If you're willing to do a...
If you're willing to do a little carburetor tuning, E85 could be a budget high-octane fuel that can make big-time horsepower.
Environmentalists and car crafters make strange, if not odd-opposite, bedfellows. The greenies are all over this not-so-new, environmentally friendly, renewable resource ethanol fuel that even has GM pushing it in its television ads. So what's all the fuss about and why should it interest you? Forget about greenhouse gases and that whole Al Gore political football. The real reason is simple: E85 fuel is a combination of 85 percent ethanol and 15 percent gasoline. Ethanol is an alcohol fuel made from the distillation of corn or other sugar-based carbohydrates, like beets or sugar cane. Straight ethanol has a race-gas-style octane rating of 115. Mixed with 15 percent 87-octane pump gas, E85 lowers this to between 103 and 105 and generally sells for less than 87-octane gasoline. You read that right. We're talking the equivalent of 105-octane race gas for the price of moose-piss pump gas.
There's much more to this story that you need to know, and the devil is most definitely in the details, so you've got to read this whole story to get the facts straight. Yes, you'll have to modify your carburetor to use it; yes, your mileage might suffer by as much as 20 percent; and yes, E85 is not available everywhere-yet. But we successfully tested this stuff in a 12.5:1 compression small-block Chevy against race fuel, and we not only made good power, but we also made a little more torque to boot. Now are you interested? And if you're already thinking this might make a great fuel for a supercharged or turbocharged engine-congratulations-you're thinking like a true car crafter.
Using E85 requires dramatic...
Using E85 requires dramatic increases in jet changes and metering block modifications to supply enough fuel to the engine to compensate for E85's reduced Btu heat capacity.
What is Ethanol?
Think moonshine and you're on the right track. The stuff of Appalachian legend also makes an outstanding fuel. But don't confuse ethanol with methanol, which is a completely different fuel distilled from wood or coal. Ethanol is an oxygen-bearing fuel with a chemical makeup of C2H6O. That formula adds power by carrying its own oxygen (nitromethane is CH3NO2-lots 'o oxygen). By way of its three-carbon chemical construction and that single oxygen molecule, the Btu (British thermal unit) heat output of ethanol is not nearly as robust as that of gasoline. The numbers tell the story. One gallon of ethanol is worth 76,000 Btus, while gasoline is around 114,000 Btus. E85 is created by adding 15 percent gasoline to ethanol, which ups the heat count to roughly 83,000 Btus per gallon. By way of comparison, methanol generates a mere 56,800 Btus per gallon, or almost exactly half the Btus of gasoline. This means E85 creates roughly 27 percent less heat output per gallon than gasoline. This is partly why we must burn around 25 to 30 percent more E85 (at wide-open throttle) compared with gasoline to achieve similar results. Stamp this number on your forehead because this volume change is critically important when it comes time to modify the carburetor to flow more fuel.
Part of the switch from gasoline...
Part of the switch from gasoline to E85 involves reducing the size of the high-speed air bleeds. The idle air bleeds remained the same at 65. The bleeds closest inboard are the high-speed bleeds (arrows), while the outside bleeds are the idle air bleeds.
Because we must burn more E85 than gasoline to make the same amount of heat in the combustion chamber, E85 is currently not the dashing hero as an alternative daily-driver fuel. While there is a 27 percent reduction in heat, ethanol's strong octane rating allows the use of a higher static compression ratio to take advantage of that resistance to detonation. This means if you were to run E85 in an 11:1 or 12:1 compression engine, E85's higher octane would prevent detonation, which would allow you to run this higher compression ratio and take more advantage of the reduced Btu heat output by squeezing the existing air and fuel a little harder to make more power. The kicker is that right now, E85 is priced only about 30 to 50 cents a gallon cheaper than gasoline. During research for this story, we priced E85 at a gas station in Ames, Iowa, at $2.60 a gallon, which is significantly below the price of 93-octane premium at $3.05 per gallon and far less expensive than $5 to $6 per gallon for 100-octane unleaded race gasoline. Higher-octane race gas is even more expensive. With reduced mileage, E85 only becomes economically attractive from a mileage standpoint when E85 is significantly cheaper per gallon. Also keep in mind that the government is currently subsidizing ethanol at around 50 cents per gallon. If ethanol use increases dramatically in the next few years, expect the government to yank that subsidy in order to cash in. The other big problem with E85 is availability. Because corn is the most popular base stock for ethanol, the Corn Belt states of Iowa, Nebraska, Missouri, and Minnesota are the places where E85 is most prevalent. There are only 15 states that do not offer E85, concentrated mainly in the upper northeast United States along with Alaska, Hawaii, Arkansas, Louisiana, and Alabama. The entire state of California has only one bulk outlet, in San Diego, where E85 can be purchased by the public. But take heart, this situation is rapidly changing, and within a year or two, the E85 landscape could change. But for those of you in the Midwest states, you have no excuse for not checking this stuff out.