Update

include/FluidSim/Turbocharger.hpp

@@ -9,6 +9,7 @@ namespace fluidsim::port {
 // RHB31/VZ21-size mean-line approximation. Geometry, losses and coefficients
 // are estimates, not a digitized or validated manufacturer performance map.
 struct TurboConfig {
+    static TurboConfig gt17(); // estimated Saab GT1752-size calibration
     double shaft_inertia{4e-6}; // kg m^2, compressor+turbine+shaft rigid rotor
     double compressor_radius{.018}, turbine_radius{.0135};
     double compressor_head_coefficient{.60}, compressor_efficiency{.65};
@@ -58,6 +59,7 @@ public:
     double fluid_energy() const;
     // Intended for standalone initialization/tests, never an imposed running speed.
     void set_initial_rpm(double rpm);
+    void set_wastegate_duty(double duty) { gate_duty_ = std::isfinite(duty) ? std::clamp(duty, 0., .85) : 0.; }
 
 private:
     std::array<Port*, 4> internal_;
@@ -68,6 +70,7 @@ private:
     double wastegate_flow_{}, wastegate_lift_{};
     std::uint64_t limited_transfers_{};
     bool connected_{};
+    double gate_duty_{}; // pneumatic bleed fraction; zero restores spring boost
     static double nozzle(double upstream_pressure, double upstream_temperature,
                          double downstream_pressure, double area);
     double transfer_flow(Volume0D& inlet, Volume0D& outlet, Port& inlet_external,