O 540 on auto fuel

[Bjorn]

Due to high fuel prices on 100LL and the decreasing availability here in europe i want to have an engine running on auto fuel
The O 540 B can run on auto fuel, but what about the rest of the O 540 / IO 540 ?
What harm does auto fuel do on an engine certified for 100LL ?
If anybody have some information or some link to where i can find some technical correct information I would be happy
Bjorn

[Battson]

You need to be sure that the compression ratio of the engine allows for a lower octane fuel, and check there are no parts in your engine and wider fuel system (e.g. typically the fuel pump diaphragm or fuel injection servo diaohragms) which are susceptible to additives in various automotive fuels. My IO-540 (Bob Barrows) is rated for high octane auto fuel.

[Denali]

@ Battson

Is your auto fuel compatible IO-540 from Bob Barrows able to tolerate any ethanol, and if so to what extent? Thanks.

[Battson]

I haven't looked into that. AFAIK, ethanol doesn't really a feature in New Zealand, but I am only running AVGAS at this stage anyway. Auto fuel is hard to get to our airport any any quantity without a certified mobile tank.

[Mark Goldberg]

I believe carbs like auto fuel more than injected engines. And the B series 540 engines (with low compression) is the one I would select if using auto fuel is what you want.

No one runs gas with alcohol in aircraft engines. Mark

[alaskabearhawk]

Ethanol (alcohol) is hydroscopic...very bad for aircraft:

http://www.aopa.org/News-and-Video/All-News/2008/April/29/Ethanol-threatens-auto-fuel-supply-for-some-pilots

http://generalaviationnews.com/2012/12/05/ethanol-testing-made-easy/

[Denali]

Regarding the Ethanol,

In some parts of the United States it is almost impossible to find auto gas that does NOT have ethanol. I hate the ethanol, and even try to run my lawn equipment with ethanol free, but that has been well nigh impossible to find, at ;least in my area. And yes I understand it is bad for aircraft use, and that the variability of auto gas can present issues with fuel injection.

I read somewhere that all auto gas in Alaska is ethanol free. If that is still true, Alaskans are blessed.

[alaskabearhawk]

It's true. We are exempt from oxygenated fuels.

[Bjorn]

I found this art If you use petrol for your family car, classic car, boat, motorcycle, Quad, lawnmower, strimmer, rotavator, chainsaw, generator, pump or any other type of equipment that has a petrol engine, you need to know about Ethanol in your fuel. What is Ethanol? Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colourless liquid. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a solvent and as an alcohol fuel. In common usage, it is often referred to simply as alcohol or spirits. Where does it come from? Ethanol is sustainable and domestically produced from renewable resources such as corn, grains and potatoes. Why add Ethanol to Petrol? Ethanol is good for our agricultural economy and helps us reduce our dependency on foreign petroleum products. On the “green” side they are aimed at improving air quality and reducing air pollution from fuel emissions. What proportion of the fuel is Ethanol? Permitted ethanol content in petrol is 5% which is to rise to 10% in 2013. However we are led to believe supermarket fuels may already have as much as 10% ethanol blended in. We hear a 15% mix is on its way in the USA. While this is good for the domestic farmer and our environment, Ethanol can cause serious problems to your engine and fuel system. Generally vehicles built after 1996 have been designed with Biofuels in mind, but earlier cars and engines with carburettors are going to need help. What types of problems have been encountered? 1) Water accumulation in the fuel tank - ethanol absorbs water from the air. The water condenses in the fuel tank and will pull the ethanol out of suspension with the petrol. This is bad news because it strips the octane out of the petrol, leaving you with a layer of octane-poor fuel on top and a water-ethanol layer mixture on the bottom. If this gets sucked into the combustion chamber, you will have poor starting and very rough running with potentially engine damage. 2) Deposit is like to build up - Ethanol when mixed with water readily forms Gums in the fuel system much quicker than fuel without Ethanol. These Gums coat fuel system components including filters, carburettors, injectors, throttle plates and will then form varnish and carbon deposits in the intake, on valves, and in the combustion chamber. 3) Lower fuel mileage, Decreased performance and acceleration. Ethanol contains less chemical energy than petrol does, and this means less mileage for the driver. 3-5% drops in mileage are expected. 4) Corrosion of internal engine components - Water contamination may cause fuel system corrosion and severe deterioration. 5) Contaminants in fuel system – water, degraded rubber, plastic, fibreglass and rust may get drawn in. 6) It could encourage microbial growth in fuel. Ethanol being organic and hygroscopic may allow the growth of fungus. 7) Short shelf life - as short as 90 days Corrodes plastic and rubber - Ethanol is a strong, aggressive solvent and will cause problems with rubber hoses, o-rings, seals, and gaskets. These problems are worse during extended storage when significant deterioration could take place. Hoses may delaminate, o-rings soften and break down, and fuel system components made from certain types of plastics could either soften or become hard and brittle, eventually failing. Fuel system components made from brass, copper, and aluminium may oxidize. The dissolved plastics and resins now in the fuel could end up in blocked fuel filters or gummy deposits. 9) Melts Fibreglass - bikes and boats with fibreglass fuel tanks can have structural failure as the Ethanol will break down and pick-up some of the materials the tanks are made from. Again this material, dissolved from the tank, can be carried through the fuel system and can cause damage to carburettors, fuel injectors and can actually get into the combustion chambers.

[Bjorn]

The article i found describe some disadvantage of using ethanol in auto fuel.
Do I understand right that those who use auto fuel on their engine use only pure auto fuel (no ethanol mix) or are some engine modified to run on the ethanol mixed fuel ?
Which comp ratio does the Bob Barrows IO 540 have ?
Thanks for reply Bjorn

[Battson]

Compression is standard 8.50:1, no higher is acceptable.