AFR readings

Mopar Racers Forum

  1. moparstud440

    moparstud440 Well-Known Member

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    For those of you guys running 93 pump gas what AFR range at WOT are you shooting for?
     
  2. PRH

    PRH Well-Known Member

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    I generally tune WOT for best power....... and the A/F ratio is what it is.

    I can’t think of any Mopar engine I’ve ever tested that made the best power with the A/F ratio so lean it would hurt itself.

    If you’re new to using an A/F ratio gauge....... it’s probably a good idea to familiarize yourself with Lambda, and what the gauge is actually telling you, with regards to different fuels.
     
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    • rumblefish360

      rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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      That ^^^^^ is really what your shooting for.
      Nevermind what is and is not perfect according to the world at large.

      But here is a question….. are you able to run at a track to know what works best?
       
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      • moparstud440

        moparstud440 Well-Known Member

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        Car is a drag car only. For years I used to mix Sunoco 110 with 93 pump gas as I had issues on really hot days with the fuel boiling in the carb and creating a stumble when I tried to run just 93. I have since switch my fuel system from a dead head to a by pass system to help keep the fuel cooler and have went back to straight 93. When I was mixing fuel I was doing 2 gal 110 to 3 gal 93 and my AFR reading was 12.7 at WOT. Now with straight 93 it is 13.3. The car does have a snorkel style hood scoop and I didn't used to run an air cleaner, but this year I installed a 9" filter and used a K&N Drag filter (Grey and can pretty much see thru it). I need to install some new plugs to get a good reading on them, but this past weekend the car which is usually pretty consistent was deadly consistent in the 5 runs I made.
         
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        • 92b

          92b FABO Gold Member FABO Gold Member

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          Does your 93 have a blend of ethanol in it?
           
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          • roccodart440

            roccodart440 Well-Known Member

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            Sounds like it wants to be richer to me.
             
          • moparstud440

            moparstud440 Well-Known Member

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            I'm pretty sure it does, I just get it at a regular gas pump and I don't know of anywhere around here that sells ethanol free gas.
             
          • PRH

            PRH Well-Known Member

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            If your gauge is set up for “straight gas”(14.7:1 stoich), then when it’s reading “13.3:1”, that is basically .905 lambda........ which is 12.75:1 if you’re running E10 gas.

            .91 lambda is on the lean end of the normal WOT tuning range for E10.
            Try going a little richer and see if it likes it.
             
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            • rumblefish360

              rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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              I bought an innovative dual 02 sensor set up.
              I’m having trouble getting the dang thing to read most of the time. So far, it’s read the AFR on both sides twice out of the 6 times it even reported anything.

              When it’s working, it at least points me in a direction.
               
            • Hysteric

              Hysteric Well-Known Member

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              Do the spark plugs correspond to the AFR?
               
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              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                12.8-13.5 is where most make best wot power. No definites.
                 
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                • crackedback

                  crackedback FABO Gold Member FABO Gold Member

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                  Grounds and power with any interference makes them go wonky.

                  I direct ground mine to battery
                   
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                  • rumblefish360

                    rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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                    Ditto, right to the battery are both wires. I go through the steps and everything is ether fine and I start the vehicle and get nothing or I get nothing. Just “HTR” that does t go off most of the time.

                    Time to call innovative
                     
                  • crackedback

                    crackedback FABO Gold Member FABO Gold Member

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                    Check the connector at the sensor. Make sure all the wires/pins are engaged fully. They are have a history of not being all in, so to speak. Might have a bad sensor off the go.
                     
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                    • Mattax

                      Mattax Just the facts, ma'am FABO Gold Member

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                      At least two of us have found poor connections at the power plug (used with the dash cigar lighter socket).

                      photos in these two posts
                      Proform 850 dialing it in closer
                       
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                      • 383Scampman

                        383Scampman Well-Known Member

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                        Power : 12.2-1 @ WOT
                        Cruise: 14.6-1
                        using AEM x series
                        18-36" from head , 36: perferred
                         
                      • Mattax

                        Mattax Just the facts, ma'am FABO Gold Member

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                        Thats the truth thumbs_up-gif.gif
                        Using lambda the fuel doesn't real matter.

                        IMO the main use of the logger at the dragstrip is to observe the trends.
                        Examples posted here where I'm looking at how flat the AFR is.
                        Also cudafever does the same here Proform 850 dialing it in closer

                        If I was changing jets I'd be looking to see if the AFR shifted as expected by the jet change.
                        When timing is adjusted, if there is an AFR change - generally that's not a change in Fuel to Air supplied but a change in the burn that effects the left over O2. (Think of it this way, if the AFR curve is fairly flat at WOT, then clearly a there is a pretty wide range of velocity and volumetric flow where the carb is providing the same fuel to air volume.)
                         
                        Last edited: Apr 30, 2022
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