Ron Lee

Ron Lee

Well Known Member
My hangar buddy just found 91 octane, ethanol free, auto gas for under $2 USD. After discussion with several people about the implications, concerns, and possible negative aspects I added seven gallons of the cheap auto gas to 8 gallons of 100 LL. The 100LL was from Longmont (KLMO) at $2.86 a gallon which is good compared to $4.39 at my airport.

So one tank will carry this hybrid fuel mix for cruise as I evaluate it. Because I usually cruise at 65% or so (maybe a bit less), I am not concerned about problems.

This mix is less than 50% of the cost of 100LL just a few months ago. Cost is not the real driver since I had just drastically cut flying hours in response to high fuel prices.
 
Autogas

Ron

Can you disclose where you found ethanol-free gasoline in Colorado? I am at Cenntenial and would like to use it again.
 
Well.. same here.. cheapest avgas around here is $3.50 and Premium (93) ethanol-free car gas is $1.84 so it's almost 2 for 1 deal... I also do a mix in one tank...
 
Hope you Colorado pilots will help us pass state legislation to prohibit the blending of ethanol in all premium unleaded so you don't have to worry about getting it in the future. Please join your fellow pilots in the Pacific Northwest to pass this important legislation, or better yet try to get FBO's to add mogas service on airports as they can always order ethanol free gasoline. See http://www.e0pc.com
 
My 160 hp O-320 never saw a drop of 100-LL in its first 885 hours of life. Now I can't find anything without ethanol or I would be using it still. Seems like good stuff to me.

Bob Kelly
 
Todd, ethanol remains a serious concern to me. First off I am anti-ethanol for many reasons. But aircraft use is still is no-no. Perhaps I am uninformed. Even the auto gas use is being done cautiously with proper regard for situations where it may not be good in my plane.

I just realized we have one source of auto gas on the airport. I need to see what grade and if ethanol free. If so, then it solves the logistics problems of filling and hauling multiple 5 gallon gas cans.
 
I've been on the dark side so long I can see the light!

fuel_tank.JPG


Over 5,000 gallons pumped into aircraft so far. Right now fuel at my airport is $5.60 / gallon and I buy 92 octane for $1.95. That is a savings of $36.50 per hour flying the -10, and $18.25 per hour flying the -3. Your milage may vary. ;)

Yes, the fuel tanker is scheduled in for maintenance & new paint.

About the only precautions you need to take with mogas is storage. Don't let it sit in the tanks & fuel system for more than a month without flying the plane and adding fresh fuel. You don't want it to sit and get gummy or build up varnish, but that takes a long time so running the engine will keep that from happening. Running a tank of 100LL every so often is a good thing too, it will desolve any buildup.

When in doubt about the fuel sitting too long I just drain the tanks by removing the quick drains and put the old fuel into my vehicles, then add fresh 100LL fuel to the plane and do a ground runup before adding more auto gas. I've never had a problem, and this maybe over kill, but it makes me (and the plane) feel good.

JMHO
 
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Auto Gas - Is there more research?

From the continued sound of many articles we are within a couple years of running no-lead fuel in all our planes. I keep hearing from Cirrus owners that Cirrus is very concerned about this.
I hear many people running auto gas with no issues but they are doing because of cost.

I was just wondering if there are some groups doing real studies on this issue and if there is any data accessible on-line?
I know there are companies trying to offer a replacement fuel and doing research with other additives.

Is there information out there that says I can run premium fuel today with no issues and have the same reliability as 100LL? There are some aircraft with STC's for auto gas but does this mean it is just as safe? In your opinion has the proper studies been completed?

What is going to happen to engines with high compression and turbos once this occurs?

I hear a wide range of opinions on this topic all over the web but I can't find any strong data to help me form an educated opinion on this topic.

Just very curious.
Thanks in advance.
 
My basic understanding is that ethanol will eat away things that aren't supposed to be eaten. Having said that ethanol free is ok. Sure we can agree on that ... to an extent. Well what about lubrication? The lead content is there to aid in lubrication as well. Mogas contains no other lubricants unless added.

I heard a rule of thumb once; "Every 10th fill run 100-LL". I have seen flight training units mix 60-40 (100-LL 60%, Mogas 40%). I have also have seen operators add lubricants to the mogas for their own hybrid mix. What do mogas users do to compensate for the lack of lubrication?
 
Seems to me that if you fly cross countries very much you will have to fill up with 100LL at most airports away from home anyway, so the periodic use of 100LL is a non-issue--it happens whether you want to or not.
 
I have the superior IO360 with fuel injection, Precision. I have the Vans electric fuel pump. Do I have any issues with any internal parts NOT agreeing with the auto fuel, with or without alky.
 
allbee said:
I have the superior IO360 with fuel injection, Precision. I have the Vans electric fuel pump. Do I have any issues with any internal parts NOT agreeing with the auto fuel, with or without alky.
Click to expand...

Steve,
Your Vans electric fuel pump is made by Airflow Performance. Their parts are all designed to withstand unleaded fuels. All their O-rings, seals and diaphrams are made of flouro-silicone. Floro-silicone is impervious to the additives used in unleaded gas. It's even unaffected by ethanol.
Charlie Kuss
 
Adam Oke said:
My basic understanding is that ethanol will eat away things that aren't supposed to be eaten. Having said that ethanol free is ok. Sure we can agree on that ... to an extent. Well what about lubrication? The lead content is there to aid in lubrication as well. Mogas contains no other lubricants unless added.

I heard a rule of thumb once; "Every 10th fill run 100-LL". I have seen flight training units mix 60-40 (100-LL 60%, Mogas 40%). I have also have seen operators add lubricants to the mogas for their own hybrid mix. What do mogas users do to compensate for the lack of lubrication?
Click to expand...

Do a search on John deakin who wrote a few articles on this and concluded the "lead is required for lubrication" is a myth..As I know the newer Lycs and clones have used hardened valve seats for many years I am inclined to agree.

I remember a number of classic car owners back in the UK that would eat valve seats when they were forced to use unleaded fuel....As I have well over 300 hours on unleaded gas (and others have a LOT more) then if the same were true I'd need new cylinders now for sure.

I think the only thing lead does in a normally aspirated Lycosaurus is gum up the oil with lead deposits... Turbo normalised motors seem to need 100 Octane otherwise they suffer from detonation..But this is a seperate issue to the so called need for lead

With 8.5:1 pistons and electronic ignitions with a substantial timing advance at low power and high altiude, the thing runs beautifully on unleaded..even unleaded with 10% ETOH...

Frank
7a IO390..Now featuring 10% ETOH
 
Mogas Vapor Pressure

Vapor pressure of mogas has not been mentioned in this discussion.

If you are going to run with auto fuel, it is prudent to know its vapor pressure and the only way to have that information is to test it. Vapor pressure is not a function of octane or ethanol. It is more a seasonal function of how the fuel companies blend their product. Winter fuel has a lower test value on the Hodges meter and can be unusable in spring if temperatures rise before summer blends hit the market.

The easiest method of checking vapor pressure is with the Hodges test kit. It is available from Peterson Aviation

http://www.autofuelstc.com/autofuelstc/pa/PetersenAviation.html
 
Ron Lee said:
>...
I just realized we have one source of auto gas on the airport. I need to see what grade and if ethanol free. If so, then it solves the logistics problems of filling and hauling multiple 5 gallon gas cans.
Click to expand...
If the "...source of auto gas on the airport." is selling it commercially it had better be ethanol free or the seller is opening himself up to a huge liability issue. Auto gas is an approved aviation fuel by way of the STC process, but the EAA and Petersen STCs both specify that ethanol is not approved. If there is any question about ethanol, the commercial operator can consult the order paperwork that the distributor must supply. The operator should be ordering gasoline made to ASTM D-4814 without ethanol, and the distributor better supply same or he is in breach of contract.

Both EAA and Petersen have done tests and found no way to approve ethanol blending. I have talked to Todd Petersen on numerous occasions and so can you, send an email to him on his web site. He is a very approachable and helpful person. He is adamant that ethanol has no place in aviation fuel. He also told me that vapor pressure was of some concern 20 years ago when both he and the EAA were developing auto fuel STCs but said that modern auto fuel has very tight vapor pressure specs now, sometimes better than avgas. You can still use his tester if you have doubts.
 
chaskuss said:
Steve,
Your Vans electric fuel pump is made by Airflow Performance. Their parts are all designed to withstand unleaded fuels. All their O-rings, seals and diaphrams are made of flouro-silicone. Floro-silicone is impervious to the additives used in unleaded gas. It's even unaffected by ethanol.
Charlie Kuss
Click to expand...

Ok, how about the precision parts and the manual fuel pump on the engine.
 
allbee said:
Ok, how about the precision parts and the manual fuel pump on the engine.
Click to expand...

Steve,
The later revision updates to the Bendix (aka Precision) servos, and fuel distributors will contain red colored diaphrams and seals. This indicates the use of Floro-Silicone materials. The older (bad) seals and diaphrams are black in color.
Charlie Kuss
 
Thank you, I now feel good. I plan also to use auto fuel. On my lines going to the engine, I also made sure there were no sharp turns. Should be good to go.
 
N1593Y said:
If the "snipped

Both EAA and Petersen have done tests and found no way to approve ethanol blending. I have talked to Todd Petersen on numerous occasions and so can you, send an email to him on his web site. He is a very approachable and helpful person. He is adamant that ethanol has no place in aviation fuel. He also told me that vapor pressure was of some concern 20 years ago when both he and the EAA were developing auto fuel STCs but said that modern auto fuel has very tight vapor pressure specs now, sometimes better than avgas. You can still use his tester if you have doubts.
Click to expand...

I agree with Dean's comments above. I have spoken at length with Todd Petersen, regarding auto fuel and Lycoming fuel injection systems.
Charlie Kuss
 
N1593Y said:
Both EAA and Petersen have done tests and found no way to approve ethanol blending. I have talked to Todd Petersen on numerous occasions and so can you, send an email to him on his web site. He is a very approachable and helpful person. He is adamant that ethanol has no place in aviation fuel. He also told me that vapor pressure was of some concern 20 years ago when both he and the EAA were developing auto fuel STCs but said that modern auto fuel has very tight vapor pressure specs now, sometimes better than avgas. You can still use his tester if you have doubts.
Click to expand...

I have plenty of doubt about mogas vapor pressure. I've tested every purchase poured into my tanks for the past 4 years with the Subaru engine and it is all over the board from 36 kPa to the high 40's (with Hodges tester). I've tested 100LL also, it typically comes in at 62 kPa. The only mogas coming near it is E85, it tested at 60 kPa. Ethanol, in my opinion, enhances vapor pressure.

However, the corrosive affects (in an aircraft system) of any amount of ethanol is of major concern. For sure the technology to make it safe is available, the problem is no manufacturer of certified components wants to spend the money to meet the standards for using this stuff. Plus there is a lot of boggy man information floating around about using it and people wouldn't use it even if it were certified.

I plan to use it with the Lycoming (after the engine is broke in) but I remain concerned about long term aluminum corrosion. So far my tanks look OK but I really don't know what the future holds. The good news right now, at least in Missouri, is that the cost of fuel vrs ethanol has triggered a quirk in the law which does not make adding ethanol mandatory. But which fuel has it is not known to the public. The signs still say, "Up to 10% ethanol MAY be in the fuel". Some local guys recently bought fuel without ethanol from a co-op so it can be had if one is interested and shops around. Many farmers do not like the stuff which seems ironic.
 
I've tested 87 octane many times with my Hodges tester and have never not found it in the green. I have been surprised at how closely it tests to 100LL.

If you're looking for ethanol-free fuel, you will find it at your local farm bureau. Here in Indiana I just go to the Co-Alliance pump about three miles down the road, swipe my card, pump it into my cans, and pay the bill each month. I have talked with some folks at the refinery, and they told me ethanol is not in their refining process.

I've run ethanol-blended fuel many times, and generally don't have a problem with it unless its warm out. The only issue I'll run into is vapor lock on the ground or vapor lock with a hot start (carbed engine.) Both of these problems could be taken care of with a purge system to purge the carb and to have the boost pump on.
 
OAT

David,

In testing the Mogas are you taking into account the changes is temperature?..The VP will be lower on a 100F day vs a 40F day for the same fuel sample. As you test every batch, do you also compare that to a sample of 100LL at the same time?

Oh someone asked about system components...The AFP system also uses flourosilicone.

I think the problem areas as far as ethanol goes is the fuel tank drain orings..(easily replaced) and the mechanical fuel pump diaphram.

I don't have a mechanical fuel pump so I don't know what can be done for that.

As to aluminium corrosion using ETOH..I have no definate proof but i really don't think there is an issue...Time will tell I guess..:)

Frank IO360 wingroot pumps only
 
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