Ethanol and Two-Cycle Oil

A fuel mixture containing only 10% ethanol will burn just like regular gasoline although it contains less energy. In fact gasoline containing 10% ethanol is sold in most areas of the country. Mixtures containing more than 10% ethanol e.g. E 85, may cause deterioration of fuel system components. I suggest you contact the manufacturer of the 2 cycle engine and ask if fuel containing large amounts of ethanol will harm the engine. Several countries in the world, notably Brazil, run virtually all of their gasoline engines on nearly pure ethanol which they distill from sugar cane.

Premium gasoline is a waste of money in a two cycle engine and will not benefit the engine in any way

Dennis Waller

"Premium gasoline is a waste of money in a two cycle engine and will not benefit the engine in any way"

For what it's worth, the place where I work has dozens of 2 cycle tools (Echo mostly)used by many inexperienced workers. The repair shop insists that we use premium fuel in this equipment. They say it extends the life of the equipment. This shop has no reason to recommend this, other than their experience, I guess.

Good Luck

Premium Gasoline: This fuel is formulated to reduce detonation, a complicated chemical reaction in which the fuel/air mixture in the combustion chamber explodes spontaneously rather than burning quickly. This explosion can damage the engine by disrupting the layers of gasses that surround the surfaces of the combusion chamber which act as insulation. Detonation allows heat of combustion to be transferred to the surfaces of the combustion chamber which can melt aluminum parts and the rapid rise in pressure from the explosion can blow holes in the cast iron parts. Detonation becomes a major problem as the compression ratio rises and it is the main reaon why few gasoline engines have compression ratios much above 10:1 although maximum efficiency would be reached by a ratio of 16:1. Two cycle engines have relatively low compression ratios and therefore the use of premium gasoline is a waste of money.

Dennis Waller

Thanks for the enlightenment.

Sometimes premium is used in high proformance 2 strokes, to prevent siezing during extended high speed operation. the compression ratio of 2 strokes increases depending on rpm, reeds, port shape, pipe design... not as straight forward as on a 4 stroke.

I pay 10% more for premium grade gas. And I use only Echo 2 stroke oil. And I'm happy to do it.

Dennis, it is my understanding that the higher the octane rating, the slower more complete the burn, thus giving more power to each stroke. Tetraethyllead was previously used to achieve this, however, the government, trying to protect us all from each other, banned the use of lead containing gasoline in the 1970's. I am not sure what is used now, I do know that MTBE is used as an oxygenate for decreasing undesirable green house gasses

I just stumbled across this.

High fuel octane does not have an inherently slower more complete burn. In fact, for completeness of burn, one would generally want a faster burn time. "Octane rating" really refers only to the onset of combustion, and especially the likelihood that the mixture detonates (explodes, with the whole mixture, or remaining mixture, burning all at once, rather than smoothly moving flame front). If the mixture is not detonating (which can be heard as pinging, which sounds like marbles in your cylinders) then there is no advantage at all in power delivered by a higher octane fuel.

Some fuels such as H2 are very high octane, but also have very fast flame fronts, and as a result very quick burn times. In other words, burn time and octane rating are unrelated.

A potentially confusing aspect of this is that modern turbocharged engines can produce more power on high octane fuels than on low octane. This is not because high octane fuels burn more powerfully, but because modern turbo engines automatically adapt to low octane fuels, reducing peak cylinder pressures and temperatures to prevent the onset of detonation. Just as a high compression engines require high octane fuel to prevent engine damage from detonation, turbo engines also require high octane to achieve full rated hp. Given electronic controls, it is easy to derate the engine (using e.g., knock sensing) to produce less less power on low octane fuels.

Tell us more, what percentage ethanol?

what ratio of oil?

What kind of motor?

You can probably just adjust the jetting...

I believe the only thing you need to be concerned of using alcohol (ethanol) combined with gasoline, in any circumstance, is the fact that alcohol will eat away any rubber components of an engine. Fuel lines, some reed valve parts on 2 stroke engines, and a host of seals, sealants and rubber coated gaskets...

Otherwise, you're good to go.

JL Mealer
MealerAMC
http://mealercompanies.com

Does the ethanol thin the properties provided by the 2 cycle oil ?

To clarify: petroleum 2-stroke oil will not dissolve in ethanol but synthetic will.

Greater than 10% ethanol to gasoline blend ratio will deteriorate the crank case bearings quickly and even with a doubled ratio of 50:1 will by attrition destroy the crank case bearings in a rapid fashion.

It's a result of intensity of force causing higher crank case temperature due the 50% increase of Btu per piston stroke generated using fuel blends having ethanol ratios above 10%

The calorific value of ethanol is lower than petrol.

Ethanol does allow cooler running of the exhaust valves and is an octane improver, pure ethanol rating at about 128.

Ethanol is also a poorer solvent than petrol. Generally, seals which will handle petrol have no problem with ethanol.

The disadvantage of ethanol is that if the % is too great, it will absorb water and cause corrosion. This often leads to people claiming that it attacks the seals. It usually doesn't, but the water corrodes the metal in contact with the seal.