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Thread: Return of the Twincharge: 2/18 - Datalog comparisons!

  1. #31
    SLi nOOb
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    Questions (and let me know if I'm asking the right or wrong ones):

    1. Does each forced induction appendage (turbo and supercharger) have their own unique tunes, considering that they operate and generate power different ways? If they're working together, how will that particular tune pan out for them?

    2. Will they still be able to work together as one in the midrange rpm area like your last twin setup? With the way you have the intake piping set up, I can't imagine the Supercharger getting in the way of the turbo psi pressure once it gets going.

    3. Have you thought about a destroker EJ25 of some kind? This way, you could attain the high rpm and relieve some stress of forced crank acceleration, and cram even more air in those chambers without the aforementioned added stress of trying to get the 257 crank to spin high.

  2. #32
    SLi O.G. anothernord's Avatar
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    Quote Originally Posted by Alucard View Post
    Questions (and let me know if I'm asking the right or wrong ones):

    1. Does each forced induction appendage (turbo and supercharger) have their own unique tunes, considering that they operate and generate power different ways? If they're working together, how will that particular tune pan out for them?

    2. Will they still be able to work together as one in the midrange rpm area like your last twin setup? With the way you have the intake piping set up, I can't imagine the Supercharger getting in the way of the turbo psi pressure once it gets going.

    3. Have you thought about a destroker EJ25 of some kind? This way, you could attain the high rpm and relieve some stress of forced crank acceleration, and cram even more air in those chambers without the aforementioned added stress of trying to get the 257 crank to spin high.


    There's no way to change tunes with the stock WRX ECU, so I have to have one tune for everything. The supercharger simply lets the engine get more airflow at low RPM, so, in this case, for example, I just have to make sure the cells for the high-load, low-rpm have good timing and air-fuel values. They both give air to the engine, so it's just a matter of what load conditions they give air to the engine.

    The supercharger most definitely creates a restriction to the turbo above a certain point. The turbo will, very quickly, outflow the supercharger, so there isn't very much of the operating range where they can work in true series mode. The turbo in this setup is much bigger than my previous one.

    The valvetrain is really the limiting part of this engine for high-rev operation. All the EJ crankshafts have pretty similar inertias, if that's what you're talking about, so they don't really care as much about how fast they're accelerated. As long as oil clearances and flow rates are there, all is well on the bottom end. Plus, these cams don't really offer enough duration at high RPM's to create power very efficiently. And my tach only goes till 7,000 anyway.

  3. #33
    SLi O.G. anothernord's Avatar
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    Alright folks! I finally got around to working on the "crossover code", which controls the bypass and SC clutch during WOT.

    Basically, when the throttle is floored, and the manifold pressure is below the setpoint, the SC turns on, and bypass closes. As soon as the turbo starts trying to take over, the pressure will go above the max that the SC provides, and the system will disconnect the blower and open the bypass.
    Last edited by anothernord; 02-29-2016 at 10:32 AM.

  4. #34
    SLi Lurker nepbug's Avatar
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    Nice, but the video is so shaky and short that it's hard to catch anything.

    You can't leave this thread without a good quality video.

    Sent from my VS985 4G using Tapatalk

  5. #35
    SLi O.G. anothernord's Avatar
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    You can see that the boost jumps up right away with the SC, then increases more after it opens the valve!

    Datalog results:



  6. #36
    SLi O.G. anothernord's Avatar
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    Here's a still crappy but better video. Low boost, ~13 psi.


  7. #37
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    Quote Originally Posted by anothernord View Post
    You can see that the boost jumps up right away with the SC, then increases more after it opens the valve!

    Datalog results:


    Do you have a boost plot or a dyno plot? I'm very interested in your results. Sent you a very long PM about a similar (potential) build.

  8. #38

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    awesome build

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