SFI SYSTEM


  1. FUNCTION


    1. The Dual VVT-i control is designed to control the intake and exhaust camshaft within a range of 75° and 55° respectively (of Crankshaft Angle) to provide valve timing optimally suited to the engine condition. This improves torque in all the speed ranges as well as increasing fuel economy and reducing exhaust emissions.

    2. The Dual VVT-i operation angle has been achieved. During partial load driving, the Atkinson cycle is entered, pumping loss is further reduced and fuel economy is enhanced.

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    3. In order to ensure engine startability, an intermediate lock mechanism is used for the intake side VVT-i. For details, see VVT-i CONTROLLER in the 8GR-FKS ENGINE MECHANICAL section.

    4. The following effects can be achieved due to the advanced angle and retarded angle of the intake and exhaust valves.


      1. Operation Model Diagram

        Figure 1. Upon Starting and Idling

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        *1 Exhaust Valve Opening (Advanced Position)
        *2 Intake Valve Opening (Intermediate Position)
        *3 Ensuring Starting Ability

        Figure 2. At Partial Load

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        *1 Exhaust Valve Opening (Retarded Position)
        *2 Intake Valve Opening (Retarded Position)
        *3 Atkinson Cycle

        Figure 3. At Partial Load to Heavy Load

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        *1 Intake Valve Opening (Advanced Position)
        *2 Exhaust Valve Opening (Retarded Position)
        *3 Using Internal EGR or Improving Exhaust Ability