Running higher octane gas?

[Sarge 3,462]

The typical "green ooze" - glad you caught it early before it turned into the destructive "white powder", which is the result of the ethanol eating away at the die-cast metal parts.

 

I have found by my own experience that air cooled engines do indeed run cooler overall on the 91 octane that is typically available without the ethanol added. Common non-ethanol 87 does seem to run them a bit hotter, although it's pretty negligible - except at the exhaust temperature. I'm sure it's down to valve timing differences in many engines as to which direction they go, and the era in which those engines were built.

@EricF has given about the best description I've seen yet, thanks.

 

Sarge

[recklessridr 2]

Recent debates and publicity concerns surrounding the introduction and use of "Green Fuels", has raised the question of the effects of these alcohol based fuels on the materials used in our components.

The use of ethyl alcohol mixed with petrol up to concentration of 10% (E10) has been common practise in the USA since the fuel crisis of the 1970's. This blend is now regularly available in Australia and in limited supply throughout Europe. Higher levels of mixes, of 22% to 85% (E22 to E85) are used in Brazil and the latest trend has been for vehicle manufacturers to develop Flexible Fuel Vehicles (FFV's).

These FFV's and South American vehicles have all been specifically designed to accommodate the use of these high concentrations of ethanol.


Advantages and Disadvantages

The addition of ethanol to petrol has an effect on both the performance of an engine and also its interaction with the different materials it comes into contact with.

    •    Change in Octane Number

The addition of ethanol, up to a certain level, improves the octane number ,giving better anti-knock properties that can be helpful to older and higher performance engines that were designed for high octane fuels.

    •    Change in Volatility

A fuel's ability to vaporise has an effect on performance and on emissions. The addition of ethanol has the effect of lowering the temperature at which the fuel vaporises, thereby improving combustion and cold starting. However It can increase the possibility of a vapour lock.

    •    Increase in Oxygen Content

In addition to hydrogen and carbon , ethanol also contains oxygen. The replacement of hydrocarbons with oxygen has the effect of weakening the air-to-fuel ratio. This lowers emissions, lowers mpg and raises NOx in vehicles without a three way catalyst.

    •    Effect of Water Solubility

The addition of ethanol causes fuel to become hygroscopic (absorbs water). This has several different effects. It becomes acidic and conductive causing both a chemical reaction with certain materials and galvanic reaction causing corrosion. As water is heavier than petrol, a layering effect can occur with stored fuel, having a higher water content settling to the bottom where fuel pick-ups are located.

    •    Lubricating Effect

When mixing with 2 stroke fuels it has been noted this can cause phase separation in breaking down the oil and petrol content,causing a loss of lubrication. Under other conditions it can act as a solvent, washing oils from metal surfaces thereby increasing engine wear.

    •    Permeability

Ethanol readily permeates through elastomers and plastics, resulting in a deterioration of these materials.


Component Design Compatibility

For fuel blends containing less than 5% ethanol, the concentration is low enough not to cause any significant effect. For 5% to 10% blend, some changes are recommended, (albeit that the USA has been subjected to this concentration for sometime without any known problems). For above 10% the effects of ethanol are known to cause problems and the necessary modification that would be required would extend beyond those of just our product content in a vehicle.


Summary

E0 to E10 blended fuels have been in use in the USA since the late 1970's and have had no significant effect on the performance or durability of our product. Using blends above E10 are not recommended as effects of these have yet to be fully investigated.

The company is already effecting changes of materials in sensitive components. Needles will be produced in nickel silver whilst orifices will be made from manganese bronze. Diaphragms and O rings to be upgraded to Viton or other suitable material. Rubber petrol pipe to be internally lined or upgraded. This ongoing process should be completed by 2012.

[recklessridr 2]

this was copied from the AMAL carb tech page.  the carbs  in our wheel horses are made from the same stuff.  hope this helps to dis[ell some of the confusion concerning OCTANE,, seals .. o=rings,,,, etc.

 

BTW,,, they also deal in ZENITH  &  SU  carbs,,,,, FYI

[boovuc 1,090]

All my stuff, lawn mowers, tractors, the zero turn, generators and in my 2-stroke chainsaws, blowers and weed-eaters get 100 octane Aviation fuel. Up to a three year shelf life so it's not necessary to add anything to it. There is no Ethanol in it. Using it to mix a 50:1 2-stroke mix, it makes my saws run way better than regular gas mixed. I can also say that the KT17's I own run much better with it. The old K Kohlers run the same between both but I don't worry about leaving fuel in them over the winter and I know my generator will be good to go with it in there. If I'm going to be using a machine a lot, I'll throw regular gas in it but for the most part, I don't use it in small engines. It's $4.68 a gallon when I purchased it two weeks ago at our local airport. It really seems to make all the engines I use it in run cooler but irregardless, I have never had a carb go south using it and I had plenty of issues before I switched.

[Lee1977 6,214]

It's my understanding that there isn't enough ethanol produced for all the gas sold. The distributor has to pay the groverment if it's not available so that cost get pasted along to the consumer. That's why most gas pumps say "may contain 10%  ethanol". I see ever so often people post ethanol never cause a problem with my small engine. It may be they never got enough ethanol to cause a problem. I forgot to run my vacuum engine dry and let it sit a year with ethanol in it. It would not start so I fill the carb. with a stabilizer mixed with a small amount of gas and let it sit about 30 minuets. It started up and smoked like an old steam train for a few minuets.

I can now get no ethanol 87 at QT for $2.999 and 93 at Citgo for $3.199. I just cleaned the gas tank on my 80 Toyota 4 Wheel Drive that hasn't been on the road in 20 years. It will only get no ethanol gas.