MOGAS/E85 etc.?

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dwalker

Well-Known Member
I am considering building my Corvair flight engine to be E85 compatible. This is going together as a 3.4litre, "high" compression, 5th bearing engine using a modern sequential EFI (one injector per cylinder) and coil near plug (one coil per cylinder). I cannot think of anything that is not already being done- SS valves, new valve seats, etc.- in the motor. The fuel tank is already gas/alcohol resistant, and of course the fuel lines will be modern lines designed for use with alcohol fuels.
I anticipate the engine will run cooler on the E85 as well as much cleaner at a slight usage penalty.

rv6ejguy

Well-Known Member
Yes, should run cooler but fuel consumption will be much higher. Let us know how this works!

Chris Matheny

Well-Known Member
HBA Supporter
E85 is also .5lb/Gal heavier than gas. You do get cooler temps from vaporizing more fuel. To get more power or to make the switch worth it I would raise compression ratio also. Raising compression will also help with cold starting. With a carburetor and low compression (under 10:1) you will probably have a hard time starting in anything 45F and under without preheating. I have ran a few carb equipped engines on it and these have been my experience. Carb ice is more likely with added fuel being vaporized also so that is a risk you need to think about.

rv6ejguy

Well-Known Member
Raising the CR would be a good idea, will lower the BSFC a bit to offset the lower BTU content and richer mixture.

Will be EFI so no carb ice.

TFF

Well-Known Member
It will be an interesting experiment. Although you have the potential for more power or cooler engine, I would think E10for regular operation and a 7th injector on E85 for anti detonation for takeoffs if conditions warrant. That would keep the range up.

dwalker

Well-Known Member
Back in about 2010 or 11 we ran my 13BREW powered RX7 at the Pikes peak Hill Climb on E85. It made [email protected] 17-18psi of boost, corrected for altitude @5200ftASL.
It never gave me a lick of trouble starting, in fact, at 8500ft ASL, at about 4AM with temps in the high 30's F, it started first push of the button every time.
It did use slightly more fuel than Sunoco 100Unleaded, but not the mathematical "1/3" more based on Stoich, for the same power level on the 100, the E85 ran leaner with more room before knock or excessive heat. I wish I had the data from fuel use, but my fuel calcs were off- bad data in = bad data out- and we ran out of fuel 1/4 mile from the finish, as the driver was able to stay in boost far more than modeled based on practice. We used 8gallons of E85 in 12 miles.

The Corvair will only be high compression based on its very low normal compression, somewhere in the 9/1 range I would expect. I would much prefer to run 10 or higher, but for that I would need to have pistons made and rethink/model the cam and heads.

Using the modern Bosch EV-6 injectors being flex fuel would not be an issue, but having a separate e85 tank in addition to a normal fuel tank is probably sub-optimal. If that were a consideration I would simply leave it on E10/pump gas, add a turbo with water injection and run takeoff/emergency boost for takeoff then pull the boost back.

Pilot-34

Well-Known Member
Yes, should run cooler but fuel consumption will be much higher. Let us know how this works!
.
My bet is that if this engine is built optimized for E85 it will get better mileage!

Kinda like running gasoline in a diesel engine your mileage will suck

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Chris Matheny

Well-Known Member
HBA Supporter
Sorry, I somehow missed the EFI. EFI will start fine at lower temps because of better atomization of the fuel than a carb. You could always just use a flex fuel sensor and let your EFI adjust the fueling map based on ethanol content. I can tell you from testing I have gotten from 70% to 90% ethanol from the pump at different times of year. I often wondered if doing a throttle body injection system for E85 would be an advantage as it would give the fuel longer to atomize before entering the cylinder allowing for a slightly leaner mixture to be used than port EFI.

dwalker

Well-Known Member
Sorry, I somehow missed the EFI. EFI will start fine at lower temps because of better atomization of the fuel than a carb. You could always just use a flex fuel sensor and let your EFI adjust the fueling map based on ethanol content. I can tell you from testing I have gotten from 70% to 90% ethanol from the pump at different times of year. I often wondered if doing a throttle body injection system for E85 would be an advantage as it would give the fuel longer to atomize before entering the cylinder allowing for a slightly leaner mixture to be used than port EFI.
Yeah the biggest issue with e85 is the lack of consistency. For higher body applications we mixed our own from e100.

HBA Supporter

dwalker

Well-Known Member
No interest in developing my own.

I'm using the AEM Infinity. Back when I was cool I did a lot of development work and beta testing for them so very familiar with the products.

pfarber

Well-Known Member
There was an FAA proof of concept program that ran 100% ethanol through a 172 and for 14 years. Never had an issue other than rejetting. The engine had less wear than a similar hour AVGAS engine.

Ethanol got a bad rap from crappy mechanics not realizing what alcohol would do to rubber.

dwalker

Well-Known Member
There was an FAA proof of concept program that ran 100% ethanol through a 172 and for 14 years. Never had an issue other than rejetting. The engine had less wear than a similar hour AVGAS engine.

Ethanol got a bad rap from crappy mechanics not realizing what alcohol would do to rubber.
Ethanol also dissolves all the varnish and gunk left in fuel lines, carbs, etc. and has gotten an undeserved reputation for clogging things up. When I have done the E85 conversion to 90's turbo cars I did it knowing the cars had 10 years of fuel gunk in the tank, lines etc. and planned to change fuel filters extremely often until all the crap had been cleaned out.

STDJantar2

Active Member
Since 2002 here in Brazil Embraer manufactures an ag plane named Ipanema (after Rio´s beach and music Girl from Ipanema) that is ethanol powered. Its engine is a Lyc 540 injected. More the 1000 have been produced, seems a sign of success. Yes, Lycoming DOES make an alcohol engine. For more info go to Portal Embraer

reo12

Active Member
Back in about 2010 or 11 we ran my 13BREW powered RX7 at the Pikes peak Hill Climb on E85. It made [email protected] 17-18psi of boost, corrected for altitude @5200ftASL.
It never gave me a lick of trouble starting, in fact, at 8500ft ASL, at about 4AM with temps in the high 30's F, it started first push of the button every time.
It did use slightly more fuel than Sunoco 100Unleaded, but not the mathematical "1/3" more based on Stoich, for the same power level on the 100, the E85 ran leaner with more room before knock or excessive heat. I wish I had the data from fuel use, but my fuel calcs were off- bad data in = bad data out- and we ran out of fuel 1/4 mile from the finish, as the driver was able to stay in boost far more than modeled based on practice. We used 8gallons of E85 in 12 miles.

The Corvair will only be high compression based on its very low normal compression, somewhere in the 9/1 range I would expect. I would much prefer to run 10 or higher, but for that I would need to have pistons made and rethink/model the cam and heads.

Using the modern Bosch EV-6 injectors being flex fuel would not be an issue, but having a separate e85 tank in addition to a normal fuel tank is probably sub-optimal. If that were a consideration I would simply leave it on E10/pump gas, add a turbo with water injection and run takeoff/emergency boost for takeoff then pull the boost back.
My experience in auto use with carburetors using E85/E10 50/50 ratio was around 12 - 13% fuel economy loss. I have an ethanol plant near me so can buy E-85 usually $1. per gallon less that E-10. For my trip to Osh with the motorhome I filled 9 gallons of E-85 and 8 gallons of E-10 and got 10.9mpg. With regular to E-10 fill ups - around 12.5 - 13.5 mpg for the rest of the trip. Powerplant - 1990 Buick Electra 3800 so it is not designed for ethanol. There are issues with ethanol fuels. It is 1200 times more hygroscopic than neat gasoline. Thus - it absorbs water out of the air that exchanges in the fuel tank between fill ups and temperature changes. This water mixes with the alcohol and makes it heavy - dropping to the bottom of the tank. There - it can come into contact with dirt and the combination of dirt and water can support an anaerobic bacterial growth. The by-product of an anaerobic bacteria is acidic. The acid will dissolve tern/galvanizing plating, die cast metals and can etch aluminum. In automobiles this metals contaminated fuel destroys catalytic converters. The metals can deposit in the piston rings and cause them to bind in the piston grooves and damage cylinder walls. It also can deposit on valve stems causing the valves to stick in the guides. The alcohol is also damaging to many elastomers. Often softening them and causing them to swell. Epoxy resins are often dissolved by the alcohol or suffer significant reduction in strength when in prolonged contact with the fuel. I've used the cleaning capability of E-85 to clean the fuel systems of small engines. However - I did discover that E-85 and pre-mix oil did not work. Ethanol is polar opposite of petroleum gasoline. Detergents are added to the ethanol to ensure mixing of the ethanol with the gasoline. When oil is added to E-85 I found that the dye in the premix oil would stay in suspension but there were insufficient detergents for the addition of oil. The oil would precipitate out of solution over the course of days. The fuel container could be agitated and the fuel and oil would mix again - only to have the oil drop out of suspension again within a few days. dwalker Well-Known Member My experience in auto use with carburetors using E85/E10 50/50 ratio was around 12 - 13% fuel economy loss. I have an ethanol plant near me so can buy E-85 usually$1. per gallon less that E-10. For my trip to Osh with the motorhome I filled 9 gallons of E-85 and 8 gallons of E-10 and got 10.9mpg. With regular to E-10 fill ups - around 12.5 - 13.5 mpg for the rest of the trip. Powerplant - 1990 Buick Electra 3800 so it is not designed for ethanol.
There are issues with ethanol fuels. It is 1200 times more hygroscopic than neat gasoline. Thus - it absorbs water out of the air that exchanges in the fuel tank between fill ups and temperature changes. This water mixes with the alcohol and makes it heavy - dropping to the bottom of the tank. There - it can come into contact with dirt and the combination of dirt and water can support an anaerobic bacterial growth. The by-product of an anaerobic bacteria is acidic. The acid will dissolve tern/galvanizing plating, die cast metals and can etch aluminum. In automobiles this metals contaminated fuel destroys catalytic converters. The metals can deposit in the piston rings and cause them to bind in the piston grooves and damage cylinder walls. It also can deposit on valve stems causing the valves to stick in the guides.
The alcohol is also damaging to many elastomers. Often softening them and causing them to swell. Epoxy resins are often dissolved by the alcohol or suffer significant reduction in strength when in prolonged contact with the fuel.
I've used the cleaning capability of E-85 to clean the fuel systems of small engines. However - I did discover that E-85 and pre-mix oil did not work. Ethanol is polar opposite of petroleum gasoline. Detergents are added to the ethanol to ensure mixing of the ethanol with the gasoline. When oil is added to E-85 I found that the dye in the premix oil would stay in suspension but there were insufficient detergents for the addition of oil. The oil would precipitate out of solution over the course of days. The fuel container could be agitated and the fuel and oil would mix again - only to have the oil drop out of suspension again within a few days.

Lot to unpack here.

I have never had an issue with E85 and water, but then I do not leave it sitting for months. I also am not using in a marine environment, which is where most of the issues occur.

A fellow just did an experiment where he mixed a bunch of 2 stroke oils with E85to see how long each stayed suspended. Redline Alcohol 2-stroke stayed in suspension over 2 months with no sign of separation, others did not perform as well.

Alcohol DOES damage many thing, but since 1989 all cars sold in the US have been mandated to be alcohol fuel compatible. This was because the alcohol fuels of the time, without the additive packages in use now, would eat the aluminum components and destroy rubber, which is obviously dangerous.

Fuel of all types is not the friend of epoxy resin, which is why fuel tanks are constructed or sealed using polyester resins.

Now, I have run a LOT of e85 in various vehicles, from stock cars and trucks to highly boosted cars making immense power for the displacement. I have used various pre-mixes but again, I now tend to ONLY use Redline Racing two stroke or the Silkolene 2-stroke that is approved for alcohol fuels, and nothing else. If you are running a pre-mix to attempt to add some lubricity, stick with Redline. I tend to only premix the rotary engines, as piston engines tend to have more than enough oil floating around.

I have never seen any deposits left by E85. In fact the opposite has been the case, where the engine, no matter how carboned up, is in short order rendered exceptionally clean. This is also often a double edged sword as the carbon that was keeping a valve tight in its bore or sealing a gap is removed, revealing wear issues.

I am going to say that I am speaking of modern, not carbureted old school engines- IE 1990-up production engines with port EFI.

reo12

Active Member
I hope you understood that the deposits I mentioned were the result of a bacterial infestation - usually the result of prolonged inactivity - producing acids that attack the venerable metals in the old fuel systems. It is these metals that can cause damage to the engine.

The possibility of corrosion within the fuel system was addressed in the early 90's. Auto manufacturers ceased using galvanized fuel tanks and switched to plastic. They ceased using steel fuel lines that were galvanized inside. Most switched to plastic. Any diecast components in contact with fuel are now nickel plated to resist the acids that MIGHT occur.

A vehicle in constant use will agitate the fuel sufficiently so that water is typically kept in suspension and consumed before a bacterial infestation can occur.

Personally - I use alcohol modified fuels when I have a need to - like cleaning varnished fuel systems and when it is financially practical. Many distributors charge about the same price for E-85 as they do for neat gasoline or E-10. That is a money loosing proposition for the consumer as E-85 will have a higher consumption rate. www.yellowhose.com can help find E-85 fuel sources in Michigan.

pjphilli

Member
HBA Supporter
This is a pleasant and welcome surprise to me seeing curiosity and exploration in alternative fuels on this forum. Many of the post made are technically pretty close, enough within "Ozark Math" that the points made are absolutely valid, e.g: concepts of increased cooling (That's from higher latent heat of vaporization versus gasoline), the fuel mileage observations on non-optimized engines (not taking advantage of effective ~116 octane with higher compression), the fact it will clean a dirty system, it will affect rubber not formulated to handle it, etc.

A couple comments for clarity, and disclosure: I'm in this biofuels industry serving as Technical Director for my employer. There was somewhere above mentioned similar to "Ethanol does not mix in gasoline because its polar opposite to petroleum gasoline". That's 100% in error. Not all alcohols, but Ethanol is what's called a polar-covalent compound. Ethanol is 100% miscible into covalent hydrocarbon gasoline, at any concentration. Ethanol being polar-covalent means its also 100% miscible in water at any concentration (why melting ice in your scotch and water does not separate into layers you notice while sipping it.). Something not typical in industry, but common in the gallon gas can of lawn mower fuel sitting for a few years is "phase separation". E-XX (say E-10) retail gasoline will absolutely have the ability to absorb water. It's part of why gas lines aren't freezing in the winter from water ice. The tiny bit of water you may see when you check tanks and gascolator on pre-flight would not be found running an ethanol fuel because it will be dissolved into the fuel...BUT it can only hold so much polar water before rejection by the covalent hydrocarbon. The ethanol/water will phase separate and settle below the hydrocarbon. Phase separated fuel should never be used in an internal combustion engine.

The only time I've ever seen microbiological activity in tanks has been in fuel storage hydrocarbon gas tanks, diesel, etc.. If tanks are not sumped regulary just like you do on pre-flight, the water that condenses or infiltrates from somewhere will develop into a substantial layer (Think fuel tanks on a ship... water added as fuel is consumed for ballast as an example). This water layer on the bottom is where microorganisms will get a foot-hold.

Very happy to discuss, offer opinion, etc as desired on this topic. Be Safe and Well - Phil

Rhino

Well-Known Member
Good stuff here. How does a newer aircraft engine, i.e. Lycoming or Continental, stand up to alcohol? Have they been made resistant to the damaging effects of alcohol like auto engines have? My current project uses a Jabiru, which is designed to use mogas, but there could be a different aircraft/engine in my future.

dwalker

Well-Known Member
This is a pleasant and welcome surprise to me seeing curiosity and exploration in alternative fuels on this forum. Many of the post made are technically pretty close, enough within "Ozark Math" that the points made are absolutely valid, e.g: concepts of increased cooling (That's from higher latent heat of vaporization versus gasoline), the fuel mileage observations on non-optimized engines (not taking advantage of effective ~116 octane with higher compression), the fact it will clean a dirty system, it will affect rubber not formulated to handle it, etc.

A couple comments for clarity, and disclosure: I'm in this biofuels industry serving as Technical Director for my employer. There was somewhere above mentioned similar to "Ethanol does not mix in gasoline because its polar opposite to petroleum gasoline". That's 100% in error. Not all alcohols, but Ethanol is what's called a polar-covalent compound. Ethanol is 100% miscible into covalent hydrocarbon gasoline, at any concentration. Ethanol being polar-covalent means its also 100% miscible in water at any concentration (why melting ice in your scotch and water does not separate into layers you notice while sipping it.). Something not typical in industry, but common in the gallon gas can of lawn mower fuel sitting for a few years is "phase separation". E-XX (say E-10) retail gasoline will absolutely have the ability to absorb water. It's part of why gas lines aren't freezing in the winter from water ice. The tiny bit of water you may see when you check tanks and gascolator on pre-flight would not be found running an ethanol fuel because it will be dissolved into the fuel...BUT it can only hold so much polar water before rejection by the covalent hydrocarbon. The ethanol/water will phase separate and settle below the hydrocarbon. Phase separated fuel should never be used in an internal combustion engine.

The only time I've ever seen microbiological activity in tanks has been in fuel storage hydrocarbon gas tanks, diesel, etc.. If tanks are not sumped regulary just like you do on pre-flight, the water that condenses or infiltrates from somewhere will develop into a substantial layer (Think fuel tanks on a ship... water added as fuel is consumed for ballast as an example). This water layer on the bottom is where microorganisms will get a foot-hold.

Very happy to discuss, offer opinion, etc as desired on this topic. Be Safe and Well - Phil
This all aligns with my experiences- the only time I have personally seen phase separation- which is talked about a LOT in the marine world- is in a boat that say at anchor in a marina for over a year without starting or moving.

The only real issue I have with e85 in high output engines is its lack of consistency from tank to tank. We have to some degree worked around this by using a "flex fuel sensor" which monitors the alcohol content of the fuel in real time and which allows the ECU to adjust fuel/timing/boost/etc. accordingly.