ENGINE UNIT

The cylinder head structure has been simplified by separating the camshaft housing (cam journal portion) from the cylinder head sub-assembly.

An aluminum alloy with superior heat conductance is used for the cylinder head sub-assembly. Weight reduction is achieved due to a reduction in the number and thickness of parts.

A valve lash adjuster assembly is positioned on the upper portion of the cylinder head, and the oil supply passage that runs to the valve lash adjuster assembly is installed in the cylinder head sub-assembly.

The shapes of the intake air port, injector fuel injection and combustion chamber are optimized to improve fuel economy via high-speed combustion and expand the driving range at the stoichiometric air-fuel ratio by improving combustion.

The entire cylinder head has been made thinner to achieve weight reduction.

The exhaust manifold is built into the cylinder head to achieve size and weight reduction. The length and diameter of the exhaust ports are optimized to ensure excellent exhaust cooling and engine performance.

The shape of the water jacket is optimized to reduce the temperature of combustion chamber components and minimize the temperature difference between cylinders. These 2 improvements achieve a high compression ratio, which achieves high torque, high engine output and low fuel consumption.

The water jacket inside the cylinder head uses a 2-stage construction. Coolant is concentrated in the bottom of the water jacket to improve the cooling of the combustion chamber. Also, the wall between the upper and lower water jackets is reinforced to support the high pressure and heat load increase due to supercharging.

In order to reduce the temperature of the exhaust gas that flows into the turbocharger sub-assembly to ensure the reliability of the intake system and expand the driving range limited by the stoichiometric air-fuel ratio, the exhaust manifold integrated into the cylinder head is cooled by the water jacket inside the cylinder head, cooling the exhaust gas.