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Resize the SI Engine

By default, the spark-ignition (SI) engine dynamometer reference application engine is configured with a 1.5-L dynamic gasoline engine. Based on a desired maximum engine power and the number of cylinders, you can resize the dynamic engine (SiEngineCore) for different vehicle applications.

To resize the engines, use the dynamometer reference application. After you open the reference application, click Resize Engine and Recalibrate Controller. In the dialog box, enter values for:

  • Desired maximum power

  • Desired number of cylinders

After you apply the changes, the reference application:

  • Resizes the dynamic engine and engine calibration parameters. The Recalibrate Engine dialog box provides the updated engine performance characteristics based on the resized calibration parameters.

  • Recalibrates the controller and mapped engine model to match the resized dynamic engine.

You can use the variants in other applications, for example, in vehicle projects that require a larger engine model.

Create SI Engine Models with Twice the Power

  1. If it is not already open, open a copy of the SI engine reference application project by entering

  2. In the SiDynReferenceApplication model window, click Recalibrate Controller.

    The reference application performs a dynamometer test to calibrate the engine controller for the default 1.5-L dynamic engine. For engine speeds 2000–5000 rpm, the measured engine torque approaches 180 N.m. The steady-state results for measured engine torque as a function of torque command and engine speed are similar to this plot.

  3. In the SiDynReferenceApplication model window, click Resize Engine and Recalibrate Controller.

    The dialog box opens with default values for Desired maximum power and Desired number of cylinders. These values represent the calibration parameters for the default 1.5-L dynamic engine.

    The dialog box provides the calibration parameters for the current engine design. The parameters are similar to these.

  4. In the Resize Engine and Recalibrate Controller dialog box, enter values that represent approximately twice the maximum power and number of cylinders. For example, set:

    • Desired maximum power to 230.

    • Desired number of cylinders to 8.

    Click Resize Engine. The reference application:

    • Resizes the dynamic engine (SiEngineCore) and engine calibration parameters. The Recalibrate Engine dialog box provides the updated engine performance characteristics based on the resized calibration parameters.

    • Recalibrates the controller (SiEngineController) and mapped engine model (SiMappedEngine) to match the resized dynamic engine (SiEngineCore).

    After resizing and recalibration, the dialog box provides the calibration parameters for the resized engine. The parameters are similar to these.

  5. Examine the dynamometer steady-state results. For engine speeds 2000–5000 rpm, the measured engine torque approaches 350 N.m. This result is approximately twice the power of the default dynamic engine. The steady-state results for measured engine torque as a function of torque command and engine speed are similar to this plot.

  6. To save the engine controller, resized engine mapped variant, and resized dynamic engine variant, in the SiDynReferenceApplication model window, save the reference application.

By default, this process creates:

  • An updated SI engine controller

  • Two engine variants — mapped and dynamic

To see the parameters associated with the controller and engine variants:

  1. In MATLAB®, use the PROJECT SHORTCUTS tab to open these models:

    • SiEngineController

    • SiMappedEngine

    • SiEngineCore

  2. Use the Model Explorer to view the resized parameters:

    Engine ModelModel Explorer

    Controller — SiEngineController

    Mapped — SiMappedEngine

    Dynamic — SiEngineCore

  3. In the SiDynoReferencApplication > Engine System > Engine Plant > Engine > SIMappedEngine subsystem, open the Mapped SI Engine block. On the Power tab, plot the actual torque as a function of engine speed and commanded torque.

See Also

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