7875 + 5.9 + E85 + Megasquirt

Forced Induction Mopar

  1. subcom

    subcom Well-Known Member

    Messages:
    1,543
    Likes Received:
    795
    Joined:
    Sep 17, 2010
    Location:
    South Florida
    Local Time:
    2:58 PM
    I thought that too, but we completely disabled it by setting the tpsdot threshold to like 500%. My tuner thought it was either FPR or my E85 isn't E85 but maybe less making it richer, but I've measured it and it's E85 on the money. And as far as AFR control, it's very minimum under boost. 10% I believe is what we have it set at to force it to honor what's commanded in the VE table and not try to adjust to meet the AFR targets. It seems that turning down my base fuel pressure might work, but that will throw the whole tune off, so don't want to go that route. Thanks!
     
    • Like Like x 1
    • turbovan

      turbovan Well-Known Member

      Messages:
      206
      Likes Received:
      126
      Joined:
      Feb 25, 2016
      Location:
      Phx,AZ
      Local Time:
      12:58 PM
      Are you using meth injection on these runs?
      What do the intake air temps look like when it’s going rich?
      You’ve been trying to work this out for a while…that’s gotta be frustrating!
       
    • TT5.9mag

      TT5.9mag Two atmospheres are better than one

      Messages:
      2,610
      Likes Received:
      2728
      Joined:
      May 5, 2016
      Location:
      So cal
      Local Time:
      11:58 AM
      Usually when spikes or dips occur in fuel pressure on the logs I start to look at injector duty cycle to see what they’re doing.
       
    • TT5.9mag

      TT5.9mag Two atmospheres are better than one

      Messages:
      2,610
      Likes Received:
      2728
      Joined:
      May 5, 2016
      Location:
      So cal
      Local Time:
      11:58 AM
      Are your injectors scaled correctly?
       
    • TT5.9mag

      TT5.9mag Two atmospheres are better than one

      Messages:
      2,610
      Likes Received:
      2728
      Joined:
      May 5, 2016
      Location:
      So cal
      Local Time:
      11:58 AM
      Another random thought. How large is your return line?
       
    • Hemirunner

      Hemirunner Well-Known Member

      Messages:
      457
      Likes Received:
      321
      Joined:
      Jul 20, 2011
      Location:
      Down South
      Local Time:
      1:58 PM
      Where did you order the connectors and boots from?
       
    • subcom

      subcom Well-Known Member

      Messages:
      1,543
      Likes Received:
      795
      Joined:
      Sep 17, 2010
      Location:
      South Florida
      Local Time:
      2:58 PM
      Not sure what this is in the context of Megasquirt or tuning in general but I'll definitely research it. Thanks.
       
    • subcom

      subcom Well-Known Member

      Messages:
      1,543
      Likes Received:
      795
      Joined:
      Sep 17, 2010
      Location:
      South Florida
      Local Time:
      2:58 PM
      8AN Feed and return (1/2"). I've thought about the return being a bottleneck somewhere, but not sure where. I might check my connection at the return on the gas tank to see how it looks.
       
    • subcom

      subcom Well-Known Member

      Messages:
      1,543
      Likes Received:
      795
      Joined:
      Sep 17, 2010
      Location:
      South Florida
      Local Time:
      2:58 PM
      Ebay vendor named "uni_mall"
       
    • TT5.9mag

      TT5.9mag Two atmospheres are better than one

      Messages:
      2,610
      Likes Received:
      2728
      Joined:
      May 5, 2016
      Location:
      So cal
      Local Time:
      11:58 AM
      Scaling is basically telling the ecu an accurate flow capability of your injectors. The only way to know the correct info is to have the injectors flow tested. Some aftermarket injectors come with test data, good ones at least do. In megasquirt it’s done with “req fuel” and “dead time”. Those parameters along with entering the correct size (ie 1000cc or 750cc or whatever yours are) must be stupid accurate. If you have 1000cc injectors and they flow 993cc at your fuel pressure and your ecu thinks they flow 1000 then all the calcs will be off.
       
    • TT5.9mag

      TT5.9mag Two atmospheres are better than one

      Messages:
      2,610
      Likes Received:
      2728
      Joined:
      May 5, 2016
      Location:
      So cal
      Local Time:
      11:58 AM
      Yea -8 is plenty big as long as there’s no bottle neck somewhere. In your log with the vacuum reference connected I see 7.3 psi of boost and 62.1 psi of fuel pressure. If your base FP is 58 and your reg is 1:1 you should have 65.3 psi so the reg is not bumping it up or you don’t have enough fuel pump. Maybe the MS is seeing this and trying to compensate.
       
      • Like Like x 1
      • subcom

        subcom Well-Known Member

        Messages:
        1,543
        Likes Received:
        795
        Joined:
        Sep 17, 2010
        Location:
        South Florida
        Local Time:
        2:58 PM
        Ruled this out. I have about a 6” rubber hose at the end of my return line. I took it off to inspect to see if it had a kink or collapsed or was rotten but it looked fine.
         
      • subcom

        subcom Well-Known Member

        Messages:
        1,543
        Likes Received:
        795
        Joined:
        Sep 17, 2010
        Location:
        South Florida
        Local Time:
        2:58 PM
        Gotcha. Mine are decapped LS Flex fuel injectors and they did come matched with flow data but not dead time so my req fuel may not be perfect. Mine are set at 1.25 . From what I’ve read dead time plays a big role at idle and cruise but is less important under WOT/boost.
         
      • Turbosmblk

        Turbosmblk Member

        Messages:
        15
        Likes Received:
        10
        Joined:
        Mar 12, 2021
        Location:
        Alabama
        Local Time:
        1:58 PM
        What is the timeline from when it dips into the 10s until you lift? To me it seems like it’s longer than a split second. If we’re talking a matter of 3-5 seconds to me it looks like fuel needs to be removed from the VE table
         
      • subcom

        subcom Well-Known Member

        Messages:
        1,543
        Likes Received:
        795
        Joined:
        Sep 17, 2010
        Location:
        South Florida
        Local Time:
        2:58 PM
        That seems to be the case. I went back and looked at my previous tunes and at one point my tuner added a lot of fuel to the VE table in the areas where I'm going rich. I've been slowly removing fuel in those cells and AFR is falling into place. I've also wired my 2-step and started testing it. It still needs some tuning since I'm now getting into parts of the VE table that have never been touched but I'm able to make about 3psi on the foot brake at 2300rpm.
         
        • Like Like x 1
        • turbovan

          turbovan Well-Known Member

          Messages:
          206
          Likes Received:
          126
          Joined:
          Feb 25, 2016
          Location:
          Phx,AZ
          Local Time:
          12:58 PM
          Glad you’re finally getting the fuel dialed in!

          Do you have any plans for trying to drop your 60ft next time you go to the track?
           
        • subcom

          subcom Well-Known Member

          Messages:
          1,543
          Likes Received:
          795
          Joined:
          Sep 17, 2010
          Location:
          South Florida
          Local Time:
          2:58 PM
          The plan is to try and leave a little harder off of the 2-step. No suspension changes just yet. Want to see what I can get out of the current setup. We have one last TNT this year in a couple of weeks I hope to make.
           
        • TT5.9mag

          TT5.9mag Two atmospheres are better than one

          Messages:
          2,610
          Likes Received:
          2728
          Joined:
          May 5, 2016
          Location:
          So cal
          Local Time:
          11:58 AM
          Pull timing out of it on the two step. It puts a lot of heat in the exhaust and spools the turbo. You’ll make more than 3 psi. Although foot braking you probably can’t hlod back much more than that.
           
        • turbovan

          turbovan Well-Known Member

          Messages:
          206
          Likes Received:
          126
          Joined:
          Feb 25, 2016
          Location:
          Phx,AZ
          Local Time:
          12:58 PM
          Hopefully that hits the tires harder for you. What does your converter flash to?

          If you can get some video(especially slow motion) the guys in the Mopar Racers Forum are pretty great at providing suspension feedback.
           
          Last edited: Dec 7, 2021
        • turbovan

          turbovan Well-Known Member

          Messages:
          206
          Likes Received:
          126
          Joined:
          Feb 25, 2016
          Location:
          Phx,AZ
          Local Time:
          12:58 PM
          I haven’t messed with the 2 step on mine yet, how much timing are you allowing it to pull? Can it go negative? My previous MSD 2 step would build 5psi at 2500 in neutral so I wouldn’t think the car would be any more difficult to hold back than 0psi at the same rpm.
           
        • subcom

          subcom Well-Known Member

          Messages:
          1,543
          Likes Received:
          795
          Joined:
          Sep 17, 2010
          Location:
          South Florida
          Local Time:
          2:58 PM
          "Soft Limit Retard" - drops timing to 1 degree in my settings. It does allow you to go negative on that setting. My converter flashed to 3500rpm.
          Screen Shot 2021-12-07 at 12.03.24 PM.png
           
        • TT5.9mag

          TT5.9mag Two atmospheres are better than one

          Messages:
          2,610
          Likes Received:
          2728
          Joined:
          May 5, 2016
          Location:
          So cal
          Local Time:
          11:58 AM
          Not sure how far you can go on MS in the negative but I’m not familiar enough with it. On the Holley stuff with a transbrake and big power we’ve set as low as 7 degrees on the 2step and leave on about 8 psi.
           
        • subcom

          subcom Well-Known Member

          Messages:
          1,543
          Likes Received:
          795
          Joined:
          Sep 17, 2010
          Location:
          South Florida
          Local Time:
          2:58 PM
          Drove the Valiant down to the track last night for some TnT. Made 3 passes. The first and last aren’t really worth mentioning cause I broke the tires loose on both and ran a 7.90 and a 7.60. The 2nd pass I did a smoky burnout and got the car to hook well coming out of the hole even though it spun a little in 2nd and ran a 7.05/103mph.
          This was at about 11-11.5psi. I’m pretty much out of injector if I go above that. Duty cycle was getting into the 90% range at that point. This was launching off of the 2-step. Nothing crazy but I was building about 2psi on the line and quickly hitting 10psi coming off the line.
          6C1D350B-42F8-4B78-8A85-6469A928DFE1.jpeg
           
          • Like Like x 3
          • subcom

            subcom Well-Known Member

            Messages:
            1,543
            Likes Received:
            795
            Joined:
            Sep 17, 2010
            Location:
            South Florida
            Local Time:
            2:58 PM
            I also got a Dragy. Pretty accurate and a little more generous to me on that 7.05 run.
            90A2143C-2E4F-4537-838E-40BDCD956763.png
             
          • dusted

            dusted FABO Gold Member FABO Gold Member

            Messages:
            632
            Likes Received:
            610
            Joined:
            Sep 24, 2006
            Location:
            Creedmoor, NC
            Local Time:
            2:58 PM
            So close to a 6 second run! Really good mph. Didn’t it run a 6.90ish before or am I thinking of someone else?
             
          1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
            By continuing to use this site, you are consenting to our use of cookies.