How much ethanol is too much

[Cap'n Jack]

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!

Don't try drinking it. It's another way to go blind as methanol preferentially damages the optic nerve.

 

[Dan Thomas]

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.

Stratoflex had to get certification for that.

 

[Cap'n Jack]

Stratoflex had to get certification for that.

Yes, exactly!

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?

Apparently, Parker/Stratoflex will.

Please see my citations in post #64 for Aircraft Spruce and Parker/Stratoflex.

 

[Tools]

If I read and understand all this do I get a honorary degree in chemical engineering? Askin for a friend…. Wow. Wow…

 

[Pinecone]

I also could be wrong, but if so, why do some racers bother with running ethanol rather than gasoline?

1) Higher octane

2) the class rules require it (Indy Cars).

 

[pfarber]

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:

View attachment 132875

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):

View attachment 132876

For the IO-540s:

View attachment 132878

And that applies to ALL IO-540 models. No ethanol. At all.
https://drs.faa.gov/browse/excelExternalWindow/ED61CF457FEE2DC686258250006AC097.0001

You didn't read the study, did you? Baylor said the FAA certified the IO-540 and o-235.

So who's wrong? Baylor? Peer reviewed studies? Or some guy with google and not reading past the first search page result?
Please READ the information and stop randomly googling.

Here we go.. AGAIN: https://afdc.energy.gov/files/pdfs/2896.pdf

Even with cited sources, peer reviewed studies, and links to .GOV and .EDU source materials some rando still thinks I'm making this up because THEY have weak google-fu.

Everything I am posting is coming from the Baylor study from the 90's. You can read it.. every word. PLEASE DO.

 

[Mikey52]

I wonder what carb modifications were done. After the valve recession was noticed.


And what is the Stc number? Can't seem to find it.

 

[Dan Thomas]

You didn't read the study, did you? Baylor said the FAA certified the IO-540 and o-235.

So who's wrong? Baylor? Peer reviewed studies? Or some guy with google and not reading past the first search page result?
Please READ the information and stop randomly googling.

Here we go.. AGAIN: https://afdc.energy.gov/files/pdfs/2896.pdf

So, let's see who certified what:


The certification was by Baylor, NOT BY THE FAA. Critical difference there. Show me in that document where the FAA certified the O-235s and O-540s to run on ethanol. https://afdc.energy.gov/files/pdfs/2896.pdf

Everything I am posting is coming from the Baylor study from the 90's.

Sure. The Baylor studies from the '90s. If the FAA had certified the O-235 and O-540 for ethanol, the TCDS would show it by now. The TCDS is the authoritative document published by the FAA for such things. Let's have a look at the O-235's TCDS:


Hm. See when it was last revised? January 31, 2020. That's at least 27 years after the Baylor studies. If the engine was indeed certified for use on ethanol, the TCDS would have shown that a long time ago.



The O-540 TCDS:



April 20, 2013, 20 years after the Baylor studies, and there is no certification shown for use on ethanol.

If you use fuels other than the engine was certified for, or STC'd for, you are in big trouble when it quits or when some FAA inspector discovers it. Mogas STCs specifically prohibit the use of gasolines containing ethanol:



And yes, ethanol qualifies as an alcohol.

 

[MacFlier]

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?

I do

 

[Domenick]

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.

Is the ethanol used in racing denatured or pure?

The potential lethal dose of methanol is 15 ml. That is 1 tablespoon.
The median lethal dose is 100 ml. That is less than 1/2 a cup.

The standard liquor shot is 44 ml, but consumable alcohol is 80 proof (40%) pure ethanol. 5 shots of pure methanol is 110 ml.

Methanol toxicity - Wikipedia

en.wikipedia.org

 

[Pinecone]

So, let's see who certified what:
View attachment 132899

The certification was by Baylor, NOT BY THE FAA. Critical difference there. Show me in that document where the FAA certified the O-235s and O-540s to run on ethanol. https://afdc.energy.gov/files/pdfs/2896.pdf

Sure. The Baylor studies from the '90s. If the FAA had certified the O-235 and O-540 for ethanol, the TCDS would show it by now. The TCDS is the authoritative document published by the FAA for such things. Let's have a look at the O-235's TCDS:

View attachment 132900
Hm. See when it was last revised? January 31, 2020. That's at least 27 years after the Baylor studies. If the engine was indeed certified for use on ethanol, the TCDS would have shown that a long time ago.



The O-540 TCDS:

View attachment 132901

April 20, 2013, 20 years after the Baylor studies, and there is no certification shown for use on ethanol.

If you use fuels other than the engine was certified for, or STC'd for, you are in big trouble when it quits or when some FAA inspector discovers it. Mogas STCs specifically prohibit the use of gasolines containing ethanol:

View attachment 132903

And yes, ethanol qualifies as an alcohol.

Do you understand how certification works?????

FAA does not certify things, They set the parameters for testing, may observe some tests, and then they issue the STC.

The STC modifies the TCDS. The airframe or engine manufacturer did not do the testing and certification, so there is no basic to change the TDCS. And the STC work is proprietary to the company owning the STC.

 

[Cap'n Jack]

Is the ethanol used in racing denatured or pure?

The potential lethal dose of methanol is 15 ml. That is 1 tablespoon.
The median lethal dose is 100 ml. That is less than 1/2 a cup.

The standard liquor shot is 44 ml, but consumable alcohol is 80 proof (40%) pure ethanol. 5 shots of pure methanol is 110 ml.

Methanol toxicity - Wikipedia

en.wikipedia.org

It is denatured ethanol to avoid taxes on it. They can put 2-propanol, gasoline (hydrocarbons and aromatic compounds), or other things in it. The E98 might not be 98% ethanol!

https://www.dlra.org.au/safety-data-sheets/powerpluse98-msds.pdf

https://www.sunocoracefuels.com/content/userfiles/files/fuel-selector/SUNOCO-Denatured-Ethanol-E98_US-SDS_22July20192.pdf

 

[Doc Holliday]

Do you understand how certification works?????

FAA does not certify things, They set the parameters for testing, may observe some tests, and then they issue the STC.

The STC modifies the TCDS. The airframe or engine manufacturer did not do the testing and certification, so there is no basic to change the TDCS. And the STC work is proprietary to the company owning the STC.

So what is the STC number to run ethanol in these engines? I would like to read up on it.

Thanks.

 

[Bob Noel]

Do you understand how certification works?????

FAA does not certify things, They set the parameters for testing, may observe some tests, and then they issue the STC.

The STC modifies the TCDS. The airframe or engine manufacturer did not do the testing and certification, so there is no basic to change the TDCS. And the STC work is proprietary to the company owning the STC.

apparently I don't understand the process today.

I thought an applicant proposes to the FAA how they (the applicant) intend to meet certification requirements. The FAA can reject or accept the plan. The FAA doesn't have to tell the applicant if the applicant is exceeding the requirements nor does the FAA have to explain specifically how to correct deficiencies ("bring me a rock" is not a bad simplification of the process).

When did the process change?

 

[Dan Thomas]

The Baylor University paper says this:



So we go to the FAA's STC site, https://drs.faa.gov/browse/STC/doctypeDetails

where all STC holders are listed alphabetically, and see if Baylor is listed as an STC holder:



Nope. Not there. So we check the names of the authors of that study, as listed on the header of the paper:


And we see this:



And Mr Tubbs is not listed:



Nor is Zanin:



So we check out the two STCs issued to Dr. Shauck:

https://drs.faa.gov/browse/excelExternalWindow/EBFE06A026CE1AAF8625702800648327.0001

And sure enough, there's an airframe certified to run on ethanol, but only the Piper PA-25 (Pawnee, a single-place cropsprayer):



And the other STC granted to Dr. Shauck:
https://drs.faa.gov/browse/excelExternalWindow/8ACA8B27ED9A07A98625702800641E1C.0001



It covers a few models of the O-540, and a few of the IO-540 as well. So we have the first STC that was the airframe certification since no engines are listed, and the second covers the engines that might be found in the PA-25.

So it turns out that P. Farber is partly right, as far as this goes. There is no STC granted to Dr. Shauck, his colleagues, or Baylor University or its Renewable Aviation Fuel Development Center to run an O-235 or a Cessna 152 airframe on ethanol. None at all. It may have been applied for as per the paragraph from the paper at the head of this post, but never granted.

Edit: I made a few textual changes there, and did a little more digging. The STC database decided to show me this STC for the O-235 to run on ethanol: https://drs.faa.gov/browse/excelExternalWindow/975B5C200682D2708625740300821009.0001

It came up when searching under Dr. Shauck's name but the STC is issued to some Texas outfit. Shauck must have been involved with it.



Still no STC for the 152 airframe, and you need STCs for both the engine and airframe to be legal. But maybe if I check "Shauck" again in a few days, the database might find one.

 

[chemgeek]

A potential problem with ethanol is that is has about double the vapor pressure of avgas. Higher ethanol content will create a higher potential for fuel line vaporization and vapor lock. Ethanol is also hygroscopic, so water absorption by fuel is also a potential issue. The extent of the potential problems scale with ethanol content.

 

[455 Bravo Uniform]

So who's wrong? Baylor? Peer reviewed studies?

I read the study you posted.

In academia, some papers end up at the end of a cul de sac, while others end up on a main road. Sometimes it’s because the study results couldn’t be verified or repeated, or not enough interest or funding (insert conspiracy theories, but funding begets studies that get funded, while others that may be unpopular or go against the grain can get hung out to dry).

I haven’t done it yet (I will, later tonight) but you can go to a publication database and see how many other authors in the field cited this report, and all of the prior and later works from these authors. That usually tells you about the significance of the results.

 

[455 Bravo Uniform]

Ethanol is also hygroscopic, so water absorption by fuel is also a potential issue. The extent of the potential problems scale with ethanol content.

Since ethanol & water are miscible, up to some point water in the fuel should be no problem. At what point does it become a problem where it affects power or ability to combust?

 

[Capt. Geoffrey Thorpe]

At what point does it become a problem where it affects power or ability to combust?

At the point which the water and ethanol separate from the gasoline.

"at 60 degrees F, water can be absorbed by a blend of 90%
gasoline and 10% ethanol up to a content of 0.5 volume percent
before it will phase separate. This means that approximately 3.8
teaspoons of water can be dissolved per gallon of the fuel before
the water will begin to phase separate."

https://www.epa.gov/sites/default/files/2015-09/documents/waterphs.pdf

 

[455 Bravo Uniform]

At the point which the water and ethanol separate from the gasoline.

"at 60 degrees F, water can be absorbed by a blend of 90%
gasoline and 10% ethanol up to a content of 0.5 volume percent
before it will phase separate. This means that approximately 3.8
teaspoons of water can be dissolved per gallon of the fuel before
the water will begin to phase separate."

https://www.epa.gov/sites/default/files/2015-09/documents/waterphs.pdf

Thanks. I was referring to the 100% ethanol potion of this discussion with my question.