E85: A Primer
Okay, here's a hot button topic for you: Alternative fuels and, in particular, E85. While it might not be as controversial as, say, a Bose sound system, it is (or should be) far more important to the hardcore performance enthusiast. Why? Three words: cheap race gas.
There are a myriad of issues that can be argued regarding the pros and cons of E85. Because the ethanol used to produce it is largely derived from corn, E85 production has been blamed for everything from the rising cost of T-bone steaks to the skyrocketing price of tortilla shells in Mexico. E85 is currently all the rage among domestic auto manufacturers (mainly due to CAFE credits offered for producing flex-fuel vehicles), but it is often looked upon negatively by the high-performance crowd. I think that's a mistake, and I'll tell you why.
The U.S. Department of Energy classifies E85 as an alternative fuel that "burns cleaner than gasoline and is a completely renewable, domestic, environmentally friendly fuel that enhances the nation's economy and energy independence." As the name implies, E85 is a blend of 85 percent ethanol and 15 percent gasoline. Many believe the "85" is an indication of the fuel's octane rating. Not true, as the appellation bears no reflection on this number, which is actually 105.
So what's ethanol? It is a form of alcohol that happens to be a renewable fuel produced by the fermentation of plant sugars. In the U.S., ethanol is typically produced from corn and other grain products. Other sources, such as agricultural and forestry wastes or purpose-grown "energy crops," can also be utilized. One such alternative source is switch grass, which is easily renewable and produces far more ethanol per acre than corn. Brazil, which has been largely E85-powered for decades, economically produces ethanol from sugar cane.
There's no question that petroleum consumption in the United States is constantly on the rise and that we currently import more than half of the oil we consume. E85 has the potential to reduce our use of foreign oil, but it is really too soon to say by how much. It also has the potential to reduce pollution caused by motor vehicles. Uncle Sam says that E85-powered vehicles produce lower hydrocarbon and benzene emissions compared with gasoline-powered ones. They also generate fewer carbon dioxide (CO2) emissions. Widely acknowledged as a harmful greenhouse gas, CO2 is considered to be a major contributor to global warming.
But for performance addicts, E85's biggest selling point-and the one the political wonks completely overlook-is its stratospheric octane rating. In forced-induction applications, the added octane makes it possible to run more boost without harmful detonation. Those of us running naturally aspirated engines ought to give E85 consideration as well. To me, the ability to utilize more ignition timing and eventually increase the compression ratio makes it a no-brainer. With E85 in the tank, running a street engine with a compression ratio as high as 13:1 is no problem.
Things to Consider
Availability is a key consideration when contemplating an E85 conversion. My home state of Minnesota just happens to possess the largest concentration of E85 fueling stations in the nation. At the time of this writing, there are more than 320 facilities here in the Great White North. That's more than double the next-most E85-friendly state, Illinois, which has approximately 150 stations.
As with conventional gasoline, E85 prices fluctuate daily (or hourly, it seems, at some stations). In Minnesota, E85 can often be found for $.40 per gallon less than 87-octane gasoline. The last time I filled D6C's tank, E85 was $2.29 per gallon-approximately 25 percent cheaper than 92-octane premium, at $2.89. And what about race gas? My last check found 100-octane unleaded hovering at the $4.50-per-gallon mark.
Many sources proclaim that E85 exacts a 30 percent fuel-mileage penalty the instant it hits your tank. And sure enough, OEM flex-fuel vehicles often do exhibit such a loss. That's enough to completely negate any financial gain of running the fuel, though it may still leave you with a warm, green fuzzy feeling while piloting your Suburban through rush-hour traffic. But while there's no disputing that E85 contains less energy potential per gallon than conventional gasoline, one tuner we spoke with stated that the mileage differential can be reduced to approximately 10 percent with proper tuning.
When it comes to Corvettes, E85 compatibility is largely determined by model year. If your Vette was built within the last 10 years, you should be in good shape. Older cars can be converted too, but will require a little more work. Essentially, anything in the fuel system that is not alcohol-compatible should be replaced. That could include fuel pumps, lines, and carburetor components. You will also need to richen the mixture by whatever means are appropriate, be they larger jets in the carb or bigger injectors. Lastly, you should take advantage of the higher octane by advancing your ignition timing.