Replies to This Discussion

Permalink Reply by John Austin on July 12, 2013 at 8:02am

Ed,

I think you need to specify which engine you're talking about. Jabiru, for instance, recommends avgas or premium unleaded, ethanol-free auto gas (which is what I'm running now). 10% ethanol is permissible, but they then recommend the Bing carb be overhauled every 2 years as a precaution. I suspect the recommendations will be quite different for Rotax, Continental, UL, etc.

John

N750A

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Permalink Reply by Ed G Novak on July 12, 2013 at 9:40am

Sorry 0-200

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Permalink Reply by Richard Rost on July 13, 2013 at 2:31pm

I think the O-200 is STCed for auto gas. You can check it on the FAA web site.

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Permalink Reply by Bob Pustell on July 13, 2013 at 9:43pm

It is STC'd for Non-Ethanol autogas. That applies to certified engines in certified airframes. As an experimental aircraft (with an experimental engine -- the moment your O-200 got bolted into an experimental airframe it lost its certified status) you can burn anything you want in your aircraft legally. You owe it to yourself and your passengers to be smart and safe about it, but you can burn whatever you want to.

I plan to avoid the use of ethanol laced fuel but I also plan to build my fuel system and engine with ethanol tolerant components. Even with an ethanol tolerant fuel system you need to be careful, the ethanol will draw moisture out of the air through the fuel system vents and can eventually exceed the ethanol's ability to hold the water, then it forms a nasty and corrossive amalgum that can eat your fuel system metal components, even if the rubber parts are ethanol tolerant.

If I do end up running some ethanol fuel I will only have it in one tank and not use it for takeoff or landing, only cruise flight. I will build easy drain provisions into the tank that may carry ethanol contaminated fuel sometimes. Any ethanol fuel left after the flight will be drained if I am not going to fly again within a day or three - if it sits in the tanks it can cause trouble.

A friend and neighbor has been running his RV-8 on ethanol contaminated automotive premium fuel for several years now. He reports no ill effects. To be honest, he is not as careful as I think one should be when using this stuff, but through good luck or good planning he has done well so far.

So, short summary, I hope to never need the stuff but I plan to build my machine to tolerate it. I will not leave it in the tanks for more than a few days. Any I drain out will go into a car, not back into the airplane. I will always leave the fuel lines and carb bowl filled with non-ethanol fuel before shutting down and I will not take off, land or fly near the ground with the engine running on the stuff. That is my plan, anyhow. Take these thoughts/advice with huge grains of salt, I am no expert.

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Permalink Reply by Mark Maltais on July 14, 2013 at 11:57am

Ethanol is just plain crap any way you look at it.  Thank the Green-Nazis for this stuff.  It's bad on components, bad with moisture and puts out less HP per gallon.  There is NO good side to this garbage.  So far some gas stations here that sell premium still don't add this junk to their fuel, but I'm sure it's only a matter of time!!! :(

I'm building to be able to tolerate this stuff as well, but I'm not sure how the carb will hold out, although the plane my engine was in could use auto fuel with an STC so we'll see.

I've heard that if you "blend" the auto fuel with some avgas once in a while it helps but I haven't looked into that.

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Permalink Reply by Ken Ryan on July 14, 2013 at 12:51pm

I hope this site isn't turning into one where people feel comfortable venting their political beliefs. How about we stick to airplane stuff?

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Permalink Reply by Mark Maltais on July 14, 2013 at 4:57pm

How is this political? It's bad stuff period IMHO!!!

Please feel free to post any benefits of ethanol.  I'd like to hear anything positive about this stuff.  So far I've never heard anything good, except driving up the price of corn!!!  It's even wrecked havoc on the trikes I race!!!

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Permalink Reply by Jimmy Young on July 14, 2013 at 8:39pm

In reply to Bob Pustell's post,

I've got a question: If 10% ethanol unleaded auto gas can create a nasty corrosive amalgum that can eat a fuel system's metal components, why don't we hear about car fuel systems being destroyed on a regular basis by it?
I'm not an advocate of it's use or non-use. But, all autos that I'm familiar with have vented fuel tanks, most have metal tanks and fuel lines, it has been in use for a couple of decades now, and I've never heard of ethanol-related problems in fuel systems for autos. I know there are some old style rubber O-rings, gaskets, fiberglass tanks and seals that will dissolve in ethanol, but assuming one knows all of these components in one's plane are of the modern ethanol-resistant type, I don't understand why there is a problem with it.

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Permalink Reply by Mark Maltais on July 14, 2013 at 9:28pm

Airplanes fuel systems can be made tolerant to ethanol.  Problems happen when they sit for a while, something most private airplanes do. If a plane is sitting with ethanol in it's tanks for more than a month, the fuel will become corrosive!  It's been known to eat fuel lines which can slowly break up and clog fuel filters with fuel line pieces.  It can be a nightmare on older carbs that would otherwise be fine.

Another issue is the ethanol absorbs moisture, then, even worse it separates from the gasoline and it does not separate nicely like it does with avgas.  When ethanol separates it settles into a jelly like bunch of crap in the bottom of the tank.  IF you can clean the mess up, the fuel is still shot because you will lose octane rating because the ethanol provides part of the fuel octane rating and who would use it anyways?

I think the EAA recommends draining any ethanol fuel out of you plane and carbs if it's going to sit for more than 30 days and especially over the winter or it will cause corrosion in your fuel system.  It's not much of an issue if you fly and fuel up your plane regularly.

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Permalink Reply by Bob Pustell on July 16, 2013 at 10:28pm

As I said in my first post, Jimmy, I am no expert. However, based on what I have learned......... As you point out, modern cars do just fine with the ethanol contaminated fuel. I run my cars on it. However, modern cars have sealed fuel systems -- they do not vent to the outside world through a vent line and they do not have carbs with a fuel bowl vented to the outside world. What venting a modern car fuel system gets, it gets through the emission system. When you screw the fuel cap back on after refueling, the fuel never sees fresh air again.

The problem we face (and that owners of antique cars, tractors, etc face) is that our fuel tanks and carbs are vented directly to the world through a simple vent tube or hole of some kind. Water vapor in the air is absorbed through that vent by the ethanol in the fuel. Given enough time, the ethanol gets saturated, cannot hold any more water. This starts a process called phase seperation which results in a corrossive goop forming in your fuel system that eats many metals, many fuel lines, fuel tank sensor floats, all kinds of things. This is on top of the fact that the ethanol can damage many gasket, seal, hose and float materials to begin with.

So, we have two problems to address. First, we need to use components that are not damaged by exposure to ethanol when building our fuel system. Seals, gaskets, floats, fuel pump diaphragms, flexible fuel lines etc all must be ethanol tolerant parts. Then, once we have an ethanol tolerant fuel system, we must make sure the fuel does not stay in the tanks long enough that phase seperation happens. When that happens your fuel system gets big troubles.

Modern cars can handle the stuff. Older vehicles, all airplanes, small engines (lawn mowers, weedwackers, chainsaws, etc etc) cannot. We can build our fuel systems with ethanol tolerant components (and we would be foolish not to at this point in time) but we cannot stop water vapor/humidity from getting taken in by the ethanol in the fuel. Burn or drain the nasty fuel promptly and you should be ok, but ya never know. I plan to use the stuff only as a last resort and then I will be sure it does not stay in the plane for very long. I will never park the plane with it in the fuel lines or carb, I will always run avgas or ethanol free Mogas for long enough before shutdown to be sure that is what is in the plumbing and the carb.

I do not run ethanol contaminated fuel in my small engines, by the way. When I can get it, I run ethanol free Mogas in them. When I cannot get "real" Mogas, I run Avgas in my lawn mower, snow blower, chainsaw, etc. So far, no problems with any of them. Many of my friends and neighbors have had their small engine ruined by ethanol containing fuel.

If you want to design and install a non-vented fuel system similar to modern cars you would be much safer using the nasty fuel, but you would also add complication, expense and weight to your plane.

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Permalink Reply by Chris Aysen on July 15, 2013 at 11:32am

I have a Nissan Frontier which I burn ethanol every tank fill-up. I use the vehicle everyday. I have had good service but gas milage is better with non-ethanol. That has to be a reason for that. I have thrown away 2 gas powered weedeaters, 2 push lawn mowers, and a pressure washer because I left the ethanol gas set for too long in the units. I would imagine I could have had them fixed but the cost would have been close to what they were worth. My advice would be don't run ethanol unless you absolutely have to and if you do; burn it out as soon as possible. My two cents.

 

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Permalink Reply by Bob Pustell on July 16, 2013 at 10:40pm

The reason you get better fuel milage when running non-ethanol fuel, Chris, is because ethanol has less BTU's of energy per gallon. When you burn a gallon of ethanol you get less energy than when you burn a gallon of "real" gasoline. So, it takes more ethanol contaminated fuel to generate the same amount of energy provided by a lesser amount of non-ethanol fuel. Therefore, you burn more fuel to cover the same distance driven if you have the ethanol fuel in the tank. The "Flex Fuel" vehicles that can burn E85 fuel (85% ethanol instead of the ten percent in our pump gas) get terrible fuel milage when running on E85, they lose over half their MPG.

That, by the way, is why Diesel vehicles get better fuel milage than a comparable gasoline engined vehicle -- Diesel has considerably more BTU's per gallon than gasoline does.

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