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Who's running 10% ethanol fuel

N

Nashpdman

Active Member
I’m planning on running “pump” gas in the RV10 I’m building and have some questions. Who’s is running off the shelf pump gas? Meaning, 10% ethanol mix fuel you can buy at any gas station. 93 octane is readily available where I live. What did you do in preparation for ethanol? What fuel lines did you run? Has anyone experienced any issues with Proseal while using ethanol? Any issues with detonation and/or how did you prevent it? What fuel/ignition systems are you running? I’m planning on SDS or EFIII so I’ll be able to control the timing. The engine I’m building has piston oil squirters, which should also help with detonation issues. Thanks in advance!

Mike
Nashville TN
 
I run a mix 60/40 of 100LL to 93 E10 mogas.

In a fuel injected engine, even with the boost pump on, you may get a stumble with a hot engine, when opening the throttle, such as during a go around when the throttle has been closed for a prolonged amount of time and then there is a need for increased fuel flow, especially in a hot environment.

Might also happen after a prolonged taxi and when the throttle is opened for take off, you might get a stumble until increased fuel flow pushes all the hot fuel out.

The likely cause of this is the mogas is boiling in the injector lines during low fuel flow operations.

To combat this, I make periodic throttle inputs to keep the fuel flow from being static, thus keeping it from boiling.

Also experienced this in a carbureted O-360 with about 60% mogas. Hot engine, aircraft sat in the sun so the fuel tanks were heated to near ambient. On take off the engine surged and quit at rotation...luckily with 8000 feet of runway left. Put the acft in the shade, removed the cowling, let everything cool off and it ran perfectly.

Be careful.
 
WA85 said:
I run a mix 60/40 of 100LL to 93 E10 mogas.

In a fuel injected engine, even with the boost pump on, you may get a stumble with a hot engine, when opening the throttle, such as during a go around when the throttle has been closed for a prolonged amount of time and then there is a need for increased fuel flow, especially in a hot environment.

Might also happen after a prolonged taxi and when the throttle is opened for take off, you might get a stumble until increased fuel flow pushes all the hot fuel out.

The likely cause of this is the mogas is boiling in the injector lines during low fuel flow operations.

To combat this, I make periodic throttle inputs to keep the fuel flow from being static, thus keeping it from boiling.

Also experienced this in a carbureted O-360 with about 60% mogas. Hot engine, aircraft sat in the sun so the fuel tanks were heated to near ambient. On take off the engine surged and quit at rotation...luckily with 8000 feet of runway left. Put the acft in the shade, removed the cowling, let everything cool off and it ran perfectly.

Be careful.
Click to expand...

What type of fuel injection are you running?
 
Ethanol in aircraft fuel.

I have a Superior IO-360 engine that I bought new 2006.
The last 12 years I have running on Mogas 98 which is 5 % ethanol.
I live in Europe, so it would compare to 93 US apart from the % of ethanol.
Ethanol increase the octane number of the fuel making it more knock resistant.
I have two SureFly electronic ignition at 25 deg and enabled advanced
timing. It works well. I have found that insulation of the fuel line, firewall
forward is help-full. Climbing direct to 12.000 ft will generate fluctuating fuel pressure readings for the first 5 minutes after leveling of. Engine runs fine.
This is also true for 100LL in the summer.
If the engine is hot after a flight, the fuel line fire wall forward is hot.
Before take of I always run the engine on 15-1800 rpm until there is cold
fuel in the lines. If the engine runs fine on 700 rpm it is ready for take of.
If you compare with the Austrian made Rotax engine it is allowed to 15 %
ethanol. Business is all about making money.
My understanding is that Superior prohibits alcohol because of liability concerns. There is nothing in the fuel servo that don't work with ethanol.
I believe that most if not all fuel hoses sold today are made for some % of ethanol.
My tanks are made of vinyl ester so there is no sealant used in them.

Good luck
 
I’ve been running car gas (both with and without ethanol) for a long time in my 360 powered -8, and I’m planning on doing the same in my 390 powered -14. If I’m not planning on flying for a few weeks (which rarely happens) I wouldn’t let ethanol sit in the tanks. I’ve never seen a problem with the car gas causing any problems with pro-seal. Both SDS and EFII are designed to work perfectly with ethanol laced fuel, and due to the high pressure fuel rail, constant fuel flow, and fuel return line system, vapor lock will never be an issue. Also, both SDS and EFII have automatic timing advance/retard based on MP, so unless you’re running really high compression pistons, detonation should never be a problem.
 
Over the past 15 years I’ve run roughly 3000 gallons of mogas (mostly E10) through my RV-8 with no issues at all. Engine is a stock carbureted O-360-A1D. Fuel system is stock, no changes to it.

My technique is to keep one tank with straight 100LL while the other side gets a mogas/avgas mix; I taxi, takeoff, land and park on the straight avgas tank, while cruise/descent is on the mogas tank. I might climb on the mogas tank if it’s not too hot and I keep the speed up to keep the CHTs down. I have three 5 gallon jugs to haul fuel to my hangar, so my max mogas load is 15 gallons in a 21 gal tank.

The only time I’ve ever had any mogas issues was on a trip to OSH years ago (2012 I think? It was hot!); I stopped at Mexico, MO where they had non-ethanol 91 mogas at the SS pumps. I topped both tanks with mogas, then boogied for OSH… landed on 27 then had a looooong hot taxi to HBC. The vapor lock was kicking in at that point, had to run the boost pump with short bursts of power just to get to my spot. Note to self; no more mogas headed into OSH!
 
I've got almost 1200 hours on 93E10 in my 9A since early 2016. I ran it originally on stock injectors with Bendix servo, then upgraded to the full SDS.
 
mogas

Another Mogas user here.
Your compression ratio is the most important factor here. Next is fuel/ignition system.
I've been running Costco Premium for the last two years. Octane as it comes out of the pump.
0-360, 8.5-1 compression, SDS fuel and ignition, Teflon fuel lines, Andair 6 port valve with returns to tanks, oil changes every 25 yours, 20x50 Phillips oil, 600 hours to date. Running Lean of/at peak as much as possible.
I have a 110 gallon transfer tank with a 20 foot grounded hose in back of van. Use 100LL on trips.
No problems hot or cold.
My happy three cents worth.
Merry Christmas Art
 
Mogas issues

I have flown almost 1000 hours on Mogas long before ethanol was added. This was in an O-320 powered Grumman Yankee taildragger (my poor man’s RV-6).

I have had all the stumbling issues from vapor lock especially on a quick turn like dropping someone off and trying to take off right away.

Pros…no fouled plugs and saved a ton of money.

Cons…vapor lock needs to be managed and it’s an effort to transport. Also Mogas does not store well and will varnish up.

I run 100LL in my RV-10 but would not be afraid to use 93+ mogas with 8.5/1. Not sure if the extra $$ for rec fuel is worth it.
 
E-10

I have been using E-10 from gas stations in my 0-360 9A for over 10 years.
Vapor lock stumble has happened on taxi after flight on very hot day.
No pro seal issues.
Friend of mine uses almost pure ethanol E-98 in his injected 6A.
 
Thanks for all the responses!
The fact that the SDS & EFII systems use a constant flow/return fuel system, thereby supply a constant supply of cool fuel, should eliminate the majority of the issues noted. I'm using new Superior 8.5-1 cylinders so that shouldn't be an issue. Seems to me, listening to Mike Busch's webinars, a semi-synthetic oil would be best. That way, on trips where I'm forced to use 100LL, at least the oil will have some ability to deal with the lead. :):)
 
91 AKI

I've been running 91AKI pump gas in my UL350iS engine on my RV-12 for years. Here in California that means "up to 15%" ethanol. Each time I've tested the fuel I get from my local station, it's been in the 8-12% range.

The UL engine is an air-cooled flat four and is similar to an O-200, but with an EFII and 8.7:1 compression. At about 100 hours, I replaced the cylinders (off topic, but it was due to excess oil leaks that UL mitigated with an upgraded cylinder base design); I took the opportunity to install 9:1 pistons at that time. With over 500 hours on the engine, it still looks new via borescope inspection and compressions are 78-79 over 80.

I have tested my 540-X on an engine stand using 91AKI with 15% ethanol as well (discussed at length in the Traditional Engine forum) at 9:1 CR. The summary is it ran well and I plan to run on the same pump gas when I start flying it. I also have an SDS EFII and am able to control ignition advance for intake air and engine conditions, which is a great tool to mitigate margin to detonation (which is the general concern for running lower octane fuel; with its higher octane number, ethanol increases the margin to detonation).

As mentioned, with fuel injection running at higher pressure (45psi vs ~5-7psi carburetored), and constant cooling return flow (~250-300% return flow), the issue of vapor locking is effectively eliminated.

To your concern over the effects of ethanol on the engine itself, using Viton seals resolves nearly all of the issues. The only other real concern is production of aluminum triethoxide, Al(OC2H5)3 - however that concern is generally very over stated. It requires the presence of water to form and is a very slow reaction, taking very long time to occur. For example, I use an aluminum tank in the bed of my truck to haul fuel to the airport. That tank has been in use since 2018 with fuel in it continuously; standing most of the time. I drained the tank to inspect it this last September and found there is zero presence of aluminum corrosion in the tank (which is evidenced by a white, somewhat slimy, corrosion layer. The tank still looks very new.

If you were going to leave your aircraft in storage for longer than 3-6 months, then I would recommend draining (or consuming) the ethanol containing fuel from your tanks, but otherwise "fahgetaboutit".

I no longer have my RV-12, but before it left me, I inspected my fuel tank with a borescope and it looked pristine.
 
rongawer said:
I've been running 91AKI pump gas in my UL350iS engine on my RV-12 for years. Here in California that means "up to 15%" ethanol. Each time I've tested the fuel I get from my local station, it's been in the 8-12% range.

The UL engine is an air-cooled flat four and is similar to an O-200, but with an EFII and 8.7:1 compression. At about 100 hours, I replaced the cylinders (off topic, but it was due to excess oil leaks that UL mitigated with an upgraded cylinder base design); I took the opportunity to install 9:1 pistons at that time. With over 500 hours on the engine, it still looks new via borescope inspection and compressions are 78-79 over 80.

I have tested my 540-X on an engine stand using 91AKI with 15% ethanol as well (discussed at length in the Traditional Engine forum) at 9:1 CR. The summary is it ran well and I plan to run on the same pump gas when I start flying it. I also have an SDS EFII and am able to control ignition advance for intake air and engine conditions, which is a great tool to mitigate margin to detonation (which is the general concern for running lower octane fuel; with its higher octane number, ethanol increases the margin to detonation).

As mentioned, with fuel injection running at higher pressure (45psi vs ~5-7psi carburetored), and constant cooling return flow (~250-300% return flow), the issue of vapor locking is effectively eliminated.

To your concern over the effects of ethanol on the engine itself, using Viton seals resolves nearly all of the issues. The only other real concern is production of aluminum triethoxide, Al(OC2H5)3 - however that concern is generally very over stated. It requires the presence of water to form and is a very slow reaction, taking very long time to occur. For example, I use an aluminum tank in the bed of my truck to haul fuel to the airport. That tank has been in use since 2018 with fuel in it continuously; standing most of the time. I drained the tank to inspect it this last September and found there is zero presence of aluminum corrosion in the tank (which is evidenced by a white, somewhat slimy, corrosion layer. The tank still looks very new.

If you were going to leave your aircraft in storage for longer than 3-6 months, then I would recommend draining (or consuming) the ethanol containing fuel from your tanks, but otherwise "fahgetaboutit".

I no longer have my RV-12, but before it left me, I inspected my fuel tank with a borescope and it looked pristine.
Click to expand...

Thanks for the info! I'm planning on a transfer tank as well, probably like a 50gal from Tractor Supply. Can't imagine how much the savings will be!
 
rongawer said:
…….I have tested my 540-X on an engine stand using 91AKI with 15% ethanol as well (discussed at length in the Traditional Engine forum) at 9:1 CR. The summary is it ran well and I plan to run on the same pump gas when I start flying it. I also have an SDS EFII and am able to control ignition advance for intake air and engine conditions, which is a great tool to mitigate margin to detonation (which is the general concern for running lower octane fuel; with its higher octane number, ethanol increases the margin to detonation)…….
Click to expand...

That’s good to hear. I’ve been running car gas (both with and without ethanol) for a long time in my 180 hp parallel valve with 8.5:1 CR and she’s never missed a beat. I’m also planning on doing the same in my 390 powered -14. That engine has 8.9:1 CR and I was a little bit concerned that I’d be flirting with potential detonation issues with those higher compression ratios, so your findings are reassuring.
 
Mogas 91 E10

I too have been running mostly on mogas for over 10 years now.
The engine is a IO-540 8:5 to 1 with Airflow Performance fuel injection.
Ignition is an impulse coupled mag for the bottom plugs and a LSE lighstpeed ignition. The only significant change to a "stock" installation is the addition of a constant flow return line to ensure a constant supply of cool fuel especially during taxi and low power flight regimes.
I typically carry avgas in my left tank and mogas in my right.
Avgas for take off, landing and parking and mogas for climb, cruise and descent. I tested extensively to ensure that the engine and fuel system installation would run trouble free with both avgas and or mogas and requires no special handling technique from the pilot.
The installation has been trouble free, summer winter and in between.
I do not keep mogas stored in the hangar but keeping the tanks full with fresh pump gas is a fairly simple matter using 5x 5 gallon cans.
For longer trips when refueling is necessary away from home, I simply fill up at the airport with avgas like everyone else.
The mogas thing is not an obsession with me, I just wanted to see if it can be done safely. Saving some money in the process is a nice benefit as are the clean plugs and being a step ahead of the lead burners.
 
rongawer said:
ethanol increases the margin to detonation).
.
Click to expand...

Need to exercise caution with this logic. The octane rating can be used to help assess detonation risk and higher octane means greater detonation margin. However, while pure ethanol has a higher octane rating then auto fuel, the octane rating of a blended fuel stands alone. 93 octane mogas (no ethanol) will have the same detonation margin that 93 octane E10 gas has. Once that ethanol is blended with gas, it is the octane rating of the blend that matters and the fact that one gets there via the ethanol content and the other gets there via toluene makes no difference, as they both are rated at 93 octane and therefore provide the same detonation margin.

Larry
 
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lr172 said:
Need to exercise caution with this logic. The octane rating can be used to help assess detonation risk and higher octane means greater detonation margin. However, while pure ethanol has a higher octane rating then auto fuel, the octane rating of a blended fuel stands alone. 93 octane mogas (no ethanol) will have the same detonation margin that 93 octane E10 gas has. Once that ethanol is blended with gas, it is the octane rating of the blend that matters and the fact that one gets there via the ethanol content and the other gets there via toluene makes no difference, as they both are rated at 93 octane and therefore provide the same detonation margin.

Larry
Click to expand...

True, the published octane rating on the pump is the octane rating for the fuel. Taken out of context, one could believe that they have a higher octane rating with ethanol than what is published.

In spite of that, ethanol does act to increase the blend octane, not lower it, which is what has been stated in other posts. Therefore using ethanol acts to increase the margin to detonation in the blend, not reduce it. The fact that the fuel contains ethanol should not cause concern over increased risk of detonation.
 
Vans has a service bulletin posted on another thread. Based on boat experience and Vans recommendations I would not let Ethanol fuel sit in the tanks more than 30 days.
 
sailvi767 said:
Vans has a service bulletin posted on another thread. Based on boat experience and Vans recommendations I would not let Ethanol fuel sit in the tanks more than 30 days.
Click to expand...

Having had to replace large aluminum fuel tanks in a boat, I can confirm that ethanol laced fuel will definitely create corrosion issues unless that aluminum tank can be sealed from outside air. This is the primary reason that most large marinas now get an ethanol free recreation fuel. MANY tanks replaced 10-20 years ago.
 
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lr172 said:
Having had to replace large aluminum fuel tanks in a boat, I can confirm that ethanol laced fuel will definitely create corrosion issues unless that aluminum tank can be sealed from outside air. This is the primary reason that most large marinas now get an ethanol free recreation fuel. MANY tanks replaced 10-20 years ago.
Click to expand...

This is true - BUT - it was also during a time when most of the ethanol production used acid (sulfuric, IIRC) in the final production to dry it out and remove the excess water from distillation. It was difficult to avoid contamination of the final product with the acid which produced an acidic fuel mix, which did the damage to the tanks. Current production processes do not use the acid process for drying the ethanol.
 
airguy said:
This is true - BUT - it was also during a time when most of the ethanol production used acid (sulfuric, IIRC) in the final production to dry it out and remove the excess water from distillation. It was difficult to avoid contamination of the final product with the acid which produced an acidic fuel mix, which did the damage to the tanks. Current production processes do not use the acid process for drying the ethanol.
Click to expand...

That could be true. But do know from research that ethanol fuels can have phase separation and pure water can develop as the bottom layer. I suspect that boats are more problematic as they often go unused for many months and therefore this water layer sits in contact with the tank bottom for a long time without removal or agitation. In my case, the bottom skin corroded through and found 0 evidence of corrosion anywhere but the bottom skin. No expert, but believe that direct long term submersion in water will cause AL to corrode. Not my area of expertise so definately not speaking with authority on this. I suspect that if acid were the cause, we would have seen more issues with steel gas tanks and it seems that the problem was isolated to marine vessels with their extensive use of Aluminum and composite tanks. I have never heard of this in the plastic and steel tanks used in cars.

Certainly not trying to persuade foks from using E10, just to research the issues that can come from that and develop practices to mitigate any issues.
 
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