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Thread: Boost rises with RPM. Should it taper?

  1. #1
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    Boost rises with RPM. Should it taper?

    Hi,

    I have a 2018 3.5 Ecoboost F150. I'm just curious if the boost should be rising with RPM or should it decrease? I'm thinking it should peak, then drop as rpms rise. For instance, at wot, the turbo would peak at 19 psi, then taper to like 17. These numbers are just an example.

    Thanks!
    Last edited by SVT_Z06; 01-17-2025 at 10:36 AM.

  2. #2
    Senior Tuner veeefour's Avatar
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    Well depends on a tune

  3. #3
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    Quote Originally Posted by veeefour View Post
    Well depends on a tune
    Right. I'm trying to understand if that's what everyone is seeing in their logs.

    Is boost peaking, then tapering off? Is boost flat during the whole run?

    Which provides the best performance and quickest times?

    This would be for stock turbos.

  4. #4
    Advanced Tuner skylinedan's Avatar
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    Make it and hold it, that's the name of the game

  5. #5
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    On my 2018 Ecoboost Mustang, with stock turbo, the boost will peak, and then drop off, as the RPM increases.
    Off Road/Quarter Mile Drag Car/Not Street Legal
    2018 base Ecoboost Mustang, 10R80 automatic transmission and 01A optional factory electronics

    Modifications: Custom dual feed 3x3x4 air intake, NX 11910 Turbocharger, Aftermarket and custom charge pipes, Turbosmart plumb back BOV, Air to Air intercooler, Auxiliary water to air Intercooler, Port Injection kit with auxiliary controller, 3" turbo to rear axle drag pipe, trunk mounted battery and icebox, Drag radials.

  6. #6
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by SVT_Z06 View Post
    Right. I'm trying to understand if that's what everyone is seeing in their logs.

    Is boost peaking, then tapering off? Is boost flat during the whole run?

    Which provides the best performance and quickest times?

    This would be for stock turbos.
    Well depends on a turbo and how efficient the engine can pump. Low boost and correct overlap boost might hold to the end like diesel.
    Going more serious on boost, closer to turbocharger flow limit, overlap that supports power not the best "bleed" boost might tend to
    decrease as rpm goes higher - and that is quite normal to see