With the objective of further enhancing the engine performance of the Acura brand and the environmental performance of the Honda brand in relation to the North American market, where there is a need for powertrains with driving force margin for SUVs and pickup trucks, Honda has developed a 3.0 L turbocharged engine and a 3.5 L naturally aspirated engine. Both engines adopt the same newly developed valvetrain structure and share main engine geometries.
These newly developed engines are equipped with a compact new valvetrain structure combining Hydraulic Lash Adjusters and roller rocker arms with a valve-lifter based Variable Cylinder Management system which has an internalized switching mechanism. This newly developed valvetrain made it possible to incorporate dual overhead cam structure without enlarging the cylinder head shape relative to the single overhead cam structure. It further achieves this while permitting application of a Variable Cylinder Management system and of a Variable Timing Control for intake and exhaust valves to this engine.
Sharing the main engine geometries and components for each type of engine, primarily the new valvetrain structure, also facilitated changes in reciprocating and other parts, and minor changes such as the mounting of a turbocharger and increases in fuel injection system pressure, enabling the required enhancements in engine and environmental performance to be achieved.
Regarding the turbocharged engine, the twin-scroll type turbocharger combined with the V6 engine made it possible to increase power and enhance boost pressure responsivity while preventing enlargement even over the single turbocharger. That turbocharged engine achieves maximum power of 265 kW and maximum torque at 1400 rpm of 480 Nm, raising the figures for the existing engine by 26.7% for power, and 35.2% for torque.
Regarding the natural aspiration engine, the high fuel pressure system and the multi-stage injections made it possible to reduce emissions by reducing fuel adhesion in the cylinders and enhancing homogeneity. It further enables enhancement of the thermal efficiency by combining dual Variable Timing Control and high-tumble ports and piston crown shape designed to maintain tumble flow. That natural aspiration engine achieves a maximum power of 213 kW and a maximum torque of 355 Nm. In terms of environmental performance, the thermal efficiency is 37.5%, an increase over the 36.5% of the existing engine. A vehicle equipped with this engine was also able to achieve LEV III and SULEV30 standards as well as particulate matter (PM) of 1 mg/mile.