"Boost per throttle position" on high boost engines?

Discussion in 'Car Modding' started by Oskar, Jun 21, 2023.

  1. Oskar

    Oskar Registered

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    I'm struggling to get a high boost engine to have descent throttle response.
    At half throttle the engine will be making no boost and 300hp, but then climb up to full boost and produce 1000hp with the same throttle position (and 1500hp with throttle at 100%).
    As far as I understand the base engine sim doesn't have a boost target per throttle position possibility. Even though you can have multiple target boost pressures, just not selectable by the throttle %.
    So my thinking was to try and bleed off the boost with the blow off valve. But this seems to do nothing. I've even tried settings as high as
    DumpValve=(20000,10000,1.5)
    Which according to the notes in the physics calculator file should be more than 1000x more than needed to bleed off all "excess" boost as a function of pressure drop over the throttle plate.
    Is there a known bug, or something that isn't implemented with the dump valve?
    Or some simpler way to do what I want?
    Basically at 50% throttle, the boost target should be 50% of full boost.
     
  2. Lazza

    Lazza Registered

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    My foray into turbos was too many years ago to help solve your issue... but.. are you sure your DumpValve line is in Pascals? You're not expecting it to be kPa? (hmm.. is that the idea? lol)
     
    Last edited: Jun 21, 2023
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  3. Oskar

    Oskar Registered

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    According to the comment in the physics calculator file
    "// throttle body pressure drop to fully open dump valve, same for fully closed, dump mass flow per Pascal"
    And I tried bumping the flow up over 1000x more than what would seem reasonable. Meaning that should compensate for any unit conversion bug in the code (compared to the comment). But seems to do nothing.
    Doing some hack to get the throttle position mapped for boost target would work also, I just don't know if that's even possible in rF2 somehow.
    Wonder if the -80's turbo F1 mod people have any solution to this? Or most likely just works the same as what I'm running into :D
     
  4. Oskar

    Oskar Registered

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    Update:
    The DumpValve function does definitely do something. Putting in some crazy numbers does change how the engine boosts. But 100% clear that there is some bug with how it works. Still haven't figured out how to tune it though.
    Hopefully will get that figured out tomorrow.
     
  5. Oskar

    Oskar Registered

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    Update:
    ok, with some more repeatable testing... not so sure that the DumpValve settings actually do anything again. Just not enough access to engine data to say what's happening (if anything).
    How could I get a dev to comment on the DumpValve? (or allow the game to map boost target to throttle position)
     
  6. Oskar

    Oskar Registered

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    Update:
    I think I figured out another way to get rid of the boost creep issue at part throttle. Remove it completely by some type of "anti-lag" setup, so that the engine is always at the boost target.
    Should be doable by totally fudging the turbo values. But without that, maybe with wacky mixture map values?
     
  7. Oskar

    Oskar Registered

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    Update:
    1: DumpValve does in fact work. There just seem to be some coding limiting when it's "used".
    2: Tuning extremely unrealistic turbo values to get full boost from 5% throttle upwards solves the part throttle "boost-creep" throttle response runaway issue. Not in a realistic way though. But you can pretend that you have anti-lag instead :D
     
  8. Navigator

    Navigator Registered

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    Spend a lot of time in the past on turbo's; I'm curious now, may I see your engine file?
     
  9. Oskar

    Oskar Registered

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    Turbo section of what I was working on to start with:
    Code:
    TurboInertia=1.3e-3
    TurboFriction=(0.002,2.5)
    TurboStaticFrictionWatts=200
    TurbineFlowTable=(0,0.032)
    TurbineFlowEffects=(1,0.1)
    TurbineFlowEffects=(1.022,0.13)
    TurbineFlowEffects=(1.044,0.16)
    TurbineFlowEffects=(1.066,0.19)
    TurbineFlowEffects=(1.088,0.22)
    TurbineFlowEffects=(1.11,0.25)
    TurbineFlowEffects=(1.132,0.28)
    TurbineFlowEffects=(1.154,0.31)
    TurbineFlowEffects=(1.176,0.34)
    TurbineFlowEffects=(1.2,0.37)
    TurbineFlowEffects=(1.225,0.4)
    TurbineFlowEffects=(1.26,0.44)
    TurbineFlowEffects=(1.3,0.48)
    TurbineFlowEffects=(1.35,0.52)
    TurbineFlowEffects=(1.45,0.57)
    TurbineFlowEffects=(1.62,0.61)
    TurbineFlowEffects=(1.9,0.65)
    TurbineFlowEffects=(2.8,0.7)
    TurbineFlowEffects=(3,0.7)
    IntakeVolumePerRevolution=1.9868
    ExhaustBaseProperties=(1175,1180,0.187,0.222,-3.35e-5)
    CompressorTable=(10504,0.10)
    CompressorPressRatio=(0.5)
    CompressorEfficiency=(0)
    CompressorSurgeLineFlow=0
    CompressorPressRatio=(1.01,1.04,1.03,1.02,1.006,1.001,1,1,1,1,1,1,0.99,0.98,0.97,0.96,0.95)
    CompressorEfficiency=(0.25,0.45,0.59,0.45,0.4,0.35,0.3,0.25,0.2,0.15,0.1,0.05,0,0,0,0,0)
    CompressorSurgeLineFlow=0.019
    CompressorPressRatio=(1.02,1.08,1.09,1.08,1.07,1.045,1.02,1.001,1,1,0.995,0.99,0.985,0.98,0.975,0.95,0.9)
    CompressorEfficiency=(0.25,0.45,0.59,0.45,0.4,0.35,0.3,0.25,0.2,0.15,0.1,0.05,0,0,0,0,0)
    CompressorSurgeLineFlow=0.037
    CompressorPressRatio=(1.03,1.115,1.15,1.15,1.13,1.1,1.065,1.025,1.002,1,1,1,1,1,1,1,1)
    CompressorEfficiency=(0.25,0.45,0.59,0.45,0.4,0.35,0.3,0.25,0.2,0.15,0.1,0.05,0,0,0,0,0)
    CompressorSurgeLineFlow=0.058
    CompressorPressRatio=(1.43,1.43,1.44,1.43,1.4,1.33,1.22,1.07,1.025,1.008,1.002,1,1,1,1,1,1)
    CompressorEfficiency=(0.2,0.51,0.53,0.66,0.71,0.68,0.56,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2)
    CompressorSurgeLineFlow=0.08
    CompressorPressRatio=(1.72,1.72,1.72,1.73,1.72,1.7,1.65,1.55,1.4,1.11,1.04,1,0.995,0.99,0.985,0.98,0.975)
    CompressorEfficiency=(0.2,0.2,0.46,0.58,0.66,0.72,0.73,0.68,0.58,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2)
    CompressorSurgeLineFlow=0.104
    CompressorPressRatio=(2.11,2.11,2.11,2.11,2.13,2.14,2.12,2.1,2,1.85,1.6,1.05,1.03,1.01,1.002,1.001,1)
    CompressorEfficiency=(0.2,0.2,0.2,0.4,0.58,0.66,0.71,0.73,0.73,0.68,0.54,0.2,0.2,0.2,0.2,0.2,0.2)
    CompressorSurgeLineFlow=0.13
    CompressorPressRatio=(2.6,2.6,2.6,2.6,2.6,2.6,2.61,2.62,2.62,2.55,2.4,2.15,1.75,1.1,1.04,1.01,1)
    CompressorEfficiency=(0.2,0.2,0.2,0.2,0.4,0.58,0.64,0.7,0.72,0.74,0.72,0.66,0.5,0.3,0.2,0.2,0.2)
    CompressorSurgeLineFlow=0.16
    CompressorPressRatio=(3.2,3.2,3.2,3.2,3.2,3.2,3.2,3.2,3.25,3.25,3.2,3.05,2.85,2.45,1.8,1.01,1)
    CompressorEfficiency=(0.2,0.2,0.2,0.2,0.2,0.2,0.59,0.62,0.68,0.71,0.72,0.73,0.7,0.62,0.6,0.3,0.2)
    CompressorSurgeLineFlow=0.19
    CompressorPressRatio=(4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.05,3.9,3.7,3.2,2.3,1)
    CompressorEfficiency=(0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.4,0.64,0.67,0.69,0.7,0.69,0.64,0.4,0.2)
    CompressorSurgeLineFlow=0.19
    CompressorPressRatio=(4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.7,4.5,3.5,1)
    CompressorEfficiency=(0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.64,0.66,0.66,0.56,0.2)
    CompressorSurgeLineFlow=120
    BoostTurboPressure=(150000,50000)
    WastegateBoostMeasurement=1
    Wastegate=(-10000,0,20000,1.3)
    IntakeLeak=1e-7
    DumpValve=(0.002,0.0001,20)
    And the "fake anti-lag" that I settled on for now:
    Code:
    TurboInertia=5e-4
    TurboFriction=(0.0015,0.8)
    TurboStaticFrictionWatts=100
    TurbineFlowTable=(0,0.032)
    TurbineFlowEffects=(1,0.1)
    TurbineFlowEffects=(1.5,0.4)
    TurbineFlowEffects=(1.5,0.4)
    TurbineFlowEffects=(1.5,0.4)
    TurbineFlowEffects=(1.5,0.4)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.5,0.7)
    TurbineFlowEffects=(3.8,0.7)
    IntakeVolumePerRevolution=1.9868
    ExhaustBaseProperties=(1175,1180,0.187,0.222,-3.35e-5)
    CompressorTable=(10504,0.11)
    CompressorPressRatio=(0.5)
    CompressorEfficiency=(0)
    CompressorSurgeLineFlow=0
    CompressorPressRatio=(1.01,1.04,1.03,1.02,1.006,1.001,1,1,1,1,1,1,0.99,0.98,0.97,0.96,0.95)
    CompressorEfficiency=(0.3,0.55,0.59,0.45,0.4,0.4,0.4,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3)
    CompressorSurgeLineFlow=0
    CompressorPressRatio=(1.02,1.08,1.09,1.08,1.07,1.045,1.02,1.001,1,1,0.995,0.99,0.985,0.98,0.975,0.95,0.9)
    CompressorEfficiency=(0.55,0.55,0.59,0.45,0.4,0.4,0.4,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3)
    CompressorSurgeLineFlow=0
    CompressorPressRatio=(1.03,1.115,1.15,1.15,1.13,1.1,1.065,1.025,1.002,1,1,1,1,1,1,1,1)
    CompressorEfficiency=(0.55,0.55,0.59,0.45,0.4,0.4,0.4,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3)
    CompressorSurgeLineFlow=0
    CompressorPressRatio=(1.43,1.43,1.44,1.43,1.4,1.33,1.22,1.07,1.025,1.008,1.002,1,1,1,1,1,1)
    CompressorEfficiency=(0.6,0.6,0.6,0.66,0.71,0.68,0.56,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3)
    CompressorSurgeLineFlow=14
    CompressorPressRatio=(1.72,1.72,1.72,1.73,1.72,1.7,1.65,1.55,1.4,1.11,1.04,1,0.995,0.99,0.985,0.98,0.975)
    CompressorEfficiency=(0.65,0.65,0.65,0.65,0.66,0.72,0.73,0.68,0.58,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3)
    CompressorSurgeLineFlow=22
    CompressorPressRatio=(2.11,2.11,2.11,2.11,2.13,2.14,2.12,2.1,2,1.85,1.6,1.05,1.03,1.01,1.002,1.001,1)
    CompressorEfficiency=(0.65,0.65,0.65,0.65,0.65,0.66,0.71,0.73,0.73,0.68,0.54,0.3,0.3,0.3,0.3,0.3,0.3)
    CompressorSurgeLineFlow=34
    CompressorPressRatio=(2.6,2.6,2.6,2.6,2.6,2.6,2.61,2.62,2.62,2.55,2.4,2.15,1.75,1.1,1.04,1.01,1)
    CompressorEfficiency=(0.65,0.65,0.65,0.65,0.65,0.65,0.65,0.7,0.72,0.74,0.72,0.66,0.5,0.3,0.3,0.3,0.3)
    CompressorSurgeLineFlow=45
    CompressorPressRatio=(3.2,3.2,3.2,3.2,3.2,3.2,3.2,3.2,3.25,3.25,3.2,3.05,2.85,2.45,1.8,1.01,1)
    CompressorEfficiency=(0.65,0.65,0.65,0.65,0.65,0.65,0.65,0.65,0.68,0.71,0.72,0.73,0.7,0.62,0.6,0.3,0.3)
    CompressorSurgeLineFlow=65
    CompressorPressRatio=(4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.1,4.05,3.9,3.7,3.2,2.3,1)
    CompressorEfficiency=(0.55,0.55,0.55,0.55,0.55,0.55,0.55,0.55,0.55,0.64,0.67,0.69,0.7,0.69,0.64,0.4,0.3)
    CompressorSurgeLineFlow=90
    CompressorPressRatio=(4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.85,4.7,4.5,3.5,1)
    CompressorEfficiency=(0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3,0.3)
    CompressorSurgeLineFlow=125
    BoostTurboPressure=(150000,50000)
    WastegateBoostMeasurement=1
    Wastegate=(-15000,0,30000,1.3)
    IntakeLeak=1e-7
    //DumpValve=(100000,50000,1e-8)
     
  10. Navigator

    Navigator Registered

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    No, I meant the whole file: there should be an error in there.
     
  11. Navigator

    Navigator Registered

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    So, it is not needed anymore?
     
  12. Oskar

    Oskar Registered

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    Nope.
    Think it's concluded that rF2 doesn't allow boost-by-throttle position. Blow off valve can't be used to simulate that either since there's some strange code limits to when the blow off valve is actually calculated.
    But another way to fix the throttle response issue is to just always have full boost. So making a "fake anti-lag" turbo like I posted above works.
    As far as I can tell, that's the only way in rF2 to make high boost cars work.
    Force feedback throttle pedal could help also. But not sure how much of a thing that is :D
     
  13. Navigator

    Navigator Registered

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    Just for fun, send me the first 5 lines of the engine.ini
    Maybe I can show you something.
     
  14. Oskar

    Oskar Registered

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    Code:
    ReferenceConditions=(101325,1.204,0.073)
    RPMBase=(0,-30,-30,0,0.96)
    VolumeFract=(0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)
    MixtureFract=(0,0,0,0)
    RPMBase=(250,-28.82,100,0.2822,0.993)
     
  15. Navigator

    Navigator Registered

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    No, not the fault I was hoping for.
    Sorry, can't help you further.
     

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