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Ridge Runner posted 04-28-2009 08:40 AM ET (US)
[Nota Bene: the values for BTU/Gallon cited are in dispute. The calculation of percentage difference between them is not correct. See below for further discussion and perhaps more accurate values--jimh.]
A 9:1 gasoline and ethanol mixure has 84.2k BTU/Gallon and regular gasoline 125k BTU/Gallon, a 3.4% difference. Does the horsepower of an engine see a 3.4% reduction? I've read that the 3.4% will effect MPG, but does a outboard have 3.4% less horsepower?
Peter posted 04-28-2009 08:57 AM ET (US)
Here is information taken from a Gasoline Gallon Equivalent (GGE) Table
Fuel Type
Unit of Measure
BTUs Per Unit
Gallon Equivalent

Gasoline, regular unleaded, (typical)
gallon
114,100
1.00 gallon

Gasoline, RFG, (10% MBTE)
gallon
112,000
1.02 gallons

Diesel, (typical)
gallon
129,800
0.88 gallons

Liquid natural gas (LNG), (typical)
gallon
75,000
1.52 gallons

Compressed natural gas (CNG), (typical)
cubic foot
900
126.67 cu. ft.

Liquefied petroleum gas (LPG or propane)
gallon
84,300
1.35 gallons

Methanol (M-100)
gallon
56,800
2.01 gallons

Methanol (M-85)
gallon
65,400
1.74 gallons

Ethanol (M-100)
gallon
76,100
1.50 gallons

Ethanol (E-85)
gallon
81,800
1.40 gallons

Bio Diesel (B-20)
gallon
129,500
0.88

Straight gasoline has 114k BTU per gallon. Straight ethanol has 76k BTU per gallon, a 90/10 mixture would have approximataly 110k BTU per gallon (114k * 0.9 + 76k * 0.1). The E10 gasoline gallon equivalent 1.036 (114k/110k = 1.036). Basically, your engine will produce 3.4 percent less power per power stroke on E10 than it would on straight gasoline because there is 3.4 percent less energy in the same quantity of fuel. To make the same power per stroke would require 1.036 times more fuel induced into the combustion chamber.
Tohsgib posted 04-28-2009 10:31 AM ET (US)
In other words...yes.
TransAm posted 04-28-2009 11:02 AM ET (US)
Wow, I figured there was some insignificant effect, but 3-4%, that's significant. Other than introducing more fuel in the combustion chamber, can this loss of power be reasonably recovered?
Tohsgib posted 04-28-2009 11:18 AM ET (US)
Yes...fill up at a marina that does not have ethanol. My marina also has stabilizers and water absorber additives in it. It is only like $.30 more than the pump.
TransAm posted 04-28-2009 11:45 AM ET (US)
What if your marina is E-10?
Tohsgib posted 04-28-2009 11:48 AM ET (US)
Should not be...go to a different marina. I am 99% positive that [ValvTect] fuel is non-ethanol so look for it.
L H G posted 04-28-2009 11:53 AM ET (US)
So, I assume outboard engines are rated for HP on pure gasoline? I doubt the manufacturers would be so magnanimous to rate them on E-10. I guess that means if you buy a 300 HP engine, immediately you are only getting 290HP. Then add in the 10% allowable "fudge factor" up or down, and you could really be getting a lot less HP than you are paying for. A 300 could only be putting out 260HP.
If we go to E-15, which we probably will, all of us will need to be buying more HP than we think we really need. If one is going to buy a 225, probably a 250 should be bought instead. A lower pitch prop might be needed on existing engines. Just another cost to consumers of "going green".
I thought all internal combustion engines needed to be modified if more than 10% ethanal is used?
Buckda posted 04-28-2009 12:11 PM ET (US)
Isn't it "ValvTect"? http://www.valvtect.com
There is no information on the site that indicates that they do not use the ValvTect additives in E-10 fuels. The company makes fuel additives and blend them in with the fuels. JimH likes to refer to this as a "witches brew" when individuals do this to their fuels, but I'm a fan of finding your own blend that makes you feel better.
Many marinas sell fuel that is not "ethanol enhanced" - but not all.
Ridge Runner posted 04-28-2009 12:25 PM ET (US)
Down in Port Charlotte, FL I can fill up with [ValvTect] fuel which does not have ethanol, I have verified this. In NJ all fuel has ethanol, its state law. In Wisconsin they have ethanol in regular and mid-grade and premium is ethanol free. It’s interesting I have two carbureted Yamaha two-cycles a 90hp and a 50hp and I have run both fuels in each, I can tell the difference. When I pull skiers it “seems” to take longer to get someone up, also the mid-range to full throttle-up “seems” different. Now on my 25’ CC w/twin Yamaha F115’s and Conquest w/twin Mercury Optimax 225’s I don’t really notice any difference. I’m not sure if it’s because they are larger boats or because the EMM’s that control the fuel flow through the injectors are compensating.
Buckda posted 04-28-2009 12:30 PM ET (US)
Also -
I'm no fan of ethanol - but there are some interesting companies that are investigating synthetic fuels.
The US Air Force is investigating jet fuel from RenTech - a California company that has a proof-of-concept refinery manufacturing synthetic Jet and Diesel fuel for research purposes. This fuel has more energy per pound than petroleum -derived fuels and can be generated for a profit at about the equivalent of $70/barrel oil prices. Feedstock can be biomass, agricultural bagesse or oil/natural gas. They claim that there are no modifications needed for current motors and the fuel can be delivered via pipeline (not truck/train, as is required of ethanol for transport). Not cheap, but there are companies working on alternatives that don't rob the energy. Hopefully we'll at least have some other options in the next few years.
TransAm posted 04-28-2009 12:31 PM ET (US)
Maybe that guy with the Rib boat and 300 E-tec is burning straight ethanol?
Ridge Runner posted 04-28-2009 12:48 PM ET (US)
Can a supercharged engine that is operating by forced induction and compressing the air/fuel mixture compensate for the energy difference?
BQUICK posted 04-28-2009 02:07 PM ET (US)
Don't forget about the loss in MPG also......
weekendwarrior posted 04-28-2009 02:51 PM ET (US)
No use of ethanol will not by definition reduce horsepower, but you will need to burn more of it to get the same horsepower. On an closed-loop FI engine the computer will handle this for you. On a carbed engine your jetting might not be optimal as-is so you've got a 50/50 shot. Consumer Reports compared a truck (Chevy Tahoe I think) on e10 and e85. For both fuels performance was virtually identical but the mileage on e85 was significantly worse. See the test at consumerreports.org.
ASIDE: nitro methane is less energy dense than gasoline, BUT you can burn about eight times as much of it with the same amount of air (the nitro is already oxadized). The top fuel dragsters burn nitro because they can burn so much more of it than they could gas that it more than makes up for the difference in energy density.
weekendwarrior posted 04-28-2009 08:30 PM ET (US)
Just a follow up, here's a link to one of the articles about ethanol tests on consumer reports, and an excerpt from the article:
http://www.consumerreports.org/cro/cu-press-room/pressroom/archive/2006/10/0610_eng0610e85_ov.htm?resultPageIndex=1&resultIndex=3&searchTerm=e85%20test

In regards to E85 vs gasoline:
"Overall fuel economy on the Tahoe dropped from an already low 14 mpg overall to 10. In highway driving, gas mileage decreased from 21 to 15 mpg; in city driving, it dropped from 9 mpg to 7."

And here's the performance and emissions numbers for the same test:
URL:
http://www.consumerreports.org/cro/cars/new-cars/news/2006/ethanol-10-06/tests-of-ethanol-vs.-gasoline/1006_ethanol_test_1.htm?resultPageIndex=1&resultIndex=2&searchTerm=e85%20test
Test results: E85 vs. gasoline
This chart shows how our 2007 Chevrolet Tahoe performed while running on E85 and gasoline in three fuel-economy tests and overall, in four acceleration tests, and in three emissions tests for gasoline vehicles.

[This chart didn't copy/paste so well, but here goes]
E85 GASOLINE*
Fuel economy, mpg
City 7 9
Highway 15 21
150-mile trip 13 18
Overall 10 14
Acceleration
0-30 mph, sec. 3.4 3.5
0-60 mph, sec. 8.9 9.1
45-65 mph, sec. 5.7 5.8
Quarter-mile, sec./mph
16.8/84.6 16.9/84.5
Emissions, parts per million
Nitrogen oxide 1 9
Hydrocarbons 1 1
Carbon monoxide 0 0
Jerry Townsend posted 04-28-2009 09:41 PM ET (US)
Easy guys - There are a couple of issues being discussed - energy content, which is based on energy per pound - and mpg - which is based on energy per gallon. Talking of energy performance and milesage in the same sentence is akin to comparing apples and oranges.
Talking about energy alone - gasoline has an average combustion energy of about 20,300 Btu/Lb while ethanol has an average combustion energy of about 12,800 Btu/Lb. Therefore, E10 has about 0.96 of the energy content of gasoline and E15 has about 0.94 the energy content of gasoline. Since the fuel flow rates are about the same, the horsepower ratios are as given above.
Now, when talking about mpg - or some other measure involving volume such as gallons or ... - the density of each fluid becomes a factor. The density of ethanol is about 49 Lb/CuFt while the average density of gasoline is about 44 Lb/CuFt. So - E10 will give about 0.97 the mileage of gasoline. E15 will give about 0.96 the mileage of straight gasoline.
Incidently - the governing relationship is:
mpg
-------------- = Constant
(Btu/Lb) * Den
And frankly, when one factors in the cost of all farming operations and refining - there is a marked energy expenditure in using any form of ethanol. The controlling factos - political, emissions, political, greed and political.
---- Jerry/Idaho
jimh posted 04-29-2009 06:41 AM ET (US)

quote:
A 9:1 gasoline and ethanol mixure has 84.2k BTU/Gallon and regular gasoline 125k BTU/Gallon, a 3.4% difference.
Something is wrong in the math here.
E10 = 84,200 BTU/Gallon
Gasoline = 125,000 BTE/Gallon
Difference = 40,800 BTU/Gallon
Expressed as a percent of difference with respect to Gasoline, E10 is
40800/12500 = 0.3264 x 100 = 32.64 percent lower
seahorse posted 04-29-2009 08:41 AM ET (US)
Using EPA information, gasoline contains about 114,500 BTU per gallon, and ethanol contains about 76,100 BTU per gallon. So a gallon of E10 would contain about,
0.9 * 114,500 BTU + 0.1 * 76,100 BTU = 112,000 BTU
of energy. This is 3.4% less energy than normal gasoline.

http://www.epa.gov/oms/rfgecon.htm
seahorse posted 04-29-2009 08:43 AM ET (US)
0.9 * 114,500 BTU + 0.1 * 76,100 BTU = 112,000 BTU

My mistake, the formula should read"
0.9 * 114,500 BTU + 0.1 * 76,100 BTU = 110,660 BTU
jimh posted 04-29-2009 08:55 AM ET (US)
It looks like the fundamental problem in the initial statement is that the values given for the BTU/Gallon are in error.
ORIGINAL VALUES PROPOSED:
E10 = 84,200 BTU/Gallon
Gasoline = 125,000 BTU/Gallon
VALUES SUGGESTED BY seahorse:
E10 = 110,660 BTU/Gallon
Gasoline = 114,500 BTU/Gallon
Using the actual values we see a difference of 3,840-BTU/Gallon. Expressed as a percentage, this would be
3840/114500 = 0.0335 x 100 = 3.35 percent.
So the initial values are wrong in regard to the energy content, but the suggested percentage difference is correct. I will append a note to that effect to the original article to make this clear.
Jerry Townsend posted 04-29-2009 01:50 PM ET (US)
The numbers I used are from established engineering handbooks as:
Gasoline : 20300 Btu/Lb, 44 lb/cuft, =>
5.95 lb/gal
Ethanol: 12800 Btu/Lb, 49 lb/cuft =>
6.55 lb/gal
Then, the energy content of:
gasoline: 119,403 Btu/Gal
E10 : 19,550 Btu/Lb or 115,299 Btu/Gal

and of E15: 19,175 Btu/Lb or 114,709 Btu/Gal
I have no idea where those other numbers are coming from - not only the energy (heat of combustion) but the density - as as I mentioned above, when talking about performance in gallons - the density is involved. --- Jerry/Idaho
weekendwarrior posted 04-29-2009 02:26 PM ET (US)
All number crunching aside, I think the questions in laymans terms are (1) will ethanol reduce my hp, and (2) will ethanol reduce my mileage. The answer is, for closed loop fi your hp should not change but your mileage will decrease. For carbed and open loop fi your hp will likely be reduced and we have not yet seen any imperical data for mileage.
jimh posted 04-29-2009 09:09 PM ET (US)
Jerry--Thank you for the clarification on the source of your data. I am inclined to accept it as more accurate.
seahorse posted 04-29-2009 11:24 PM ET (US)

quote:
The numbers I used are from established engineering handbooks as:
gasoline: 119,403 Btu/Gal

quote:
Using EPA information, gasoline contains about 114,500 BTU per gallon

quote:
Jerry--Thank you for the clarification on the source of your data. I am inclined to accept it as more accurate

This is getting interesting, there must be a number of sources for the heat energy of gasoline and each one has a different amount.
MIT Engineering even has a higher number, 138,500 BTU, as shown in the following link:
http://engineering.mit.edu/ask/question.php?id=39

The EPA says The energy content of conventional gasolines varies widely from batch to batch and station to station and shows different BTU's for summer and winter blend fuels ranging from 108,000 up to 117,000 BTU's.
http://www.epa.gov/oms/rfgecon.htm

No matter which BTU rresult is used for calculations, gasoline mixed with ethanol in any concentration has less energy.
jimh posted 04-30-2009 07:42 AM ET (US)
To clarify, I don't trust the EPA to tell us about ethanol. The credibility of our government in regard to accurate information about ethanol is not very good in my opinion. An engineering handbook written without a vested interest in ethanol being successful is probably more trustworthy.
seahorse posted 04-30-2009 09:07 AM ET (US)
I agree with you, Jim.
Because there is such a wide variation in gasolines, for ICOMIA horsepower certifications and for emission testing, a reference fuel is used so that each test is repeatable and everyone has to use it for consistancy.
To control the test process and keep all
manufacturers on an equal footing, a
specific fuel must be used. This is known
as “Reference Fuel A”.
This fuel has known hydrogen-carbon contents and is reproduced in consistent known
blends. The atomic weights of every compound in the fuel and the percentage of each
compound in the fuel is known. This provides the scientific control to all of the tests. The
fuel we, as consumers, purchase for our vehicles and boats by comparison, is typically
much cleaner in terms of emissions output. Additionally, the compounds in the fuel we buy
at the pumps are not consistent from batch to batch or from one area of the country to
another. These inconsistencies in local fuel sources would not provide a controlled
reference for emission testing

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Author	Topic: Does Ethanol Reduce Horsepower?
Ridge Runner	posted 04-28-2009 08:40 AM ET (US) [Nota Bene: the values for BTU/Gallon cited are in dispute. The calculation of percentage difference between them is not correct. See below for further discussion and perhaps more accurate values--jimh.] A 9:1 gasoline and ethanol mixure has 84.2k BTU/Gallon and regular gasoline 125k BTU/Gallon, a 3.4% difference. Does the horsepower of an engine see a 3.4% reduction? I've read that the 3.4% will effect MPG, but does a outboard have 3.4% less horsepower?
Peter	posted 04-28-2009 08:57 AM ET (US) Here is information taken from a Gasoline Gallon Equivalent (GGE) Table Fuel Type Unit of Measure BTUs Per Unit Gallon Equivalent Gasoline, regular unleaded, (typical) gallon 114,100 1.00 gallon Gasoline, RFG, (10% MBTE) gallon 112,000 1.02 gallons Diesel, (typical) gallon 129,800 0.88 gallons Liquid natural gas (LNG), (typical) gallon 75,000 1.52 gallons Compressed natural gas (CNG), (typical) cubic foot 900 126.67 cu. ft. Liquefied petroleum gas (LPG or propane) gallon 84,300 1.35 gallons Methanol (M-100) gallon 56,800 2.01 gallons Methanol (M-85) gallon 65,400 1.74 gallons Ethanol (M-100) gallon 76,100 1.50 gallons Ethanol (E-85) gallon 81,800 1.40 gallons Bio Diesel (B-20) gallon 129,500 0.88 Straight gasoline has 114k BTU per gallon. Straight ethanol has 76k BTU per gallon, a 90/10 mixture would have approximataly 110k BTU per gallon (114k * 0.9 + 76k * 0.1). The E10 gasoline gallon equivalent 1.036 (114k/110k = 1.036). Basically, your engine will produce 3.4 percent less power per power stroke on E10 than it would on straight gasoline because there is 3.4 percent less energy in the same quantity of fuel. To make the same power per stroke would require 1.036 times more fuel induced into the combustion chamber.
Tohsgib	posted 04-28-2009 10:31 AM ET (US) In other words...yes.
TransAm	posted 04-28-2009 11:02 AM ET (US) Wow, I figured there was some insignificant effect, but 3-4%, that's significant. Other than introducing more fuel in the combustion chamber, can this loss of power be reasonably recovered?
Tohsgib	posted 04-28-2009 11:18 AM ET (US) Yes...fill up at a marina that does not have ethanol. My marina also has stabilizers and water absorber additives in it. It is only like $.30 more than the pump.
TransAm	posted 04-28-2009 11:45 AM ET (US) What if your marina is E-10?
Tohsgib	posted 04-28-2009 11:48 AM ET (US) Should not be...go to a different marina. I am 99% positive that [ValvTect] fuel is non-ethanol so look for it.
L H G	posted 04-28-2009 11:53 AM ET (US) So, I assume outboard engines are rated for HP on pure gasoline? I doubt the manufacturers would be so magnanimous to rate them on E-10. I guess that means if you buy a 300 HP engine, immediately you are only getting 290HP. Then add in the 10% allowable "fudge factor" up or down, and you could really be getting a lot less HP than you are paying for. A 300 could only be putting out 260HP. If we go to E-15, which we probably will, all of us will need to be buying more HP than we think we really need. If one is going to buy a 225, probably a 250 should be bought instead. A lower pitch prop might be needed on existing engines. Just another cost to consumers of "going green". I thought all internal combustion engines needed to be modified if more than 10% ethanal is used?
Buckda	posted 04-28-2009 12:11 PM ET (US) Isn't it "ValvTect"? http://www.valvtect.com There is no information on the site that indicates that they do not use the ValvTect additives in E-10 fuels. The company makes fuel additives and blend them in with the fuels. JimH likes to refer to this as a "witches brew" when individuals do this to their fuels, but I'm a fan of finding your own blend that makes you feel better. Many marinas sell fuel that is not "ethanol enhanced" - but not all.
Ridge Runner	posted 04-28-2009 12:25 PM ET (US) Down in Port Charlotte, FL I can fill up with [ValvTect] fuel which does not have ethanol, I have verified this. In NJ all fuel has ethanol, its state law. In Wisconsin they have ethanol in regular and mid-grade and premium is ethanol free. It’s interesting I have two carbureted Yamaha two-cycles a 90hp and a 50hp and I have run both fuels in each, I can tell the difference. When I pull skiers it “seems” to take longer to get someone up, also the mid-range to full throttle-up “seems” different. Now on my 25’ CC w/twin Yamaha F115’s and Conquest w/twin Mercury Optimax 225’s I don’t really notice any difference. I’m not sure if it’s because they are larger boats or because the EMM’s that control the fuel flow through the injectors are compensating.
Buckda	posted 04-28-2009 12:30 PM ET (US) Also - I'm no fan of ethanol - but there are some interesting companies that are investigating synthetic fuels. The US Air Force is investigating jet fuel from RenTech - a California company that has a proof-of-concept refinery manufacturing synthetic Jet and Diesel fuel for research purposes. This fuel has more energy per pound than petroleum -derived fuels and can be generated for a profit at about the equivalent of $70/barrel oil prices. Feedstock can be biomass, agricultural bagesse or oil/natural gas. They claim that there are no modifications needed for current motors and the fuel can be delivered via pipeline (not truck/train, as is required of ethanol for transport). Not cheap, but there are companies working on alternatives that don't rob the energy. Hopefully we'll at least have some other options in the next few years.
TransAm	posted 04-28-2009 12:31 PM ET (US) Maybe that guy with the Rib boat and 300 E-tec is burning straight ethanol?
Ridge Runner	posted 04-28-2009 12:48 PM ET (US) Can a supercharged engine that is operating by forced induction and compressing the air/fuel mixture compensate for the energy difference?
BQUICK	posted 04-28-2009 02:07 PM ET (US) Don't forget about the loss in MPG also......
weekendwarrior	posted 04-28-2009 02:51 PM ET (US) No use of ethanol will not by definition reduce horsepower, but you will need to burn more of it to get the same horsepower. On an closed-loop FI engine the computer will handle this for you. On a carbed engine your jetting might not be optimal as-is so you've got a 50/50 shot. Consumer Reports compared a truck (Chevy Tahoe I think) on e10 and e85. For both fuels performance was virtually identical but the mileage on e85 was significantly worse. See the test at consumerreports.org. ASIDE: nitro methane is less energy dense than gasoline, BUT you can burn about eight times as much of it with the same amount of air (the nitro is already oxadized). The top fuel dragsters burn nitro because they can burn so much more of it than they could gas that it more than makes up for the difference in energy density.
weekendwarrior	posted 04-28-2009 08:30 PM ET (US) Just a follow up, here's a link to one of the articles about ethanol tests on consumer reports, and an excerpt from the article: http://www.consumerreports.org/cro/cu-press-room/pressroom/archive/2006/10/0610_eng0610e85_ov.htm?resultPageIndex=1&resultIndex=3&searchTerm=e85%20test In regards to E85 vs gasoline: "Overall fuel economy on the Tahoe dropped from an already low 14 mpg overall to 10. In highway driving, gas mileage decreased from 21 to 15 mpg; in city driving, it dropped from 9 mpg to 7." And here's the performance and emissions numbers for the same test: URL: http://www.consumerreports.org/cro/cars/new-cars/news/2006/ethanol-10-06/tests-of-ethanol-vs.-gasoline/1006_ethanol_test_1.htm?resultPageIndex=1&resultIndex=2&searchTerm=e85%20test Test results: E85 vs. gasoline This chart shows how our 2007 Chevrolet Tahoe performed while running on E85 and gasoline in three fuel-economy tests and overall, in four acceleration tests, and in three emissions tests for gasoline vehicles. [This chart didn't copy/paste so well, but here goes] E85 GASOLINE* Fuel economy, mpg City 7 9 Highway 15 21 150-mile trip 13 18 Overall 10 14 Acceleration 0-30 mph, sec. 3.4 3.5 0-60 mph, sec. 8.9 9.1 45-65 mph, sec. 5.7 5.8 Quarter-mile, sec./mph 16.8/84.6 16.9/84.5 Emissions, parts per million Nitrogen oxide 1 9 Hydrocarbons 1 1 Carbon monoxide 0 0
Jerry Townsend	posted 04-28-2009 09:41 PM ET (US) Easy guys - There are a couple of issues being discussed - energy content, which is based on energy per pound - and mpg - which is based on energy per gallon. Talking of energy performance and milesage in the same sentence is akin to comparing apples and oranges. Talking about energy alone - gasoline has an average combustion energy of about 20,300 Btu/Lb while ethanol has an average combustion energy of about 12,800 Btu/Lb. Therefore, E10 has about 0.96 of the energy content of gasoline and E15 has about 0.94 the energy content of gasoline. Since the fuel flow rates are about the same, the horsepower ratios are as given above. Now, when talking about mpg - or some other measure involving volume such as gallons or ... - the density of each fluid becomes a factor. The density of ethanol is about 49 Lb/CuFt while the average density of gasoline is about 44 Lb/CuFt. So - E10 will give about 0.97 the mileage of gasoline. E15 will give about 0.96 the mileage of straight gasoline. Incidently - the governing relationship is: mpg -------------- = Constant (Btu/Lb) * Den And frankly, when one factors in the cost of all farming operations and refining - there is a marked energy expenditure in using any form of ethanol. The controlling factos - political, emissions, political, greed and political. ---- Jerry/Idaho
jimh	posted 04-29-2009 06:41 AM ET (US) quote: A 9:1 gasoline and ethanol mixure has 84.2k BTU/Gallon and regular gasoline 125k BTU/Gallon, a 3.4% difference. Something is wrong in the math here. E10 = 84,200 BTU/Gallon Gasoline = 125,000 BTE/Gallon Difference = 40,800 BTU/Gallon Expressed as a percent of difference with respect to Gasoline, E10 is 40800/12500 = 0.3264 x 100 = 32.64 percent lower
seahorse	posted 04-29-2009 08:41 AM ET (US) Using EPA information, gasoline contains about 114,500 BTU per gallon, and ethanol contains about 76,100 BTU per gallon. So a gallon of E10 would contain about, 0.9 * 114,500 BTU + 0.1 * 76,100 BTU = 112,000 BTU of energy. This is 3.4% less energy than normal gasoline. http://www.epa.gov/oms/rfgecon.htm
seahorse	posted 04-29-2009 08:43 AM ET (US) 0.9 * 114,500 BTU + 0.1 * 76,100 BTU = 112,000 BTU My mistake, the formula should read" 0.9 * 114,500 BTU + 0.1 * 76,100 BTU = 110,660 BTU
jimh	posted 04-29-2009 08:55 AM ET (US) It looks like the fundamental problem in the initial statement is that the values given for the BTU/Gallon are in error. ORIGINAL VALUES PROPOSED: E10 = 84,200 BTU/Gallon Gasoline = 125,000 BTU/Gallon VALUES SUGGESTED BY seahorse: E10 = 110,660 BTU/Gallon Gasoline = 114,500 BTU/Gallon Using the actual values we see a difference of 3,840-BTU/Gallon. Expressed as a percentage, this would be 3840/114500 = 0.0335 x 100 = 3.35 percent. So the initial values are wrong in regard to the energy content, but the suggested percentage difference is correct. I will append a note to that effect to the original article to make this clear.
Jerry Townsend	posted 04-29-2009 01:50 PM ET (US) The numbers I used are from established engineering handbooks as: Gasoline : 20300 Btu/Lb, 44 lb/cuft, => 5.95 lb/gal Ethanol: 12800 Btu/Lb, 49 lb/cuft => 6.55 lb/gal Then, the energy content of: gasoline: 119,403 Btu/Gal E10 : 19,550 Btu/Lb or 115,299 Btu/Gal and of E15: 19,175 Btu/Lb or 114,709 Btu/Gal I have no idea where those other numbers are coming from - not only the energy (heat of combustion) but the density - as as I mentioned above, when talking about performance in gallons - the density is involved. --- Jerry/Idaho
weekendwarrior	posted 04-29-2009 02:26 PM ET (US) All number crunching aside, I think the questions in laymans terms are (1) will ethanol reduce my hp, and (2) will ethanol reduce my mileage. The answer is, for closed loop fi your hp should not change but your mileage will decrease. For carbed and open loop fi your hp will likely be reduced and we have not yet seen any imperical data for mileage.
jimh	posted 04-29-2009 09:09 PM ET (US) Jerry--Thank you for the clarification on the source of your data. I am inclined to accept it as more accurate.
seahorse	posted 04-29-2009 11:24 PM ET (US) quote: The numbers I used are from established engineering handbooks as: gasoline: 119,403 Btu/Gal quote: Using EPA information, gasoline contains about 114,500 BTU per gallon quote: Jerry--Thank you for the clarification on the source of your data. I am inclined to accept it as more accurate This is getting interesting, there must be a number of sources for the heat energy of gasoline and each one has a different amount. MIT Engineering even has a higher number, 138,500 BTU, as shown in the following link: http://engineering.mit.edu/ask/question.php?id=39 The EPA says The energy content of conventional gasolines varies widely from batch to batch and station to station and shows different BTU's for summer and winter blend fuels ranging from 108,000 up to 117,000 BTU's. http://www.epa.gov/oms/rfgecon.htm No matter which BTU rresult is used for calculations, gasoline mixed with ethanol in any concentration has less energy.
jimh	posted 04-30-2009 07:42 AM ET (US) To clarify, I don't trust the EPA to tell us about ethanol. The credibility of our government in regard to accurate information about ethanol is not very good in my opinion. An engineering handbook written without a vested interest in ethanol being successful is probably more trustworthy.
seahorse	posted 04-30-2009 09:07 AM ET (US) I agree with you, Jim. Because there is such a wide variation in gasolines, for ICOMIA horsepower certifications and for emission testing, a reference fuel is used so that each test is repeatable and everyone has to use it for consistancy. To control the test process and keep all manufacturers on an equal footing, a specific fuel must be used. This is known as “Reference Fuel A”. This fuel has known hydrogen-carbon contents and is reproduced in consistent known blends. The atomic weights of every compound in the fuel and the percentage of each compound in the fuel is known. This provides the scientific control to all of the tests. The fuel we, as consumers, purchase for our vehicles and boats by comparison, is typically much cleaner in terms of emissions output. Additionally, the compounds in the fuel we buy at the pumps are not consistent from batch to batch or from one area of the country to another. These inconsistencies in local fuel sources would not provide a controlled reference for emission testing