Flex-Fuel 3

[SolderingGunslinger]

What is the difference between an automobile with a gasoline only or E10 (10% Ethanol blend) engine and fuel system and an automobile with a Flex-Fuel engine and fuel system which can operate on everything from Unleaded regular through E85 (85% Ethanol, 15% Unleaded Gasoline).

I remain,

The Old Soldering Gunslinger

 

[CESSNA1]

SOLDERINGGUNSLINGER:

The 10% ethanol goes back to the energy crises of the late 70's early 80's. It was found that pure ethanol would attack and destroy gaskets and seals in an automobile engine, but a 10% blend would not. Brazil learned this when they switched to an alcohol society in the early 80's and engine seals were being attacked by the ethanol. Ethanol is a good anti-knock fuel so it replaced the tetraethyl lead in gasoline. Ethanol has a lower energy content than gasoline so mileage suffered slightly.

Brazil had to change out the gaskets and seals in their automobile engines so they were compatiible with alcohol. I suspect that the same is true for the flex-fuel engines. Mileage will probaly suffer as the percentage of ethanol is increased.

Alcohol also has a negative energy ratio. That is it takes more energy to make alcohol than you get out of it. Solar and other renewable energy sources would be preferred to make alcohol for a motor fuel.

Regards
Dave

 

[franzh]

One additional comment;
Flex fuel vehicles utilize total fuel system components that are alcohol tolerant. Fuel tanks, fuel lines, injectors, seals, o-rings, fuel pumps, etc. are included. Basic engine components are unchanged. Ethanol will attack certain metals, rubbers, and synthetic compounds.
Brazils experience demonstrated that Ethanol is not simply a drop in fuel, at least, at the levels desired there. Brazil used bio-waste as the feed stock for Ethanol and made more profit from exporting any petroleum products than Ethanol. Many of the vehicles there used two fuels, gasoline to start and get the engine warm, then switch over to Ethanol, then back to gasoline when shutting off to purge the fuel system.
Flex fuel vehicles also utilize fuel system sensors to detect the presence of Ethanol, usually by capacitance sensing, then uses the oxygen sensor to trim the fuel mixture based on the after combustion event.
Franz

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