Yes, A Chevy 350 Can Run On E85, But Don't Just Start Filling Up The Tank

If your small-block Chevy is laying down some serious horsepower — especially if those beans are courtesy of a high compression ratio or boost — you've probably considered switching to E85 fuel. At the risk of being labeled Captain Obvious, E85 is comprised of 85% ethanol and 15% gasoline. Typically, E85 has an octane rating somewhere between 100 and 105, which blows away ~93 octane premium gasoline. Actually, E85 is nearly as potent as specialty race gas, but corn-based ethanol is way less expensive. It's becoming easier to access, too. According to the U.S. Department of Energy, "more than 4,200 public E85 stations in 44 states offer high-level ethanol blends."

However, one of the arguably many downsides to E85 is that its heat value, measured in BTUs per gallon, is approximately 27% lower than gasoline. In plain-speak, that means that engines running E85 will burn approximately 27% more fuel. Still, E85 is much cheaper than race gas and octane boosting additives that it kinda offsets the lousy fuel economy. That said, the considerable extra volume of fuel moving through the fuel system — combined with E85's reputation as a moisture magnet and destroyer of rubber fuel components — means that special modifications are required before you can start filling up your tank with corn.

Some mass-market vehicles are equipped from the factory to run E85. However, the peak popularity for such "flex fuel" cars and trucks was reached about 15 years ago. Although E85 was clearly a flop with the general public, what about converting older engine designs for performance sake? For example, Chevy's ubiquitous 350 cubic-inch V8 and its derivatives like the 383 stroker?

If your engine is still sporting an old-school carburetor, it'll need to be modified for the 25% to 30% higher fuel volume that results with E85. Kits are available with everything necessary to convert an existing Holley carb to run E85, but if the idea of tiny screws, squirters, and air bleeds scattered all over the garage floor is daunting, you can also buy a new off-the-shelf E85 carb from multiple vendors in the aftermarket.

If your preference is fuel injection, Holley's Sniper EFI is reportedly E85 compatible with some caveats like periodically flushing the system with gasoline to remove deposits. Other types of EFI, including factory setups, have also been converted to E85 by swapping electronic modules and/or fitting larger fuel injectors. If you're lucky, a complete conversion kit is available. Such is the case for certain small-block Chevy V8s like the L98 with tuned port fuel injection that powered Corvettes and certain F-bodies throughout the 1980s and early 1990s. One seemingly popular resource for such kits is eFlexFuels.

Once the carburetor or fuel injection system has been replaced or modified, it's time to tackle the rest of the fuel delivery system. Beside the obvious need for a larger fuel pump, the entire remainder of the fuel system such as fuel filters, fuel lines, and pressure regulators should be carefully evaluated for both increased fuel flow and the ability to stand up to the alcohol in E85 fuel.

Ethanol fuels are deadly to certain types of rubber. In fact, even controversial E15 with just 15% ethanol content can wreak havoc in vehicles older than approximately 2001. So as you might imagine, the potential for rubber degrading jumps exponentially at 85% ethanol. Sections of rubber fuel line, rubber diaphragms, and gasket seals may all need to be replaced with a different type of rubber that's compatible with ethanol fuels, like Viton. 

Finally, since the alcohol in E85 readily absorbs moisture, water can accumulate and separate inside the fuel tank and fuel system, known as phase separation. To prevent phase separation during periods of lay-up, consider a fuel treatment additive to thwart the process. In summary, if your engine — small-block Chevy or otherwise — is crying out for higher octane fuel, E85 is certainly an option to pricey race gas, but be sure to factor in the upfront cost and labor required.