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Thread: AFR with Meth & C16?

  1. #1

    Default AFR with Meth & C16?

    If you have a boosted engine on C16 and spray straight methanol (Alky Control dual nozzle kit) what AFR ratio do you command in the Holley?

  2. #2


    My issue with it, is if you put two different fuels in an engine with different stoichiometric AFRs, what ratio do you command in the Holley A/F Ratio table? Maybe I’m over thinking this.
    M1 is 6.45.
    C16 is 14.7.

  3. #3
    Join Date
    Nov 2014
    Ont. Canada


    A WBO2 sensor is a Lambda sensor. Stoichiometric for all fuels is Lambda 1. If you wanted to be 10% rich, you'd be at Lambda .9, 10% lean would be Lambda 1.1. When you tune for a Stoichiometric of 14.7 AFR, it's because you applied a multiplier of 14.7 to Lambda. If you wanted 10% rich on the Gasoline scale (.9 Lambda x 14.7 = 13.23 AFR). With a Lambda of 1 for all fuels, the only thing that changes is the amount of fuel it takes to get to Lambda 1. So if you are comfortable using the scale for Gasoline, just keep using it. 15% rich would be .85 Lambda x 14.7 = 12.495 AFR. I hope I explained it well enough for you to understand.

  4. #4


    ^^^ This. I wish Holley would have an option to display Lambda. Would make it much easier for people running "weird" fuels.

  5. #5


    Here's a picture of what 81TransAm guy said. Look at Gasoline AFR at 12.5, then look at meth at 5.44 and Lambda is .85 for both.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Stoichiometric to Lambda.jpg 
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  6. #6


    Command richer than what you would do on straight C16, Gasoline scale. That way the Closed Loop does not pull gasoline as methanol is introduced.

    TBH methanol isn't needed with C16 until intake temps get really hot. Most people overdo it and end up with a lot less power.

    I had one guy on E85 spray a lot of methanol, even though his intake temps were very good. I told him to turn it off and he picked up 3 tenths.

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