Why does the engine power drop when the throttle opening reaches a certain level?

When the throttle opening reaches a certain level, the engine power will decrease due to the insufficient air intake of the supercharger. The air pressure is constant, the intake temperature is constant, the intake resistance is constant, and the intake volume per unit time is constant. At low speed, the intake air is large and the torque is reduced, so when the throttle opening reaches a certain level, the engine power will be reduced. To avoid this situation, it is necessary to manually set up a pressure relief valve. When the throttle opening reaches a certain level, the engine power will reach a certain speed to limit the intake pressurization.