Saab B201 Specifications
| Engine Model: Saab B201 |
| Engine Type: 4-cycle inline 4-cylinder SOHC 8-valve liquid-cooled gasoline |
| Total Displacement: 121.1 cu.in (1.98 L) |
| Rated Engine Power: 100-110 Hp (73-81 kW) at 5500 rpm |
| Fuel System Type: Bosch LH-Jetronic 2.2 electronic fuel injection |
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The Saab B201 is a 2.0-liter,
inline-four-cylinder, single overhead camshaft (SOHC), 8-valve,
naturally aspirated gasoline engine. It is a fundamental and long-lived
member of Saab's "B-engine" family, which formed the backbone of the
company's powertrains for decades. Introduced in the late 1970s, the
B201 is essentially the 2.0-liter displacement variant of the B-engine,
known for its extreme robustness, simplicity, and over-engineered
construction. It features a cast-iron block and an aluminum cylinder
head, with a design that prioritized durability and serviceability over
high-revving performance.
The engine is renowned for its immense torque at low engine speeds,
making it exceptionally well-suited for the heavy, aerodynamic Saab 900
and early 9000 models. Its architecture, with the block tilted at 45
deg, is a signature Saab design that allowed for a lower hood line.
While not powerful by modern standards, the B201 is celebrated for its
"bulletproof" reliability, distinctive exhaust note, and ability to
accumulate extremely high mileage with proper maintenance. It embodies
Saab's engineering philosophy of safety, durability, and practicality.
Engine Family / Model: Saab B-engine series, Model B201.
Engine Type: Inline-four cylinder, longitudinally front-mounted,
inclined 45 deg to the right, four-stroke cycle, water-cooled, naturally
aspirated gasoline engine.
Fuel Management: Bosch LH-Jetronic 2.2 or similar electronic fuel
injection (EFI) on later models. Earlier versions used Bosch K-Jetronic
mechanical fuel injection or even carburetors.
Aspiration: Naturally aspirated.
Bore: 90.0 mm / 3.543 inches.
Stroke: 78.0 mm / 3.071 inches.
Displacement: 1,985 cc / 121.1 cubic inches.
Compression Ratio: 9.5 : 1 for fuel-injected versions.
Firing Order: 1-3-4-2.
Rotation Direction (from front/pulley end): Clockwise.
Maximum Power Output (DIN): 73-81 kW (100-110 Hp) at 5,200-5,500 rpm,
depending on year and specification. Maximum Torque: 150-160 Nm (111-118
lb-ft) at 3,000-3,500 rpm.
Redline: 5,800-6,000 rpm.
Fuel Requirement: Regular unleaded (91 RON) or leaded premium (for very
early models).
Emissions Compliance: Varies from non-catalyzed to early Euro standards.
Construction: Cast iron, with an exceptionally robust and heavy design.
The block is cast as a single piece and is mounted at a 45-degree angle,
a Saab hallmark that lowers the center of gravity and hood line.
Cylinder Bores: Integral (parent bore) in the casting. Standard bore
diameter is 90.00 mm (3.543 inches). The block is known for its
longevity and resistance to wear.
Crankshaft: Forged steel, supported by five main bearings. Main journal
diameter is 64 mm (2.520 inches). Crankpin diameter is 54 mm (2.126
inches).
Main Bearings: Steel-backed, lead-bronze (tri-metal) shell bearings,
known for excellent durability.
Pistons: Cast aluminum alloy with a flat or slightly dished crown.
Features three rings (two compression, one oil control). Connecting
Rods: Forged steel, I-beam design. Oil Pan: Cast aluminum oil pan, which
also acts as a structural component, adding rigidity to the lower block.
Construction: Cast aluminum alloy, cross-flow design.
Valve Arrangement: Single Overhead Camshaft (SOHC), driven by a duplex
roller chain. Two valves per cylinder (8-valve total). Valves are
actuated via rocker arms with mechanical adjustment.
Combustion Chamber: Heron-type design (also called a "bathtub" chamber).
The combustion chamber is largely formed by a depression in the top of
the piston, while the cylinder head face is nearly flat. This promotes
efficient combustion and reduces emissions. Valve Seat Angle: 45 deg.
Valve Diameter: Intake: 42.0 mm (1.654 inches). Exhaust: 36.0 mm (1.417
inches).
Valve Springs: Single coil springs.
Valve Clearance (Cold): Adjustable via screw and locknut on the rocker
arms. Clearance: Intake: 0.30-0.40 mm (0.012-0.016 inches). Exhaust:
0.40-0.50 mm (0.016-0.020 inches). Regular adjustment is a key
maintenance item. Camshaft Drive: Duplex roller chain with a manual
tensioner (spring-loaded) and guide rails. Extremely durable, often
lasting the life of the engine.
Injection System (Standard for later B201): Bosch LH-Jetronic 2.2
electronic fuel injection. This is a speed-density system using a
Manifold Absolute Pressure (MAP) sensor and an engine temperature
sensor, without an air flow meter.
Fuel Injectors: Electromagnetic, top-feed injectors mounted in the
intake manifold.
Fuel Pressure Regulator: Vacuum-referenced, mounted on the fuel rail.
Maintains system pressure around 2.5 bar (36 psi). Throttle Body:
Single-bore, cable-operated.
Air Intake: Uses a MAP sensor for load calculation. Includes an idle air
control valve.
Earlier Systems: Earlier B201 engines (pre-1984) could be equipped with
Bosch K-Jetronic continuous mechanical fuel injection or even a single
Solex or Zenith carburetor.
Type: Full-pressure, force-fed wet-sump system with a gear-type pump.
Oil Pump: Gear-type, driven by a skew gear from the crankshaft. Located
in the cast aluminum oil pan/sump. Oil Filter: Cartridge-type paper
element inserted into a canister on the side of the engine block
(earlier) or a spin-on canister (later).
Oil Cooler: An engine oil cooler is standard equipment on most B201
engines, utilizing engine coolant for heat exchange. It is mounted on
the oil filter housing.
Oil Capacity (including filter and cooler): 5.0 liters (5.3 US quarts /
4.4 Imperial quarts).
Recommended Oil Grade: API SF/SG or later. Viscosity: SAE 10W-40 or
15W-40, mineral or semi-synthetic. Saab often recommended specific
high-detergent oils.
Operating Oil Pressure: At normal operating temperature: 300-500 kPa
(3.0-5.0 bar / 44-73 psi) at 2,000 rpm. Pressure as high as 600 kPa (6.0
bar / 87 psi) when cold. Idle pressure should be above 100 kPa (1.0 bar
/ 14.5 psi).
Type: Pressurized, forced circulation system. Unique "Saab APC"
(Automatic Performance Control) on turbo models, but naturally aspirated
B201 uses a standard system.
Water Pump: Centrifugal, belt-driven from the crankshaft.
Thermostat: Wax pellet type. Opening temperature is 87°C (189°F) or 92°C
(198°F).
Radiator Pressure Cap: 100-120 kPa (1.0-1.2 bar / 14.5-17.4 psi).
Coolant Capacity (engine + radiator, approx.): 9.0 liters (9.5 US quarts
/ 7.9 Imperial quarts) for the classic Saab 900. Coolant Recommendation:
Ethylene-glycol based antifreeze mixed with demineralized water (50/50
ratio). Avoid phosphate-based coolants to protect aluminum.
Electrical System: 12-volt DC, negative ground. Features a unique design
with the battery in the trunk for weight distribution.
Ignition System: Capacitor Discharge Ignition (CDI) system, a Saab
specialty. It uses a breakerless magnetic pickup in the distributor and
a powerful external ignition coil. The system produces a very strong,
consistent spark. Later models (9000) may have direct ignition.
Distributor: Driven from the exhaust camshaft (which is driven by a gear
from the intake camshaft).
Spark Plugs: Standard copper core. Gap: 0.7-0.8 mm (0.028-0.031 inches)
for CDI systems.
Emission Controls: Early models: none or simple PCV. Later fuel-injected
models: Exhaust Gas Recirculation (EGR), evaporative emissions (EVAP)
system, and a three-way catalytic converter.
Length (from front of pulley to rear of block): 700 mm (27.6 inches).
Width (over valve cover): 650 mm (25.6 inches).
Height (from bottom of oil pan to top of valve cover): 700 mm (27.6
inches).
Dry Weight (engine only, long block): 165-175 kg (364-386 lbs).
Engine Oil and Filter Change Interval: Every 10,000 km (6,200 miles) or
12 months. Severe service: 5,000 km (3,100 miles). The oil cooler
increases capacity and helps longevity.
Spark Plugs: Replace every 20,000 km (12,400 miles) for standard copper
plugs. Ignition Timing: Check and adjust every 20,000 km or during
tune-ups. Critical for performance and economy. Valve Clearance
Adjustment: Essential. Check and adjust every 20,000 km (12,400 miles).
Incorrect clearance leads to poor performance, noisy operation, and
potential valve damage. Timing Chain: Inspect for stretch and tensioner
wear every 100,000 km (62,000 miles). The duplex chain is very durable
and rarely needs replacement. Accessory Drive Belts: Inspect and adjust
tension regularly. Replace at signs of cracking. Coolant Replacement:
Every 2 years or 40,000 km (24,850 miles). Fuel Filter: Replace every
40,000 km (24,850 miles). Air Filter: Replace every 20,000-30,000 km
(12,400-18,600 miles).
Cylinder Head Bolts (M12): Three-stage torque procedure on a cold
engine. Step 1: Tighten all bolts in sequence to 50 Nm (37 lb-ft). Step
2: Tighten all bolts in sequence to 90 Nm (66 lb-ft). Step 3: Final
pass, tighten all bolts in sequence to 110 Nm (81 lb-ft). Always follow
the specific Saab sequence from the center outwards.
Main Bearing Cap Bolts: 110-120 Nm (81-89 lb-ft).
Connecting Rod Cap Bolts: 65-70 Nm (48-52 lb-ft).
Flywheel to Crankshaft Bolts: 95-105 Nm (70-77 lb-ft).
Crankshaft Pulley Bolt: 250-270 Nm (184-199 lb-ft). Requires a special
tool to hold the pulley.
Camshaft Sprocket Bolt: 80-90 Nm (59-66 lb-ft).
Spark Plugs: 25-30 Nm (18-22 lb-ft).
Oil Pan Bolts: 20-25 Nm (15-18 lb-ft).
Valve Cover Bolts: 8-10 Nm (6-7 lb-ft).
Intake Manifold Bolts/Nuts: 20-25 Nm (15-18 lb-ft).
Exhaust Manifold Nuts: 30-35 Nm (22-26 lb-ft).
Oil Cooler Adapter to Block: 40-50 Nm (30-37 lb-ft).
The Saab B201 engine was used extensively in Saab's core models
throughout the 1980s: Saab 99 (1978-1980): The final years of the Saab
99, often with the B201 engine replacing the earlier 1.85L or 2.0L
units. Saab 900 (Classic) (1979-1993): The primary application. Used in
all naturally aspirated 2-door and 4-door 900 models (900, 900i, 900S,
900 GL, etc.) throughout the entire production run of the classic 900.
It was the standard 2.0L engine.
Saab 9000 (1985-1993): The early Saab 9000 models (9000, 9000i) used the
B201 as the base gasoline engine until it was replaced by more modern
engines. The B201 is distinct from the turbocharged B201L/T or the
16-valve B202 engines. Its application is specifically in non-turbo,
8-valve models. It is the quintessential "workhorse" engine of the
classic Saab era, prized for its indestructible nature.
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