A mechanism scheme of the variable dissimilitude lifts(VDL) of intake valves was proposed

calculated and analyzed with the finite element analysis(FEA) for a four valve gasoline engine

which could produce and regulate in-cylinder swirl by adjusting the dissimilitude angle between two intake cams to change the difference between the lifts of two intake valves. The calculation results showed that the dissimilitude angle increased when the gear helix angle increased or/and the standard pitch circle radius decreased; the turning angles

turning torques and hydraulic balancing forces of the two intake cams were different when there was a dissimilitude angle

and the intake duration was getting longer with the increase of the dissimilitude angle. The FEA results show that the safety coefficient of the camshaft is 2.04

the maximum equivalent strain is 6.73×10-4 mm

the strength and stiffness conform to the requirements

and the resonance will not occur. A test of steady flow in cylinder confirms that VDL can obtain a large scale swirl and the intake flow almost remain constant; the swirl intensity can reach 0.24 when the dissimilitude angle is 8°

the deviation of the average flow coefficient is only 0.93%

and the tumble intensity slightly increases with the increase of the dissimilitude angle. The results of performance tests of the gasoline engine with VDL show that an appropriate dissimilitude angle can make the torque at middle low speeds increase by 2.94% and the power at high speeds by 3.03%.