Yanmar 4BY2-150 Specifications
| Engine Model: Yanmar 4BY2-150 |
| Engine Type: 4-stroke inline 4-cylinder turbocharged water-cooled diesel |
| Total Displacement: 122 cu.in (1.99 L) |
| Rated Engine Power: 150 Hp (110 kW) at 4000 rpm |
| Fuel System Type: Common rail direct injection |
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The Yanmar 4BY2-150 is a 4-cylinder, inline,
common-rail marine diesel engine based on a BMW engine block. Produced
as a high-performance auxiliary and main propulsion unit, this engine
was developed for planing powerboats, small cruisers, and sailing yachts
requiring a compact, lightweight diesel with power output comparable to
gasoline engines. The 4BY2-150 combines BMW’s automotive engine
architecture with Yanmar’s marine-specific adaptations, including a
freshwater cooling system with heat exchanger, turbocharging, and
electronic common-rail fuel injection.
The Yanmar 4BY2-150 is a vertical, 4-cycle, water-cooled diesel engine
with direct injection and common-rail fuel system. The engine is
turbocharged and intercooled to maximize power output while maintaining
compact dimensions. An electronic control system using Yanmar CAN-bus
architecture manages fuel injection, engine monitoring, and interface
with vessel controls. The cooling system incorporates a heat exchanger
that isolates the engine block from raw seawater. The 4BY2-150 is
recognized for its high power-to-weight ratio, quiet operation, and
smooth power delivery across the operating range.
The Yanmar 4BY2-150 is a water-cooled, four-stroke, turbocharged diesel
engine configured for longitudinal mounting in marine applications. Its
design emphasizes high specific output, electronic control, and compact
packaging.
Engine Type: Vertical inline-4, 4-cycle, water-cooled, turbocharged
diesel
Displacement: 1.995 liters (122 cu.in)
Bore and Stroke: 84.0 mm (3.31 in) x 90.0 mm (3.54 in)
Compression Ratio: 16.5:1
Combustion System: Direct injection (common rail)
Aspiration: Turbocharged with intercooler
Firing Order: 1-3-4-2
Rotation: Counter-clockwise (viewed from flywheel)
Maximum Output (Crankshaft): 110 kW (150 hp) at 4,000 rpm
Continuous Rating: 80 kW (109 hp) at 3,600 rpm
Maximum Torque: 330 Nm (243 lb-ft) at 2,000-2,500 rpm
Idle Speed: 700 rpm
Maximum Engine Speed: 4,300 rpm (governor limited)
The cylinder block is manufactured from aluminum alloy, derived from BMW
automotive engine architecture. This material selection reduces overall
engine mass and improves heat dissipation compared to cast iron
alternatives, contributing to the high power-to-weight ratio. The
open-deck block design features cast-in-place cylinder bores machined
directly into the aluminum casting with a wear-resistant coating or iron
liner system.
The block incorporates five main bearing webs with two-bolt or four-bolt
main bearing caps depending on the variant. The crankshaft is supported
by five bearings and is constructed from forged steel to withstand the
high torque output of the turbocharged diesel. A structural aluminum oil
pan is sealed to the lower crankcase, contributing to overall engine
rigidity while serving as the oil reservoir. The block design
incorporates mounting points for the heat exchanger, turbocharger, and
intercooler.
Block Material: Aluminum alloy
Bore Diameter (finished): 84.0 mm (3.31 in)
Main Bearing Caps: Cast iron, two-bolt or four-bolt design
Cylinder Bore Deformation Limit: 0.04 mm (0.0016 in)
The cylinder head is manufactured from aluminum alloy, matching the
block material to ensure uniform thermal expansion. The DOHC valvetrain
actuates sixteen valves - four valves per cylinder - through a system of
roller finger followers and hydraulic lash adjusters. The hydraulic lash
adjusters automatically maintain zero valve clearance throughout the
engine’s service life, eliminating the need for manual valve
adjustments.
The camshafts are driven by a roller chain from the crankshaft, with an
automatic hydraulic tensioner maintaining chain tension. The common-rail
injectors are mounted centrally in the cylinder head, positioned to
deliver fuel directly into the combustion chamber. The valve train and
cylinder head are designed for the elevated cylinder pressures generated
by common-rail diesel combustion. The engine is of interference design;
in the event of timing chain failure, valve-to-piston contact occurs.
Head Material: Aluminum alloy
Valve Configuration: DOHC, 4 valves per cylinder with roller finger
followers
Valve Diameter (Intake): 32.0 mm (1.26 in)
Valve Diameter (Exhaust): 28.0 mm (1.10 in)
Valve Stem Diameter: 5.0 mm (0.20 in)
Valve Seat Angle: 45 degrees
Interference Design: Yes
The 4BY2-150 employs a common rail direct injection system. A
high-pressure fuel pump, driven by the timing chain or gear train, draws
fuel from the tank and delivers it to a common rail accumulator at
pressures up to 160 MPa (23,200 psi). The rail distributes pressurized
fuel to four solenoid or piezoelectric injectors, which are controlled
by the engine control unit (ECU) to deliver precise fuel quantities at
precisely timed intervals.
The common rail system enables multiple injection events per combustion
cycle, including pilot injection for reduced combustion noise, main
injection for power delivery, and post injection for exhaust
aftertreatment. The Yanmar electronic control system (CAN-bus
architecture) manages injection parameters based on inputs from the
crankshaft position sensor, camshaft position sensor, coolant
temperature sensor, intake air pressure sensor, rail pressure sensor,
and exhaust oxygen sensor.
Injection Type: Common rail direct injection
Injection Pressure: 160 MPa (23,200 psi) maximum
High-Pressure Pump Type: Radial piston pump
Injector Type: Solenoid or piezoelectric, centrally mounted
Fuel Requirement: Diesel fuel meeting EN 590 or ASTM D975 specifications
Fuel Cutoff: 4,300 rpm
The lubrication system is a fully pressurized, wet-sump design utilizing
a gear-type oil pump mounted to the front of the crankshaft. The oil
pump draws lubricant from the aluminum oil pan through a mesh strainer
and circulates it through a full-flow, replaceable oil filter and an
integrated oil cooler before entering the main oil gallery. From the
gallery, pressurized oil is distributed to the crankshaft main bearings,
connecting rod bearings, camshaft bearings, hydraulic lash adjusters,
timing chain tensioner, and turbocharger bearing housing.
A pressure relief valve integrated into the oil pump maintains system
pressure within operational limits. Piston cooling oil jets are
incorporated to direct a stream of oil toward the underside of each
piston crown, managing thermal loads associated with turbocharged diesel
operation.
Oil Type: Synthetic, SAE 5W-40 or 10W-40 (meeting BMW Longlife-04 or
ACEA C3)
Oil Capacity (with filter): 8.5 liters (9.0 US qt)
Oil Pressure (at 3,000 rpm): 350-450 kPa (50.8-65.3 psi)
Oil Pump Type: Gear-type, crankshaft-driven
Oil Filter Type: Spin-on or cartridge-type, full-flow
The 4BY2-150 utilizes a freshwater (closed-loop) cooling system with a
heat exchanger. This system isolates the engine block and cylinder head
from raw seawater, preventing internal saltwater corrosion. A
centrifugal-type water pump, driven by the timing chain, circulates
freshwater coolant through the engine block, cylinder head, turbocharger
center housing, and a separately mounted plate-type heat exchanger or
tube-bundle heat exchanger.
A second raw water pump, of the rubber impeller type, draws seawater
from the external environment and circulates it through the heat
exchanger to absorb heat from the freshwater circuit before discharging
overboard. A wax-pellet thermostat regulates fresh water flow to
maintain optimal operating temperature. An expansion tank allows for
coolant expansion and air separation.
Coolant Type: Ethylene-glycol based antifreeze with corrosion inhibitors
Coolant Capacity: 7.0 liters (7.4 US qt)
Thermostat Opening Temperature: 75-85 °C (167-185 °F)
Thermostat Full-Open Temperature: 95 °C (203 °F)
Heat Exchanger: Plate-type or tube-bundle type
Raw Water Pump: Rubber impeller type
| Intake and Exhaust Systems |
Intake System: Composite plastic or cast aluminum intake manifold with
integrated charge air cooler connections. The intake system incorporates
an air cleaner housing with a dry-type paper filter element. An
electronically controlled intake throttle valve is used for shutdown.
Exhaust System: Cast iron or stainless steel exhaust manifold with
integrated turbocharger mounting flange. A water-injected exhaust elbow
mixes raw seawater with exhaust gases to cool the exhaust system and
reduce noise.
12V system with a 150 ampere alternator. The alternator is belt-driven
from the crankshaft pulley and provides charging for the vessel’s
battery bank. The starting system uses a 12V, 2.0 kW electric starter
motor.
Turbocharger System: The engine is equipped with a fixed-geometry or
variable geometry turbocharger depending on the variant. Maximum boost
pressure ranges from 1.2 to 1.5 bar (17.4-21.8 psi). An air-to-water or
air-to-air intercooler reduces intake air temperature before entering
the engine, increasing air density and reducing thermal load.
Control System: Yanmar electronic control system utilizing CAN-bus
architecture. The system integrates engine control, vessel interface,
and diagnostic functions. A digital or analog control panel provides
start/stop, throttle, and monitoring functions including engine speed,
coolant temperature, oil pressure, and battery voltage.
Timing Drive: A roller chain drives the camshafts from the crankshaft
sprocket. An automatic hydraulic tensioner maintains chain tension. The
timing chain is designed for extended service life with no specified
replacement interval under normal operating conditions.
Dry Weight (without gearbox): 258 kg (569 lb)
Overall Length: 750-850 mm (29.5-33.5 in)
Overall Width: 600-700 mm (23.6-27.6 in)
Overall Height: 700-800 mm (27.6-31.5 in)
Oil Change Interval: 200 hours or annually under normal conditions.
Oil Change Interval: 100 hours under severe conditions.
Oil Filter Change: At every oil change.
Engine Coolant Replacement (freshwater side): 500 hours or 2 years.
Raw Water Pump Impeller Replacement: Annually or 200 hours.
Timing Chain Inspection: Inspect for noise at each service interval.
Fuel Filter Replacement: 200 hours or annually.
Air Filter Replacement: 200 hours or as indicated by inspection.
Heat Exchanger Anode Replacement: Annually or as indicated by anode
consumption.
Glow Plug Inspection: Check at each major service; replace as required.
Valve Clearance: Hydraulic lash adjusters; no adjustment required.
Idle Speed: Non-adjustable; controlled by ECU.
Drive Belt Inspection: Every 200 hours for tension, cracking, and
glazing.
Cylinder Head Bolts (M10 x 1.25), 1st pass: 20-25 Nm (15-18 lb-ft).
Cylinder Head Bolts (M10 x 1.25), 2nd pass: 40-45 Nm (30-33 lb-ft) plus
90° rotation.
Main Bearing Cap Bolts (M10 x 1.25): 45-50 Nm (33-37 lb-ft) plus 90°
rotation.
Connecting Rod Cap Bolts (M8 x 1.0): 20-25 Nm (15-18 lb-ft) plus 45°
rotation.
Camshaft Bearing Cap Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Intake Manifold Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Exhaust Manifold Nuts (M8 x 1.25): 23-28 Nm (17-21 lb-ft).
Turbocharger Mounting Nuts (M8 x 1.25): 30-35 Nm (22-26 lb-ft).
Glow Plugs: 10-12 Nm (89-106 lb-in).
Oil Pan Bolts (M6 x 1.0): 8-10 Nm (71-89 lb-in).
Water Pump Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Timing Chain Tensioner Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Crankshaft Pulley Bolt (M16 x 1.5): 50 Nm (37 lb-ft) plus 90° rotation.
Flywheel / Drive Plate Bolts (M10 x 1.25): 45-50 Nm (33-37 lb-ft) plus
90° rotation.
The Yanmar 4BY2-150 engine is utilized exclusively in marine
applications, primarily as propulsion for powerboats and as a
high-output auxiliary for larger sailing yachts.
Powerboats: Planing motor cruisers, center-console fishing boats, and
rigid inflatable boats (RIBs) up to approximately 30 feet in length.
Sailboats: Larger cruising yachts (40-55 feet) requiring high-output
auxiliary power for maneuverability and extended motoring.
Small Commercial Vessels: Patrol boats, workboats, and passenger vessels
requiring compact high-power-density diesel propulsion.
Stern-Drive and V-Drive Configurations: Vessels with inboard propeller
shafts or stern-drive installations.
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