Filling Up 93 Octane - Be Careful
Sep 9, 2010, 08:39 AM
#16
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The gas at the Kroger in Plano changes from e85 to e73 from truck to truck and they do NOT have to tell you a thing. I have a client in Denton that does fuel delivery for most of the lucky lady stations and they carry a blend that caries from e70 to e85 and they even have a e100. I confirmed this after Chris, our club pres, told me some info about ethanol fuels.
Sep 9, 2010, 08:46 AM
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Sep 9, 2010, 08:57 AM
#19
I only lost around 15% fuel economy so it's not bad at all. When I first switched I did it for the power but now it's more for the price. Reminds me of the good ol days when 15-20$ would get you 13 gallons of premium. I need to get a gas analyzer so I can measure the content. Hope or winter blend doesn't change much from summer or I'll be seeing you soon Kevin!
Sorry for the thread hijack op LOL
I wonder how many times I have filled up and had the pump switch to 87 on me...I'm sure more then once
Sorry for the thread hijack op LOL
I wonder how many times I have filled up and had the pump switch to 87 on me...I'm sure more then once
Sep 9, 2010, 11:04 AM
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ok help me to understand because I guess Im too old. But I seem to remember my college chemisty class.. If you have e85 and tune a car as such.. then you get e70 you have lowered the energy of the fuel if all things are equal. since your car cant tell which fuel you have; it pumps in the same amout of air...and same volume of fuel but because there is less energy you have LEANED the car out. Am I backwards?
the energy of the fuel has nothing to do with the stoich ratio. its the chemistry of the fuel that makes the mixture rich or lean.
for example, pure ethanol (C2H5OH) mixes with air (thats AIR, not oxygen... remember oxygen is only like 21% mass composition of air. if you do the reaction balance with O2, you see that C2H5OH+3O2 = 3H2O + 2CO2) at a mass ratio of 9:1 with air. thats 9 grams of air for every 1 gram of fuel. gasoline (which comes close to octane), which is C8H18 burns at 14.7:1. thats 14.7 parts air for every part fuel. the difference is so great because the fuel actually contains its own oxygen atom, which means it doesn't need as much air.
since the volume of air the engine takes in is fixed (assuming all your doing is changing the fuel, not changing injector scaling or anything), then with E85 you see that you need far more fuel for the same amount of air (i.e. scale the injectors smaller). so if you take away some of the ethanol, and replace it with gasoline, the gasoline needs more air to burn, but since air is fixed, and on a e85 scaling your throwing a lot of fuel in the engine, not all the fuel gets burnt because the large amount of gasoline consumes it quickly, leaving unburned fuel... i.e.rich.
one other thing i noticed... E70 actually has a higher energy density then E85. reason being is gasoline has a much higher energy density, and the number after the E in E85 is the % ethanol to gasoline. so E85 has 15% gasoline, and E70 has 30% gasoline. with a higher gasoline content, you have a higher energy density.
Last edited by KevinD; Sep 9, 2010 at 11:27 AM.
Sep 9, 2010, 11:07 AM
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The gas at the Kroger in Plano changes from e85 to e73 from truck to truck and they do NOT have to tell you a thing. I have a client in Denton that does fuel delivery for most of the lucky lady stations and they carry a blend that caries from e70 to e85 and they even have a e100. I confirmed this after Chris, our club pres, told me some info about ethanol fuels.
are you actually measuring this or going off what the truck driver says? cause as goofy mentioned, we outfitted his car with the ethanol content analyzer which measured the alcohol content, and the swing was minimal.
Sep 9, 2010, 11:27 AM
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the energy of the fuel has nothing to do with the stoich ratio. its the chemistry of the fuel that makes the mixture rich or lean.
for example, pure ethanol (C2H5OH) mixes with air (thats AIR, not oxygen... remember oxygen is only like 21% mass composition of air. if you do the reaction balance with O2, you see that C2H5OH+3O2 = 3H2O + 2CO2) at a mass ratio of 9:1 with air. thats 9 grams of air for every 1 gram of fuel. gasoline (which comes close to octane), which is C8H18 burns at 14.7:1. thats 14.7 parts air for every part fuel. the difference is so great because the fuel actually contains its own oxygen atom, which means it doesn't need as much air.
since the volume of air the engine takes in is fixed (assuming all your doing is changing the fuel, not changing injector scaling or anything), then with E85 you see that you need far more fuel for the same amount of air (i.e. scale the injectors smaller). so if you take away some of the ethanol, and replace it with gasoline, the gasoline needs more air to burn, but since air is fixed, and on a e85 scaling your throwing a lot of fuel in the engine, not all the fuel gets burnt because the large amount of gasoline consumes it quickly, leaving unburned fuel... i.e.rich.
one other thing i noticed... E70 actually has a higher energy density then E85. reason being is gasoline has a much higher energy density, and the number after the E in E85 is the % ethanol to gasoline. so E85 has 15% gasoline, and E70 has 30% gasoline. with a higher gasoline content, you have a higher energy density.
for example, pure ethanol (C2H5OH) mixes with air (thats AIR, not oxygen... remember oxygen is only like 21% mass composition of air. if you do the reaction balance with O2, you see that C2H5OH+3O2 = 3H2O + 2CO2) at a mass ratio of 9:1 with air. thats 9 grams of air for every 1 gram of fuel. gasoline (which comes close to octane), which is C8H18 burns at 14.7:1. thats 14.7 parts air for every part fuel. the difference is so great because the fuel actually contains its own oxygen atom, which means it doesn't need as much air.
since the volume of air the engine takes in is fixed (assuming all your doing is changing the fuel, not changing injector scaling or anything), then with E85 you see that you need far more fuel for the same amount of air (i.e. scale the injectors smaller). so if you take away some of the ethanol, and replace it with gasoline, the gasoline needs more air to burn, but since air is fixed, and on a e85 scaling your throwing a lot of fuel in the engine, not all the fuel gets burnt because the large amount of gasoline consumes it quickly, leaving unburned fuel... i.e.rich.
one other thing i noticed... E70 actually has a higher energy density then E85. reason being is gasoline has a much higher energy density, and the number after the E in E85 is the % ethanol to gasoline. so E85 has 15% gasoline, and E70 has 30% gasoline. with a higher gasoline content, you have a higher energy density.
Sep 9, 2010, 11:40 AM
#25
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the energy of the fuel has nothing to do with the stoich ratio. its the chemistry of the fuel that makes the mixture rich or lean.
for example, pure ethanol (C2H5OH) mixes with air (thats AIR, not oxygen... remember oxygen is only like 21% mass composition of air. if you do the reaction balance with O2, you see that C2H5OH+3O2 = 3H2O + 2CO2) at a mass ratio of 9:1 with air. thats 9 grams of air for every 1 gram of fuel. gasoline (which comes close to octane), which is C8H18 burns at 14.7:1. thats 14.7 parts air for every part fuel. the difference is so great because the fuel actually contains its own oxygen atom, which means it doesn't need as much air.
since the volume of air the engine takes in is fixed (assuming all your doing is changing the fuel, not changing injector scaling or anything), then with E85 you see that you need far more fuel for the same amount of air (i.e. scale the injectors smaller). so if you take away some of the ethanol, and replace it with gasoline, the gasoline needs more air to burn, but since air is fixed, and on a e85 scaling your throwing a lot of fuel in the engine, not all the fuel gets burnt because the large amount of gasoline consumes it quickly, leaving unburned fuel... i.e.rich.
one other thing i noticed... E70 actually has a higher energy density then E85. reason being is gasoline has a much higher energy density, and the number after the E in E85 is the % ethanol to gasoline. so E85 has 15% gasoline, and E70 has 30% gasoline. with a higher gasoline content, you have a higher energy density.
for example, pure ethanol (C2H5OH) mixes with air (thats AIR, not oxygen... remember oxygen is only like 21% mass composition of air. if you do the reaction balance with O2, you see that C2H5OH+3O2 = 3H2O + 2CO2) at a mass ratio of 9:1 with air. thats 9 grams of air for every 1 gram of fuel. gasoline (which comes close to octane), which is C8H18 burns at 14.7:1. thats 14.7 parts air for every part fuel. the difference is so great because the fuel actually contains its own oxygen atom, which means it doesn't need as much air.
since the volume of air the engine takes in is fixed (assuming all your doing is changing the fuel, not changing injector scaling or anything), then with E85 you see that you need far more fuel for the same amount of air (i.e. scale the injectors smaller). so if you take away some of the ethanol, and replace it with gasoline, the gasoline needs more air to burn, but since air is fixed, and on a e85 scaling your throwing a lot of fuel in the engine, not all the fuel gets burnt because the large amount of gasoline consumes it quickly, leaving unburned fuel... i.e.rich.
one other thing i noticed... E70 actually has a higher energy density then E85. reason being is gasoline has a much higher energy density, and the number after the E in E85 is the % ethanol to gasoline. so E85 has 15% gasoline, and E70 has 30% gasoline. with a higher gasoline content, you have a higher energy density.
Sep 9, 2010, 12:07 PM
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Kevin is right and gave good info. Seems like there's some confusion about octane ratings.
To put it simply, octane rating does not relate to the energy content of the fuel or heating value. It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where octane is raised by blending in ethanol, energy content per volume is reduced.
To put it simply, octane rating does not relate to the energy content of the fuel or heating value. It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where octane is raised by blending in ethanol, energy content per volume is reduced.
Sep 9, 2010, 12:09 PM
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Sep 9, 2010, 01:36 PM
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the energy of the fuel has nothing to do with the stoich ratio. its the chemistry of the fuel that makes the mixture rich or lean.
for example, pure ethanol (C2H5OH) mixes with air (thats AIR, not oxygen... remember oxygen is only like 21% mass composition of air. if you do the reaction balance with O2, you see that C2H5OH+3O2 = 3H2O + 2CO2) at a mass ratio of 9:1 with air. thats 9 grams of air for every 1 gram of fuel. gasoline (which comes close to octane), which is C8H18 burns at 14.7:1. thats 14.7 parts air for every part fuel. the difference is so great because the fuel actually contains its own oxygen atom, which means it doesn't need as much air.
since the volume of air the engine takes in is fixed (assuming all your doing is changing the fuel, not changing injector scaling or anything), then with E85 you see that you need far more fuel for the same amount of air (i.e. scale the injectors smaller). so if you take away some of the ethanol, and replace it with gasoline, the gasoline needs more air to burn, but since air is fixed, and on a e85 scaling your throwing a lot of fuel in the engine, not all the fuel gets burnt because the large amount of gasoline consumes it quickly, leaving unburned fuel... i.e.rich.
one other thing i noticed... E70 actually has a higher energy density then E85. reason being is gasoline has a much higher energy density, and the number after the E in E85 is the % ethanol to gasoline. so E85 has 15% gasoline, and E70 has 30% gasoline. with a higher gasoline content, you have a higher energy density.
for example, pure ethanol (C2H5OH) mixes with air (thats AIR, not oxygen... remember oxygen is only like 21% mass composition of air. if you do the reaction balance with O2, you see that C2H5OH+3O2 = 3H2O + 2CO2) at a mass ratio of 9:1 with air. thats 9 grams of air for every 1 gram of fuel. gasoline (which comes close to octane), which is C8H18 burns at 14.7:1. thats 14.7 parts air for every part fuel. the difference is so great because the fuel actually contains its own oxygen atom, which means it doesn't need as much air.
since the volume of air the engine takes in is fixed (assuming all your doing is changing the fuel, not changing injector scaling or anything), then with E85 you see that you need far more fuel for the same amount of air (i.e. scale the injectors smaller). so if you take away some of the ethanol, and replace it with gasoline, the gasoline needs more air to burn, but since air is fixed, and on a e85 scaling your throwing a lot of fuel in the engine, not all the fuel gets burnt because the large amount of gasoline consumes it quickly, leaving unburned fuel... i.e.rich.
one other thing i noticed... E70 actually has a higher energy density then E85. reason being is gasoline has a much higher energy density, and the number after the E in E85 is the % ethanol to gasoline. so E85 has 15% gasoline, and E70 has 30% gasoline. with a higher gasoline content, you have a higher energy density.
Damn! That is what I was gonna say..
