Saab B308E Specifications
| Engine Model: Saab B308E |
| Engine Type: 4-cycle 6-cylinder DOHC 24-valve turbocharged liquid-cooled gasoline |
| Total Displacement: 180.8 cu.in (2.96 L) |
| Rated Engine Power: 200 Hp (147 kW) at 5000 rpm |
| Fuel System Type: Multi-point electronic fuel injection |
____________________________________________________________________________________
The Saab B308E is a 3.0-liter, 24-valve V6 engine based
on the GM Ellesmere (L81) architecture, distinguished as the world’s first
asymmetrical turbocharged engine fitted to a production passenger car. Developed
during the late 1990s for Saab’s flagship 9-5 model, the B308E represented a
unique engineering solution where the turbocharger is driven exclusively by the
exhaust gases of one cylinder bank - the front three cylinders - while providing
pressurized intake air to all six cylinders.
This asymmetrical configuration enabled rapid boost response with minimal turbo
lag while simplifying the exhaust manifold routing within the narrow engine bay
of the 9-5. The engine features a 54-degree V-angle, a departure from the
conventional 60-degree V6 layout, chosen specifically to reduce overall width
for transverse mounting in Saab’s front-wheel-drive platform. The B308E was
engineered for smoothness and effortless highway cruising rather than raw
sportiness, delivering high torque at low engine speeds that gave the driving
experience characteristics similar to a larger naturally aspirated V8.
The engine utilizes the Saab Trionic 7 engine management system, incorporating
two separate Direct Ignition (DI) cassettes - one for each cylinder bank - and
an oil-to-water heat exchanger located in the V of the engine to manage thermal
loads. Produced from 1998 through 2003, the B308E was exclusively paired with
automatic transmissions and served as the executive engine choice for the Saab
9-5 Griffin and 9-5 SE V6 models.
The B308E is a four-stroke, water-cooled gasoline engine operating on the
spark-ignition principle. The engine architecture is a 54-degree V6
configuration with a total displacement of 2,962 cc (180.8 cu.in), derived from
a bore of 86.0 mm (3.39 in) and a stroke of 85.0 mm (3.35 in). This nearly
square design provides a balanced combination of low-end torque and high-rpm
capability. The compression ratio is set at 9.5:1, a value selected to balance
the competing demands of forced induction, fuel efficiency, and knock
resistance.
The valvetrain utilizes dual overhead camshafts (DOHC) per cylinder bank, with
four valves per cylinder for a total of 24 valves. The camshafts are driven by a
timing belt, a departure from the chain-driven H-series engines. The intake and
exhaust camshafts on each bank are driven by a single belt, with a tensioner
maintaining proper belt tension. The valves are actuated by bucket-type tappets
with shims for valve clearance adjustment. The firing order for this V6 engine
is 1-2-3-4-5-6, with cylinder bank assignments such that cylinders 1, 3, and 5
are on the front bank and cylinders 2, 4, and 6 are on the rear bank.
Performance outputs for the B308E reflect its focus on low-end torque and
cruising refinement. Maximum power is rated at 147 kW (200 hp) at 5,000 rpm.
Maximum torque is rated at 310 Nm (229 lb-ft) at 2,500 rpm, a low engine speed
that provides effortless acceleration without requiring sustained high rpm. The
idle speed is set at approximately 700 rpm when the engine is at operating
temperature. The engine was exclusively paired with four-speed and later
five-speed automatic transmissions, with no manual transmission option offered.
The cylinder block is manufactured from cast iron, a
material chosen for its exceptional rigidity, wear resistance, and durability
under the thermal loads generated by turbocharged V6 operation. The block
features a 54-degree V-angle, a non-standard configuration selected to reduce
overall engine width for transverse mounting in the 9-5’s engine bay. The
cylinder bores are cast directly into the block and are finished with a plateau
honing process that optimizes oil retention and piston ring sealing.
The block incorporates replaceable wet-type cylinder liners in certain service
configurations, allowing for overhaul without replacing the entire block. The
crankcase is reinforced with webbing between cylinder bores to minimize
distortion under thermal and mechanical stress. The main bearing caps are
manufactured from nodular cast iron and are secured with four bolts per cap on
the center bearings and two bolts per cap on the end bearings.
The crankshaft is manufactured from cast iron with induction-hardened bearing
surfaces, providing adequate strength for the engine’s power output. The
cylinder block incorporates the timing belt housing at the front, including the
mounting points for the timing belt tensioner and idler pulleys, as well as the
water pump mounting location.
Each cylinder bank is served by a separate aluminum
alloy cylinder head, a design that reduces weight and improves thermal
conductivity. Each cylinder head houses dual overhead camshafts - one intake and
one exhaust - supported by four bearing journals per camshaft. The timing belt
drives the front bank camshafts directly, with the rear bank camshafts driven
through the same belt via an extended belt path.
Each cylinder utilizes four valves - two intake and two exhaust - arranged in a
pent-roof combustion chamber design that optimizes breathing efficiency. The
valves are actuated by bucket-type tappets that incorporate shims for valve
clearance adjustment. The intake valves have a diameter of 33.0 mm (1.30 in),
while the exhaust valves have a diameter of 28.0 mm (1.10 in).
The exhaust valves are sodium-filled on certain variants for improved heat
dissipation under turbocharged operation. The valve seat inserts are
manufactured from sintered metal alloys selected for heat resistance and wear
durability. The cylinder head gaskets are multi-layer steel (MLS) designs,
providing robust sealing between the cast iron block and aluminum heads under
the thermal expansion differences between the materials.
The B308E is equipped with a sequential multi-point
electronic fuel injection (MPFI) system integrated with the Trionic 7 engine
management system. Fuel is delivered from an in-tank pump to a fuel rail mounted
on each cylinder head, distributing fuel to six individually controlled
injectors, each mounted in the intake port directly upstream of the intake
valve. The fuel pressure is regulated by a pressure regulator mounted on the
fuel rail, maintaining a constant pressure differential across the injectors.
The injectors are electrically actuated and are capable of precise fuel metering
based on signals from the Trionic control unit. The Trionic 7 system monitors
crankshaft position via a flywheel-mounted sensor, mass air flow, intake air
temperature, coolant temperature, throttle position, and uses the Direct
Ignition cassettes as ionization sensors to detect combustion quality and knock.
The fuel system operates at a pressure of approximately 3.0 bar (44 psi) to 3.5
bar (51 psi) depending on engine load and operating conditions.
The lubrication system is a forced-feed, full-flow
filtration design utilizing a gear-type oil pump mounted at the front of the
engine and driven by the crankshaft. The oil pump draws lubricant from the sump
through a strainer and delivers it to the main oil gallery. The system maintains
stable oil pressure across the operating range, with a pressure relief valve
calibrated to open at 4.0 bar (58 psi).
An oil-to-water heat exchanger is mounted in the V of the engine between the
cylinder banks, managing the thermal loads of the turbocharger and maintaining
oil viscosity under sustained high-load conditions. The engine employs a
full-flow spin-on oil filter mounted on the engine block. The oil pan is
constructed from stamped steel and has a capacity of 6.0 liters (6.3 US qt)
including the filter. The engine requires 5W-30 or 10W-40 fully synthetic engine
oil meeting GM-LL-A-025 or Saab specification.
The cooling system is a pressurized, water-cooled
design utilizing a centrifugal water pump driven by the timing belt. The system
maintains engine operating temperature within a range of 85°C to 95°C (185°F to
203°F) under normal conditions. The coolant circuit includes a thermostatic
bypass that facilitates rapid warm-up and reduces internal friction during cold
starts. The water pump is mounted on the front of the engine block and is
serviced in conjunction with timing belt replacement.
The charge air cooler (intercooler) is an air-to-air unit mounted in the
vehicle’s front-end cooling package, reducing the temperature of compressed air
from the asymmetrical turbocharger before it enters the intake manifold. The
asymmetrical turbocharger configuration, driven only by the front cylinder bank,
requires careful thermal management of the exhaust-driven components. A
cross-flow radiator with an electric cooling fan supplements the system at low
vehicle speeds and during idle conditions. The total coolant capacity for the
engine and cooling system is 8.0 liters (8.5 US qt) to 9.0 liters (9.5 US qt)
depending on the vehicle application.
Air Intake and Asymmetrical Turbocharging: The B308E is
equipped with a Garrett GT15 turbocharger mounted in an asymmetrical
configuration, where the turbocharger is driven exclusively by the exhaust gases
from the front cylinder bank (cylinders 1, 3, and 5). The exhaust manifold from
the front bank feeds directly into the turbocharger turbine housing, while the
rear bank exhaust manifold routes to a junction downstream of the turbine. The
compressed air from the turbocharger passes through the intercooler and then
feeds the intake manifolds of both cylinder banks. This configuration provides
rapid boost response, as the exhaust energy from only three cylinders is
concentrated on the turbine, and simplifies exhaust routing within the confined
engine bay.
Engine Management: The engine is controlled by the Saab Trionic 7 engine
management system, an integrated system that combines ignition, fuel injection,
and boost control in a single control unit. Trionic 7 utilizes two separate
Direct Ignition (DI) cassettes - one mounted on each cylinder bank - each
containing three integrated ignition coils and ionization detection circuitry.
The system uses the spark plugs as sensors to measure ionization within the
cylinder after combustion, providing real-time combustion feedback and knock
detection on a cylinder-by-cylinder basis.
Ignition System: The ignition system consists of two Saab Direct Ignition
cassettes, one for each cylinder bank. Each cassette integrates three ignition
coils and is mounted directly over the spark plugs of its respective bank. The
system uses a crankshaft position sensor for timing reference and does not
require a camshaft position sensor for normal operation. The spark plugs are
platinum-tipped for extended service life.
Exhaust System: The exhaust system incorporates separate cast iron exhaust
manifolds for each cylinder bank. The front bank manifold feeds directly into
the turbocharger turbine housing. The rear bank manifold routes to a junction
pipe that connects downstream of the turbine. A three-way catalytic converter is
positioned downstream of the turbocharger. The system includes oxygen sensors
positioned before and after the converter for closed-loop fuel control.
The engine length, measured from the timing belt cover
to the flywheel housing face, is 600 mm (23.6 in). The width, measured across
the cylinder banks at the widest point including the intake manifold, exhaust
manifolds, and turbocharger, is 750 mm (29.5 in). The height, measured from the
oil pan bottom to the top of the Direct Ignition cassettes, is 700 mm (27.6 in).
The dry weight (without fluids, starter, alternator, or air conditioning
compressor) is 170 kg (375 lb). The fully dressed weight for a vehicle
application, including all accessories, wiring harness, turbocharger, Direct
Ignition cassettes, and fluids, is 195 kg (430 lb).
The service life of the B308E under proper operating
conditions is engineered to exceed 250,000 km (155,000 mi) with regular
maintenance. Oil change intervals are recommended at 10,000 km (6,200 mi) or 12
months under normal driving conditions, with more frequent intervals of 5,000 km
(3,100 mi) recommended for severe service conditions. The engine requires 5W-30
or 10W-40 fully synthetic engine oil meeting GM-LL-A-025 or Saab specification.
The timing belt is a critical maintenance component. Replacement is mandated at
100,000 km (62,000 mi) or 6 years, whichever occurs first. The water pump should
be replaced concurrently with the timing belt due to its location within the
timing belt drive system. Failure of the timing belt results in valve-to-piston
contact due to the interference design of the engine. Replacement of the spark
plugs is required every 60,000 km (37,000 mi) for platinum-tipped plugs.
Replacement of the fuel filter is recommended every 40,000 km (25,000 mi).
The air cleaner element requires replacement every 30,000 km (18,600 mi), with
more frequent servicing in dusty environments. The coolant must be replaced
every 4 years or 80,000 km (50,000 mi), using a phosphate-free, long-life
coolant formulation. The accessory drive belt requires inspection at each
service interval, with replacement recommended every 60,000 km (37,000 mi) or
sooner if cracking or wear is evident. The oil-to-water heat exchanger located
in the V of the engine requires inspection for leaks, as failure can result in
oil contamination of the coolant or coolant contamination of the oil.
The cylinder head bolts follow a multi-stage angular
torque procedure. The M11 cylinder head bolts receive an initial torque of 40 Nm
(30 lb-ft), followed by a 90-degree angle, and a final 90-degree angle in a
specified sequence. The main bearing cap bolts are torqued to 50 Nm (37 lb-ft)
plus a 60-degree angle. The connecting rod bolts are tightened to 25 Nm (18
lb-ft) plus a 90-degree angle.
The flywheel-to-crankshaft bolts receive a torque of 60 Nm (44 lb-ft) plus a
90-degree angle. The camshaft bearing cap bolts are torqued to 12 Nm (9 lb-ft).
The spark plugs are torqued to 25 Nm (18 lb-ft). The intake manifold bolts are
torqued to 20 Nm (15 lb-ft). The exhaust manifold bolts are torqued to 25 Nm (18
lb-ft). The turbocharger mounting bolts are torqued to 35 Nm (26 lb-ft). The
Direct Ignition cassette mounting bolts are torqued to 10 Nm (7 lb-ft).
The B308E was produced from 1998 through 2003 and
served as the executive engine choice for Saab’s flagship sedan during the early
years of the 9-5 platform. The primary application was the Saab 9-5 Griffin, the
top-of-the-line luxury trim level where the B308E was positioned as the premier
powerplant, offering the smooth torque characteristics and refinement expected
of a luxury touring sedan.
The engine was also offered in the Saab 9-5 SE V6 from 1998 to 2001, serving as
the high-end engine option below the Griffin trim. The B308E was exclusively
paired with four-speed and later five-speed automatic transmissions, reflecting
its positioning as a touring and executive engine rather than a sport-oriented
powerplant.
The naturally aspirated version of this engine architecture, designated L81, was
utilized in the Saturn L-Series L300, sharing the same block and head casting
with the B308E but without the turbocharging system. The B308E was phased out
after the 2003 model year as Saab transitioned to the B235R high-output
turbocharged four-cylinder as the premier engine for the 9-5, followed by the
introduction of V6 engines from other GM sources. The B308E remains notable
within automotive engineering history for its unique asymmetrical turbocharging
configuration, which demonstrated an alternative approach to forced induction
packaging in transverse V6 applications.
____________________________________________________________________________________
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Industrial Engines Technical Specifications |
| Outboard Engines Technical Specifications |
