System Operation
Lubrication System
The engine lubrication system is of the force-feed type in which oil is supplied under full pressure to the Crankshaft, connecting rod bearings, camshaft bearing caps and variable camshaft timing (VCT) solenoids. The flow of oil to the valve tappets and valve train is controlled by a restricting orifice located in the cylinder head gasket.
The lubrication system is designed to provide optimum oil flow to critical components of the engine through its entire operating range.
The heart of the system is a positive displacement internal gear oil pump.
Generically, this design is known as a variable oil pump or vane-type pump, which operates as follows:
- The oil pump is driven from the Crankshaft.
- System pressure is limited by an integral, internally-vented relief valve which directs the bypassed oil back to the inlet side of the oil pump.
- Oil pump displacement has been selected to provide adequate volume to make sure of correct oil pressure both at hot idle and maximum speed.
- The relief valve calibration protects the system from excessive pressure during high-viscosity conditions.
- The relief valve is designed to provide adequate connecting rod bearing lubrication under high temperature and high-speed conditions.
Valve Train
The valve train uses direct acting mechanical buckets (DAMB). The camshaft lobes are positioned directly above mechanical buckets which are positioned on top of the valves.
Twin Independent Variable Cam Timing (Ti-VCT)
The Ti-VCT system allows variable control of the valves which optimizes combustion at full load providing improved power and low speed torque (broadening the torque curve) which enables variable valve overlap which provides better fuel economy and emissions and provides optimized cold start operation with improved exhaust emissions.