aluminium cylinder block is fitted with cast iron cylinder liners. Four
cast iron crankshaft bearings are fitted to the aluminium crankcase at
the casting stage. Major design changes to the aluminium cylinder head
include enhanced combustion chambers and inlet ducts, which increase
power output and torque, while lowering exhaust emissions.
new inlet manifold, in composite material, comprises six ducts of equal
length. These are mounted on an aluminium distributor attached to the
cylinder heads in the centre of the V. The distributor comprises 12
ducts, each with a variable cross-sectional area, and each feeding a
This layout optimises the flow into the cylinders.
position of the electronic throttle is precisely controlled by the
computer in response to a large number of parameters, including
accelerator pedal position, coolant temperature and incoming air
fuel consumption and lower vibration have been achieved through
extensive design studies seeking to reduce friction and to make parts
forged steel crankshaft includes five precision-ground case-hardened
bearing sections. The bearing grooves and journals are rolled in
sections. In contrast to traditional rolling techniques, this process
hardens the metal without distorting the crankshaft, thereby improving
The forged steel connecting rods feature integral oil channels for cylinder lubrication and cooling.
pistons are 40 g lighter than those in the previous version. The flat
piston tops are raised slightly in the centre, with rebates to provide
“flexible” engine flywheel reduces engine vibration at high speeds. The
flywheel consists of a cast friction ring on the clutch side and a
sheet metal damping mechanism on the engine side.
The four camshafts act directly on hydraulic tappets that automatically take up any play in the system.
A phase shifter, or variable-timing camshaft, adjusts the timing of the valve gear for optimum flow into the cylinder.
example, during acceleration at low engine speeds, valve lead and lag
take place earlier.The inlet camshafts are moved between two possible
positions by means of a double helical ramp controlled by the oil
pressure. The engine computer controls the oil intake through an
electrovalve, in accordance with engine speed, engine load and oil
temperature. The camshaft position is monitored by an angular position
Injection and ignition
engine is controlled by a Bosch ME 7.4 engine control system driving
the sequential injection system and coil-per-plug ignition. The new
multi-jet injectors are fed from two rails with no fuel return. The
fuel circuit includes a surge damper to eliminate noise and variations
Exhaust and emission control
A pre-catalyst is mounted at the outlet of each exhaust manifold, with oxygen sensors fitted at the inlet and outlet.
sensors analyse the oxygen content of the exhaust gas and transmit the
information to the engine control system, which then adjusts the fuel /
air ratio accordingly. The main catalytic converter completes the
pollution control system, ensuring emission levels compliant with the
Euro 4 standard.