Ethanol Fuel and Vintage Vehicles - Ethanol Education

Imagine for a moment that you're the quintessential hands-on hobbyist. You've noticed that your Pontiac hasn't run its best as of late and all indications point to its Rochester Quadrajet as the culprit. After removing the carburetor from the engine, you place it on the workbench and begin disassembly for a closer inspection.

Upon removing the fuel filter housing, you immediately notice that the filter's pleats are caked with crud. You then remove the carburetor's air horn and find the needle-valve's rubber tip is hard and grooved and the accelerator pump swimming in its bore. Wait a minute--what's going on here? you ponder. I put a fresh rebuild kit from the local parts store in it a couple of years back, and I haven't driven the car much since!

A quick trip to the nearest parts store yields the necessary components to get your Quadrajet back in working order. During installation, you compare said components to the replacements and find that the new accelerator-pump cup is a different color and the needle-valve's tip is soft and somewhat shiny. Without another thought, the new units are dropped in and the Quadrajet is placed back in service. It again operates flawlessly. A job well done!

So what happened? Welcome to the world of ethanol-blend fuel. Ask around and you'll likely find ethanol used as the scapegoat to any number of driveability issues and/or mechanical failures, but its presence in modern fuel isn't as catastrophic as some lead us to believe. Follow along as we learn about ethanol and its effects on specific fuel-system components, and hear one expert's opinion on how to prepare our vintage vehicles for it.

What Is Ethanol?
Ethyl-alcohol (ethanol) is a high-octane grain alcohol that's been successfully used as fuel for decades. It's among the best-known worldwide renewable fuels, i.e., fuel produced from plant or animal products. In the U.S., ethanol is most commonly extracted from the starches in corn, and the extraction process is amazingly similar to that used by moonshiners, who produce alcohol for human consumption.

Corn kernels are first ground into coarse flour to expose its starch. The flour is then mixed with water to create mash and the mash is heated to liquefy the starch. Enzymes are then added, which convert the starch into a simple sugar. Yeast is introduced to the mixture, and it's allowed to ferment for as long as 50 hours, as the sugar converts into 200-proof grain alcohol. The alcohol is then distilled out, denatured, and sent to a refinery, where it's blended with gasoline and sent to service stations for public use.

Ethanol As A Fuel
When the first internal combustion engines were built during the 1800s, they were designed to operate on a variety of fuels, from kerosene to gasoline,; ethanol was among them. Ethanol's octane rating of 113 makes it an ideal fuel for high-compression engines, but because it contains so much oxygen, less of its molecular makeup is consumed during combustion. Ethanol subsequently produces only two-thirds as much energy per volume as crude-based gasoline.

Until the mid-'70s, the per-barrel cost of crude oil was relatively low, so domestic refiners could produce gasoline at an affordable cost to consumers. When combined with the fact that gasoline is a more efficient energy source than ethanol, it's easy to see why many refiners abandoned ethanol research long ago. Some continued blending a small percentage of it with gasoline to boost its advertised octane rating a few points, however.

As the cost of crude oil rose sharply during the '70s, consumers saw an industry-wide resurgence of ethanol-blend fuel. The Environmental Protection Agency (EPA), which regulates the additives domestic refiners can blend with gasoline, determined that a low-level blend wouldn't harm engine operating and emissions systems, and yet would burn cleaner and add volume to gasoline. An ethanol cap of 10 percent was then imposed, yielding E10 fuel.