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Mogas-Engine damage?

Weasel

Weasel

Well Known Member
Has anyone here ever actually, With there own eyes, seen engine damage on a 320, 360, or 540 lycoming that was defiantly, verified a result of running too low of an octane fuel?

Please post supporting pictures and or data if you can.

I am not interested in: My a&p said he saw....., I have a buddy....etc.
 
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Is this to include higher compression cylinders, ethanol, vapor lock, etc?
 
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Wrong title

Weasel said:
Has anyone here ever actually, With there own eyes, seen engine damage on a 320, 360, or 540 lycoming that was defiantly, verified a result of running too low of an octane fuel?
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Your title refers to Mogas (auto gas) but your question refers to low-octane...Not the same thing.

I stopped using Premium unleaded when my local supplier could no longer get ethanol-free gasoline. No damage to report.
 
I don't understand your question.

Are you asking about:
A) using ethanol tainted mogas
B) using regular unleaded mogas in a low compression engine
C) using regular unleaded mogas in a high compression engine
D) using premium unleaded mogas in either a high or low compression engine
E) All of the above

As you know, using a lower than recommended octane fuel can cause pre-ignition, which is known to damage engines.

Using ethanol tainted mogas of the proper octane will not harm the engine per say but will damage rubber seals in the fuel system that are not tolerant to the stuff. In addition, there has been a number of comments about it doing long term damage to aluminum fuel lines and tanks.

That does not take into account the problem experienced by fiberglass boats and airplanes with fiberglass fuel tanks from running ethanol compromised fuel.

Mechanically, you might be hard pressed to find an engine that sustained damage that was directly attributed to ethanol.
 
I have been running 90 ethanol free "recreation fuel" I get from a local gas station in my right tank and 100 LL in the left. I only use the 100 LL for take offs and landings. Only around 70 hours so more testing is needed on my part.
 
Has anyone here ever actually, With there own eyes, seen engine damage
Click to expand...
I have but not on a Lycoming, the one in question was a 220 HP Franklin engine with 10:1 compression ratio.

Having experimented with 91 octane E10 mogas in my own airplane for a few years without any problems whatsoever, I watched my friend try out 91 octane in his Franklin.
Long story short, we observed through borescope inspection, mild detonation in the #1 Cylinder. Evidenced by a super clean grayish look of the piston and no deposits left on any part of it. No lasting damage but would have eventually ended as engine damage.

I suspect you won't get many replies if any from anyone actually seeing engine damage due to low octane ( I assume lower than 100LL)
Had you asked who actually successfully uses 91 octane mogas, you would have gotten a mountain of replies.;)
 
I've personally seen piston damage on an IO-540 in a Glasair-III that was a 10.5:1 compression engine run on 100 LL and saw heavy use as a racer. 5 of the 6 pistons had holes burned thru especially between the crowns and in the first compression ring grooves. A couple of the pistons had chunks broken around the compression ring lands. Most of the compresion rings were broken into segments. I helped the owner replace the cylinders and pistons. The new pistons were reduced to 9.5:1 compression and the aircraft was sold and is flying well still today.

Granted, this was an example of an engine run extremely hard, and not on mogas, but the damage I saw was a textbook example of detonation and preignition... just like an old 429CJ Ford big block I once owned and rebuilt (I still have that engine BTW :) )
 
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Just the opposite result. O-320-E2G, 2600+ hours SNEW, diet of regular (87 octane) mogas from the time the STC became available until our supply started to have ethanol added to regular 2 or 3 years ago. Then it was run on 91 octane free of ethanol. Zero detrimental effects in probably 1800 hours of mogas burning flight. This engine was never babied either.
 
Ethanol

So here's something I've been pondering for a while.

We know that the engine doesn't care whether fuel has ethanol in it, and that ethanol issues come from plastic or rubber parts which soften or embrittle in the presence of the alcohol.

We've known that for a great many years now.

Furthermore: We also know that there are plenty of materials that can be used in fuel systems which aren't affected by ethanol. Fuel systems in cars use components constructed from those materials out of necessity. Cheap, plentiful, reliable, well-known.

So why isn't there a whole industry building and marketing ethanol-tolerant fuel system components for experimentals?

What would need to be considered in the design of a fuel system to end up with an airplane that'll run on car fuel? Not ethanol-free mogas, which is increasingly difficult to find. Actual car fuel, of the kind that you buy in any randomly selected gas station.

I think you'd need to consider tank sealant chemistry, O-rings in fuel line joints, fuel valve seals, electric and mechanical fuel pump internals, measures to prevent corrosion from water carried by hygroscopic fuel additives, routing of fuel lines through the engine bay to minimize vapor lock, fuel flow sensor seals, engine lubricant grade and change interval, fuel gauge pickups... What else?

It seems to me that ethanol is a discretionary problem: A builder could choose to construct an ethanol-proof airplane through judicious selection of components and materials, and proceed to operate that airplane significantly cheaper than one which requires "aviation" fuel. Auto makers dealt with this decades ago. Why isn't it the "normal" desired outcome for aircraft builders?

- mark
 
Airflow research fuel injection is ethanol tolerant, I'm feeding mine thru automotive electric fuel pumps and a turn down (return) regulator. I hope it does well, I just installed it on a transplanted O-360 Lycoming.
I previously ran a Mazda Rotary engine in my RV-8 using the same fuel pumps and regulator. Any automotive electronic fuel injection based system like EFII SDS (I used Real World Solutions EFI) uses these alcohol tolerant automotive components. I missed a few other makers, (sorry).
Newt asks: "So why isn't there a whole industry building and marketing ethanol-tolerant fuel system components for experimentals?"
These Automotive based systems are currently available and are ethanol tolerant.
 
9GT said:
I have been running 90 ethanol free "recreation fuel" I get from a local gas station in my right tank and 100 LL in the left. I only use the 100 LL for take offs and landings. Only around 70 hours so more testing is needed on my part.
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I also have been running 100LL in the left for Taxi, Take Off and Landings. I figure this way there is always 100LL in the lines when the RV-10 sits in the hangar. I usually switch the right tank about 1,000ft AGL with the boost pump on. My local airport doesn't have 91 MoGas yet, but we will on our next load, so for now I mix 1/3 100LL with 2/3 87 MoGas in my right tank only, this yields 91 Octane. My RV-10 runs just fine on this mix and I can't see any difference except one time while climbing out on the mix, I shut the Boost Pump off to a test and the Fuel Pressure dropped from 25 PSI to about 10 - 12 PSI and the engine began to stumble. Without touch any engine controls I turned the Boost Pump back on it it immediately returned back to 25 PSI. I tried this multiple times with the same result, so now I just leave the boost pump on until finished with the climb on the 91 octane mix. Once at attitude and leaned out I've never seen any issues of vapor lock/engine stumble.

Ray Doerr
N519RV (RV-10, 1150 Hobbs)
 
No damage to engine. I have a O-360-A4M with fixed pitched prop on my 7 year old RV-9A with 1275 hours. I use 87 octane car gas direct from the pumps with ethanol. No problems noted. Dan
 
Mixing gas

I always hear about folks using mogas in one tank, then 100LL in the other. Anyone just mixing say mogas with avgas?
 
Tooch said:
I always hear about folks using mogas in one tank, then 100LL in the other. Anyone just mixing say mogas with avgas?
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Two years ago I began the transition to mogas in my carbed O-320 (160hp) by mixing 100LL with 93 non-ethanol pump gas. The first few times it was 75% 100LL, then worked down to 50%, then 25%, and for the past year and a half it has been 100% 93 pump gas.

The engine runs smoothly, plugs stay cleaner and the belly of the plane is much easier to clean without the lead deposits. The only difference I've found is the engine requires a bit more attention to get it started and running for the first few seconds when it is cold (<45F) because I don't have a primer system. But since I use a sump heater in winter that isn't much of an aggravation.
 
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Weasel

What is the purpose of your question.
Are you thinking about using mogas in your IO 540 powered RV-10?
With the exception of a few operators using 91 octane in high compression engines and racing, I do not believe you'll find anyone who has in fact observed damage to a Lycoming engine running mogas on compression ratios 8:1 or less. Anyway, let us know what you are shooting for.
 
N427EF said:
What is the purpose of your question.
Are you thinking about using mogas in your IO 540 powered RV-10?
With the exception of a few operators using 91 octane in high compression engines and racing, I do not believe you'll find anyone who has in fact observed damage to a Lycoming engine running mogas on compression ratios 8:1 or less. Anyway, let us know what you are shooting for.
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Yes I am planning to. And with 9.0:1 compression :eek:
 
Weasel,
Yes I am planning to. And with 9.0:1 compression
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I would caution you with that thought.

While it will run OK, there are many things you need to understand…….let me say that again …understand.

Trouble is most (99.9%) do not. Sounds harsh i know, but unless you have been part of or witnessed several detonation tests on an IO540/550 on a fully instrumented test stand when doing certification testing, you will not fully appreciate why I say this.

We can have a Skype chat some time.

By the way anything other than slick or Bendix mags are off the menu for you too!
 
I'm with newt

I've been wondering the same thing. I've got an 8 project I'm working on, and it seems with proper guidance I could build a fuel system that would shrug off ethanol. Given that cars shrug it off, we can too, right?
I'm sure there's more to it than I know now, but it can't be too hard. Where is the comprehensive guidance? Where is the how to on this? Is Proseal ok? Are the float senders ok? From the tank it's all metal tubing, so where does the next threat lie? Gascolaters? Valves? Injectors?

Can anyone put this together so we can stop dodging this issue and face it and beat it?
 
Yes I am planning to. And with 9.0:1 compression
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It's too bad you have to deal with 9:1 compression.
Everything about a mogas installation can be solved including the use of ethanol. Your problem could be solved by installing 8:1 pistons.
I've been wondering the same thing. I've got an 8 project I'm working on, and it seems with proper guidance I could build a fuel system that would shrug off ethanol. Given that cars shrug it off, we can too, right?
Click to expand...

Mogas installations work very well for a whole lot of people, me included.
A lot has been written about in this forum.

Over 300 hours on E10 mogas running over a 3 year period RV-10 IO-540
8:1 Compression 1 Slick one LSE. AFP fuel injection ( approved for all types of fuel)
I admit, 300 hours is not much to brag about, but I am following others with over a thousand hours of mogas use and showing no signs of problems.
BTW, all of my mogas friends use the ethanol contaminated variety.
I am beginning to feel guilty about filling up the tank with $ 2.98gasoline
 
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rmartingt said:
Why would that be?
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Advanced timing would bring the detonation line closer. The margin is reduced, and may be eliminated under hot day, hot start, WOT, climb conditions. While the advance is likely the same as mags under most WOT, but maybe not all. You would have to research and plot the timing advance against likely detonation conditions.
 
I don't get it

My primitive brain thinks it's hearing something like this: "Yes, you can use Mogas, but you've got to use low-ish compression pistons and no fancy electronic ignition or fuel injection and you've got to find alot of ethanol-resistant components to put in your fuel system that may be odd or hard to find."

Did I hear that right?

Why is ethanol mixed mogas working flawlessly in every car on the road, with all varieties of injection and ignition systems and compression ratios and fuel systems conceived in Detroit and Korea and Japan and Germany?

I'm fully prepared to be educated here, but I fail to see why this is so hard. Yes, there may have to be some new and non traditional thinking here, and I fully support aviation's resistance to new-fangled for the sake of new-fangled, but aren't we burning gas and air in a cylinder like all those four wheelers? Mogas is what, 2/3 the price of 100LL? So, certain types of plastic components are now off limits, and all O-rings must now be made of thus-and-such, and we buy our fuel pumps from NAPA instead of NASA. OK. Lets get on with it.

Please let the education begin, because there has to be something here I'm not understanding.
 
I have done a bit of research on this here, since I plan to be flying a long time and have no idea what will happen to the price of avgas. To me, the main points are:

Ethanol alters the vapor pressure significantly, which can cause vapor lock, especially on hot days and with winter fuel blends. One reason that some people use 100LL in one tank for takeoff/landing.

To avoid vapor lock requires some careful fuel system planning, possible return lines, and shielding of fuel lines/gascolator forward of firewall.

The compatibility issues stems from the fact that there are some components in our fuel system that nobody has gotten a straight answer on regarding ethanol tolerance from manufacturers - the one that stands out is the engine driven fuel pump. There are ethanol tolerant o-rings available for the fuel tank drain plugs.

There are some horror stories saying running ethanol through your fuel system just once will start deteriorating some components. Others have been doing it for years with no issue. I think the bottom line is determining how 'experimental' you are comfortable being, until you can verify with the maker that each and every part of your fuel system is ethanol tolerant. This would probably be hard due to liability concerns.

Personally, after my Phase 1, depending of fuel prices, I may start slowly mixing ethanol-free mogas into one tank. Where I live it is not too much more expensive the regular, but substantially cheaper than avgas. If that goes away, I will re-evaluate. Ideally, our rulers realize the folly that is ethanol to begin with and make it go away (it already cost me one outboard motor...)!

Chris
 
claycookiemonster said:
My primitive brain thinks it's hearing something like this: "Yes, you can use Mogas, but you've got to use low-ish compression pistons and no fancy electronic ignition or fuel injection and you've got to find alot of ethanol-resistant components to put in your fuel system that may be odd or hard to find."
Did I hear that right?
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No. Low compression may be required if the combustion chamber has minimal turbulence, or is simply large; our chambers have big bores and no squish. Electronic ignition is fine; it is advanced timing that can be a problem. And electronic fuel injection is entirely good in the case of fuel with a high vapor pressure (generally true with mogas), as the line pressures tend to be 40~60 psi in the hot engine compartment.

You will need ethanol-resistant components. Or you can roll the dice.

Why is ethanol mixed mogas working flawlessly in every car on the road, with all varieties of injection and ignition systems and compression ratios and fuel systems conceived in Detroit and Korea and Japan and Germany?
Click to expand...

Because they are designed for it.
 
Not hard at all

There are some horror stories saying running ethanol through your fuel system just once will start deteriorating some components. Others have been doing it for years with no issue. I think the bottom line is determining how 'experimental' you are comfortable being, until you can verify with the maker that each and every part of your fuel system is ethanol tolerant. This would probably be hard due to liability concerns.
Click to expand...

AFP fuel injection is tolerant of all fuels including pure ethanol.

The rest is up to you.
Your fuel tanks are ethanol tolerant.
Your fuel lines are ethanol tolerant, both aluminum and teflon lined hoses, whichever you decide to use.
If you don't trust the mechanical fuel pump, install dual electric pumps.
EFFI and AFP pumps are tolerant to ethanol fuel.

You do need to change the rubber o ring on the tank drains,
I bought 100 viton rings from Mcmaster for less than $5.-
That's about it.

Ethanol alters the vapor pressure significantly, which can cause vapor lock, especially on hot days and with winter fuel blends. One reason that some people use 100LL in one tank for takeoff/landing.
Click to expand...

Ethanol is the octane booster in mogas and lowers your vapor pressure as well as increasing your margin for detonation as a result of the octane boost.
Vapor lock can very easily be designed out of your fuel system by either installing a constant flow return line or using dual electric fuel pumps.
No need to blame mogas for vapor lock.

Like Dan said, cars are designed for it and you are the designer of your fuel system, if you want to be. As I pointed out, all the components are easily available and widely use in airplanes. No reason at all to think you are rolling the dice.
 
Yep I stand corrected about the ethanol worsening vapor lock {edit: see below, maybe not}. I think as time goes on you will find more and more people with long-term experience with the stuff with no ill results. At least, that's my hope...

Chris
 
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N427EF said:
Ethanol...lowers your vapor pressure...No need to blame mogas for vapor lock.
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Sorry, but the opposite is true for the percentages we are talking about in mogas.

"Adding 10% ethanol to gasoline will increase the vapor pressure of the fuel blend by about 1 pound per square inch (psi)."

Source: http://ethanolrfa.org/page/-/RFA%20Gas%20Ethanol%20Blends%20and%20Classic%20Auto.pdf?nocdn=1

Here's another source:
http://www.researchgate.net/profile/Bo_Larsen2/publication/236972023_Joint_EUCARJRCCONCAWE_Study_on_Effects_of_Gasoline_Vapour_Pressure_and_Ethanol_Content_on_Evaporative_Emissions_from_Modern_Cars/links/02e7e51a8b3a2f2e36000000

Paige
 
Most of the RVP problems in Mogas is from the butane they pump into it to get rid of the stuff. Its cheap and they have too much to get rid of. If they could pump more in and get away with it they would.

Next issue for the carby operators, or even the IO's (think fuel spiders) is the olefins (gum compounds) in items that are not used very often.

As you can see you can design around things, Ernst seems to have a grip on it but high compression, EI's that are not retarded, RVP issues, gum content, material compatibility and anything else I have missed need mitigating against.

You need to then consider how much mogas you are going to get easily at the fields you fly to, quality control of the fuel, and or storage and carrying it??..for me it is simply not worth it.

YMMV if you do what Ernst has done and the situation works for you. There is a reason or three why Avgas has hung around so long. ;)
 
One key measure of gasoline volatility is its vapor pressure. Adding 10% ethanol to gasoline will
increase the vapor pressure of the fuel blend by about 1 pound per square inch (psi). However, this is
not of great concern since the maximum volatility of all summer grades is regulated by the EPA and is
at much lower levels than gasoline sold in the late eighties. This has eliminated any hot restart/vapor
lock problems in all but the most sensitive vehicles.
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Paige, you are correct!

The same article does however point out the issue involving heat and how properly designed engine compartments have eliminated the vapor lock issue.
The same is true for properly designed fuel systems and cooling systems in airplanes.

It is a very good write up and also shows the higher octane rating of ethanol.
and its ability to resist detonation.

As always I am not trying to sell anyone on the idea of mogas just telling you that it works very well for me in all phases of flight and all seasons as well as it does for my friends who are not as vocal as I am.
 
newt said:
It seems to me that ethanol is a discretionary problem: A builder could choose to construct an ethanol-proof airplane through judicious selection of components and materials, and proceed to operate that airplane significantly cheaper than one which requires "aviation" fuel. Auto makers dealt with this decades ago. Why isn't it the "normal" desired outcome for aircraft builders?

- mark
Click to expand...

One other issue that affects airplanes more so than cars is that ethanol blends with water.

The Peterson STC provides a method for testing MOGAS for ethanol, which is to put some water in a small container, mark its level and add MOGAS. Shake well. If the water level appears to rise, you have ethanol in the fuel. Their concerns, documented in the STC, are primarily around increased chances of carb icing but also vapor lock on hot days when the airplane is parked outside and the fuel absorbs heat.
 
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science 'speriment:

This quality (that allows testing for ethanol) has made me wonder if it is possible to remove the ethanol from gasohol by letting it sit in contact with a water layer. I see a downside, which is water migrating the other way into the gasoline phase, but it might be interesting to try. Might just be a way to take this **** out of our blended fuels (thanks, Congress.)
 
wilddog said:
That could remove the ethanol but what would the octane be without it?
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Poor. It's been discussed here several times, do a search and you'll find more than you care to read...

Bottom line is forget about removing the ethanol by water-soaking your fuel, it causes far more problems than it solves.
 
As to ethanol:

http://aerobaticteams.net/vanguard-squadron.html

[The team has over 3,000 flight hours using 100% ethanol. The Vanguards are available for fly-bys for events such as parades and ground breaking ceremonies. The Squadron flies 6-10 airshow events each year. Flying across the country the team promoting ethanol as the fuel for the future. The Vanguard Squadron home is Tea, SD (Lincoln County Airport) which is very close to the largest city in South Dakota, Sioux Falls.]

See also:

Vanguard Squadron, Thunder Over the Valley, Youngstown, OH 2014
 
Modern cars have completely closed fuel systems limiting the possible outside contamination from moisture and therefore don't absorb moisture into the gas through ethanol absorption, airplanes don't have this system.
Low compression engines cannot burn off all the excessive lead and stuck valves becomes the primary concern. Ever cleaned plugs w lots of lead build up with a pick? Stuff is hard as nails, imagine what's happening to your valves and guides. I run a mixture of 50/50 or straight Mogas without ethanol for valve sake only, not economy of fuel. It's also far easier to start a carb engine when it's cold on mogas as it vaporize so much more readily.
Someone said ETHANOL increases octane, not true, ethanol is added last and varies state to state as I understand it.
 
FACT: With a 113 octane rating, ethanol is the highest performance fuel on the market and keeps today's high-compression engines running smoothly.
Click to expand...

The reference was made in response to someone wanting to remove ethanol from gasoline.
 
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