How to Blend Your Own Fuel, and Why You Should
#31
01-02-2008, 07:22 AM
Re: How to Blend Your Own Fuel, and Why You Should
The ONLY thing the higher octane is needed for is engine knock. High-performance engines are more sensitive to the octane level because they have higher compression ratios, so they tend to knock on lower octanes.
Plus, the computers in today's engines also detect knocking and will adjust the spark timing and other settings to control it.
Plus, the computers in today's engines also detect knocking and will adjust the spark timing and other settings to control it.
Bob Wilson
#32
01-02-2008, 09:59 AM
Re: How to Blend Your Own Fuel, and Why You Should
The ONLY thing the higher octane is needed for is engine knock. High-performance engines are more sensitive to the octane level because they have higher compression ratios, so they tend to knock on lower octanes.
Plus, the computers in today's engines also detect knocking and will adjust the spark timing and other settings to control it.
Plus, the computers in today's engines also detect knocking and will adjust the spark timing and other settings to control it.
So while there might not be any more energy in the fuel, you can access more of it.
Also, low octane fuel in a high compression engine can self ignite due to the compression. This is the cause of engine knocking. Adjusting the spark timing won't do jack for it. But, fuel mixtures can be adjusted to prevent it.
You can not get the full engine power off of low octane fuel.
There is also a claim by some people that they put premium in once in a while to "clean out the system". Most of the time, the detergents suppliers put into their fuels are the same in all grades.
So in reality, most cars on the road today need nothing more than the regular old 87 octane fuel.
So in reality, most cars on the road today need nothing more than the regular old 87 octane fuel.
BTW, I'm looking forward to the results of the E30 testing. I had read the articles mentioning it as the sweet spot, and have been really curious about the results.
#33
01-02-2008, 02:07 PM
Re: How to Blend Your Own Fuel, and Why You Should
Maybe I should have stated my sources - the American Petroleum Institute themselves. Here are direct quotes from their website:
http://www.api.org/aboutoilgas/gasol...ine-octane.cfm
"Octane number is a measurement of fuel’s resistance to engine knock. Engine knock is an abnormal combustion associated with using gasoline with too low of an octane number. Ordinarily, your vehicle will not benefit from using a higher octane than is recommended in the owner’s manual."
"Knock Sensors
Many modern vehicles are equipped with an electronic device that detects and eliminates light knocking before you can hear it. The devices suppress knock by retarding the spark."
"Gasoline with a higher heating value (energy content) provides better fuel economy. Traditionally, premium gasoline has had a slightly higher heating value than regular, and, thus, provides slightly better fuel economy, but it is difficult to detect in normal driving. There can be even larger differences in heating value between batches of gasoline from the same refinery, between summer and winter volatility classes, or between brands of gasoline from different refineries because of compositional differences. The differences are small and there is no practical way for the consumer to identify gasoline with a higher-than-average heating value."
But this is from the API, so they do have to claim that there is some value in that premium gasoline you are buying. They do represent the petroleum industry, you know.
And higher compression engines don't actually gain any power using higher octane gasoline, they just don't lose that portion of power that sometimes happens during acceleration from pre-ignition (knocking) that they would with lower octane. The power in the gasoline is the same, it's just the point in the compression cycle when the ignition happens that determines how much power the engine gets out of the gasoline. Knocking happens when the fuel starts to ignite before the piston reaches the top of its stroke. If that happens you lose horsepower because then some of the energy from fuel combustion is working against the power stroke of the engine. That's being a bit simplistic because the ignition phase of the stroke actually does start just before the absolute top of the stroke (Top Dead Center), usually about 10-25 degrees before TDC, but the maximum power of the combustion cycle doesn't happen until just after TDC. Knocking happens when the fuel burns too fast and the maximum power of the combustion happens before TDC instead of after. Modern engines will detect that this is happening and retard the spark so that maximum power happens after TDC.
http://www.api.org/aboutoilgas/gasol...ine-octane.cfm
"Octane number is a measurement of fuel’s resistance to engine knock. Engine knock is an abnormal combustion associated with using gasoline with too low of an octane number. Ordinarily, your vehicle will not benefit from using a higher octane than is recommended in the owner’s manual."
"Knock Sensors
Many modern vehicles are equipped with an electronic device that detects and eliminates light knocking before you can hear it. The devices suppress knock by retarding the spark."
"Gasoline with a higher heating value (energy content) provides better fuel economy. Traditionally, premium gasoline has had a slightly higher heating value than regular, and, thus, provides slightly better fuel economy, but it is difficult to detect in normal driving. There can be even larger differences in heating value between batches of gasoline from the same refinery, between summer and winter volatility classes, or between brands of gasoline from different refineries because of compositional differences. The differences are small and there is no practical way for the consumer to identify gasoline with a higher-than-average heating value."
But this is from the API, so they do have to claim that there is some value in that premium gasoline you are buying. They do represent the petroleum industry, you know.
And higher compression engines don't actually gain any power using higher octane gasoline, they just don't lose that portion of power that sometimes happens during acceleration from pre-ignition (knocking) that they would with lower octane. The power in the gasoline is the same, it's just the point in the compression cycle when the ignition happens that determines how much power the engine gets out of the gasoline. Knocking happens when the fuel starts to ignite before the piston reaches the top of its stroke. If that happens you lose horsepower because then some of the energy from fuel combustion is working against the power stroke of the engine. That's being a bit simplistic because the ignition phase of the stroke actually does start just before the absolute top of the stroke (Top Dead Center), usually about 10-25 degrees before TDC, but the maximum power of the combustion cycle doesn't happen until just after TDC. Knocking happens when the fuel burns too fast and the maximum power of the combustion happens before TDC instead of after. Modern engines will detect that this is happening and retard the spark so that maximum power happens after TDC.
Last edited by chesterakl; 01-02-2008 at 02:45 PM.
#35
01-08-2008, 11:09 AM
Re: How to Blend Your Own Fuel, and Why You Should
I was just reading up some more on E85. I don't think I saw it mentioned here, but they have a winter/summer mix of E85 too! in the winter E85 is really E70. can someone else please confirm this as it would put our table all off.
Also, even in the summer E85 is the rating of the gas before it's denatured. So it's really about E81 given the standard 4% denatured rate of normal. Flex fuel vehicles don't have a problem with the variation in percentages since they have a fuel sensor. but since we're trying to work off of a fixed value we need the proper values to start with.
Also, even in the summer E85 is the rating of the gas before it's denatured. So it's really about E81 given the standard 4% denatured rate of normal. Flex fuel vehicles don't have a problem with the variation in percentages since they have a fuel sensor. but since we're trying to work off of a fixed value we need the proper values to start with.
Last edited by MiaTurbo; 01-08-2008 at 11:22 AM.
#36
01-08-2008, 12:01 PM
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,616
Re: How to Blend Your Own Fuel, and Why You Should
Ethanol is manufactured as 200 proof, or E100 at the distillery.
This is, for all practical purposes, whisky, and could be digested by humans.
In order to comply with ATF rules, the pure "whisky" must be poisioned, or "denatured" on the premises... no 100% ethanol is allowed to leave the property, or else it would be taxed as a beverage, and cost the same as liquer. ( What does Vodka cost per gallon anyways? $40 a gallon? More? )
So to comply with ATF rules, all ethanol leaves the plant with 2.5% to 5% gasoline in it from the get go. All rail tankers, and all truck tankers are denatured with on average, 4% gasoline.
The gas station then adds 10% of whatever gasoline they have on hand ( probably in most cases the lower Octane ).
The E85 pumps in Minnesota say "contains at least 85% ethanol".
If the ethanol they got this week had 4% denaturant, they would be selling E86 this week. Next week they could get ethanol with the minimum amount of denaturant ( as gas prices rise, this is more likely ) and they could be selling E87.5
I have never ever heard of "winter E70".
-John
P.S. Cars would run fine in warm weather on pure alcohol. Indy cars run on E98, only because they too must have denaturant to comply with ATF. The 15% gasoline is added, mostly, to make it burn easier in cold weather.
This is, for all practical purposes, whisky, and could be digested by humans.
In order to comply with ATF rules, the pure "whisky" must be poisioned, or "denatured" on the premises... no 100% ethanol is allowed to leave the property, or else it would be taxed as a beverage, and cost the same as liquer. ( What does Vodka cost per gallon anyways? $40 a gallon? More? )
So to comply with ATF rules, all ethanol leaves the plant with 2.5% to 5% gasoline in it from the get go. All rail tankers, and all truck tankers are denatured with on average, 4% gasoline.
The gas station then adds 10% of whatever gasoline they have on hand ( probably in most cases the lower Octane ).
The E85 pumps in Minnesota say "contains at least 85% ethanol".
If the ethanol they got this week had 4% denaturant, they would be selling E86 this week. Next week they could get ethanol with the minimum amount of denaturant ( as gas prices rise, this is more likely ) and they could be selling E87.5
I have never ever heard of "winter E70".
-John
P.S. Cars would run fine in warm weather on pure alcohol. Indy cars run on E98, only because they too must have denaturant to comply with ATF. The 15% gasoline is added, mostly, to make it burn easier in cold weather.
Last edited by gpsman1; 01-08-2008 at 02:23 PM. Reason: PS
#37
01-08-2008, 12:07 PM
Re: How to Blend Your Own Fuel, and Why You Should
http://genomicsgtl.energy.gov/biofue...ortation.shtml
Due to ethanol's lower vapor pressure, engine ignition is more difficult in colder weather for vehicles running on fuels with high ethanol content. During winter months, gasoline is added to E85 (85% ethanol and 15% gasoline blend) to make E70 (70% ethanol and 30% gasoline), which has a vapor pressure that improves starting in cold weather. Although current practice is to "blend-down" E85, the cold-start issue is a technologically solvable engineering problem for vehicle manufacturers.
#38
01-08-2008, 02:22 PM
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,616
Re: How to Blend Your Own Fuel, and Why You Should
Fadi, thanks for the insight into this matter.
I did additional research and here is what I found.
The American Society for Testing and Materials (ASTM) and the Alliance of Automobile Manufacturers have
I did additional research and here is what I found.
The American Society for Testing and Materials (ASTM) and the Alliance of Automobile Manufacturers have
established standards for E85.
ASTM Fuel Standard Specification
To be labeled and sold as "E85", the fuel must always have a minimum content of 79% ethanol in summer months, 74% in transitional months, and 70% in winter months.
There is a chart that determines when is summer and winter per state.
Hawaii is summer for 12 months, and must have at least a 79% content all 12 months.
California is summer for 5 months and transitional for 7 months, and never winter.
Minnesota is "winter" from mid-October, to mid-May, and must only have 70%. It can have more, but not less. Minnesota is summer for only July. The rest of the time is in between, and must contain 74% minimum.
Incidently, the chart for Minnesota and Alaska is identical.
But in general, this is different for every state! How complicated can we get here folks!
Here's what else I found out. The gasoline and ethanol will separate if you mix them with 50% water. The water and ethanol will blend, and the gasoline will float to the top. So while a bit cumbersome, there is an easy way we can all test for this.
ASTM Fuel Standard Specification
To be labeled and sold as "E85", the fuel must always have a minimum content of 79% ethanol in summer months, 74% in transitional months, and 70% in winter months.
There is a chart that determines when is summer and winter per state.
Hawaii is summer for 12 months, and must have at least a 79% content all 12 months.
California is summer for 5 months and transitional for 7 months, and never winter.
Minnesota is "winter" from mid-October, to mid-May, and must only have 70%. It can have more, but not less. Minnesota is summer for only July. The rest of the time is in between, and must contain 74% minimum.
Incidently, the chart for Minnesota and Alaska is identical.
But in general, this is different for every state! How complicated can we get here folks!
Here's what else I found out. The gasoline and ethanol will separate if you mix them with 50% water. The water and ethanol will blend, and the gasoline will float to the top. So while a bit cumbersome, there is an easy way we can all test for this.
The following summary describes a "field test" procedure to determine the levels of hydrocarbon and alcohol in E85 . The following equipment is available from VWR Scientific, 800-932-5000 . Reference numbers are those used by VWR . Other equipment suppliers are available . 50 mL pipettes Cat . #52966-217 Safety bulb Cat . #53497-202 100 mL cylinders, Cat . #24762-117
Procedure for Determining Hydrocarbon Percent of Ethanol Fuel Samples
Safety Note: Hydrocarbon- and alcohol-resistant gloves are recommended when collecting samples and conducting tests . Additionally, eye protection should be utilized . Testing personnel should also carry water in plastic containers .
1. Using the suction bulb, pipette exactly 50 mL of fuel sample into the graduated cylinder.
2. Add about 48 mL of water to make the total liquid volume just under 100 mL.
3. Place a stopper in the cylinder and shake vigorously for about 15 seconds.
4. Carefully loosen the stopper to release any accumulated pressure; do not remove the stopper.
5. Close the stopper again and place the cylinder upright on a level surface. Allow the mixture to sit for about 15 minutes.
6. Record the total volume of liquid by reading the lowest part of the upper meniscus (the curved interface between the liquid and air).
7. Record the total volume of the alcohol/water layer by reading the lowest part of the lower meniscus (the curved interface between the two liquid layers).
Procedure for Determining Hydrocarbon Percent of Ethanol Fuel Samples
Safety Note: Hydrocarbon- and alcohol-resistant gloves are recommended when collecting samples and conducting tests . Additionally, eye protection should be utilized . Testing personnel should also carry water in plastic containers .
1. Using the suction bulb, pipette exactly 50 mL of fuel sample into the graduated cylinder.
2. Add about 48 mL of water to make the total liquid volume just under 100 mL.
3. Place a stopper in the cylinder and shake vigorously for about 15 seconds.
4. Carefully loosen the stopper to release any accumulated pressure; do not remove the stopper.
5. Close the stopper again and place the cylinder upright on a level surface. Allow the mixture to sit for about 15 minutes.
6. Record the total volume of liquid by reading the lowest part of the upper meniscus (the curved interface between the liquid and air).
7. Record the total volume of the alcohol/water layer by reading the lowest part of the lower meniscus (the curved interface between the two liquid layers).
Calculation • The hydrocarbon percent is calculated by:
2.1 + 1 .94 x (total volume - alcohol/water volume)
2.1 + 1 .94 x (total volume - alcohol/water volume)
• Assuming the sample was an ethanol/hydrocarbon mixture, the ethanol percent is 100 minus the hydrocarbon percent .
Thanks Again Fadi for bringing this matter to light.
-John
#40
01-11-2008, 06:50 AM
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,616
Re: How to Blend Your Own Fuel, and Why You Should
This morning I was getting irritated getting 'only' 32 MPG.
It was 15'F outside, but I did use the block heater this A.M.
What gives?! I was thinking to myself.
Oh ya.... I forgot I was using ( appox. ) 35% ethanol this week.
Until I get my graduated cylinders and pipets, I can't be sure on the %.
I did notice on "Long term fuel trim" with a ScanGauge, I was running with fuel trim at +8.5. Normally with plain gas, this number hovers about zero.
I'm not sure if that number really equals 8.5% more fuel, or if it is just some number. Ideas?
With gas, the number will be negative a few (%?) when coasting, and positive a few (%?) when accelerating, with the median about zero. With 30% ethanol and greater, this number hovers about 8.5, and goes to 12.x when accelerating, and down to 3.x when coasting.
-John
P.S. The mechanics handbook says -20 to +20 are normal values with regular gas. I wonder if that is some limit, or if +25 is possible?
The lowest I've ever noticed was -10 and greatest was +15.
It was 15'F outside, but I did use the block heater this A.M.
What gives?! I was thinking to myself.
Oh ya.... I forgot I was using ( appox. ) 35% ethanol this week.
Until I get my graduated cylinders and pipets, I can't be sure on the %.
I did notice on "Long term fuel trim" with a ScanGauge, I was running with fuel trim at +8.5. Normally with plain gas, this number hovers about zero.
I'm not sure if that number really equals 8.5% more fuel, or if it is just some number. Ideas?
With gas, the number will be negative a few (%?) when coasting, and positive a few (%?) when accelerating, with the median about zero. With 30% ethanol and greater, this number hovers about 8.5, and goes to 12.x when accelerating, and down to 3.x when coasting.
-John
P.S. The mechanics handbook says -20 to +20 are normal values with regular gas. I wonder if that is some limit, or if +25 is possible?
The lowest I've ever noticed was -10 and greatest was +15.
