Edmunds Answers



  • karjunkie 10/19/08 8:11 am PST

    Yes, you can burn pure ethanol or hydrated ethanol in a modern fuel injected car, but you will have cold starting problems. That is why most flex fuel vehicles use a mix of gasoline and ethanol (E85) that has 15% gasoline. Prior to the development of electronic fuel injection (EFI) and computerized engine management, the lower energy content of ethanol required that the engine carburetor be rejetted to permit a larger volume of fuel to mix with the intake air. EFI is able to actively compensate for varying fuel energy densities by monitoring the oxygen content of exhaust gases. However, a standard EFI gasoline engine can typically only tolerate up to 10% ethanol and 90% gasoline. Higher ethanol ratios require either larger-volume fuel injectors or an increase in fuel rail pressure to deliver the greater liquid volume needed to equal the energy content of pure gasoline. Since 1973, Brazil has manufactured cars using 100% hydrated ethanol (95% ethanol + 5% water) in modified Otto cycle motors with no problem so it is possible to do what you suggest. You will also have to remove and clean out the fuel tank and replace the fuel filter as ethanol is an extremely powerful solvent that will clog up your fuel system if it was originally run on gasoline.The bottom line is that you have to weigh the cost of conversion and the lower MPG (around 70% of gasoline) against your cost savings for the ethanol..

  • sprescott 10/09/09 9:01 pm PST

    I wouldn't risk it. There are some ruber seals o rings and other components that may react different to alcohol. Also with todays computerized cars calibration is critical.gass and alcohol have significant flash and burn caractoristics. Research this fully,from many sources. The flex fuel concept in the market place is still ,so we in the field are going through a learning curve and still gathering knowledge.

  • figuwx 06/21/11 4:34 pm PST


    what you are talking about is illegal from an EPA perspective.

    With that said,

    I used to do high performance supras. Currently the high horsepower folks love it.

    What was needed to to a Flex-fuel conversion was the flex-Fuel sensor, an EMS/Engine computer capable of adjusting injectors pulse width and ignition timing based on E% reading off the flex-fuel sensor, injectors to support power level requirements and of course fuel pumps.

    All in all. Not an inexpensive retrofit if doing it right.

    careful with those "kits". Unless the OEM computer has been designed with Flexfuel in mind. The OEM computer does not have the necessary +- AFR adjustments (usually 15% hence why E10 works great) to go from E10 to E85 without killing the engine.

    You have been warned!


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