Given 1 gallon of E85, how many gallons of E10 are needed to make E30? Once we know this ratio, it will hold for any quantity. (1*(.85e + .15g)) + (n*(.10e + .90g)) = (1+n)*(.30e + .70g) ## adding 1 gallon of E85, "n" gallons of E10, to make E30 .85e + .15g + .10en + .90gn = (1+n)*.30e + (1+n)*.70g .85e + .15g + .10en + .90gn = .30e + .30en + .70g + .70gn .85e + .15g - .30e -.70g = -.10en + .30en -.90gn + .70gn (.85 - .30)e + (.15 - .70)g = (-.10en + .30en) + (.70gn - .90gn) (.55)e + (-.55)g = (.20)en + (-.20)gn (.55)e + (-.55)g = ((.20e) + (-.20)g)) *n ((.55)e + (-.55)g) / ((.20e) + (-.20)g) = n .55 * (e-g) / .20* (e-g) = n ## the "(e-g)" term confirms nothing was lost in the earlier algerbra .55 / .20 = n 2.75 = n Ok, so with this approach: Column 1 0 E85 E10 E30 1 0.25 0.69 0.938 2 0.5 1.38 1.875 3 1.0 2.75 3.750 4 1.5 4.13 5.625 5 2.0 5.50 7.500 6 2.5 6.88 9.375 7 3.0 8.25 11.250 Now if the local Jet station will let me pre-pay for exact amounts, it should be fairly straight forward. Estimate the amount to fuel to add, right column, and pre-pay the amounts of E85 and E10 needed. There is a credible report that E30 can lead to engine tuning to achieve equivalent power levels as straight gas. This is something I plan to test with our Atkinson engines but first I need to way to mix it in my tank. Bob Wilson
What do you hope to accomplish? "energy content" of the fuel is not the same thing as "power output" from the engine. In a Prius you will not see a difference in power output when using ethanol: ethanol contains 30% less energy per gallon than gasoline, so the car will command the engine to turn more revolutions to produce the same power and also get fewer MPGs. Further, how do you propose to do any engine tuning to increase power? If you do succeed in acccessing the engine tuning controls it will certainly increase polluting emissions (although the ethanol, which inherently burns cleaner, will partly offset that). You already know that the fuel system and engine components are not warranted to tolerate more the E10, so I won't bother with that warning :_>
Hi Richard, I appreciate your concerns but the paper is very interesting. Whether or Atkinson engine and "tune" to make use of E30 is the unknown. It may not work. For those interested in the paper: "2007-EERC-11-02" should Google it up. I was also able to find paper in opposition to E30. Their chief complaint is the exhaust temperature at higher power setting might rise and do harm to the catalytic converter. Certainly it makes sense to put in an exhaust temperature probe and measure the effect. Now there is a fairly simple mitigation, cooled exhaust gas injection. Experimentation is not for everyone and needs to be done with 'eyes wide open.' But informed experimentation is how we eventually master these systems. It is so nice to "know" what works and doesn't work. Bob Wilson
The PDF doesn't seem to work for me.. but this press release seems to be about the same study: http://www.ethanol.org/pdf/contentmgmt/Press_Release_12507-1.pdf
Bob it's important to note that the opposition link is really a different matter altogether. The effects of going from E10 to E15 for ALL vehicles is quite different than the effects of going from E10 to E30 in one specific model. The EWG letter says that it is mainly older vehicles that had the increased exhaust temps and that "[m]odern vehicles equipped with oxygen sensor-based, closed-loop control systems are calibrated to appropriately compensate for higher levels of oxygen in ethanol blend." The testing was done at WOT. I'm not sure that represents a real-world test.
Try Google for the title: "OPTIMAL ETHANOL BLEND-LEVEL INVESTIGATION" But like I said, folks need to go into any testing with their eyes 'wide open.' So far, the strongest objection is a 25-30C increase in exhaust temperatures at wide-open throttle. This definitely needs to be part of any testing. First test: 5.542 E10 - $11.97, $2.159/gallon 2.037 E85 - $4.40, $2.159/gallon I filled on "flash" so there was probably a couple of gallons still in the tank of E10. But so far, nothing remarkable to report. It'll take some hill-climb data before I'll have any results to share. Bob Wilson
