[Diy_efi] Is E85 worth it?

[Tim M]

Interesting.

I knew about the higher octane and I knew that more advance would 
increase the mileage. So one can assume that the knock sensor "window" 
similar to the lamda window would take advantage of the fuel.

The cost of E85 in my area is roughly 90-95 % that of regular.

So now back to my original question has anybody done any real world 
mileage comparisons?

I am also considering a diesel vehicle since I do some occasional 
towing, but the diesel offerings here in the states are limited. I am 
trying to stay level headed about it and not just go get the 
Duramax/allison 2500 truck... Anybody know when the 3.0L Jeep Cherokee 
diesel is coming out? (although I am guessing they are going to be very 
proud of this vehicle)

Thanks,
Tim


Torbj?rn Forsman wrote:
> Older FFV cars (like the Ford Taurus from around 1996) have a fuel 
> quality sensor which measures the dielectricity constant of the fuel. 
> It is sort of a capacitor which uses the fuel as the dielectric, 
> together with a capacitance measuring circuit.
> Today's FFV vehicles usually don't have any such sensor but uses the 
> ordinary lambda control and adaptation functionality of the ECU to 
> adapt for different fuel mixtures. In fact, some non-FFV vehicles have 
> a large enough adaptation "window" to run well on either gasoline or 
> E85, if they only get somewhat higher fuel pressure or larger injectors.
>
> The difference in fuel consumption between gasoline and E85 is often 
> smaller than one might believe from the heat values of the fuels. This 
> is due to E85's higher hydrogen content and lower carbon content than 
> gasoline. The exhaust gases will contain more water steam and less 
> CO2, which gives the engine better thermal efficiency as the steam 
> takes more room per mole (please refer to any thermodynamics text book 
> for more details). Additionally, the higher octane number of E85 
> permits earlier ignition and higher compression ratio than we are used 
> to from gasoline engines.
> As it is more difficult to evaporate E85 than gasoline, it is very 
> important to make sure that everything concerning the fuel 
> vaporization is in best possible order. Good intake air preheating 
> helps much, as well as using modern types of injectors and a 
> relatively high fuel pressure.
>
> Best regards
>
> Torbj?rn Forsman
>
>
> Garrett P. Beauregard wrote:
>> Yes.  There is a sensor that detects the mix. No clue how it works, 
>> but it
>> does and it's seamless.
>>
>> Garrett
>>
>> -----Original Message-----
>> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
>> Behalf Of C. J. Frederick
>> Sent: Thursday, August 24, 2006 9:24 PM
>> To: diy_efi at diy-efi.org
>> Subject: RE: [Diy_efi] Is E85 worth it?
>>
>>
>> I often wondered what happens when you have, lets say an 1/8 tank of 
>> one or
>> the other fuel and have to fill up with the opposite fuel.  Can the ECM
>> seamlessly adjust for a mix (E85 and gas) in the tank?
>>
>> CJ
>>
>>
>>
>>> E85 has about 70% of the energy content of gasoline. So, e85 needs 
>>> to cost
>>> 70% of the price of gasoline to break even. The last number I saw was
>>> something like 450 stations in the US had E85. With most E85 being 
>>> supplied
>>> by local refiners, prices and availabilty will vary. The NEVC 
>>> website has
>>> some good info, but they play down the disparity in energy and economy:
>>> http://www.e85fuel.com/index.php
>>>
>>> There is also some "value" associated with the reduced pollution when
>>> running E85, but that doesn't accrue monetary benefits in your wallet.
>>>
>>> Remember that you can still run old-fashioned gasoline in a FFV 
>>> until E85
>>> becomes more widespread and cost effective.
>>
>>
>>
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