Camshafts And Valve System
The engine has double pairs of overhead camshafts, one intake camshaft and one exhaust camshaft in each cylinder bank. The intake camshafts are located in the middle of the engine while the exhaust camshafts are placed on the outside.
The camshafts are made of cast iron. They are hollow to keep the weight down. Each camshaft pair is mounted in its respective cylinder head with five loose bearing caps per camshaft.
The camshafts work directly on the valve stem via the valve lifters. There is a certain amount of play (valve play) between the valve depressors and the cam lobes. Valve play is adjusted to make up for the longitudinal differences between the valve and cylinder head that occur upon warm-up. The valve depressors are solid and made of steel.
Each camshaft has a CVVT unit. The reset angle is 40.5 crankshaft degrees for the intake camshafts and 42.5 crankshaft degrees for exhaust camshafts.
- Intake camshafts open -8° to 32, 5° before top dead center (BTDC) and close 60° to 19.5° after the bottom dead center.
- Exhaust camshafts open 62° to 19.5° before bottom dead center and close -10° to 32.5° after the top dead center (TDC).