Yanmar 6BY3-260 Specifications
| Engine Model: Yanmar 6BY3-260 |
| Engine Type: 4-stroke inline 6-cylinder turbocharged water-cooled diesel |
| Total Displacement: 183 cu.in (2.99 L) |
| Rated Engine Power: 260 Hp (191 kW) at 4000 rpm |
| Fuel System Type: Common rail direct injection |
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The Yanmar 6BY3-260 represents the third and
final evolution of the BMW-based 3.0-liter common rail marine diesel
series. Compared to its 6BY2 predecessor, the 6BY3 incorporates an
upgraded electronic control unit, a redesigned fuel filtration system,
and improved oil pipework for enhanced reliability in marine
environments. This six-cylinder, in-line engine produces 260 horsepower
while maintaining the compact dimensions and light weight that made the
BY series popular for high-performance planing vessels.
The Yanmar 6BY3-260 features a second-generation Bosch common rail fuel
system, turbocharging with a seawater-cooled charge-air cooler, and
meets stringent US EPA Tier 3 and EU RCD 2 emission standards. The
engine is available in sterndrive configuration with Yanmar ZT370 drive
(6BY3-260Z model) or for inboard installations with KMH50A/KMH51A
gearboxes.
Engine Type: Inline 6-cylinder, 4-stroke, turbocharged water-cooled
diesel.
Valvetrain: DOHC (Double Overhead Camshaft), 4 valves per cylinder (24
total).
Displacement: 2.993 L (2993 cc / 183.0 cu.in).
Bore: 84.0 mm (3.31 in).
Stroke: 90.0 mm (3.54 in).
Compression Ratio: 16.5:1.
Fuel System: Direct injection with Bosch second-generation common rail
system.
Aspiration: Turbocharged with seawater-cooled charge-air cooler
(intercooler).
Maximum Output (Marine Crankshaft): 260 hp (191 kW) at 4000 rpm.
Continuous Rating: 198 hp (147 kW) at 3600 rpm.
Maximum Engine Speed (No Load): 4200 rpm.
Idle Speed: 700 rpm.
Emission Standards: US EPA Tier 3, EU RCD 2, IMO Tier 2, BSO II.
Fuel Consumption (at 4000 rpm): 53.6 L/h (14.2 gph).
Fuel Consumption (at 3200 rpm): 29.5 L/h (7.8 gph).
Fuel Condition Reference: Density at 15°C = 0.842 g/cc.
The cylinder block is constructed from high-grade cast iron, providing
the rigidity and vibration damping necessary for continuous marine duty
cycles. The inline six-cylinder configuration ensures natural primary
and secondary balance without requiring balance shafts. The block
features cast-in cylinder liners.
Seven main bearings support the crankshaft to ensure stability under the
high loads generated by turbocharging and common rail combustion
pressures. The lower crankcase is sealed by a fabricated steel oil pan,
which serves as the oil reservoir. A gear-driven timing case at the
front of the block drives the camshafts and the high-pressure fuel pump.
The cylinder head is manufactured from aluminum alloy to reduce overall
engine mass. The DOHC arrangement operates twenty-four valves via
hydraulic lash adjusters, eliminating periodic valve clearance
adjustments. Four valves per cylinder optimize volumetric efficiency and
promote air swirl for complete combustion.
Valve Arrangement: 24 valves; DOHC with hydraulic lash adjusters.
Intake Valve Diameter: 29.0 mm (1.14 in).
Exhaust Valve Diameter: 25.0 mm (0.98 in).
Valve Seat Angle: Intake 45°, Exhaust 45°.
The cylinder head incorporates common rail injectors mounted vertically
and centered over each piston. Glow plugs are fitted for cold start
assistance. The valve train is driven by a maintenance-free timing chain
at the front of the engine.
The engine employs a second-generation Bosch common rail direct
injection system with an electronic control unit that provides total
intelligent engine management. A high-pressure fuel pump generates fuel
pressure stored in a common rail accumulator, which supplies all six
injectors simultaneously. Electronically controlled injectors enable
multiple injection events per combustion cycle.
System Type: Bosch common rail direct injection, second generation.
Fuel Pressure (Maximum): 1600 bar (23,206 psi).
Injector Type: Piezo or solenoid-actuated multi-stage injectors.
Rail Type: Common rail accumulator with pressure sensor and pressure
relief valve.
Fuel Filter System: Redesigned dual-stage filtration with integrated
water separator and priming pump.
The electronic control unit receives sensor inputs for coolant
temperature, fuel pressure, camshaft position, crankshaft position,
inlet air temperature, boost pressure, and throttle position to
calculate precise fuel delivery per cylinder.
Injection Timing: Variable, fully electronic (managed by ECU).
Cold Start Aid: Glow plugs with automatic post-heating cycle.
Fuel Grade: Diesel fuel meeting EN 590 or ASTM D975 specifications.
The lubrication system is a forced-feed, wet-sump design utilizing a
gear-type pump to circulate oil under pressure to all critical moving
parts. Improved oil pipework on the 6BY3 enhances reliability and
reduces the risk of the internal oil pipe loosening, a known issue on
earlier BY series engines.
Lubrication Type: Forced lubrication with gear-type pump.
Total Oil Capacity (with filter): 9.5 L (10.0 qt).
Recommended Oil Grade: SAE 15W-40 meeting API CF-4 or higher.
Oil Pan Capacity: 8.0 L (8.5 qt).
Oil Pump Type: Gear-type pump with integrated pressure relief valve.
Oil Filter: Full-flow spin-on cartridge type.
Oil Cooler: Integrated, coolant-cooled plate-type heat exchanger.
The oil sump is fabricated steel and includes a drain plug accessible
from the underside. The system includes an oil pressure relief valve to
prevent excessive pressure during cold starts. A dipstick is provided
for oil level monitoring.
The cooling system is an indirect, fresh water (coolant) circuit with a
heat exchanger for raw seawater cooling. A belt-driven centrifugal fresh
water pump circulates coolant through the cylinder block and head before
passing through a heat exchanger where raw seawater absorbs the heat. A
seawater-cooled charge-air cooler reduces intake air temperature to
increase density and combustion efficiency.
Cooling Type: Fresh water cooling with heat exchanger (indirect).
Coolant Capacity (engine, heat exchanger, and intercooler): 12.0 L (12.7
qt).
Fresh Water Pump: Belt-driven centrifugal type with cast iron housing.
Seawater Pump: Belt-driven flexible rubber impeller pump.
Thermostat Opening Temperature: 82°C (180°F).
Intercooler Type: Seawater-cooled air-to-liquid.
Heat Exchanger: Shell and tube type with sacrificial zinc anodes for
corrosion protection.
Raw seawater is drawn through a strainer, circulated through the heat
exchanger, intercooler, and exhaust mixing elbow, then discharged
overboard. The fresh water cooling loop maintains consistent engine
operating temperatures regardless of seawater conditions.
Electrical System: A 12V electrical system includes a 2.0 kW electric
starter motor and a high-output 12V 180A alternator standard on the 6BY3
(upgraded from 150A on the 6BY2). The alternator provides ample capacity
for multiple batteries, electronics, and onboard systems. An optional
12V 230A alternator is available for heavy electrical loads.
Control System: Yanmar VC10 electronic control system provides
single-lever throttle and shift operation with NMEA 2000 and CAN-bus
compatibility. The system includes electronic engine synchronization for
twin installations, troll mode, and integrated diagnostics. Control
options include Classic (Hybrid) mechanical backup and Unlimited
(Electronic) fully electronic configurations.
Turbocharger System: A wastegated turbocharger regulates boost pressure
to prevent over-boosting at high engine speeds. The turbocharger center
housing is cooled by engine coolant and receives pressurized oil from
the engine lubrication system.
Exhaust System: A water-cooled mixing elbow injects raw seawater into
the exhaust stream, cooling exhaust gases to safe temperatures for
onboard exhaust hose routing and reducing exhaust noise. A high-rise
mixing elbow option is available to prevent seawater backflow into the
turbocharger under following sea conditions.
Drive Systems: The KMH50A or KMH51A hydraulic multi-disc clutch gearbox
with 8° down-angle is available for inboard shaft drive installations.
The ZT370 sterndrive with hydraulic clutch and twin counter-rotating
duoprop propellers is offered for the 6BY3-260Z model, providing
superior handling and acceleration.
Dry Weight (engine only, without gearbox): 328 kg (723 lb).
Overall Length (with KMH41A gearbox and L-type elbow): 1069 mm (42.1
in).
Overall Width: 762 mm (30.0 in).
Overall Height: 717 mm (28.2 in).
Sterndrive Model Dimensions (without sterndrive): 1027 mm x 770 mm x 785
mm (40.4 in x 30.3 in x 30.9 in).
Oil Change Interval: 200 hours or annually, whichever occurs first.
Oil Filter Replacement: Every oil change.
Fuel Filter Replacement: 200 hours or annually; primary and secondary
filters.
Coolant Replacement: 2 years, using approved ethylene glycol antifreeze.
Seawater Pump Impeller: Inspect every 100 hours.
Seawater Pump Impeller: Replace every 200 hours or annually.
Zinc Anode Inspection: 100 hours; replacement when 50% consumed.
Valve Clearance: Hydraulic lash adjusters require no scheduled
adjustment.
Timing Chain: Inspection only if abnormal noise develops.
Turbocharger Inspection: 500 hours for bearing play and seal integrity.
Thermostat Check: Annually; replace if opening temperature deviates.
Cylinder Head Bolts (Stage 1): 30 Nm (22 lb-ft).
Cylinder Head Bolts (Stage 2): 90 Nm (66 lb-ft).
Connecting Rod Cap Bolts: 40 Nm (30 lb-ft).
Main Bearing Cap Bolts: 100 Nm (74 lb-ft).
Flywheel Bolts: 80 Nm (59 lb-ft).
High-Pressure Fuel Pump Mounting Bolts: 25 Nm (18 lb-ft).
Common Rail Mounting Bolts: 25 Nm (18 lb-ft).
Injector Clamp Bolts: 12 Nm (9 lb-ft).
Intake Manifold Bolts: 20 Nm (15 lb-ft).
Exhaust Manifold Nuts: 30 Nm (22 lb-ft).
Turbocharger Mounting Nuts: 45 Nm (33 lb-ft).
Turbocharger Oil Feed Line: 30 Nm (22 lb-ft).
Starter Motor Mounting Bolts: 50 Nm (37 lb-ft).
Alternator Mounting Bolts: 35 Nm (26 lb-ft).
Oil Pan Bolts: 15 Nm (11 lb-ft).
Seawater Pump Mounting Bolts: 20 Nm (15 lb-ft).
Fresh Water Pump Mounting Bolts: 25 Nm (18 lb-ft).
The Yanmar 6BY3-260 is produced as a marine propulsion engine for
recreational and light commercial vessels.
Marlow Pilot 34: Twin 260 hp 6BY3-260 diesels provide power for this
39-foot 8-inch downeast-style cruiser, achieving a top speed of 23.9
knots at 4100 rpm.
Xtenders 6.9M Beachlander: Single 260 hp engine powers this 6.9 m carbon
superyacht tender to 40 knots, designed for the 85m S/Y Aquijo.
Compass Tenders Sports RIB 7.5M: Twin 260 hp engines drive this crew
launch tender capable of 40 knots, built for the 78m motor yacht Titan.
Vismara Gynko: Twin 260 hp engines with 2.18:1 reduction ratio power
this 35-knot luxury performance yacht.
Leopard 43 Powercat: Twin 6BY3-260 engines on shaft drives deliver
17-knot cruise and 22-knot maximum speed for this 43-foot power
catamaran.
VanDutch 40: Twin 6BY3-260 engines provide inboard direct drive
propulsion for this 40-foot premium day boat through ZF 63A 2.5:1
reduction gears.
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