Newly Developed Inline 4 AR Series SI Engine

A newly developed AR series 4-cylinder engine has achieved high fuel efficiency through the following: adopting roller rocker arms for the valvetrain system and a variable output oil pump to reduce the friction losses, optimizing the combustion chamber and its cooling system for high compression ratio, and adopting VVT-i (Variable Valve Timing-intelligent) for both intake and exhaust camshafts to enhance thermal efficiency of the engine. Engine torque has been enhanced across the entire range of engine speeds while high performance at low engine speed is achieved by adopting a variable induction intake manifold system (ACIS-III). Output power has been enhanced by making the intake and exhaust systems highly efficient. A hinge type tumble control valves were developed to improve emissions at low temperature by improving combustion when the engine is cold in order to comply with the U.S. Cold-NMHC. Noise and vibration have been reduced by enhancing the rigidity of cylinder block and crankcase and reducing radiant noise of intake manifold and chain cover. Two displacements, 2.5-liter and 2.7-liter, with common bore diameters have been designed to meet vehicle demands.