gas mileage and fuel blends
#1
06-08-2007, 08:07 PM
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gas mileage and fuel blends
I just got done with a couple week vacation towing my rv from fl to Mass and then back.
From FL to VA I got about 8.5mpg, from VA to Mass I got about 11.5mpg (according to the edge programmer, and also backed up by my manual calculations). These were at the same speeds. To get the same mpg below VA I had to drive 50mph, versus the 65 I was doing up north.
On the return trip Mass-VA was 11.5 then VA-FL was 8.5.
stuff above VA was also mountain driving so I'm confused as to why my mpg went up so much.
Are the fuel blends that much of a difference?
From FL to VA I got about 8.5mpg, from VA to Mass I got about 11.5mpg (according to the edge programmer, and also backed up by my manual calculations). These were at the same speeds. To get the same mpg below VA I had to drive 50mph, versus the 65 I was doing up north.
On the return trip Mass-VA was 11.5 then VA-FL was 8.5.
stuff above VA was also mountain driving so I'm confused as to why my mpg went up so much.
Are the fuel blends that much of a difference?
#2
06-09-2007, 01:32 AM
Yes, mine goes in the crapper when we get out summer gas (Oxygenated blend).
I don't know how the tree hugging hippies figure Oxygenated fuel helps, I burn a butt load more of it to do the same job.
I wish the green peas types would just stick to riding the bus and leaving the rest of us the heck alone.
I don't know how the tree hugging hippies figure Oxygenated fuel helps, I burn a butt load more of it to do the same job.
I wish the green peas types would just stick to riding the bus and leaving the rest of us the heck alone.
#3
06-09-2007, 09:39 AM
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Yep, I have noticed exactly the same thing. I believe that the summer blends here in Texas max out the 10% of ethanol that are posted on the pumps. In the summer, many larger cities require the cleaner burning summer blends to reduce emissions and thus pollution. As we all know ETOH has less energy than its gasoline counterpart. Test show that FFV engines running E85 get a full 33% less mileage from a tank than they do when running the 90/10 blend. Your mileage difference is just around 37%. So it would stand to reason that our gas mileages suffer during the summer driving season especially in larger cities in the south.
Last edited by Oxlander; 06-09-2007 at 09:42 AM.
#4
06-09-2007, 02:08 PM
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I thought it was the WINTER blends that reduced fuel economy???
Anyway, ethanol is the "oxygenator" used these days and we know that this fuel burns much more cleanly (less harmful emmissions) but it generates less energy than dino gas. So, most can expect a 15% to 20% loss in fuel economy (not sure where the 30% figure comes from). So, if dino fuel is $3/gallon, you need to find E85 for $2.40/gallon or less in order to make up for the loss in economy.
That opinion was free.
Anyway, ethanol is the "oxygenator" used these days and we know that this fuel burns much more cleanly (less harmful emmissions) but it generates less energy than dino gas. So, most can expect a 15% to 20% loss in fuel economy (not sure where the 30% figure comes from). So, if dino fuel is $3/gallon, you need to find E85 for $2.40/gallon or less in order to make up for the loss in economy.
That opinion was free.
#5
06-10-2007, 09:11 PM
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On page 38 of the following study, the Colorado Department of Public Health and Environment states
"Fuel economy overall showed a decrease with the oxygenated fuel. This is to be expected because of the lower heating value or energy content of the 10% ethanol blend. The dilution of a base hydrocarbon fuel with 10% ethanol results in a reduction of the energy content of approximately 3%. Calculations based on the test fuels used in this program showed an estimated average reduction of -3.4% in the btu/gallon for the ethanol blend."
http://www.cdphe.state.co.us/ap/down/oxyfuelstudy.PDF
So, an increase in oxygenates like ETOH, reduces the BTUs in fuel and thus the trend of decreasing fuel economy. In the summer blends, the oxygenate ETOH is used to reduce the OVC (organic volatile compounds) found in "winter blend" fuels which evaporate at an ambient temp. ~100*F. These OVCs are thought to contribute to ozone (O3) induced smog which is prevalent in metro areas found in the south.
In addition, oxygenates increase the overall octane levels in the fuels to which they are added. Here in the greater Houston area regular unleaded is 89 octane and super unleaded is 93 octane. This is what leads me to believe that Texas' summer blends max out the ETOH additive of 10% for the E10 gasoline.
So until I see evidence to the contrary, I will continue to believe that summer blends reduce fuel economy when compared to winter blends.
The 30% figure comes from the EPA data concerning E85 fuel operating in FFV.
http://www.epa.gov/SmartwayLogistics...tsheet-e85.htm
In the second paragraph under "Affordability" you will find the following statement:
In general, E85 reduces fuel economy and range by about 20-30 percent, meaning an FFV will travel fewer miles on a tank of E85 than on a tank of gasoline.
In the paragraph under "Benefits" you will find this statement regarding emissions reduction:
When made from corn, E85 reduces lifecycle GHG emissions (which include the energy required to grow and process corn into ethanol) by 15-20% as compared to gasoline.
Maybe thats where you picked up the 15-20% data. Not sure?
"Fuel economy overall showed a decrease with the oxygenated fuel. This is to be expected because of the lower heating value or energy content of the 10% ethanol blend. The dilution of a base hydrocarbon fuel with 10% ethanol results in a reduction of the energy content of approximately 3%. Calculations based on the test fuels used in this program showed an estimated average reduction of -3.4% in the btu/gallon for the ethanol blend."
http://www.cdphe.state.co.us/ap/down/oxyfuelstudy.PDF
So, an increase in oxygenates like ETOH, reduces the BTUs in fuel and thus the trend of decreasing fuel economy. In the summer blends, the oxygenate ETOH is used to reduce the OVC (organic volatile compounds) found in "winter blend" fuels which evaporate at an ambient temp. ~100*F. These OVCs are thought to contribute to ozone (O3) induced smog which is prevalent in metro areas found in the south.
In addition, oxygenates increase the overall octane levels in the fuels to which they are added. Here in the greater Houston area regular unleaded is 89 octane and super unleaded is 93 octane. This is what leads me to believe that Texas' summer blends max out the ETOH additive of 10% for the E10 gasoline.
So until I see evidence to the contrary, I will continue to believe that summer blends reduce fuel economy when compared to winter blends.
The 30% figure comes from the EPA data concerning E85 fuel operating in FFV.
http://www.epa.gov/SmartwayLogistics...tsheet-e85.htm
In the second paragraph under "Affordability" you will find the following statement:
In general, E85 reduces fuel economy and range by about 20-30 percent, meaning an FFV will travel fewer miles on a tank of E85 than on a tank of gasoline.
In the paragraph under "Benefits" you will find this statement regarding emissions reduction:
When made from corn, E85 reduces lifecycle GHG emissions (which include the energy required to grow and process corn into ethanol) by 15-20% as compared to gasoline.
Maybe thats where you picked up the 15-20% data. Not sure?