Sponsored
Thub
Well-Known Member
- Joined
- Mar 7, 2018
- Threads
- 16
- Messages
- 120
- Reaction score
- 43
- Location
- Elgin, Illinois
- First Name
- Jim
- Vehicle(s)
- 2018 GT 6 speed
Speaking from experience in a different car, I would get 250 miles to a tank on gas and about 190 on E85. It generally worked out to about the same cost.
- Joined
- Oct 25, 2014
- Threads
- 226
- Messages
- 2,801
- Reaction score
- 950
- Location
- Dearborn Heights, Michigan
- Website
- www.livernoismotorsports.com
- First Name
- S550 HQ
- Vehicle(s)
- 2016 Mustang GT (TVS 2650) (6R80)
E85 will always be alot cheaper, i know around here right now 93 is going for about $3.10 a gallon and e85 is only $1.50 so that is quite a huge drop even if it doesnt last quite as long still should be a saving as long as your not out foot to the floor all day everyday :cheers:
gearhead2685
Well-Known Member
- Joined
- May 24, 2017
- Threads
- 9
- Messages
- 905
- Reaction score
- 266
- Location
- Back in North Dakota
- Vehicle(s)
- 2016 mustang
LOL E85 is not for mileage its for horsepower........
Sponsored
- Joined
- Oct 25, 2014
- Threads
- 226
- Messages
- 2,801
- Reaction score
- 950
- Location
- Dearborn Heights, Michigan
- Website
- www.livernoismotorsports.com
- First Name
- S550 HQ
- Vehicle(s)
- 2016 Mustang GT (TVS 2650) (6R80)
Always nice to get more power while spending the same or less though, just a bonus! :cheers:
moffetts
Well-Known Member
- Joined
- Nov 30, 2015
- Threads
- 14
- Messages
- 978
- Reaction score
- 325
- Location
- San Mateo CA
- Vehicle(s)
- Black Whippled 2015 GT PP
No comprende
- Joined
- Oct 25, 2014
- Threads
- 226
- Messages
- 2,801
- Reaction score
- 950
- Location
- Dearborn Heights, Michigan
- Website
- www.livernoismotorsports.com
- First Name
- S550 HQ
- Vehicle(s)
- 2016 Mustang GT (TVS 2650) (6R80)
Glad your enjoying it can't wait to join you myself! :cheers:
Sponsored
plc268
Well-Known Member
- Joined
- Jun 2, 2015
- Threads
- 31
- Messages
- 1,853
- Reaction score
- 648
- Location
- Central Texas
- First Name
- Patrick
- Vehicle(s)
- 2015 Mustang GT Premium Race Red
I get 13.5 on e85 and 18.5 on 93
oesman
Well-Known Member
- Joined
- Feb 18, 2016
- Threads
- 24
- Messages
- 407
- Reaction score
- 107
- Location
- Houston, TX
- First Name
- Dmitry
- Vehicle(s)
- 2016 Mustang GT PP
Mileage will be directly proportional to the change in stoichiometric mixture, which is a better way to figure out how your current mileage will change. By definition gasoline is said to have a 14.64:1 air to fuel ratio. Ethanol on the other hand is said to have a 9:1 air to fuel ratio. To give you some background:
These are the ratios at which all the fuel should be burned, often refereed to as "stoich". If you have more fuel you're rich and if you have more air you're lean. Air fuel ratios are clearly fuel mixture dependent and in reality fuel mixtures like gasoline are a slew of chemicals and additives; The result is that actual stoich points are varied. No one is running perfect 14.64 gasoline or perfect 9.0 ethanol on the street. Outside of race or lab quality fuels where you are told the stoich point on the label, you don't know what your fuel's actual stoich point is. Furthermore these values are based on mass rather than volume so it would be much more difficult to calculate without knowing the chemical composition of the mixture. If we knew the exact composition it would be fairly easy based on molar mass.
To deal with this your car's oxygen sensors are used to check the gases coming out of your headers against the atmosphere and produce "lambda" equivalence ratio values, where 1.0 is stoich and anything less is rich and anything more is lean. This way the sensor/computer doesn't care what fuel you run, it can tell if you're rich or lean no matter what the stoich point of your fuel is. Your aftermarket AFR gauges or built-in AFR gauge in the car can multiply oxygen sensor lambda values by what they think your fuel's stoich point is. This is where you get errors on gauges because of fuel changes, gauge assumes you run gasoline and multiplies any lambda value from the oxygen sensor by 14.64. So if you pour in E85 your AFR gauge will be way off unless it's re-calibrated to know the stoich point changed. This is why I like seeing lambda values on my gauges more so than AFR values, more accurate for the purpose of telling lean/rich.
So if we know that stoich points of fuels are varied and cars use lambda values from oxygen sensors to deal with this. What can we do to calculate mileage accurately? The easiest way is to make some assumptions:
Most gasoline has ethanol in it, marine and a few other applications won't, but most of what you get from the pump is somewhere between gasoline and E10. We can use some basic math to see the following:
Pure Gasoline: 14.64 AFR * 1.0 = 14.64 AFR
Pure Gasoline and %10 Ethanol (E10): 14.64 AFR * 0.9 + 9 AFR * 0.1 = 14.08 AFR
So lets take the average of the two and assume most street gasoline is somewhere around 14.36 AFR to be safe since we know it has some ethanol in it, up to 10%.
Now let's look at E85:
Pure Gasoline and %85 Ethanol (E85): 14.64 AFR * 0.15 + 9 AFR * 0.85 = 9.85 AFR
So how much more fuel do you have in E85 vs street gasoline? We now know that for every 14.36 grams of air we need one gram of street gas and for every 9.85 grams of air we need one gram of e85. Like this:
100g air / 14.36 AFR = 6.96g of street fuel
100g air / 9.85 AFR = 10.15g of e85 fuel
What's the percentage increase of fuel delivery for our same 100g of air?
(10.15g - 6.96g) / 6.96g * 100 = 45.8%
So we see our fuel delivery will grow by 45.8%, this is of course by mass.
Now by volume @ STP:
Street Gasoline = 755 g/L
Ethanol = 789 g/L
E85 = (755g * 0.15 + 789g * 0.85) = 784 g/L
Liters of street gasoline per 100g of air: 6.96g / 755 = 0.0092 liters
Liters of E85 per 100g of air: 10.15g / 784 = 0.0129 liters
Percent change = (0.0129 - 0.0092) / 0.0092 * 100 = 40.2%
Now of course densities change with temperature and pressure (hence why I said @ STP), but this gives you an idea. If you have a lead foot or you hypermile, using this method you will get much more tailored results to your particular driving vs. asking others what kind of mileage they get.
One thing to note a lot of E85 isn't really E85 either, it could be a LOT less ethanol sometimes and yield better mileage (lower octane/performance). It's a very inconsistent fuel at least around here. So just how we mentioned gasoline is some variance between E0 and E10 there is a wide swing for E85 too. Get a tester kit to see what's coming out of your pumps, they're like $6 for one of the E85 kits. Furthermore your car will not always run at lambda 1.0.
EDIT: Had to fix math, it's still early lol.
These are the ratios at which all the fuel should be burned, often refereed to as "stoich". If you have more fuel you're rich and if you have more air you're lean. Air fuel ratios are clearly fuel mixture dependent and in reality fuel mixtures like gasoline are a slew of chemicals and additives; The result is that actual stoich points are varied. No one is running perfect 14.64 gasoline or perfect 9.0 ethanol on the street. Outside of race or lab quality fuels where you are told the stoich point on the label, you don't know what your fuel's actual stoich point is. Furthermore these values are based on mass rather than volume so it would be much more difficult to calculate without knowing the chemical composition of the mixture. If we knew the exact composition it would be fairly easy based on molar mass.
To deal with this your car's oxygen sensors are used to check the gases coming out of your headers against the atmosphere and produce "lambda" equivalence ratio values, where 1.0 is stoich and anything less is rich and anything more is lean. This way the sensor/computer doesn't care what fuel you run, it can tell if you're rich or lean no matter what the stoich point of your fuel is. Your aftermarket AFR gauges or built-in AFR gauge in the car can multiply oxygen sensor lambda values by what they think your fuel's stoich point is. This is where you get errors on gauges because of fuel changes, gauge assumes you run gasoline and multiplies any lambda value from the oxygen sensor by 14.64. So if you pour in E85 your AFR gauge will be way off unless it's re-calibrated to know the stoich point changed. This is why I like seeing lambda values on my gauges more so than AFR values, more accurate for the purpose of telling lean/rich.
So if we know that stoich points of fuels are varied and cars use lambda values from oxygen sensors to deal with this. What can we do to calculate mileage accurately? The easiest way is to make some assumptions:
Most gasoline has ethanol in it, marine and a few other applications won't, but most of what you get from the pump is somewhere between gasoline and E10. We can use some basic math to see the following:
Pure Gasoline: 14.64 AFR * 1.0 = 14.64 AFR
Pure Gasoline and %10 Ethanol (E10): 14.64 AFR * 0.9 + 9 AFR * 0.1 = 14.08 AFR
So lets take the average of the two and assume most street gasoline is somewhere around 14.36 AFR to be safe since we know it has some ethanol in it, up to 10%.
Now let's look at E85:
Pure Gasoline and %85 Ethanol (E85): 14.64 AFR * 0.15 + 9 AFR * 0.85 = 9.85 AFR
So how much more fuel do you have in E85 vs street gasoline? We now know that for every 14.36 grams of air we need one gram of street gas and for every 9.85 grams of air we need one gram of e85. Like this:
100g air / 14.36 AFR = 6.96g of street fuel
100g air / 9.85 AFR = 10.15g of e85 fuel
What's the percentage increase of fuel delivery for our same 100g of air?
(10.15g - 6.96g) / 6.96g * 100 = 45.8%
So we see our fuel delivery will grow by 45.8%, this is of course by mass.
Now by volume @ STP:
Street Gasoline = 755 g/L
Ethanol = 789 g/L
E85 = (755g * 0.15 + 789g * 0.85) = 784 g/L
Liters of street gasoline per 100g of air: 6.96g / 755 = 0.0092 liters
Liters of E85 per 100g of air: 10.15g / 784 = 0.0129 liters
Percent change = (0.0129 - 0.0092) / 0.0092 * 100 = 40.2%
Now of course densities change with temperature and pressure (hence why I said @ STP), but this gives you an idea. If you have a lead foot or you hypermile, using this method you will get much more tailored results to your particular driving vs. asking others what kind of mileage they get.
One thing to note a lot of E85 isn't really E85 either, it could be a LOT less ethanol sometimes and yield better mileage (lower octane/performance). It's a very inconsistent fuel at least around here. So just how we mentioned gasoline is some variance between E0 and E10 there is a wide swing for E85 too. Get a tester kit to see what's coming out of your pumps, they're like $6 for one of the E85 kits. Furthermore your car will not always run at lambda 1.0.
EDIT: Had to fix math, it's still early lol.
Sponsored
Last edited: