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Old 06-26-2012, 11:13 PM
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BarelyAWake BarelyAWake is offline
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Join Date: Jul 2009
Location: Maine
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Default Re: Regular with up to 10% booze-a-haul, or high octane w/out?

Direct personal experience isn't conjecture, the conclusions one draws may be however.

Regardless, the detrimental effects of ethanol & blends while sometimes overstated, are well known & documented in galvanic effect, hygroscopic nature and it's propensity for the degradation of elastomers.

Try keyword searching "ethanol harmful effects on engines";

As the ethanol concentration increases from zero to 15%, it effectively raises the solubility parameter (measured as the total Hansen Solubility Parameter) so that it approaches the values of most dispenser polymers. Therefore, the propensity for the fuel to permeate into and dissolve polymeric components is enhanced. Standard gasoline fuel delivery systems contain elastomeric materials having excellent compatibility and stability with hydrocarbon fuels. However, the ethanol molecule is relatively small and highly polar due to the –OH group. In addition, the tendency to introduce hydrogen bonding is high. These features enable its permeation into and interaction with the elastomer structure, which can result in swelling and softening of elastomers. Another negative feature associated with permeation is that soluble components, especially plasticizers added to impart flexibility and durability in the elastomer, may be leached out, thereby affecting the mechanical properties of the compounded elastomer component and degrading the ability of the component to perform its intended function. This affect is exacerbated under alternating wet/dry conditions.
Current high compression neat ethanol engine designs are approximately 20 to 30% less fuel efficient than their gasoline-only counterparts.[31]

Ethanol contains soluble and insoluble contaminants.[32] These soluble contaminants, halide ions such as chloride ions, have a large effect on the corrosivity of alcohol fuels. Halide ions increase corrosion in two ways; they chemically attack passivating oxide films on several metals causing pitting corrosion, and they increase the conductivity of the fuel. Increased electrical conductivity promotes electric, galvanic, and ordinary corrosion in the fuel system. Soluble contaminants, such as aluminum hydroxide, itself a product of corrosion by halide ions, clog the fuel system over time.

Ethanol is hygroscopic, meaning it will absorb water vapor directly from the atmosphere. Because absorbed water dilutes the fuel value of the ethanol (although it suppresses engine knock) and may cause phase separation of ethanol-gasoline blends, containers of ethanol fuels must be kept tightly sealed. This high miscibility with water means that ethanol cannot be efficiently shipped through modern pipelines, like liquid hydrocarbons, over long distances.[33] Mechanics also have seen increased cases of damage to small engines, in particular, the carburetor, attributable to the increased water retention by ethanol in fuel.[34]
For our application however, the above is easily compensated for as the corrosive galvanic effect on aluminum alloys with an E10/E15 is negligible and the elastomer gaskets/seals and lines are easily replaced with alcohol resistant components.
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