Yanmar 4LHA STE Specifications
| Engine Model: Yanmar 4LHA STE |
| Engine Type: 4-stroke inline 4-cylinder turbocharged water-cooled diesel |
| Total Displacement: 210.8 cu.in (3.45 L) |
| Rated Engine Power: 230 Hp (169 kW) at 3300 rpm |
| Fuel System Type: Direct injection |
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The Yanmar 4LHA-STE is a 4-stroke, vertical,
water-cooled marine diesel engine from the LHA series. This engine
serves as the high-output predecessor to the 4LHA-STP, delivering robust
power for planing hulls through a mechanical direct injection system.
Produced primarily for marine propulsion applications, the 4LHA-STE
combines a 3.455-liter displacement with turbocharging and an
intercooler to achieve 230 hp at 3,300 rpm. The engine is designed for
vessels requiring high power-to-weight ratio, including sport fishing
boats, express cruisers, and commercial craft operating in planing mode.
The Yanmar 4LHA-STE represents a high-performance marine diesel
architecture emphasizing power density and reliability in planing hull
applications. Its inline 4-cylinder configuration with a 100 mm bore and
110 mm stroke provides favorable torque characteristics for accelerating
planing hulls. The cast iron cylinder block with parent-bore design
offers durability without replaceable liners.
The overhead valve (OHV) valvetrain with eight valves provides a simple,
serviceable layout accessible for valve lash adjustment. The direct
injection combustion system, combined with a turbocharger and
intercooler, delivers high specific output while maintaining mechanical
fuel system simplicity. The freshwater cooling system with a heat
exchanger isolates the engine block from seawater contact. The
counter-clockwise rotation viewed from the flywheel end matches standard
marine propeller configurations for single and twin-engine
installations.
Engine Type: Vertical inline 4-cylinder, 4-cycle, water-cooled,
turbocharged diesel
Family: Yanmar LHA Series
Displacement: 3.455 liters (210.8 cu.in)
Bore x Stroke: 100.0 mm x 110.0 mm (3.94 in x 4.33 in)
Compression Ratio: 18.4:1
Firing Order: 1-3-4-2
Aspiration: Turbocharged with air-to-seawater intercooler
Maximum Output (Crankshaft): 169 kW (230 hp) @ 3,300 rpm
Continuous Rating (Crankshaft): 140 kW (190 hp) @ 3,100 rpm
Maximum Engine Speed (No Load): 3,600 rpm
Idle Speed: 700 rpm
Rotation Direction: Counter-clockwise when viewed from the stern
(flywheel side)
Valvetrain: OHV, 8 valves (2 valves per cylinder).
Mechanical pushrods and rocker arms. Direct injection combustion system.
The cylinder block is constructed from cast iron with a deep-skirt
design, providing structural rigidity for sustained high-load marine
operation. The block utilizes a parent-bore design with cylinder bores
machined directly into the cast iron casting. The cylinder bores are
induction-hardened to resist wear under extended service intervals.
Five main bearings support the crankshaft. The water jacket surrounds
each cylinder with cast-in coolant passages optimized for uniform
thermal distribution at high power outputs. The camshaft is located
within the cylinder block, driven by a gear train from the crankshaft.
The engine mounting feet are integrated into the lower block casting,
accommodating flexible marine engine mounts for vibration isolation from
the hull structure.
The cylinder head is manufactured from cast iron, selected for thermal
stability and resistance to distortion under turbocharged diesel
combustion pressures. It employs an OHV configuration with the camshaft
located within the cylinder block. The eight valves are arranged with
two valves per cylinder in a vertical orientation. Valve actuation is
achieved via mechanical pushrods and rocker arms, with screw-and-locknut
adjusters for valve lash setting.
The combustion system utilizes direct injection with a re-entrant bowl
machined into the piston crown. The cylinder head incorporates separate
intake and exhaust ports on opposite sides. The exhaust manifold is
designed to mount the turbocharger. Valve seats are induction-hardened,
with valve guides manufactured from cast iron.
The engine is equipped with a mechanical direct injection fuel system.
An in-line injection pump is mounted to the side of the cylinder block,
driven by a gear from the camshaft. The injection pump incorporates a
mechanical governor, providing speed control and load response for
marine propeller law operation.
Injection timing is adjustable via shims between the pump mounting
flange and the block. Each cylinder receives fuel from a nozzle-type
injector, with injector opening pressure calibrated to 200-220 bar
(2,900-3,190 psi). A fuel supply pump draws fuel through a primary
filter and water separator assembly. Excess fuel returns to the tank via
a spill line.
The lubrication system is a forced lubrication configuration using a
gear-type oil pump. The oil pump, driven by the crankshaft, draws oil
from the sump and circulates it through a full-flow disposable spin-on
oil filter. An oil cooler of the seawater-cooled type maintains oil
temperature within operational limits under sustained high-load
operation.
Oil galleries within the block and cylinder head supply pressurized oil
to the main bearings, connecting rod bearings, camshaft bearings, rocker
arm assemblies, and turbocharger bearing housing. The turbocharger
receives oil through a dedicated supply line. A pressure relief valve
maintains system pressure within specified limits. Total oil capacity is
dependent on oil pan configuration and installation angle.
The cooling system is a freshwater (indirect) cooling design with a heat
exchanger, isolating the engine block from seawater contact. A
belt-driven centrifugal freshwater pump circulates coolant through the
cylinder block, cylinder head, intercooler, and the heat exchanger. The
intercooler is of the air-to-seawater type, reducing intake air
temperature after the turbocharger for increased charge density.
The heat exchanger transfers heat from the freshwater circuit to the
seawater circuit. A wax-type thermostat regulates freshwater flow. A
rubber-impeller seawater pump, separate from the freshwater circuit,
supplies cooling water to the heat exchanger, oil cooler, and exhaust
injection elbow.
Glow Plug System: The engine is equipped with glow plugs for cold-start
assistance. One glow plug per cylinder is installed in the cylinder
head, controlled by a key-switch circuit with a pre-heat indicator lamp.
Timing System: The camshaft and injection pump are driven by a gear
train housed at the front of the engine. The crankshaft gear drives an
idler gear, which in turn drives the camshaft gear and injection pump
gear. This gear-driven arrangement eliminates timing belt or chain
replacement requirements.
Governor System: The mechanical governor integrated into the injection
pump is calibrated for marine propeller law characteristics.
Turbocharger System: A fixed-geometry turbocharger provides forced
induction. The turbocharger is mounted to the exhaust manifold, with
boost pressure regulated by a wastegate actuator.
Intercooler System: An air-to-seawater intercooler reduces intake air
temperature after the turbocharger, increasing charge density and
reducing thermal load on the engine.
Exhaust System: A water-injected exhaust elbow mixes seawater with
exhaust gases, cooling the exhaust system and reducing surface
temperatures.
Emission Control: The engine incorporates a positive crankcase
ventilation (PCV) system. No catalytic converter is present.
Electrical System: The charging system consists of a 12V, 80A
alternator. The starter motor is a 12V, 2.5 kW (3.4 hp) unit.
Dry Weight (Bobtail, Without Gearbox): 365 kg (805 lb)
Dry Weight (with KMH50A Gearbox): 420 kg (926 lb)
Overall Length (Bobtail): 800 mm (31.5 in)
Overall Length (with Gearbox): 1,000 mm (39.4 in)
Overall Width: 700 mm (27.6 in)
Overall Height: 800 mm (31.5 in)
Bore Pitch: 115 mm (4.53 in)
Engine Oil Capacity: 8.0-10.0 liters (8.5-10.6 qt) dependent on oil pan
config.
Engine Oil Specification: SAE 15W-40 meeting API CD, CE, CF, or higher.
Engine Oil Pressure (at idle, warm): Minimum 1.0 bar (15 psi).
Engine Oil Pressure (at 3,300 rpm, warm): 3.0-4.5 bar (44-65 psi).
Coolant Capacity (Freshwater Circuit): 6.0 liters (6.3 qt).
Coolant Specification: Ethylene glycol-based antifreeze with corrosion
inhibitors.
Valve Clearance (Cold, Intake): 0.20 mm (0.008 in).
Valve Clearance (Cold, Exhaust): 0.25 mm (0.010 in).
Valve Clearance Inspection Interval: Every 500 operating hours.
Injector Opening Pressure: 200-220 bar (2,900-3,190 psi).
Fuel Injection Timing: 12-14° before top dead center (BTDC).
Oil Change Interval: 250 operating hours or annually, whichever occurs
first.
Fuel Filter Replacement Interval: 250 operating hours.
Coolant Change Interval: Every 1,000 operating hours or 2 years.
Idle Speed (In Gear, Engine Warm): 700 rpm.
High Idle No-Load Speed: 3,600 rpm.
Cruising RPM Range (Continuous Operation): 3,000-3,100 rpm.
Maximum Fuel Consumption: 48-50 l/h (12.7-13.2 gal/h) at max rated
output.
Compression Pressure: Standard: 28-32 bar (406-464 psi) at cranking
speed.
Cylinder Head Bolts, Stage 1: 50 Nm (37 lb-ft)
Cylinder Head Bolts, Stage 2: 90 Nm (66 lb-ft)
Cylinder Head Bolts, Stage 3: 127-137 Nm (94-101 lb-ft)
Main Bearing Cap Bolts: 100-110 Nm (74-81 lb-ft)
Connecting Rod Cap Bolts: 60-65 Nm (44-48 lb-ft)
Camshaft Bearing Cap Bolts: 20-25 Nm (15-18 lb-ft)
Flywheel Bolts: 80-90 Nm (59-66 lb-ft)
Crankshaft Pulley Bolt: 200-250 Nm (148-184 lb-ft)
Intake Manifold Nuts: 20-25 Nm (15-18 lb-ft)
Exhaust Manifold Nuts: 30-35 Nm (22-26 lb-ft)
Injector Hold-Down Clamp Bolts: 25-30 Nm (18-22 lb-ft)
Glow Plugs: 15-20 Nm (11-15 lb-ft)
Rocker Arm Shaft Bracket Bolts: 25-30 Nm (18-22 lb-ft)
Valve Cover Bolts: 8-10 Nm (6-7 lb-ft)
Oil Pan Bolts: 15-20 Nm (11-15 lb-ft)
Oil Pump Mounting Bolts: 25-30 Nm (18-22 lb-ft)
Water Pump (Freshwater) Mounting Bolts: 20-25 Nm (15-18 lb-ft)
Seawater Pump Mounting Bolts: 15-20 Nm (11-15 lb-ft)
Turbocharger Mounting Nuts: 35-40 Nm (26-30 lb-ft)
Injection Pump Mounting Nuts: 30-35 Nm (22-26 lb-ft)
Engine Mount (Bracket to Block): 50-60 Nm (37-44 lb-ft)
Heat Exchanger Mounting Bolts: 20-25 Nm (15-18 lb-ft)
The Yanmar 4LHA-STE engine is utilized across a range of marine vessel
applications requiring high power output for planing hull operation.
Sport Fishing Boats (28-34 Feet): The 4LHA-STE powers sport fishing
vessels from manufacturers including Grady-White, Boston Whaler,
Pursuit, and Regulator, providing the speed required to reach offshore
fishing grounds efficiently.
Express Cruisers (30-36 Feet): Express cruiser and weekend cruiser
applications utilize single or twin 4LHA-STE installations for planing
hull performance in coastal cruising.
Downeast Boats (28-32 Feet): Traditional Downeast-style lobster boats
and cruisers received the 4LHA-STE as a power option for its combination
of displacement mode fuel efficiency and planing capability.
Commercial Craft (30-40 Feet): Small commercial vessels including pilot
boats, patrol craft, water taxis, and light utility vessels utilize the
4LHA-STE for reliable high-output propulsion.
KMH50A Gearbox Configuration: The engine is commonly paired with the
KMH50A hydraulic transmission, an 8° down-angle gearbox providing smooth
shifting and a reduction ratio suitable for planing hull propellers.
ZF63A Gearbox Configuration: The ZF63A hydraulic transmission, also
offering an 8° down-angle, is another standard pairing for the 4LHA-STE,
providing durable operation for high-output applications.
HSR Series Gearbox Configuration: Hydraulic storage-reduction gears from
the HSR series are used in specific installations requiring specialized
reduction ratios or direct-mounted accessories.
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