Lightweight design.
The six-cylinder boxer engine is
a highly compact unit offering
excellent cylinder charging and
torque characteristics as well
as optimum balance and minimal
vibration. With the cylinders
arranged horizontally on either
side of the crankshaft, the
layout is key to the car’s low
centre of gravity.
The alloy crankcase consists
of two main sections, each
containing one bank of cylinders.
The crankshaft runs in eight main
bearings and is driven by forged
connecting rods. For optimum
durability, we’ve used forged
aluminium pistons running in
Nikasil-coated aluminium liners
and featuring individual oil-spray
cooling. Key benefits include lower
frictional resistance and longer
service life.
The cylinder heads are made
from a lightweight alloy which
is extremely resistant to high
temperature. Each bank of
cylinders has two overhead
camshafts driving a set of four
valves – two inlet and two exhaust
– on each individual cylinder.
The valves are arranged in a ‘V’
configuration and feature a highly
efficient dual-spring design.
Engine performance is further
enhanced with the aid of bothVariable Turbine Geometry (VTG –
see page 32) and VarioCam Plus
(variable valve timing and lift
on inlet side – see page 38). The
benefits are not only greater
power and torque, but also better
fuel economy and lower emissions.
Dry-sump lubrication.
This classic dry-sump system
with separate oil reservoir
ensures consistent oil pressures
throughout the engine. In doing
so, it compensates for even the
most extreme and prolonged
gravitational loads.
After passing through the engine,
every drop of oil is returned
directly to the external reservoir.
The flow is driven by two pairs of
scavenge pumps in the cylinder
heads and a further two pumps in
the crankcase. Gas is removed
from the returning oil by means of
a defoaming device in the
reservoir. As a result, the oil
level in the reservoir remains
virtually constant at all times.
The oil is returned to the
lubrication points in the engine
by means of a dedicated
oil-feed pump. With a further
scavenge pump in each of the
twin turbocharger units, the
new 911 Turbo has a total of nineseparate pumps to drive the
lubrication system.
The oil level can be checked from
inside the car via the standard
on-board computer. This solution
is not only cleaner and more
convenient than a conventional
dipstick, it is also significantly
more accurate.
· 30 ·· 31 ·The new 911 Turbo |
Drive
Main rotating assembly and valve gear
Engine cooling.
The 911 Turbo engine features
cross-flow water cooling with fully
integrated coolant management.
This technology ensures a
consistent flow of coolant to each
of the engine’s cylinders. All
coolant passages are integral to
the block, thus eliminating the
need for external hoses. Each
cylinder receives a fresh supply
of coolant which has not been
pre-warmed by the engine. As well
as improving reliability, this
helps to minimise maintenance
requirements. Waste heat from
the oil is transferred to the
coolant via two oil/water heat
exchangers. The coolant is routed
through twin radiator modules
ahead of the front wheels and a
centrally placed unit in the nose.
Engine management.
Optimum performance is assured
at all times with the aid of
the Motronic ME7.8.1 engine
management system. On the new
911 Turbo, this powerful ECU is
responsible for all engine-related
functions and assemblies (see
diagram). Key among these are
the Variable Turbine Geometry
(VTG), VarioCam Plus and
electronic throttle system – one
of the essential prerequisites
for the standard Porsche Stability
Management (PSM). The results:
optimum economy, emissions
and performance, regardless of
driving style.Another important task performed
by the engine management
system is cylinder-specific knock
control. By preventing pre-ignition
at high engine speeds, this
function can avert costly damage
to the pistons and cylinders. Since
temperatures tend to vary in
different parts of the engine, each
cylinder is monitored separately.
If a risk is detected, the individual
ignition timing is adjusted.
The EU-compliant on-board
diagnostics system provides
continuous fault detection and
early warning for the exhaust
and fuel supply systems. The
resulting benefits are active
prevention of harmful emissions
as well as consistent rates of
fuel consumption.
· 40 ·· 41 ·The new 911 Turbo |
Drive
Input data Used to regulate /control
Engine management system
(Motronic ME7.8.1)
Engine load
Pressure upstream from throttle
Throttle-valve angle
Engine speed (from crankshaft)
Camshaft phase angles
Throttle-pedal position
Lambda signal
Knock sensor signal
Ignition
Fuel injection
Throttle valve
Heating elements in lambda sensors
Fuel pump
Fuel-tank venting
CAN interface to
all-wheel drive control unit CAN interface to transmissionMoment interface to Porsche
Stability Management (PSM)
VarioCam Plus
– camshaft phase angle
– valve lift control
Electronic controller for
Variable Turbine Geometry (VTG)
Bypass valve
Secondary air injection
Engine-bay fan
Starter
On-board diagnostics
Air-conditioning compressor
Interface to instrument cluster
Radiator fans
Vehicle speed
Air-conditioning settings
Engine immobiliser status
Clutch pedal switch
Ambient air pressure
Temperatures
– coolant
– airflow upstream from throttle
– engine oil
– air in engine compartment
– ambient air
Exhaust-gas temperature
