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E85/100 octane tune

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  • E85/100 octane tune

    I was looking at running 100+octane or E85. I have two options:

    Option 1:
    I called JWT and they said I'd have to bring my car in and they would dyno/tune my car for a price not yet finalized but no more than a standard JWT rom tune.

    Option 2:
    Calumsult, wideband, and knock light and attempt to tune myself

    Addicted to Motorsports

  • #2
    Well do you know anything about tuning? If you want an E85 tune, I hope you have some pretty big injectors.

    We (RS Enthalpy) would have to bring the car in for an E85 tune if we touched it at all. We do mail-order 100 octane tunes all the time, though.
    She's built like a Steakhouse, but she handles like a Bistro.


    • #3
      I'm hoping to make this my tuning experience. Obviously I wouldnt try to tune for the E85 from the get go. I'll optimize the fuel maps with 91/93 first and make sure I familiarize myself with tunerpro, calumsult, and logworks before I jump into timing adjustments and tuning for E85.

      Are you saying the stock 270 injectors wont flow enough for a KA w/ bolt on's?
      Addicted to Motorsports


      • #4
        270's on E85 won't flow enough for much of anything. They're fine on regular gasoline though. For E85 I'd look at 370's for an NA KA.
        She's built like a Steakhouse, but she handles like a Bistro.


        • #5
          I wonder what makes JWT think they can make the 270's work with E85. Looks like I'll be stuck buying 100+octane for events.
          Addicted to Motorsports


          • #6
            Probably because you can just jack the base fuel pressure way up. I forgot about that one. Especially on an NA setup. Run the stock 270's, buy and adjustable FPR (which will cost 4 times as much as a used set of 370's) and start from there.
            She's built like a Steakhouse, but she handles like a Bistro.


            • #7
              You can get adjustable FPRs for like 50 bucks?


              • #8
                Nope, I told them that's not within the SCCA STS rules.

                3. Fuel pressure regulators may be replaced in lieu of electronic
                alterations to the fuel system. It is not permitted to electronically
                modify the fuel system AND replace a fuel pressure

                Correct me if I'm wrong but a 270 @ 4 bar would be aprox 315. Doesnt seem like that would be able to run E85 considering the marginal differece. I wonder if i could use the stock fuel map, bump the fuel pressure w/ FPR and only tune timing w/ a rom tune? 270, 315(45), 370(55), 30%of 270 is 80 ahh forget it I'll run 100 octane.
                Last edited by ckcadavona; 03-20-2008, 11:53 AM.
                Addicted to Motorsports


                • #9
                  Well besides all that, I think it would be hard to convice a sanctioning body that you "only tuned the timing and didn't touch the fueling" inside your tuned ECU. Injectors and a ROM tune is the right way to go. I'm really not intimately familiar with how much more E85 you need versus regular gasoline. I think it's 30-40% more fuel, right? In that case, just pop some 370's in there with a stock ECU and try that out. 370's are 37% bigger than 270's.
                  She's built like a Steakhouse, but she handles like a Bistro.


                  • #10
                    You need about 20-27% more injector for E85 IIRC - they change the blend around summer to winter to help with cold starting(i.e. some places it gets down to about E75, some places it stays E85 year round).

                    I plan on trying to run E85 on my car sometime soon, but I don't know how far I'll go with 740s. I'll probably run out of injector before I get to 18 psi.
                    '18 Chevrolet Volt - Electric fun hatch for DD duty!

                    DefSport Koni Sleeve and Spring Perch Buy!!!


                    • #11
                      Please be aware of the flushing of fuel systems that happens with E-anything the alcohol cleans out the crap in your tank/lines and your fuel filter gets to deal with it. You'll need to change your fuel filter every ~500-100 miles for the first bit to maintain flow, and if you are near the ceiling of your pump's capacity (within 25% ) lets not neglect that either.

                      DIY-EFI mailing list came up with about 25% correction for E-85. so 3.75 Bar should about get you where you want to be...sort of. If any one wants any more info I can E-mail them the pertinent topics from the mailing list.

                      I am SKULLWORKS


                      • #12
                        3.75 bar is not 25% more fuel. It's 11% more than 3 bar. It's squareroot (new pressure/old pressure). You should also take into account that the factory reg with a high flow pump will keep you at 3.5bar base fuel pressure.
                        She's built like a Steakhouse, but she handles like a Bistro.


                        • #13
                          I know this post is a bit old, but I have a lot of E85 tuning experience. We've been pushing it a lot around here (KS).

                          You really need bigger injectors and a new tune from the ground up. Ethanol doesn't burn like regular 100octane fuel does and requires different timing maps.

                          Also, the fuel isn't an even 30% increase across the board like the numbers on paper would tell you. First off, most stock tunes are too rich in the top end anyway, and with ethanol, you don't need to run as high of a Lambda as you do with pump gas. From my experience, you generally need AT MOST 30% fuel increase in the mid-range from the stock settings, and then usually down to 10-20% increase in the top end. This should yield you a pretty flat lambda across the board.

                          Another thing to remember is the because of the way the ethanol burns you can run MUCH leaner lambda's at part throttle than you can with gasoline. Most of my tunes are only adding 5-15% fuel at part throttle, and I usually turn off the closed loop as it actually causes you to consume MORE fuel than you do with a straight tune in part throttle. (the O2 sensor aims for stoich. which isn't best for fuel economy).

                          As for timing, it's totally different, the main difference being the you are generally going to run more timing everywhere, and are going to want to add a little timing once you pass peak TQ, and then ramp the timing up more once you pass peak HP and the revs climb. The reason for this is that ethanol burns slower than gasoline, and as such the flame front propagates to slowly (compared to gasoline) in the higher revs, which is causes you to have to add timing to keep the power up.

                          The main advantage that I've found with it is that detonation is basically eliminated in every car that I've tuned with it. This is applicable for up to 300whp. Over that, I don't have any experience with it yet.