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(CVVT System Model)

Fig 1: CVVT System Engine Load Versus Speed Graph (1 Of 2)

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Courtesy of KIA MOTORS AMERICA, INC.

Fig 2: CVVT System Engine Load Versus Speed Graph (2 Of 2)

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Courtesy of KIA MOTORS AMERICA, INC.

Driving Condition	Exhaust Valve		Intake Valve
Driving Condition	Valve Timing	Effect	Valve Timing	Effect
(1) Low Speed/Low Load	Completely Advance	Valve Under-lap Improvement of combustion stability	Completely Retard	Valve Under-lap Improvement of combustion stability
(2) Part Load	Retard	Increase of expansion work Reduction of pumping loss Reduction of HC	Retard	Reduction of pumping loss
(3) Low Speed/High Load	Retard	Increase of expansion work	Advance	Prevention of intake back flow (Improvement of volumetric efficiency)
(4) High Speed/High Load	Advance	Reduction of pumping loss	Retard	Improvement of volumetric efficiency