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Thread: boost bypass control??

  1. #41
    Potential Tuner
    Join Date
    Feb 2019
    Posts
    5
    Quote Originally Posted by Diesel_Enthuse View Post
    GarageBill you've got no idea how helpful this is, great work
    My pleasure! The SIMOS 3.0T/B8/B8.5 is our bread and butter, and while I use WinOLS to tune them, I know that HPTuners is doing some good work with the platform. We are also finishing up our B8.5 S4 turbo to get over that 610bhp hump we've been at with the supercharged configuration

    I figured I'd add to this by illustrating a quick (albeit crude) logic flow for the S8.4/8.5/16/18.1/18.10 ECU:

    1. You plant your right foot
    2. Pedal request maps reference rpm and pedal percentage and apply a factor (usually this factor is 1.00 at WOT)
    3. The factor is multiplied by the "maximum allowed torque" maps depending on the transmission
    4. The resulting torque request in nm is referenced as an axis against the "setpoint mass airflow" tables, which results in an airflow request in mg/stk
    5. The resulting airflow (after all limiters are applied) is referenced against the "indicated engine torque" map(s) which spits out an indicated torque for the TCU and other maps to reference (hence why some people artificially lower it, which again is not the right way to go about it)

    That is a very over-simplified summary but will get people 90% of the way there. There are a few limiters present but by following this path you will be able to spot them easily and raise them accordingly.

    Ignition timing is where a large amount of power is made with these engines as well. The MBT maps are "additional reference ignition angle", which is what the ECU will try to make under optimal conditions. Basic ignition angle maps are worst-case scenario and (if you're doing things right) don't need to be touched.

    Boost by stage should roughly be 12.5psi Stage 1, 15psi Stage 2, 18+psi Stage 2+ (dual pulley depending on ratio)

    Have fun!

    Bill
    Last edited by GarageBill; 04-04-2023 at 05:29 PM.