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Mogas vs. 100LL?

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Doran Jaffas

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Jun 25, 2019
Messages
224
Another question...is it worth $1.00/gallon more to burn Ethanol free gas?
I use a combination of 100 LL and mogas. The av fuel here in Michigan is still more per gallon but my 0-200A in my Tailwind W8 needs some lead for top end lubricant. Straight mogas with Marvel Mystery Oil works well as well but the price per gallon comes out close .
There are fixed costs involved with airplane ownership. give yourself a reality check and if you feel like you have to constantly find cheaper ways to operate when you may need to take an honest look at whether or not you can afford the airplane. Airplane ownership does not have to be expensive but it usually means you have nothing else that you spend the money on other than the basics of life. For those of us fortunate enough to be able to own our own aircraft and have a few other things we still get reality checks every once in awhile.
 

Andreas K

Member
Joined
Aug 18, 2016
Messages
8
Location
Beautiful Wisconsin
Just started my '87 911 and my BMW motorcycle sitting with E10 and full tanks for half a year in my unheated garage after a Wisconsin winter. No problem. Started my chainsaw and leaf blower sitting with 2-cycle mix, no problem. Started my neighbors JD riding lawn mower sitting outside in snow and rain with what ever gas was left in the tank. No problem. There are millions of cars at the dealer ships waiting to be sold sitting for month all over the US in various climates. Never heart of any fuel related starting issues.
So I think that there is a lot of myth when it comes to E10.

I had a bad Mogas experience in my friend RV9 with an O-320. Half the tanks had 100LL in it, toped of with E-free Mogas. Engine stutter at rotation speed, 2nd try the engine quits at 40 mph on the runway. The fuel was bad. I bet I just bought water from the bottom of the tank.

Lesson learned for me: on a x-country I will buy 100LL because it lasts longer, is more controlled. At my home base I buy Mogas because I know where it is coming from and it sells quickly. I even would be fine putting E10 in my tanks if it's bought from a station that sells a lot of it.

When it comes to that Chevy engine I would certainly fly with E10. If you have an O2 sensor in a closed loop you need to run lead free, otherwise you sensor will go bad. You also got make sure you are using a non synthetic oil in your engine since lead and synthetic oils don't mix well. Best way to prevent vapor lock is a fuel pump in each tank. Downside: if that pump fails you are loosing the fuel in that tank. Lot's of decisions. Good Luck.

@TXFlyGuy: What is the g-limit of your gear box?
 

Doran Jaffas

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Joined
Jun 25, 2019
Messages
224
Not to be flippant, but the highest level of safety is to not fly the airplane. And frankly, you can't afford "the highest level of safety possible", because it's impossible to achieve. That's speaking from someone who's been in NASA and big aerospace flight test for decades.

You need to be honest with yourself here:. You are flying a very low production airplane with an auto conversion engine, the configuration of which by your own admission has never been flown before. You are effectively flying a prototype with radically non standard systems. Your attempt to buy down risk is admirable, but you are WAY outside the bell curve of homebuilt aviation here (and that's pretty bad in itself).
Any time one aviates we are in effect testing the aircraft and our skills. As we become more comfortable in the cockpit we take on new challenges in small bites...if we are using our intelligence correctly. Different birds require us to add skills until once again we are comfortable. Even the same make and model will fly with different qualities. Add an unproven engine and or control surfaces and extra skills are needed along with thought processes not many private pilots have.
EAB aircraft in most cases are no more or less difficult to fly than their certified counterparts. To the contrary, many of what are on their certified counterparts started in the experimental aircraft movement so to speak. The reason that incidents and accidents are higher then the certified counterparts is that most experimental aircraft are higher-performing and given the training of today many pilots are not equipped for the sensitivities of the higher performance aircraft. I own and fly a Wittman Tailwind W8 regularly. It is an extremely nice airplane but it is not a Cessna 150 or 172. With any transition to any aircraft one should get a qualified pilot instructor to help them through that transition in turn limiting their chances for an uninvited circumstance. Enough said.
 

Rockiedog2

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Joined
Dec 11, 2012
Messages
2,341
Any time one aviates we are in effect testing the aircraft and our skills. As we become more comfortable in the cockpit we take on new challenges in small bites...if we are using our intelligence correctly. Different birds require us to add skills until once again we are comfortable. Even the same make and model will fly with different qualities. Add an unproven engine and or control surfaces and extra skills are needed along with thought processes not many private pilots have.
EAB aircraft in most cases are no more or less difficult to fly than their certified counterparts. To the contrary, many of what are on their certified counterparts started in the experimental aircraft movement so to speak. The reason that incidents and accidents are higher then the certified counterparts is that most experimental aircraft are higher-performing and given the training of today many pilots are not equipped for the sensitivities of the higher performance aircraft. I own and fly a Wittman Tailwind W8 regularly. It is an extremely nice airplane but it is not a Cessna 150 or 172. With any transition to any aircraft one should get a qualified pilot instructor to help them through that transition in turn limiting their chances for an uninvited circumstance. Enough said.
Seems to me you repeatedly contradicted yourself in the second paragraph. There are definitley degrees of difficulty associated with flying EABs vs certified. There is no real standard for EAB flying characteristics but we can reasonably expect certain predictable responses in cert airplanes.
 

Rockiedog2

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Dec 11, 2012
Messages
2,341
Of course we're gonna fly the thing.
In my experience, the major 121 carriers do a good job of attaining the "highest level of safety possible". But they still crash.
We can minimize the risk, but not eliminate it.
 

TXFlyGuy

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Joined
Apr 25, 2012
Messages
1,861
Location
Republic of Texas
Of course we're gonna fly the thing.
In my experience, the major 121 carriers do a good job of attaining the "highest level of safety possible". But they still crash.
We can minimize the risk, but not eliminate it.
Take US certified major legacy carriers. Accident rate that approaches zero. But there is no such thing as 100% safe, with zero risk. But fly on American, Delta, United, or Southwest, and you are as safe as you can get.
 
Joined
Apr 7, 2020
Messages
15
Should be fine. But I don't have any experience with stainless tanks.
I don't have a lot off experience in aviation but in industrial controls stainless is definitely considered compatible with ethanol. I'm not sure if there is a better suited material actually.
 

TFF

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Apr 28, 2010
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13,476
Location
Memphis, TN
I think Rockiedog flys his homebuilts because he retired flying 121 planes and does not want back on one.
 

Rockiedog2

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Joined
Dec 11, 2012
Messages
2,341
I think Rockiedog flys his homebuilts because he retired flying 121 planes and does not want back on one.
yeah TFF.
I retired early, best thing I ever did. Knew most every panhandler in downtown OAK first name basis. Used to hang out with em down in front of McD's. Several x had a dollar handed to me...decided time to hang it up; must be lookin pretty bad.
 

skydawg

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Joined
Jul 26, 2016
Messages
46
Location
Denver, Colorado
The Corsair engine website has a section detailing issues with MOGAS in aircraft. It seems biggest is ethanol's water absorbing quality and it's faster octane evaporation. Their engines seem to have an extra filter for each pump because of potential contamination with MOGAS.

www.corsairpower.com
 

TXFlyGuy

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Apr 25, 2012
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1,861
Location
Republic of Texas
Here is their summary:

There is no fundamental reason MOGAS cannot be safely used to power automotive engines in aircraft applications. The same concerns of octane ratings, effects of ethanol, and useful life of gas remain the same. However, because aircraft cannot simply pull over when engine troubles occur, these same concerns must be considered with greater scrutiny. Routine maintenance must include additional checks to ensure the quality of fuel, shorter storage periods of fuel, and develop an effective schedule of checking filter elements and components. The results will be a far cheaper aircraft to operate, cleaner tailpipe emissions into our air supply, and greater fuel options/availability throughout the world.
 

Doran Jaffas

Well-Known Member
Joined
Jun 25, 2019
Messages
224
Here is their summary:

There is no fundamental reason MOGAS cannot be safely used to power automotive engines in aircraft applications. The same concerns of octane ratings, effects of ethanol, and useful life of gas remain the same. However, because aircraft cannot simply pull over when engine troubles occur, these same concerns must be considered with greater scrutiny. Routine maintenance must include additional checks to ensure the quality of fuel, shorter storage periods of fuel, and develop an effective schedule of checking filter elements and components. The results will be a far cheaper aircraft to operate, cleaner tailpipe emissions into our air supply, and greater fuel options/availability throughout the world.
I use rec fuel. No alcohol. To get top cylinder lubrication I use an oil additive. 100 LL in the 0-200A plugs a lot of things one doesn't want plugged.
I do not use it for financial economic reasons. At 4 gph that is not an issue.
 

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rv7charlie

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Nov 17, 2014
Messages
849
Location
Jackson
Eric,

I suspect that he meant that all of *his* tanks are stainless. (Though that is surprising to me; that's got to be a significant weight penalty over aluminum.)
Tanks are made of all sorts of stuff. My Kolb has a rotomolded plastic tank.

Ethanol is not a particularly big deal in aluminum. There's a 'squadron' of RVs up in the corn belt flying on E100, and I'm pretty sure their tanks and fuel lines are basically stock RV parts (aluminum). Lots of alt engine guys are running E-gas in aluminum airframes with aluminum tanks/lines, and RVx drivers running E10 in injected Lycs are becoming more common.

Methanol is a different story, but you won't find methanol in pump mogas in the USA; only used in racing fuel.

Charlie
 

skydawg

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Joined
Jul 26, 2016
Messages
46
Location
Denver, Colorado
One more thing about converting an airframe to ethanol engine, especially older aircraft, is changing out original soft lines and seals for are ones ethanol compatible. The Corsair engine kit came with new hoses and o-rings and easy enough to replace. I didn't change out the wing drain o-rings and one started began leaking about 6 months later.

The install instructions for my c172 conversation kit also makes a point about making sure tanks are clean as ethanol acts as a solvent and can dislodge existing contamination into fuel line. It also says check filters every 5 hours for first 20 hours of operation on ethanol fuel.
 
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