EcoModder Forum GREEN CAR JOURNAL, Spring 2009 article (GAS vs. E85 MPG ratings)

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 10-16-2009, 01:30 AM #1 (permalink) ...beats walking...   Join Date: Jul 2009 Location: . Posts: 6,190 Thanks: 179 Thanked 1,525 Times in 1,126 Posts GREEN CAR JOURNAL, Spring 2009 article (GAS vs. E85 MPG ratings) ...anybody see the table on page 29, "2009 E85 Flexible-Fuel Vehicles," that lists 41 different 2009 flex-fuel vehicles and their respective GAS and E85 MPG ratings? ...well, I graphed the MPG numbers and here are the results (H=MPG.hwy, C=MPG.city): I) Average City MPG vs. Hwy MPG linear equation: GAS: H = 1.5087(C) - 1.1775, RR = 0.8998 E85: H = 1.5639(C) - 1.2182, RR = 0.9450 II) Average MPG ratios: E85/Gas for City and E85/Gas for Hwy: CITY: average = 0.712, stddev = 0.043 HWY: average = 0.721, stddev = 0.035 ...although these numbers only represent the 41 vehicles listed, they illustrate that E85 yields about 71% of GAS milage in the city, and about 72% of GAS milage on the highway. ...I have both Excel and graphs if others want to see the raw numbers. Last edited by gone-ot; 10-16-2009 at 01:37 AM..
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 10-16-2009, 01:34 AM #2 (permalink) (:     Join Date: Jan 2008 Location: up north Posts: 12,762 Blue - '93 Ford Tempo Last 3: 27.29 mpg (US) F150 - '94 Ford F150 XLT 4x4 90 day: 18.5 mpg (US) Sport Coupe - '92 Ford Tempo GL Last 3: 69.62 mpg (US) ShWing! - '82 honda gold wing Interstate 90 day: 33.65 mpg (US) Moon Unit - '98 Mercury Sable LX Wagon 90 day: 21.24 mpg (US) Thanks: 1,585 Thanked 3,552 Times in 2,216 Posts That's probably right. __________________
 10-16-2009, 12:37 PM #3 (permalink) Hypermiler     Join Date: Dec 2007 Location: Texas Posts: 2,321 PaleCivic (retired) - '96 Honda Civic DX Sedan 90 day: 69.2 mpg (US) PaleFit - '09 Honda Fit Sport Team HondaWagons 90 day: 44.06 mpg (US) Thanks: 611 Thanked 432 Times in 282 Posts According to Gasoline gallon equivalent - Wikipedia, the free encyclopedia those numbers exactly match the BTU content of the two fuels - E85 has 71.8% the BTUs of gasoline. Interpolating E10 between the two gives you 3.3% lower mpg for E10. __________________ 11-mile commute: 100 mpg - - - Tank: 90.2 mpg / 1191 miles
 10-16-2009, 12:43 PM #4 (permalink) ...beats walking...   Join Date: Jul 2009 Location: . Posts: 6,190 Thanks: 179 Thanked 1,525 Times in 1,126 Posts ...looks like we've got some "cross-corrolation" going on...two different ways of saying/proving the samething: 1) ethanol reduces MPG. 2) the reduction is roughly linear to their volume percentage. 3) the energy content reduction is proportional to theeir volume percentage and their BTU values.
 10-16-2009, 01:02 PM #5 (permalink) Master EcoModder   Join Date: Feb 2009 Location: Phoenix Posts: 595 Thanks: 106 Thanked 113 Times in 71 Posts Wait so you're telling me a substance which has around 71% the energy content does about 71% the work? UNPOSSIBLE!! __________________ 2005 Escape 2.3 MT 2WD 2002 Mustang 3.8 AT 2015 Ram 1500 5.7L 4WD 2002 Motobecane 700DS
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Quote:
 Originally Posted by shovel Wait so you're telling me a substance which has around 71% the energy content does about 71% the work?
...yeah, but its octane is more-better! (wink,wink)

...which, don't mean a thing unless you have a variable compression ratio engine!

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Quote:
 Originally Posted by Old Tele man ...yeah, but its octane is more-better! (wink,wink) ...which, don't mean a thing unless you have a variable compression ratio engine!
you'd think we would have come up with a way of making something like that... without being ridiculously complicated and convoluted of course.
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2015 Ram 1500 5.7L 4WD
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 10-16-2009, 04:50 PM #8 (permalink) Master EcoModder   Join Date: Jul 2008 Location: Silly-Con Valley Posts: 1,479 Thanks: 199 Thanked 262 Times in 199 Posts We have plenty of them on the road right now. Turbochargers effectively emulate that situation. More compression ~= more boost, though the equivalence is far from exact and the relationship is likely not even linear. In older turbocharged motors, you can see that the engineers who designed them traded off lower compression for more boost, or higher compression for less boost. (The higher compression means better off-boost performance, generally.) Think of your average Camry (AKA overweight modern "mid size car") being propelled by a 1.3 liter motor, but with the ability to have the same sort of power that the better four-cylinder Camrys make right now. Sounds like a reasonable recipe for good mileage, yes? -soD
 10-18-2009, 03:44 PM #9 (permalink) ...beats walking...   Join Date: Jul 2009 Location: . Posts: 6,190 Thanks: 179 Thanked 1,525 Times in 1,126 Posts ...well, I know GM made a variable-compression ratio diesel engine to compete against the Chrysler turbine-engine back when Carter was president...used engine oil to pump-up a piston within a piston as I vaguely recall.
 10-19-2009, 02:03 PM #10 (permalink) Master EcoModder   Join Date: Jul 2008 Location: Silly-Con Valley Posts: 1,479 Thanks: 199 Thanked 262 Times in 199 Posts I don't remember that one, but Saab put together a variable-compression engine where the cylinder head was hinged on one side, and you opened up the hinge for more volume and lower compression. Sounded like a bit of a nightmare keeping everything sealed up, but supposedly it worked. They used it in conjunction with a turbocharger, and varied the compression more or less inversely to the boost. -soD