5 ms·

E10 fuel is about 3% [1] less efficient than more pure gasoline, and much harder on car engines, even ones designed for it (unsourced, but so my gearhead friend

E10 fuel is about 3% [1] less efficient than more pure gasoline, and much harder on car engines, even ones designed for it (unsourced, but so my gearhead friends have told me) So, no, maybe consumers are making the smart choice. [1] http://www.eia.gov/tools/faqs/faq.cfm?id=27&t=10 http://www.eia.gov/tools/faqs/faq.cfm?id=27&t=10

revelation 11y ago
I've mentioned the theoretical energy density, and notice that this is what the EIA uses to derive the 3% efficiency loss. This is a highly theoretical value; combustion engines are very complex beasts and theoretical energy density is a poor predictor of their efficiency, but what is known is that higher octane ratings are beneficial for fuel efficiency. Since ethanol has a high (>=100) octane rating, it might actually improve fuel consumption despite being less energy dense. Also, E15 and higher fuel blends have been in widespread use in the US for 10+ years now. I don't think car engines die quicker in the US.
- bri3d 11y ago
  http://feerc.ornl.gov/pdfs/pub_int_blends_rpt1_updated.pdf http://feerc.ornl.gov/pdfs/pub_int_blends_rpt1_updated.pdf Here are some fairly extensive test cycles applied to real-world engines, which found that the effect closely mirrors the theoretical reduction in energy density (3-4% for E10, ~7% for E20). Higher octane ratings are not generally beneficial for fuel efficiency unless the engine has been designed for them (compression ratio, cam profile, timing, tune). Dropping higher-octane fuel into an engine designed for a lower-octane fuel will generally not affect economy.
cplease 11y ago
> and much harder on car engines, even ones designed for it (unsourced, but so my gearhead friends have told me) Bollocks. The energy content is slightly lower, but there is zero harm to automobile engines. Your unsourced "gearhead" friends share a common misconception and prejudice against ethanol. There is absolutely no issue with E10 fuel in cars with model years as far back as the '90s, or even earlier. Very old classic cars may have issues with some fuel line components, but even there E10 will not wreck the engine. As a fuel E10 is extensively tested on gasoline autos. Two-stroke engines are another matter. And 2001 and newer autos can run E15.

revelation 11y ago

I've mentioned the theoretical energy density, and notice that this is what the EIA uses to derive the 3% efficiency loss. This is a highly theoretical value; combustion engines are very complex beasts and theoretical energy density is a poor predictor of their efficiency, but what is known is that higher octane ratings are beneficial for fuel efficiency. Since ethanol has a high (>=100) octane rating, it might actually improve fuel consumption despite being less energy dense. Also, E15 and higher fuel blends have been in widespread use in the US for 10+ years now. I don't think car engines die quicker in the US.

bri3d 11y ago
http://feerc.ornl.gov/pdfs/pub_int_blends_rpt1_updated.pdf http://feerc.ornl.gov/pdfs/pub_int_blends_rpt1_updated.pdf Here are some fairly extensive test cycles applied to real-world engines, which found that the effect closely mirrors the theoretical reduction in energy density (3-4% for E10, ~7% for E20). Higher octane ratings are not generally beneficial for fuel efficiency unless the engine has been designed for them (compression ratio, cam profile, timing, tune). Dropping higher-octane fuel into an engine designed for a lower-octane fuel will generally not affect economy.

cplease 11y ago

> and much harder on car engines, even ones designed for it (unsourced, but so my gearhead friends have told me) Bollocks. The energy content is slightly lower, but there is zero harm to automobile engines. Your unsourced "gearhead" friends share a common misconception and prejudice against ethanol. There is absolutely no issue with E10 fuel in cars with model years as far back as the '90s, or even earlier. Very old classic cars may have issues with some fuel line components, but even there E10 will not wreck the engine. As a fuel E10 is extensively tested on gasoline autos. Two-stroke engines are another matter. And 2001 and newer autos can run E15.