Isuzu 8PB1 Specifications
| Engine Model: Isuzu 8PB1 |
| Engine Type: 4-stroke V-block 8-cylinder liquid-cooled diesel |
| Total Displacement: 684 cu.in (11.2 L) |
| Rated Engine Power: 235-275 Hp (174-205 kW) at 2800 rpm |
| Fuel System Type: Direct Injection |
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The Isuzu 8PB1 is an 8-cylinder,
V-configuration diesel engine from the Isuzu P-series family. This
engine was produced primarily for heavy commercial vehicles and marine
propulsion applications. The P-series engine family includes the 8PA1,
10PB1, and 12PB1 variants, with the 8PB1 representing the 8-cylinder
evolution within this lineage. The engine was introduced around 1979 as
part of a major model update and was designed to comply with Japanese
1979 emissions regulations.
The Isuzu 8PB1 is a naturally aspirated V8 diesel engine known for its
robust construction and durability in heavy-duty applications. The
engine shares its fundamental architecture with the larger 10PB1 and
12PB1 models within the P-series family. It features an overhead valve
(OHV) valvetrain and is available in both naturally aspirated and
turbocharged configurations designated as 8PB1-T.
In marine applications, the UM8PB1 variant was produced between 1982 and
1990 for workboats and marine propulsion. The engine employs a liquid
cooling system, which in marine installations includes a heat exchanger
for raw water cooling. The 8PB1 represents the intermediate step between
the earlier 8PA1 and the later 8PC1 and 8PD1 series engines.
Engine Family: Isuzu P-series.
Configuration: 90° V8, 4-stroke diesel.
Displacement: 11,217 cc (11.2 L / 684 cu.in) .
Bore x Stroke: 115 mm x 135 mm (4.53 in x 5.31 in).
Firing Order: 1-5-3-6-2-4.
Aspiration: Naturally Aspirated (NA) or Turbocharged (8PB1-T).
Aspiration: Turbocharged (8PB1-T).
Valvetrain: Overhead Valve (OHV).
Maximum Power (NA): 235 hp (174 kW).
Maximum Power (Turbocharged): 275 hp (205 kW).
Rated Speed: 2,800-3,000 rpm.
Emission Standard: Japanese 1979 emissions compliance.
Material: Cast iron.
Configuration: 90-degree V8.
Cylinder Liners: Replaceable wet-sleeve design.
Number of Cylinders: 8.
Bore Diameter: 115 mm (4.53 in) .
Main Bearings: 5 main bearing caps (one between each pair of opposing
cylinders).
Construction: Heavy-duty cast iron block designed for high continuous
load applications in truck and marine environments.
Material: Cast iron (separate heads per cylinder bank).
Valvetrain: Overhead valve (OHV) with pushrods and rocker arms.
Valves per Cylinder: 2 (1 intake, 1 exhaust).
Total Valves: 16.
Valve Arrangement: In-line within each cylinder head.
Valve Clearance (Cold - Intake): 0.20-0.30 mm (0.008-0.012 in).
Valve Clearance (Cold - Exhaust): 0.30-0.40 mm (0.012-0.016 in).
Cylinder Head Gasket: Composite metal construction.
System Type: Direct injection (mechanical).
Injection Pump: Inline mechanical injection pump (Bosch / Zexel type).
Governor: Mechanical centrifugal type with variable speed control.
Injectors: Mechanical nozzle-and-holder type.
Injection Timing: Not specified in available documentation.
Fuel Filter: Spin-on type with integral water separator.
Fuel Type: Diesel No. 1-D or No. 2-D.
System Type: Gear-type positive displacement pump, full-flow filtration.
Oil Capacity (including filter): 18.0-20.0 L (19.0-21.0 qt).
Oil Pressure (Hot, Rated Speed): 300-400 kPa (43-58 psi).
Oil Specification: API CI-4 or CJ-4; SAE 15W-40.
Oil Change Interval: 250 hours or 10,000 km (6,200 miles).
Oil Filter: Full-flow spin-on element.
Oil Pan: Stamped steel or cast aluminum with drain plug.
System Type: Water-cooled with centrifugal water pump.
Coolant Capacity (engine only): 12.0-14.0 L (12.7-14.8 qt).
Thermostat (Opening Temperature): 76-82°C (169-180°F).
Thermostat (Full Open): 90-95°C (194-203°F).
Coolant Specification: Ethylene glycol base, corrosion-inhibited formula
for diesel engines.
Water Pump Drive: V-belt or gear-driven depending on application.
Marine Variant: Heat exchanger system for raw water cooling (UM8PB1).
Electrical System: 24 V (standard for heavy commercial vehicles).
Starter Motor: 24 V / 5.0-6.0 kW.
Alternator: 24 V / 35-50 A.
Glow Plugs: 8 units (24 V) with intake air heater for cold starting.
Dry Weight (complete engine): 550-600 kg (1,210-1,320 lb).
Length (fan to flywheel housing): 1,150 mm (45.3 in).
Width (overall): 850 mm (33.5 in).
Height (oil pan rail to rocker cover top): 950 mm (37.4 in).
Oil Change Interval (truck): 10,000 km (6,200 miles).
Oil Change Interval (industrial/marine): 250 hours.
Fuel Filter Change Interval: 500 hours or 20,000 km (12,400 miles).
Valve Lash Inspection Interval: 1,000 hours or 40,000 km (25,000 miles).
Coolant Change Interval: 2,000 hours or 2 years.
Injection Timing Check Interval: 2,000 hours.
Air Filter Service: Dry-type; replace at 500 hours.
Cylinder Head Bolts (M14), Stage 1: 60 Nm (44 lb-ft).
Cylinder Head Bolts (M14), Stage 2: 120 Nm (89 lb-ft).
Connecting Rod Bolts (M12): 80 Nm (59 lb-ft).
Main Bearing Cap Bolts (M14): 130 Nm (96 lb-ft).
Flywheel to Crankshaft Bolts (M12): 100 Nm (74 lb-ft).
Flywheel Housing to Block: 70 Nm (52 lb-ft).
Rocker Arm Shaft Bracket: 45 Nm (33 lb-ft).
Intake Manifold (M10): 25 Nm (18 lb-ft).
Exhaust Manifold (M10): 30 Nm (22 lb-ft).
Injector Hold-Down Clamp: 25 Nm (18 lb-ft).
Glow Plug: 20 Nm (15 lb-ft).
Oil Pan Drain Plug (M18): 50 Nm (37 lb-ft).
Thermostat Housing Bolts (M8): 15 Nm (11 lb-ft).
Valve Cover Bolts (M6): 10 Nm (7.4 lb-ft).
Marine: UM8PB1 variant for workboats and marine propulsion (1982-1990
production) .
Heavy Trucks: Isuzu heavy-duty truck series (preceding the 8PC1 and 8PD1
series).
Dump Trucks: Heavy dump truck applications with naturally aspirated
configuration.
Tractors: Heavy tractor units (turbocharged configuration available).
Industrial: Stationary power units and generator drives.
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