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Running On Corn: Pros and Cons to E85

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Changing over to E85 requires modifying your fuel system to keep things clean. Keep from botching a project before you have the chance to enjoy it.

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E85 is a great tool for forced induction Mustangs. By reducing hot spots in the combustion chamber and cooling the intake charge, E85 is a great way to keep your Mustang running longer with high horsepower numbers.

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What is E85?

E85 is a blend of regular gasoline and ethanol. Generally, it contains about 85% ethanol and 15% gasoline. These amounts may vary, however, as it is blended specifically for the climate in which it is being sold. Due to the higher ethanol content, E85 has a greater resistance to detonation than regular gasoline and will also have a cooling effect on your engine.

Testing E85 for Ethanol Content

If you are running E85, it is always a good idea to test your fuel for ethanol content before fueling up. Testing is very simple to do, and should only take you a few minutes. There are specific and easy to use E85 test kits available. You just add water to the tube at a pre-measured line, add fuel on top of it, and shake it. The water will mix with the ethanol and separate from the gasoline. This will allow you to see what percentage of the fuel is gas and what percentage is ethanol.

What Are the Benefits of E85?

E85 can be perfect for the high horsepower or high compression build, as long as it is readily available in your area. Because of E85s increased resistance to detonation, it allows for more power without the cost of expensive race fuels. Even at low power levels, E85 can also be a much safer fuel than normal pump gas. Much like methanol injection, the alcohol present in E85 is great for cooling down your incoming air/fuel charge. This is incredibly important when you are running a supercharged or turbocharged set up. When air is compressed with forced induction, it causes the air to heat up. The cooler the air charge, the denser it will be and therefore the more power you will be able to make. Aside from cooling the incoming air charge, E85 will reduce hotspots in the combustion chamber that can trigger preignition with regular gas.

Setting Your Mustang Up for E85

E85 has less energy content than gasoline, so it takes more fuel to get the same amount of energy when using E85. Expect your fuel consumption to increase about 20-30% over E10 gasoline. In order to deal with that issue, you may have to upgrade to larger injectors to handle the increased demand. If you do not already have an upgraded fuel pump or a boost-a-pump on your car, one will need to be installed. E85 also has a cleansing effect on fuel systems that have been running regular gasoline, so it would be a good idea to replace your inline fuel filter before the first tank of E85, and again after another couple tanks. Doing this ensures that your fuel system will remain clean. If your Mustang was made over 20 or so years ago and has rubber fuel lines, it is a good idea to replace these beforehand because the E85 will cause degradation of your fuel lines.

Is E85 Right for Me?

  • E85 is a blend of ethanol (85%) and gasoline (15%)
  • Ethanol cools your engine more so than full gasoline would
  • Testing/keeping the correct mixture in your fuel tank isn’t difficult
  • E85 reduces the risk of detonation because of its cooling properties
  • This cooling aspect makes running superchargers or turbochargers safer
  • Converting to E85 may warrant an entire fuel system upgrade, since E85 has less potential energy than gasoline
  • E85 isn’t a norm as far as fuel goes, so depending on the area you live in E85 could be completely practical or impossible

If there are several E85 stations in your area and do not use the car for road trips, E85 is a great choice. Since it is not readily available across the whole country, it is better suited for people that remain local, otherwise you might find yourself stranded with no fuel. An alternative is to have both a 93 octane tune for travel, and an E85 tune for local or race use. If you have a car with forced induction or a compression ratio over 11:1 or 12:1, E85 would be a great choice for you. Someone running lower compression ratios on a naturally aspirated engine would see some small benefits with E85, but not enough to justify the added fuel consumption.

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