E85

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E85 is a blended fuel composed of 85% Ethanol and 15% gasoline. It requires a a vastly richer mixture then straight gasoline. So an upgraded fuel delivery system is required. As of now in most countries, it will cost more per distance traveled than straight gasoline. Ethanol, being a form of alcohol, has less energy per litre -- and as with any high-octane fuel, E85 or petrol, the engine needs different tuning to take advantage of it.

Overview

Any gasoline engine can run E85 with a carburetor change and (in some cases) larger fuel lines and a higher capactity fuel pump.

The power will be down about 15%. And fuel range will be cut in half.

Modifications for E85

• Carb jets replaced with bigger ones
• Tank and fuel lines should be lined (but not required)
• fuel lines replaced with larger ones (in some cases)

To make effective use of E85, the compression ratio can be raised. However, change from 9.0 to 12.0 is need to make the same power as on straight gasoline.

A turbocharged engine can be more easily modified. Raise the boost to make up the lost power - and then gain some more. Alcohol fuel has a significant cooling effect and so permits higher boost levels.

Fuel Economy

With the same size fuel tank, E85 will travel fewer miles.

E85 is about 70% the energy per volume of gasoline and so will require about 30% higher fuel flow.

Octane and compression ratio

The E85 Australia have been tested with a RON anywhere between 100-110. It's burn rate is around 30% more then 98 RON fuel.

In USA, Octane rating of E85 is 94-96 (R+M)/2, though it is commonly marketed as 100. The Chevy hot rod crowd say you can generally only run 13.5:1 ratio with E85, so it seems consistent with the higher number.

Pump gasoline 98 octane can do 12:1 already, depending on the engine design

Corrosive effect

If any water vapor gets into Ethanol, it creates a corrosive acid, which can eat through rubber parts.

For this reason a sealed fuel system is used, such as all modern cars use anyways for emission control purposes.

Ethanol absorbs moisture from the air so must be kept air tight when in storage. Steel fuel lines would be fine. There have been some stories about the rubber lines eating out, while theoretically true, there are people that gave been running rubber lines with no problem.

You also need to consider a fuel pump that is compatible with alcohol, which has seals, diahpragms and valves resistant to alcohol.

Environment

Burning any hydrocarbon fuel releases COx to the atmosphere.

Corn-based methanol is not cost-effective except with government subsidies. A concern is the replacment of food crops with fuel crops, possibly causing food prices to rise.

Sugar cane-based ethanol is used in some countries.