Cylinder Head
Design of Cylinder Head
The design of the cylinder head corresponds largely to that of the familiar DOHC engines; modifications have been made in the details.
Features of the cylinder head:
- Compact design
- Provision for mounting ignition module in cylinder head cover
- Valve actuation via roller cam followers and micro hydraulic valve lifters
- Cylinder head designed for separate, single-part timing case above cylinder head and block
Legend for illus. G 3103:
- Spark plug
- Micro hydraulic valve lifter
- Roller cam follower
5.3.1 Design of Cylinder Head
5.3.1 Design of Cylinder Head
The cylinder head is equipped with an integrated exhaust gas recirculation duct and flanged EGR housing with exhaust gas recirculation valve.
Legend for illus. G 3104:
- Intake side
- EGR housing
- EGR valve
- Exhaust side
5.3.1 Design of Cylinder Head
Valve Actuation
The valves are driven by two overhead camshafts (DOHC). The cams actuate low-friction roller cam followers, which are supported by the micro hydraulic valve lifters and actuate the valves. Valve lash compensation is performed automatically by the micro hydraulic valve lifters.
Each cylinder has two intake and two exhaust valves. The angle between the intake and exhaust valves is 52�. The spark plugs are positioned vertically and centrally between the 4 valves.
| Technical Data: | |
|---|---|
| Intake valve disc | � 28 mm |
| Exhaust valve disc | � 25 mm |
| Valve stem | � 5 mm |
| Hydraulic valve lifter | � 12 mm |
Legend for illus. G 3105:
- Valve drive (overview)
- Valve actuation (partial view)
- Camshaft (hollow)
- Roller cam follower
- Valve
- Valve spring
- Micro hydraulic valve lifter
5.3.2 Valve Actuation
Intake Module
The intake module corresponds largely to the conventional component generally known as the "intake manifold". The difference is that several new components have been added to the parts usually associated with the intake manifold. The module is installed and removed as an assembly including the tank vent valve, engine control unit, electronic throttle valve adjuster and other components, such as the engine wiring harness with the injectors plug strip. The intake module consists of the following components:
- Throttle valve potentiometer
- Throttle valve adjuster
- Fuel pressure regulator
- Fuel lines
- Tank vent valve
- Engine control unit
- Exhaust gas recirculation duct
- Engine wiring harness with the injectors plug strip
- Injectors
- Fuel distributor pipe with service valve
- Aluminium intake manifold
5.3.3 Intake Module
Exhaust Manifold
The exhaust manifold (2) is designed to support the weight of the catalytic converter, which is flanged directly to it (see section 6.1.2 ). Exhaust gas is fed through a side duct (4) in the exhaust manifold through a bore in the cylinder head to the flanged EGR housing (see also section 5.3.1 Design of Cylinder Head, illus. G 3104)
Legend for illus. G 3107:
- Upper heat shield
- Exhaust manifold
- Lower heat shield
- Side duct for exhaust gas recirculation
