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E85 at a Speedway station in Cadillac MI has been $1 cheaper than regular unleaded for the past two weeks! T&C will not go in storage and likely will be driven now and then throughout the winter when the roads are clear and dry. Mostly starting and running fine with temps in the 20s and 30s with one startup resulting in a short lived misfire with a smell of ethanol. Will switch back to E10 if and when starting and running issues become consistent.

Getting 11 MPG in short, local trips. Engine definitely runs cooler in cold temps on E85. Will need to take occasional longer trips to drive off condensation.
 

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E85 at a Speedway station in Cadillac MI has been $1 cheaper than regular unleaded for the past two weeks! T&C will not go in storage and likely will be driven now and then throughout the winter when the roads are clear and dry. Mostly starting and running fine with temps in the 20s and 30s with one startup resulting in a short lived misfire with a smell of ethanol. Will switch back to E10 if and when starting and running issues become consistent.

Getting 11 MPG in short, local trips. Engine definitely runs cooler in cold temps on E85. Will need to take occasional longer trips to drive off condensation.
How do you determine the engine runs cooler with E85? Thermodynamics suggests both fuel types will generate the exact same amount of heat to generate any given amount of power.
 

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Going by the temperature gauge, as compared to E10 it takes longer for the engine to reach full operating temperature and sometimes never reaches this point on trips under 30 minutes.
 

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Going by the temperature gauge, as compared to E10 it takes longer for the engine to reach full operating temperature and sometimes never reaches this point on trips under 30 minutes.
This has nothing to do with the fuel you're burning and most likely everything to do with a failed thermostat.
 

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A failed/faulty thermostat is possible but unlikely in this case as a new radiator and t-stat was installed earlier this year. Experimenter bias is always possible, especially as I don't have control and other data, just a "seat of the pants" observation. May run a tank of E10 at next fillup to see if perceived warm up times are faster. Still, I get that the thermostat should compensate and provide similar warm up times regardless of the fuel being burned.

Regarding possible technical reasons for engines running cooler on E85 v. E10, I believe I read that E85 has a greater "charge cooling" effect compared to E10 due in part to richer air/fuel ratios as ethanol has a lower energy content compared to gasoline and has to be burned in greater quantities to produce similar power outputs in engines that are not fully optimized for E85. Maybe one of the engine lab boys can weigh in?
 

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The fact remains, you need to generate a given amount of combustive heat to get a given amount of power, running richer will not cause any additional cooling.
 

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As per a hi Octane Racing quote:

"The other by product of using alcohol based fuel is that it burns much “cooler” and in turn the whole engine will in most cases run much cooler...

The next interesting fact about E85 ethanol based fuels is that it reaches stoichiometry at an air/fuel ratio of 9.7:1 compared to an air/fuel ratio of 14.7:1 for gasoline meaning for any given application you will use as a minimum of 30% and in many cases closer to 50% more fuel to achieve the same result. Part of the reason for this that E85, and in fact any alcohol based fuel has a much lower calorific value or in simple terms the same amount of fuel contains much less “energy”

E85 on average produces around 25 Mega Joules of Energy per litre of fuel, while normal 98 Octane petrol will normally produce in excess of 33 Mega Joules of Energy per litre so for this reason alone we will always use much more E85 fuel to achieve the same result."

At least according to this source, engines indeed tend to run cooler on ethanol based fuels compared to gasoline.
 

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A failed/faulty thermostat is possible but unlikely in this case as a new radiator and t-stat was installed earlier this year. Experimenter bias is always possible, especially as I don't have control and other data, just a "seat of the pants" observation. May run a tank of E10 at next fillup to see if perceived warm up times are faster. Still, I get that the thermostat should compensate and provide similar warm up times regardless of the fuel being burned.

Regarding possible technical reasons for engines running cooler on E85 v. E10, I believe I read that E85 has a greater "charge cooling" effect compared to E10 due in part to richer air/fuel ratios as ethanol has a lower energy content compared to gasoline and has to be burned in greater quantities to produce similar power outputs in engines that are not fully optimized for E85. Maybe one of the engine lab boys can weigh in?
When people talks about "cooling effect", they are talking about unburned fuel passing through the intake system, very important in racing. There is not "cooling effect" in a internal combustion engine, regardless fuel used, if it burns, it produces heat.
 

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As per a hi Octane Racing quote:

"The other by product of using alcohol based fuel is that it burns much “cooler” and in turn the whole engine will in most cases run much cooler...

The next interesting fact about E85 ethanol based fuels is that it reaches stoichiometry at an air/fuel ratio of 9.7:1 compared to an air/fuel ratio of 14.7:1 for gasoline meaning for any given application you will use as a minimum of 30% and in many cases closer to 50% more fuel to achieve the same result. Part of the reason for this that E85, and in fact any alcohol based fuel has a much lower calorific value or in simple terms the same amount of fuel contains much less “energy”

E85 on average produces around 25 Mega Joules of Energy per litre of fuel, while normal 98 Octane petrol will normally produce in excess of 33 Mega Joules of Energy per litre so for this reason alone we will always use much more E85 fuel to achieve the same result."

At least according to this source, engines indeed tend to run cooler on ethanol based fuels compared to gasoline.
While it is true any given quantity of ethanol will burn cooler than the same quantity of gasoline, the fact remains, in order to develop any given amount of power you will need to create a given amount of heat; the laws of thermodynamics are quite specific on this issue.

Regarding the relative stoichiometric values, while interesting, it is pretty much irrelevant. Why? Because spark ignition engines typically run on the rich side of stoichiometric; running at stoichiometric will pretty much destroy an engine in relatively short order.
 

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So by your belief engines running on E85 do not typically run cooler than when running on E10? Looks like you choosing to look at only part of the thermodynamics picture and ignoring other mentioned factors and observations by engine experts. I therefore have nothing else to say.

Spits out hook and swims away
 

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02 FFV 3.3 T&C still cranking and running well on E85 with daytime temps below 20°F in N MI w/ E85 currently running 80 cents cheaper than regular E10. Per the E85 pump dispensed E85 may contain as little as 52% ethanol. Getting around 14 mpg mixed stop and go and highway with extended idle times for pre-trip warmups.
 
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