How much ethanol is too much

Sorry, pfarber, but I'll have to give you a [citation needed] on your statements. Some good research papers seem to contradict your statements (one is attached and a relevant part quoted below), but feel free to include documentation that supports your point of view. Also, nobody talks about 100% ethanol, but a blend of multiple molecules, where the sum is more than the individual parts.

Please explain why those references are pertinent. Which planes contain which polymers for sealants? Is it possible a C-152 uses different ways to seal the fuel?

Hate to burst everyone's bubble (not really, you'all just wrong sometimes).

What if I told you the FAA ran a Cessna 152 and an IO-540 on 100% ethanol and did nothing to airplane except a minor mixture adjustment?

The engine made MORE HP, and they could not get it to detonate.

The only thing stopping 100% ethanol is the petroleum industry and old wives tales. Rubber is not the problem. In 13 YEARS the 100% ethanol 152 never had a fuel related issue.
I'd like to see the citation for this, too. Conversely, is the C-152 typical of all planes?
 
Isn’t there a way to remove a lot of the ethanol by adding water, churning it up, letting it settle and then draining it out? Or did I dream that up?

Yes, just like that. Mix/churn the corn liquor gas with fresh water and let it settle for as long as possible. Either drain off the water from the bottom or pour off the gas from the top. Mix with equal parts of your avgas and you should be good to go.
No, because many of the other components of the fuel are also water soluble, to some degree. Toluene is a large component of automotive gasoline- up to 30 %- and is surprisingly soluble in water!! In plain water, 0.5 g or so dissolves in a liter of water. The extracted alcohol raises the solubility of toluene in the aqueous solution quite a bit. Removing the ethanol and at least some of the toluene reduces the octane rating.
 
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Remember AGE-85? (Aviation Grade Ethanol) 85%

Swift Fuels removed the word 'Ethanol' from their website but, their fuel is based on Ethanol. (Not Corn Base, It's Switchgrass).
 
Remember AGE-85? (Aviation Grade Ethanol) 85%

Swift Fuels removed the word 'Ethanol' from their website but, their fuel is based on Ethanol. (Not Corn Base, It's Switchgrass).
Just because it is "based on ethanol" doesn't mean that it is ethanol. Ethanol is ethanol, C2H6O, whether is comes from corn, switchgrass, sugar water, or ethylene. Swift processes the ethanol into hydrocarbons/alkenes/aromatic compounds of some sort that is compatible with airplane engines and their fuel systems.
 
Please explain why those references are pertinent. Which planes contain which polymers for sealants?
Various NBR (acrylonitrile butadiene rubber) formulations are used in fuel and oil hoses.
If you look at figures 14-19 in that study, you'll see that some NBR formulations exhibited (almost) no swelling in straight fuel, but close to 20% swelling in E10 gas, without the addition of additional ketones that might be present in fuel blends. A 10% ketone concentration got the swelling from 20% to 40%. The same study quotes guidelines calling for less than 15% swelling for dynamic apications.

Is it possible a C-152 uses different ways to seal the fuel?
There's less of a fuel sysyem compared to an Archer, for example, but still the same synthetic rubber hoses susceptible to swelling in the presence of ethanol and other mogas components. And he doesn't know what kind of rubber compounds are in his hoses, since the TSO and the MIL SPEC it references only calls for an "inner tube of oil-resistant synthetic rubber".

And we haven't started talking about carb seals and such.
Point still stands - ethanol has a demonstrated impact on the types of rubbers used in fuel hoses, compounded by some of the additional compounds present in mogas that avgas doesn't have.
 
Various NBR (acrylonitrile butadiene rubber) formulations are used in fuel and oil hoses.
If you look at figures 14-19 in that study, you'll see that some NBR formulations exhibited (almost) no swelling in straight fuel, but close to 20% swelling in E10 gas, without the addition of additional ketones that might be present in fuel blends. A 10% ketone concentration got the swelling from 20% to 40%. The same study quotes guidelines calling for less than 15% swelling for dynamic apications.
What planes use NBR formulations for hoses? Some planes don't. The oil lines don't count because no fuel should be in those. If it is, a swollen hose isn't the important problem.
What ketones are in fuel blends? Here's a typical SDS for automotive gas- no ketones: https://www.valero.com/sites/defaul...s_-_002-ghs_unleaded_gasoline_rev1_5-14_0.pdf and no ketones are listed. Other than the ethanol, some alkenes, and small amount of 100LL, the automotive and aviation fuels are very similar. https://www.aviation-fuel.com/pdfs/MSDS_for_AvGas_100LL_from_P66_dated_3-04-13.pdf
Some hoses are made of conductive PTFE are aren't affected by ethanol at all: https://www.herberaircraft.com/eaton_aeroquip_teflon_hoses
There's less of a fuel sysyem compared to an Archer, for example, but still the same synthetic rubber hoses susceptible to swelling in the presence of ethanol and other mogas components. And he doesn't know what kind of rubber compounds are in his hoses, since the TSO and the MIL SPEC it references only calls for an "inner tube of oil-resistant synthetic rubber".
The fuel lines on the C-152s I've flown are metal, at least until it gets into the firewall. Beyond that, it may be rubber or a different material. Even so, I wouldn't run ethanol in it until I know if the materials could stand it.
And we haven't started talking about carb seals and such.
Point still stands - ethanol has a demonstrated impact on the types of rubbers used in fuel hoses, compounded by some of the additional compounds present in mogas that avgas doesn't have.
Point stands in some cases. One needs to know their plane and the materials used. Not all planes use rubber hoses. EAB aircraft can, and often are, made to be tolerant of ethanol in auto gas. The "additional compounds" you mention, presumably ketones, don't exist in car gas.

You are making the same error pfarber did: making a sweeping generalization. Bottom line- know your plane and components and then you can make informed decisions.
 
What planes use NBR formulations for hoses? Some planes don't.
All that use TSO-C53 hoses can have NBR formulations. Short of the owner reaching out to the manufacturer of each and every hose in his fuel system, there is no way to really know.
What ketones are in fuel blends? Here's a typical SDS for automotive gas
The one you provided doesn't have any in it. The possibility of adding them has been considered, and you (the end user) have no sure way of knowing what's in the pump gas you're purchasing. As long as it meets the requirements, it can be a blend of anything that gets the refiner to the end product.
Some hoses are made of conductive PTFE are aren't affected by ethanol at all
But the rest of them aren't, and the average owner of a 172/182/PA28 and so on has no way of knowing it, short of ripping his fuel system apart and replacing everything with hoses and seals known to be tolerant of ethanol and whatever else there is (or might be added) in mogas.
The fuel lines on the C-152s I've flown are metal, at least until it gets into the firewall. Beyond that, it may be rubber or a different material. Even so, I wouldn't run ethanol in it until I know if the materials could stand it.
But that's not how this conversation started (not by you). It started as "ethanol isn't a problem". The study shows it is. And while it might be easier to ensure ethanol compatibility on a new EAB build, certified aircraft can throw a few extra hurdles at you.
Point stands in some cases. One needs to know their plane and the materials used.
And it doesn't stand in all other cases. One might not be able to do that without a complete fuel system teardown, replacing each and every component that might be susceptible (which includes fuel pump diaphragms, carb seals and so on).
Sometimes the vendor's datasheet is quite generic. Can you tell what kind of synthetic rubber is used in Aeroquip 303 hose?
The "additional compounds" you mention, presumably ketones, don't exist in car gas.
Have you looked at ALL fuel refiners and blenders, including the one supplying fuel to the island the OP will buy from? Who's generalizing now?
You are making the same error pfarber did: making a sweeping generalization.
See one line above. You did the same. I referenced a study that did look into potential fuel additives to determine their compatibility, while also looking at ethanol's effects and demonstrating it will cause swelling on rubber components expected to exist in an aircraft fuel system.
Bottom line- know your plane and components and then you can make informed decisions.
But the OP most likely doesn't know the plane that well. Even if he bought new hoses, they are still made to a standard that might make them incompatible with ethanol fuels.
 
Have you looked at ALL fuel refiners and blenders, including the one supplying fuel to the island the OP will buy from? Who's generalizing now?
Not ALL of them, but enough to see they are all nearly the same. There really aren't that many refineries. Oxygenates are ethanol, butanol, and various ethers (MTBE, ETBE, and so forth). The ethers aren't used much anymore in the USA. Acetone is added to racing fuel by the user. How about you find and cite an exception?
See one line above. You did the same. I referenced a study that did look into potential fuel additives to determine their compatibility, while also looking at ethanol's effects and demonstrating it will cause swelling on rubber components expected to exist in an aircraft fuel system.
Nope. See above
But the OP most likely doesn't know the plane that well. Even if he bought new hoses, they are still made to a standard that might make them incompatible with ethanol fuels.
The OP is a hypothetical situation. Provided it's allowed to be installed on a plane, one can install ethanol compatible lines and gaskets. Like I said, it is much easier for the owner of an EAB.
 
Provided it's allowed to be installed on a plane, one can install ethanol compatible lines and gaskets.
Do you know of any specific approvals to replace fuel system components (including carbs/injectors and pumps) on a certified aircraft with ethanol-compatible ones?
Like I said, it is much easier for the owner of an EAB.
Except OP is talking about a 182. If we had some eggs we could make some ham and eggs, if we had some ham.
 
We have that in abundant supply in Vermont, although it's more expensive than high octane auto gas. Mechanics have recommended that it be mixed with Avgas periodically for the beneficial effect of lead, which the old engines were designed around.

We have E-Free Mogas at gas stations here and a nearby airport (KBNL) has it also at near the cost of 100LL. I often mix Mogas with 100LL as my experimental loves 100LL but it doesn't love the lead. I need at least 93 octane and most of the current E-Free I can get is only 90 so I add a bit of the 100LL to bring it up.
 
Interesting discussion, thanks all.

I'm not yet on the island so I still have the opportunity to avoid cannibalism.

It's a choice of "southern route" through the island, with good weather, or "northern route" where weather is likely to be much less friendly. Unless I can confirm ethanol free mogas on the island somehow, it looks like the north route is a more sensible option.

Does anyone here speak Portuguese?
 
Concerning lead: The Aeronca folks found a late 1940s Continental bulletin that called for leaded gas for the first 50 hours of a new engine to set the rings, valves and all that. After that, you could run clear gas without lead. Which makes our unleaded fuel seem like an advanced formula. The lead is a cheap octane booster first and foremost.
 
Moderate to high concerns.

I took a class on fuel and lubricant chemistry in college. One of the lab activities was to test different rubbers in various solvents, and it was amazing how quick some of them would swell to more than double their size, or start falling apart.
I have no idea what kind of rubber hoses and o-rings are in your plane, but it's a good bet that there isn't any ethanol compatibility testing data on them.
Probably not a good thing to become a materials science test pilot over water.

I'd say you should look at having some approved fuel shipped over there. Maybe GAMI cand send you a couple drums of 100UL?
Hoses, o-rings and other rubber components were the biggest problem when 10% ethanol was introduced in the automotive world. I can’t remember how long ago that was but it might have been 20 years ago. However, long it has been, there has been time for the rubber materials and fuel systems to have left by attrition. We now have automotive and marine engines, particularly injected engines that suffer no problems at all from the use of 10% ethanol fuel.

With small engines, ethanol fuel can cause problems due to the materials that continue to be used in these products. There is still a myth among many such that they insist upon using ethanol free gasoline in everything. I use 10% ethanol in everything except small engine equipment, such as chainsaws, mowers, leaf blowers, and the like. For engines that require mix I use 100 low lead and Stihl oil, which contains Stabil. I have a 175HP mercury outboard motor 2001 vintage. All it ever sees is 10% ethanol fuel straight from the pump. It even sets up part of the year, but has never given any trouble running 10% ethanol fuel. It is fuel injected though. With an electronic injected engine the fuel stays pretty well sealed up as opposed to a vented carburetor.

All that said, I will never dream of using 10% ethanol in an aircraft. The rubber part problem coupled with the storage problems makes me keep it far away from my aircraft.
 
Do you know of any specific approvals to replace fuel system components (including carbs/injectors and pumps) on a certified aircraft with ethanol-compatible ones?
No, mainly because I'm not an A&P. I don't pretend to knowledge I don't have. I don't know which lines have a TSO approval, PMA approval, or if other documentation is needed.
This link shows replacement fuel lines for various Cessna models- for the purposes of this conversation, I'll assume they are authorized unless someone with some credentials explains otherwise. If I had a certified plane, I'd ask my A&P:

Going to the Stratoflex site, it seems those lines are made of PTFE, which is ethanol compatible:

I wouldn't be surprised if there are ethanol compatible replacement seals, diaphragms, and other parts for certified aircraft.

Except OP is talking about a 182. If we had some eggs we could make some ham and eggs, if we had some ham.
and then we discussed a C152.
@Cap'n Jack I believe you hail from the petrochem industry if I remember?
No, but I work closely with those that do. For example, I worked with several refineries to streamline their SARA analysis (saturates, asphaltenes, resins, aromatics) in the crude oil. Working with them, I updated an analysis that took 4 hours to run to about 45 minutes, and they can do further analysis on the various components, if desired. Their previous method didn't permit recovery of the sample fractions. I also worked with a refiner for analysis of some anti-knock compounds. There's some other work I'm doing that I can't discuss now.
everything except small engine equipment, such as chainsaws, mowers, leaf blowers, and the like.
I've no problem with E10, even after 6 to 9 months in storage because I add Stabil so I can store the mower/snow blower without draining the fuel. These small engines start on the second pull when I first run them. Without the additive, automotive fuel doesn't keep well at all. That reminds me...time to check that the snow blower starts so I have time to get it fixed before the rush, if needed. I've seen snow here in mid-October deep enough to dig.
coupled with the storage problems makes me keep it far away from my aircraft.
You are wise, unless you fly it often! Auto gas has more unsaturated hydrocarbons that polymerize into varnish that clogs things. The ethanol likely helps that process along.
 
Sorry, pfarber, but I'll have to give you a [citation needed] on your statements. Some good research papers seem to contradict your statements (one is attached and a relevant part quoted below), but feel free to include documentation that supports your point of view. Also, nobody talks about 100% ethanol, but a blend of multiple molecules, where the sum is more than the individual parts.

I have no problem citing my sources.. I have no idea why people think I would make this up.


You can do your own research with the cited sources from the above paper. That should get you started.

The IO-540 was a standard 150 hour certification test with ethanol. The 152 was 13 years long study.

I don't think there is a nice way to put this, but just about everything you said was disproven with the above study.

The hilarious part is that the FAA certified the o-235 AND IO-540 for use with 100% ethanol... gotta wonder if Baylor would get an STC for it. But with all the old wives tales concerning ethanol it may not gain much attention.
 
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Hate to burst everyone's bubble (not really, you'all just wrong sometimes).

What if I told you the FAA ran a Cessna 152 and an IO-540 on 100% ethanol and did nothing to airplane except a minor mixture adjustment?

The engine made MORE HP, and they could not get it to detonate.

The only thing stopping 100% ethanol is the petroleum industry and old wives tales. Rubber is not the problem. In 13 YEARS the 100% ethanol 152 never had a fuel related issue.
Of course it went farther on 100% alcohol because there is more energy per volume in ethanol than in gasoline. I agree on that and I can see it being safe if properly handled. Where I disagree with you is your proposal to close the oil fields and burn strictly alcohol. Wouldn’t you agree that we need to have food to eat? Without corn and other grains there would be no livestock feed to speak of and there would be less farmland &or food crops. You can’t have it both was.
 
I also could be wrong, but if so, why do some racers bother with running ethanol rather than gasoline?
Because it is in their rules. Methanol is preferred, but methanol has more risks involved with it than ethanol. Methanol is flammable, toxic, and poisonous if ingested, inhaled, or in contact with the skin. Ethanol is toxic, flammable, and is safe for consumption as a critical ingredient of alcoholic beverages. It can be a dangerous chemical if pure alcohol is ingested.

Racing wise, the more alky you can stuff into a cylinder the more power is made, unlike gasoline.
 
I wouldn't be surprised if there are ethanol compatible replacement seals, diaphragms, and other parts for certified aircraft.
I would be. Every time a manufacturer makes a change, the product has to be tested and certified again. So we are often stuck with the ancient polymers. For instance, the Cessna nosegear oleo has a bad habit of ripping its O-ring seal in cold weather/ That seal shrinks and grabs the piston, and movement then spins the O-ring in its groove and causes a spiral fracture. All the oil and pressure is lost real quick. That's what Buna-N will do. But there are much newer and better O-ring compounds that won't suffer that, yet a brand-new Cessna will still have the Buna-N O-rings in it. So do the brake calipers. The only place I found the newer stuff was in the fuel injection system, which is much newer and built by Precision Airmotove, not Cessna. Most of the hoses are still the old MIL-spec. Who is going to pay the freight to replace and recertify new compounds for a few hundred airplanes a year? And Cessna won't spend bucks on the legacy stuff. Someone might come up with STCs, but those aren't cheap, so most would just keep using the old stuff.
 
Ethanol and methanol does not have the same BTUs as gasoline, it has less. You get less mpg with E10 gas versus straight gasoline.
We burn twice as much methanol racing versus gasoline. The reason we use methanol is because it has an octane rating of approximately 120 and it has a cooling effect that gasoline doesn’t.
I haven’t tried drinking it but I have plenty on my skin over the years with no side effects…yet!
Btw methanol is great to clean out tanks with because it sucks up water and evaporates quickly.
 
The hilarious part is that the FAA certified the o-235 AND IO-540 for use with 100% ethanol...
As usual, a whole pile of bunk.

Lycoming's SI 1070 gives the specs for fuels their engines are certified to use:
https://www.lycoming.com/sites/default/files/attachments/SI1070AB%20Specified%20Fuels.pdf
Ethanol is NOT LISTED at all.

If we go to the Type Certificate Data Sheets for those engines, which the FAA issues to Lycoming when they certify an engine, we see this:

1724948701135.png

The dashed lines refer you back to the first entry; they're just ditto marks. That SI 1070 applies to ALL the O-235 models.
https://drs.faa.gov/browse/excelExternalWindow/0F97DB024367B9368625853C0061E215.0001
Ethanol is NOT listed anywhere.

The O-540's TCDS says this, for ALL O-540s (long list; this is just a short selection):

1724948979787.png

For the IO-540s:

1724949211515.png

And that applies to ALL IO-540 models. No ethanol. At all.
https://drs.faa.gov/browse/excelExternalWindow/ED61CF457FEE2DC686258250006AC097.0001
 
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Of course it went farther on 100% alcohol because there is more energy per volume in ethanol than in gasoline. I agree on that and I can see it being safe if properly handled. Where I disagree with you is your proposal to close the oil fields and burn strictly alcohol. Wouldn’t you agree that we need to have food to eat? Without corn and other grains there would be no livestock feed to speak of and there would be less farmland &or food crops. You can’t have it both was.
It's not one or the other. After fermentation, the remaining material becomes "distiller's grain" and is then fed to livestock, or used for other purposes.
 
I would be. Every time a manufacturer makes a change, the product has to be tested and certified again. So we are often stuck with the ancient polymers. For instance, the Cessna nosegear oleo has a bad habit of ripping its O-ring seal in cold weather/ That seal shrinks and grabs the piston, and movement then spins the O-ring in its groove and causes a spiral fracture. All the oil and pressure is lost real quick. That's what Buna-N will do. But there are much newer and better O-ring compounds that won't suffer that, yet a brand-new Cessna will still have the Buna-N O-rings in it. So do the brake calipers. The only place I found the newer stuff was in the fuel injection system, which is much newer and built by Precision Airmotove, not Cessna. Most of the hoses are still the old MIL-spec. Who is going to pay the freight to replace and recertify new compounds for a few hundred airplanes a year? And Cessna won't spend bucks on the legacy stuff. Someone might come up with STCs, but those aren't cheap, so most would just keep using the old stuff.
Please see my citations in post #64 for Aircraft Spruce and Parker/Stratoflex.
Aircraft Spruce lists fuel hoses for various Cessna and Beechcraft aircraft made under the Stratoflex brand. The Stratoflex link indicates the fuel lines are PTFE which are ethanol compatible.
 
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Racing wise, the more alky you can stuff into a cylinder the more power is made, unlike gasoline.
Same with gasoline. That's why we have turbochargers, superchargers, etc. Stuffing more fuel into a cylinder does nothing unless you can oxidize it (air).
 
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