is
available from the EAA (920) 426-
4843) as listed on their web site
www.EAA.org, regarding autogas
STCs.
Generally, with a careful mix of nine
parts gasoline and one part water,
shaken thoroughly, and allowed to stand
for 10 minutes, this mixture should yield
the same amount of water and gasoline
by volume. If the amount of ?water?
appears to increase, then suspect alcohol
mixed in the fuel and separated out with
the water."
 
bjustus said:
Someone mentioned earlier that alcohol in fuel can hold water in solution to be released later and potentially cause problems in flight.

Hopefully one of you is a chemistry guru and can explain this to me. I'm confused because I thought the test for alcohol was to put a certain amount of water in a container, add the fuel, wait a few minutes and if the water content appeared to INCREASE then you have alcohol? The fuel tester I have is graduated in a way that supports this.
Click to expand...
Ok, what we have here is a multi-component liquid-liquid phase equilibrium problem. Let me see if I can explain:

Water and hydrocarbons are different types of molecules. Water is polar, meaning that it has a negative charge on one end and a positive on the other. Hydrocarbons tend not to have charges distributed on them. One practical consequence of this is that one of these is able to dissolve only small percentages of the other. Water doesn't really dissolve in oil.

Now we have EtOH. This is a sort of hybrid molecule - it has a charged end and a non-charged end. This means it can dissolve in water or in oil. It can also improve the solubility of water in oil and vice versa. The specific balance depends on what we call a partitioning constant, essentially a measure of how much the EtOH "likes" to be dissolved in water vs "liking" to be dissolved in oil.

Now, on to the case of AvGas with 5% EtOH. If we have small quantities of water present, the water will dissolve in the AvGas due to the presence of EtOH. But, if we have a large amount of water present, the EtOH can't make it all dissolve in the water - it's too much to overcome. So, some of the EtOH will want to dissolve into the water - it likes both oil and water will want to achieve an equilibrium between the two.

So, if we take AvGas and add water, some of the EtOH will leave the AvGas phase and enter the water phase. This is how the volume of water seems to increase.

Whew!

TODR
 
Ok, here are just a couple of threads discussing H20 in fuel, ethanol, 100LL and various other issues associated with fuel. The first two links below are specifically discussing water in fuel and how ethanol affects the mixture. The other two are just two of the many other threads devoted to the discussion of fuel. Do a search on the word "Ethanol" and you will get a long list of other threads to read.

http://www.vansairforce.com/community/showthread.php?t=15462&highlight=ethanol

http://www.vansairforce.com/community/showthread.php?t=14204&highlight=ethanol

http://www.vansairforce.com/community/showthread.php?t=19214&highlight=ethanol

http://www.vansairforce.com/community/showthread.php?t=16733&highlight=ethanol

Flame me if you must (go ahead Yukon, I can take it!) but the notion that a 10% mixture of ethanol in our aircraft will cause our planes to fall out of the sky is ridiculous. Like any other change we must face, the act of changing itself is the problem and not the thing that is to be changed.

As I have posted in one of the threads above the real aversion to ethanol, diesel engines, auto engines, water cooled engines, electric engines, other blah blah blah different engines or components or designs or whatever else changes we look at is not the technical issue of the change. It is the economic impact of making that change. The difference in labor involved, the difference in understanding or knowledge about the new system are the things that restrict the change.

As an example of these systems and the arguments that have been put forth against such things as vapor lock, water contamination, fuel mixtures at altitude or whatever else is being brought up as reason against new ways of doing things I ask nay sayers to chime in on this:

Please explain to me why I can have a 350 ci water cooled V8 engine take on fuel at an altitude of about 1200' msl and then consequently drive such vehicle to an altitude of 12,000' msl and spend a solid week at that altitude without adverse consequences in the operation of said engine! While on vacation this past July I bought fuel on the plains of Kansas where the air temperature was 95 degrees. On that same tank of gasoline I drove around for a week in the mountains of Colorado never coming lower than 9500' msl while making it up to an estimated 12,000'.

To hear the arguments against all of the suggested engine changes for aircraft, I should have never been able to do this. My engine on day one should have ceased operating not to mention the fact that my brakes should have failed because the brake fluid had boiled off. I should be dead by now because of these catastrophic failures. However, I am glad to say none of these catastrophic failures happened. I returned back down off of that 12,000' mountain with nary a hiccup from that engine. My brakes did not fail me either. So go figure!

I do not believe that living at 1100 msl and driving to 12000' msl would be very much different than taking off at 1100 msl and cruising for an hour or two at 8500' msl. Whether I use 10% ethanol, a water cooled engine, electronic ignition, fuel injection, auto fuel or any number of new changes to the status quo should not matter a hill of beans. In the end the technical issues associated with using these various systems will not be as much a factor as will be the issue of paying for any of those new technologies.
 
jrsites said:
TODR, did you sleep at a Holiday Inn Express last night?
Click to expand...
No, thankfully that phase of my life is over - I quit my job that required me to be on the road every week! Muuuuuuch better. :) And all I ever got from staying at an Holiday Inn Express was fatter, not smarter - those darn cinnamon rolls!

I studied phase equilibria of organic materials as a graduate student and taught the subject several times, both to graduate students and later to consultants. I spent a little time looking at the partitioning of organic materials to tobacco smoke particles - Many hours of my youth were spent in bingo halls, collecting tobacco aerosol. You only need to see the extract from the filter once and you will never consider smoking. Ever.

TODR
 
RVbySDI said:
Ok, here are just a couple of threads discussing H20 in fuel, ethanol, 100LL and various other issues associated with fuel. The first two links below are specifically discussing water in fuel and how ethanol affects the mixture. The other two are just two of the many other threads devoted to the discussion of fuel. Do a search on the word "Ethanol" and you will get a long list of other threads to read.

http://www.vansairforce.com/community/showthread.php?t=15462&highlight=ethanol

http://www.vansairforce.com/community/showthread.php?t=14204&highlight=ethanol

http://www.vansairforce.com/community/showthread.php?t=19214&highlight=ethanol

http://www.vansairforce.com/community/showthread.php?t=16733&highlight=ethanol

Flame me if you must (go ahead Yukon, I can take it!) but the notion that a 10% mixture of ethanol in our aircraft will cause our planes to fall out of the sky is ridiculous. Like any other change we must face, the act of changing itself is the problem and not the thing that is to be changed.

As I have posted in one of the threads above the real aversion to ethanol, diesel engines, auto engines, water cooled engines, electric engines, other blah blah blah different engines or components or designs or whatever else changes we look at is not the technical issue of the change. It is the economic impact of making that change. The difference in labor involved, the difference in understanding or knowledge about the new system are the things that restrict the change.

As an example of these systems and the arguments that have been put forth against such things as vapor lock, water contamination, fuel mixtures at altitude or whatever else is being brought up as reason against new ways of doing things I ask nay sayers to chime in on this:

Please explain to me why I can have a 350 ci water cooled V8 engine take on fuel at an altitude of about 1200' msl and then consequently drive such vehicle to an altitude of 12,000' msl and spend a solid week at that altitude without adverse consequences in the operation of said engine! While on vacation this past July I bought fuel on the plains of Kansas where the air temperature was 95 degrees. On that same tank of gasoline I drove around for a week in the mountains of Colorado never coming lower than 9500' msl while making it up to an estimated 12,000'.

To hear the arguments against all of the suggested engine changes for aircraft, I should have never been able to do this. My engine on day one should have ceased operating not to mention the fact that my brakes should have failed because the brake fluid had boiled off. I should be dead by now because of these catastrophic failures. However, I am glad to say none of these catastrophic failures happened. I returned back down off of that 12,000' mountain with nary a hiccup from that engine. My brakes did not fail me either. So go figure!

I do not believe that living at 1100 msl and driving to 12000' msl would be very much different than taking off at 1100 msl and cruising for an hour or two at 8500' msl. Whether I use 10% ethanol, a water cooled engine, electronic ignition, fuel injection, auto fuel or any number of new changes to the status quo should not matter a hill of beans. In the end the technical issues associated with using these various systems will not be as much a factor as will be the issue of paying for any of those new technologies.
Click to expand...

I agree, but I also think that it is a bit psychological. People tend to stick with what they know, even if the economical aspects say othervise. The reason may be to feel secure, or it may be that they just don't want to be bothered with yet more new stuff to learn.
 
SvingenB said:
I agree, but I also think that it is a bit psychological. People tend to stick with what they know, even if the economical aspects say othervise. The reason may be to feel secure, or it may be that they just don't want to be bothered with yet more new stuff to learn.
Click to expand...
True. I so agree with your notion that it is psychological. In fact, the arguments are going to lean more towards the emotional effect those psychological factors have on the economics more than on whether the technical aspects are restricting the ability to use some new technique or technology.

I would be inclined to say it is that psychological factor that causes the economical restrictions rather than the technical factor that imposes the economical restrictions. In my opinion you are dead on with this.
 
Ethanol use in cars and planes

RVbySDI said:
...Please explain to me why I can have a 350 ci water cooled V8 engine take on fuel at an altitude of about 1200' msl and then consequently drive such vehicle to an altitude of 12,000' msl and spend a solid week at that altitude without adverse consequences in the operation of said engine!
Click to expand...

It's been a while since I slept at a Holiday Inn, but thought I would pipe in with my comments and random thoughts (and ramblings).

Re: ethanol gasoline for aviation purposes:

For one, the fuel tanks in our planes are all vented tanks. As the temperature changes, air is exchanged between the fuel tank and ambient due to expansion/ contraction. The ethanol will absorb the moisture or condensation from the humid air. As the pure ethanol content is decreased in the tank, the octane of the fuel decreases as well, and increases your risk of detonation.​
As well, the resultant condensate of water/ethanol when temperature drops, is highly corrosive to aluminum. Not good for aluminum tank, lines and carb bowl.​
In a car, the fuel tank is a somewhat sealed system. In fact, the tank is slightly pressurized I believe. These tanks are made of steel, and can withstand the pressure without bulging. Not being vented prevents external moisture (contained in ambient air) to be absorbed by the ethanol.​
Solution?

Sealed tanks.... how to do that for an airplane? My guess is as good as yours. Would need some complex venting system maybe? Steel tanks ?! I don't think so (Vans has driven that "build it light" pretty deep in my psyche). Too much weight here.​
Different materials for fuel deliver and storage. Lined aluminum tanks (we know of the disastrous results regarding earlier recommendations to coat the fuel tanks). Steel fuel lines, alternate carb materials etc. Can be done, at expense of weight.​
One test group that was using RVs with AGE85 found corrosion issues (I don't specifically recall my source on this one).​
Fuel pumps, gaskets and hoses. Yeah, this can all be swapped out to appropriate gasket material and teflon hoses. Fuel pumps that tolerate ethanol should be available as well.​
Vapor pressure? Can be somewhat resolved by pumping fuel from the tanks (cars do it that way), but need to keep fuel cool in the engine compartment. Need to rethink engine driven fuel pump (what a heat soaker that is).​
Carb? Maybe fuel injection is better. Fuel may boil in the carb and let the float sink, thus flooding it (not to mention issues with composite floats... but that can be changed too). Not sure that present aviation fuel injection systems recommend ethanol either. Don't know what issues there are with the fuel injection system.​
Use smaller cylinders like in cars? Well, we can use lower octane gasoline, but still same issues if ethanol is mandated. Smaller cylinders require redrive, since peak torque is now beyond the propeller speed range (see rotax 912/914).​
For now, though, I'll stick to premium mogas (no alcohol in these parts for premium) for the C-150 we fly, and regularly test for alcohol. Our RV will be broken in with avgas, then mogas will be used for local flights.

STCs were developed for mogas. If these problems (and others) could be resolved for ethanol blends, I'm sure someone could make a little dough by developing an STC for that, if it is possible at all.


I 'm interested in other people's thoughts and comments on this subject. Good thread.
 
Yeah OK

I'm still trying to summon the enthusiasm to do some experiments..I.e get a sample of 10%Gashol, mix it with as much water as I can get to dissolve...The freeze it and suck on it to just under boiling etc etc....Do this until the Wife finds out at least.

But...From what I hear the water tends to go into the water not the other way round..so the water sucks the ETOH OUT of solution?..Is that correct?

If so then my experiment won't work..>Doug can you help us here?

Secondly, Just how much water can a 10% mix actually hold and can we make a reasonable assumption of how much will drop out when he pressure and temp is reduced (if any).

I.e we have a 10% mix...thats 4.2 Gallons of ethanol for the average RV...Will this quantity of Ethanol drop out 1 fluid ounce or a gallon of water??

If we had actual data (by experiment or calculation) we maybe able to resolve the issue by adding a Gascolator of the appropriate capacity...the ones from Van's will also work under pressure according to the supplier.

Thats if this is even an issue.

Does anyone have data on how much water can be absorbed at various temps and pressures?...Should be a simple calculation to see how much of an issue this phase seperation is.

Frank
 
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