E85 Fuel

In September 2010 Caltex released Bio E-Flex, a blend of petrol and between 70 percent and 85 percent ethanol. It is commonly referred to as E85.

It is for use in vehicles that are specifically designed to run on petrol blends with high ethanol concentrations. These are known as flex-fuel vehicles and are capable of running on petrol alone or varying mixtures of ethanol and petrol. Flex-fuel vehicles are common in Europe and the United States. However the only vehicles currently sold in Australia for which E85 is suitable are Holden’s VE series II Commodore flex-fuel models and a handful of vehicles made by SAAB and Chrysler. E85 offers a genuine alternative to petroleum based fuels for vehicles that have been designed to use it.

To ensure correct engine performance for all seasons the ethanol content of Bio E-Flex will vary between 70 percent and 85 percent.

Fuel containing 85 percent ethanol has about 26 percent less energy content than petrol. This means that when using ethanol blends more fuel needs to be used to travel the same distance. The increase in consumption will depend on the actual amount of ethanol in the mix and the vehicle. Increases in the order of 26 percent should be expected.

The octane rating of Bio E-Flex is 105 RON (Research Octane Number), but this will vary slightly depending on the season. ULP has an octane number of 91 to 93 RON.

Bio E-Flex is typically about 20 cents / litre cheaper than ULP.

When compared with vehicles using normal petroleum products E85 can provide environmental benefits by reducing the amount of greenhouse gas emissions generated.

Caltex will have over 100 sites in Australia selling Bio E-Flex by the end of 2011.

Bio E-Flex will be the recommended fuel for Holden’s range of flex-fuel vehicles.

Fuel containing high concentrations of ethanol is only suitable for vehicles that have been specifically designed for it. The use of E85 in vehicles not designed for a high ethanol content fuel will cause drivability problems, the severity of which will depend on the individual vehicle. It will also cause fuel system damage.

Typical damage will involve deterioration of ‘rubber’ fuel system components such as hoses and diaphragms, and corrosion of various metal components. It may also cause problems with fuel tank sender units and electric fuel pumps. However the type and level of damage will depend on the individual vehicle, the level of ethanol compatible components fitted and the age and general condition of the components.  This damage may take some time to show up.

As E85 also leans the air / fuel mixture by about 30 percent it is possible engine valves could suffer due to higher combustion temperatures.

For the flex-fuel Commodore, Holden introduced stainless steel fuel tanks and lines and different engine valves and valve seats. E85 compatible fuel pumps, hoses and fuel sender units are fitted. The engine management system can identify the amount of ethanol in the tank and adjust the engine management system mapping accordingly. Other vehicles could require other changes as well. 

To find out if your car can use E85 contact your vehicle’s manufacturer or visit FCAI website.

Related topics: Ethanol, Ethanol Blends & octane number, High Octane Fuels