Yanmar 6BY2-260 Specifications
| Engine Model: Yanmar 6BY2-260 |
| 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 6BY2-260 is a 6-cylinder, inline
marine diesel engine developed through a strategic collaboration between
Yanmar and BMW, combining Japanese manufacturing precision with German
high-speed diesel engineering. Produced from approximately 2006 onward,
this engine represents a significant advancement in marine propulsion
technology, featuring a common rail direct injection system,
turbocharging, and a seawater-cooled intercooler.
The Yanmar 6BY2-260 delivers 260 hp at 4,000 rpm from a displacement of
2.993 liters, achieving an exceptional power-to-weight ratio of 315 kg
(694 lb) dry. The electronic control unit (ECU) manages fuel injection
with precision, supporting NMEA 2000 connectivity for seamless
integration with vessel instrumentation systems. The engine meets EU
RCD, EPA Tier 2, and BSO II emission standards. The Yanmar 6BY2-260 is
available with ZT350/ZT370 sterndrives or the KMH50A gearbox, making it
suitable for high-performance cruising boats, sportfishing vessels, and
day cruisers from manufacturers such as Riva, VanDutch, and Luhrs.
Engine Code: 6BY2-260
Engine Family: Yanmar BY series
Configuration: Inline 6-cylinder
Cycle: 4-cycle diesel
Displacement: 2.993 liters (3,000 cc; 183 cu.in)
Bore: 84.0 mm (3.31 in)
Stroke: 90.0 mm (3.54 in)
Maximum Output: 191 kW (260 hp; 256 bhp) at 4000 rpm
Maximum Torque: 550 Nm (406 lb-ft) at 2000-2500 rpm
Aspiration: Turbocharged with seawater-cooled intercooler
Fuel System: Common rail direct injection
Combustion System: Direct injection
Rotation Direction: Counter-clockwise (standard marine configuration)
Dry Weight: 315 kg (694 lb)
Emission Compliance: EU RCD, EPA Tier 2, BSO II
The cylinder block is constructed from cast iron with a high-strength
alloy composition to withstand the increased cylinder pressures
generated by common rail injection and turbocharging. The block features
an inline 6-cylinder configuration with a deep-skirt design for enhanced
rigidity. A structural oil pan reinforces the lower crankcase area,
reducing vibration and noise transmission.
The crankshaft is precision-forged and supported by seven main bearings.
The connecting rods are manufactured from forged high-strength steel.
Pistons are aluminum alloy with cooling galleries and reinforced ring
lands to manage thermal loads under sustained high-speed operation.
The cylinder head is manufactured from aluminum alloy with a cross-flow
design. The valvetrain uses a dual overhead camshaft (DOHC) arrangement
with four valves per cylinder - two intake and two exhaust - actuated by
roller finger followers. Hydraulic lash adjusters eliminate the need for
periodic valve clearance adjustments.
The intake and exhaust camshafts are driven by a silent-type timing
chain system with automatic hydraulic tensioners. The combustion chamber
is a pent-roof design with the fuel injector mounted centrally for
optimal mixture formation. Glow plugs are installed for cold-start
assistance.
The fuel system employs a common rail direct injection architecture
developed with BMW technology. A high-pressure fuel pump - mounted to
the engine front - generates rail pressures capable of supporting the
260 hp output. The common rail distributes pressurized fuel to six
electronically controlled injectors.
The Engine Control Unit (ECU) governs injection timing, injection
duration, and rail pressure, enabling multiple injection events per
combustion cycle for reduced combustion noise, improved cold-start
behavior, and optimized fuel consumption. A low-pressure fuel lift pump
draws fuel from the tank and supplies it to the high-pressure pump. Dual
fuel filters with water separation protect the precision injection
components. The system includes a fuel cooler to stabilize fuel
temperature.
The lubrication system is a pressurized, full-flow wet-sump design
utilizing a trochoid-type oil pump driven from the crankshaft front. The
oil pump draws fluid from a structural aluminum oil pan. A full-flow
spin-on oil filter is mounted to the engine block.
An oil cooler, integrated into the lubrication circuit, maintains
optimal oil temperature under sustained high-load operation. Recommended
oil viscosity is 15W-40 conforming to API CI-4 or higher diesel
specifications. A low oil pressure alarm provides warning pressure
drops.
The cooling system is a freshwater indirect cooling arrangement with a
heat exchanger. A belt-driven centrifugal fresh water pump circulates
coolant through the cylinder block, cylinder head, turbocharger bearing
housing, and intercooler. A wax-element thermostat regulates coolant
flow. The heat exchanger transfers heat from the freshwater circuit to
the seawater circuit.
A belt-driven seawater pump (rubber impeller type) draws raw water
through a sea strainer and circulates it through the heat exchanger, oil
cooler, intercooler, and exhaust mixing elbow. The freshwater capacity
(engine and heat exchanger) is 13.5 liters (14.3 qt). A separate
seawater-cooled intercooler reduces intake air temperature after the
turbocharger, increasing charge density and power output.
| Intake and Exhaust Systems |
Intake System: The intake system includes a dry-type air filter suitable
for marine engine room environments. The intake manifold is constructed
from composite plastic or aluminum alloy.
Exhaust System: The exhaust manifold is constructed from cast iron. A
mixing elbow injects seawater into the exhaust stream to cool gases
before they exit through the wet exhaust hose and transom fitting. A
high-rise mixing elbow option is available for vessels with higher
exhaust outlet requirements.
The engine is equipped with a 12-volt electric starting motor. A
150-ampere single-pole alternator provides substantial charging capacity
for vessel house loads. Glow plugs with a controller system assist cold
starting. A full wire harness connects the ECU, sensors, and actuators.
An air heater is available for extreme cold-weather operation.
Turbocharging System: The engine is equipped with a wastegated
turbocharger. The wastegate limits maximum boost pressure to protect the
engine during high-load operation. Compressed air from the turbocharger
passes through the seawater-cooled intercooler before entering the
intake manifold.
Engine Management System: The Engine Control Unit (ECU) is a 32-bit
system managing fuel injection, timing control, air-fuel ratio, and
engine protection functions. The ECU supports NMEA 2000 connectivity for
integration with vessel displays, electronic control head, and LCD
instrumentation. The system provides continuous monitoring of critical
engine parameters with configurable alarms.
Dry Weight (engine only): 315 kg (694 lb)
Overall Length: 1,200-1,300 mm (47-51 in)
Overall Width: 800-900 mm (31-35 in)
Overall Height: 700-800 mm (28-31 in)
Engine Oil Capacity (with filter change): 12.0-14.0 liters (12.7-14.8
qt)
Engine Oil Specification: 15W-40, API CI-4 or higher diesel oil
Oil Change Interval: 250 hours or 12 months
Freshwater Capacity (engine + heat exchanger): 13.5 liters (14.3 qt)
Coolant Specification: Ethylene glycol-based diesel coolant for
mixed-metal systems
Coolant Change Interval: 2,000 hours or 24 months
Seawater Pump Capacity: 140 L/min (37 gpm) at 4000 engine rpm
Seawater Pump Maximum Lift: 2,000 mm (78.75 in)
Seawater Pump Impeller Replacement Interval: 500 hours or 12 months
Thermostat Opening Temperature: 71-77°C (160-170°F)
Valve Clearance: Hydraulic lash adjusters - no adjustment required
Fuel Filter Replacement Interval: 250 hours
Air Filter Replacement Interval: Clean every 250 hours; replace as
required
Drive Belt Tension: Automatic spring tensioner - no adjustment required
Idle Speed (low, no load): 750-850 rpm
Rated Speed (maximum): 4000 rpm
Cylinder Head Bolts (Stage 1): 30 Nm (22 lb-ft).
Cylinder Head Bolts (Stage 2): 90 Nm (66 lb-ft).
Connecting Rod Cap Bolts: 45 Nm (33 lb-ft).
Main Bearing Cap Bolts: 100 Nm (74 lb-ft).
Crankshaft Pulley Bolt: 200-250 Nm (148-184 lb-ft)
Flywheel Bolts: 80-100 Nm (59-74 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: 20-25 Nm (15-18 lb-ft)
Exhaust Manifold Nuts: 35-45 Nm (26-33 lb-ft)
Turbocharger Mounting Nuts: 45 Nm (33 lb-ft).
Turbocharger Oil Feed Line: 30 Nm (22 lb-ft).
Glow Plugs: 15-20 Nm (11-15 lb-ft)
Rocker Arm Pedestal Bolts: 20-25 Nm (15-18 lb-ft)
Oil Pan Bolts: 15-20 Nm (11-15 lb-ft)
Water Pump Bolts: 20-25 Nm (15-18 lb-ft)
Seawater Pump Mounting Bolts: 20-25 Nm (15-18 lb-ft)
Starter Motor Mounting Bolts: 40-50 Nm (30-37 lb-ft)
Heat Exchanger Mounting Bolts: 25-30 Nm (18-22 lb-ft)
Riva Iseo (2023 model year): The 6BY2-260 powers the Iseo day cruiser, a
8.24 m (27 ft) vessel with 2.50 m (8.2 ft) beam. This application pairs
the engine with a ZT350 Duoprop sterndrive, achieving efficient power
delivery and maneuverability.
VanDutch 40 (2011 model year): Twin 6BY2-260 engines provide 520
combined horsepower for the VanDutch 40 cruiser. This installation uses
direct drive inboards for sport cruising applications.
Luhrs 28 (2007-2009 model years): The Luhrs 28 sportfishing vessel is
equipped with twin 6BY2-260 engines, each producing 260 hp. Each engine
has logged 232-489 hours in documented installations, demonstrating the
engine's durability in offshore applications.
High-Performance Cruising Boats: The 6BY2-260 serves as primary
propulsion for express cruisers, sportfishing boats, and day boats from
7-12 meters (23-40 feet).
Sterndrive Applications (6BY2-260Z variant): The "Z" suffix indicates
sterndrive configuration, paired with Yanmar ZT350 or ZT370 hydraulic
sterndrives. These drives feature Duoprop counter-rotating propellers
for superior grip and maneuverability.
Direct Drive Applications (6BY2-260 variant): Models without the "Z"
suffix use direct drive configurations with Yanmar KMH50A marine gearbox
or similar transmissions for conventional shaft drive installations.
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