•  To increase intake air amount and combustion efficiency, the S-DAIS controls the size of the intake ports and the air length in the intake pipes by opening or closing the SSV, VDI valve, APV, and VFAD valve (with VFAD)according to engine speed and load condition.

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•  At the low-speed range, the secondary and auxiliary ports close, and a high velocity intake air amount is fed from only the primary port. Due to this, better combustion efficiency is obtained by the improved fuel atomization, producing high torque output.

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•  When the engine speed reaches the medium range, the SSV opens and intake air from the secondary port begins. Due to this, the intake air amount increases, improving torque at the engine medium-speed range.

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•  When the engine speed reaches the medium-to-high range, the VFAD (with VFAD) and APV open.

•  When the VFAD valve (with VFAD) opens, intake air resistance is reduced by the shortening of air length in the fresh-air duct pipe.

•  When the APV opens, air from all intake ports is fed, improving torque at the medium-to-high-speed range.

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•  When the engine speed reaches the high range, the VDI valve opens, and the actual length of the intake air in the pipe is shortened to efficiently provide dynamic air charging effect.

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•  When the intake ports are shut abruptly, the intake air does not stop due to the inertia effect and it becomes compressed and highly pressurized. This pressurized air becomes a reflected high-pressure wave that pressurizes the intake air in the rotor chambers. This is dynamic air charging pressurization. The intake air amount is increased by the dynamic air charging effect, improving torque at the high-speed range.

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