Volvo Penta D6-350 Specifications
| Engine Model: Volvo Penta D6-350 |
| Engine Type: 4-cycle inline 6-cylinder turbocharged freshwater-cooled diesel |
| Total Displacement: 336 cu.in (5.5 L) |
| Rated Engine Power: 350 Hp (257 kW) at 3500 rpm |
| Fuel System Type: Common rail direct injection |
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The Volvo Penta D6-350 is a high-performance,
inline 6-cylinder, 5.5-liter diesel engine designed for marine
propulsion. This engine is a landmark model within the D6 series, being
one of the first mass-produced marine diesels to combine a mechanical
Roots-style supercharger with an exhaust gas turbocharger. This
dual-charging system eliminates turbo lag, delivering immediate throttle
response and massive low-end torque for rapid planing of leisure and
commercial vessels.
The engine integrates common-rail fuel injection with an Electronic
Vessel Control (EVC) system, offering precise electronic shift and
throttle functions alongside comprehensive engine monitoring. The D6-350
is tailored for high-speed planing hulls, including sport cruisers,
flybridge yachts, patrol boats, and rescue craft. It is available in
several configurations: with the DPH Aquamatic sterndrive (featuring
DuoProp counter-rotating propellers), as an inboard shaft-drive variant
with hydraulic gearboxes, or as the IPS450 integrated pod drive system.
Engine Designation: D6-350 A-B (varies by emission compliance and
control system version).
Engine Type: Inline 6-cylinder, 4-stroke, water-cooled diesel.
Displacement: 5.5 liters (336 cu.in).
Bore x Stroke: 103 mm x 110 mm (4.06 in x 4.33 in).
Compression Ratio: 17.5:1.
Aspiration: Turbocharged, mechanically supercharged (Roots-type), and
seawater aftercooled.
Crankshaft Power: 257 kW (350 hp) at 3500 rpm.
Full Throttle Operating Range: 3400-3600 rpm.
Maximum Torque: Approximately 680 Nm (502 lb-ft) at 2100-2400 rpm.
Firing Order: 1-5-3-6-2-4.
Idle Speed (in gear): 600-650 rpm.
Emission Compliance: IMO MARPOL Annex VI Tier II; EPA Tier 3 for certain
markets; RCD (Recreational Craft Directive) for EU.
Electrical System: 12V or 24V depending on configuration; alternator
rating 115A (12V) or 70A (24V).
The cylinder block is manufactured from high-strength cast iron with a
deep-skirt design. A ladder frame made of cast aluminum or nodular iron
is bolted to the bottom of the block, enclosing the lower crankcase and
serving as the main bearing cap support. This ladder frame construction
maximizes crankshaft bearing rigidity, significantly reducing vibration
and mechanical noise at high engine speeds.
The block incorporates wet-type, replaceable cylinder liners, permitting
overhaul without discarding the entire block. The water jacket surrounds
each cylinder bore fully, ensuring uniform heat dissipation under
continuous high-load operation. The block includes an integrated oil
gallery that supplies pressurized lubricant to the main bearings,
connecting rods, camshaft bearings, and piston cooling jets. An
additional mounting interface on the side of the block supports the
mechanical supercharger housing.
The cylinder head is constructed from cast aluminum alloy, reducing
overall engine weight while providing adequate thermal conductivity for
the 4-valve combustion chamber design. The head features a double
overhead camshaft (DOHC) configuration, with one camshaft actuating the
intake valves and the second actuating the exhaust valves. Four valves
per cylinder (two intake, two exhaust) are arranged in a pent-roof
combustion chamber. The central injector position provides uniform fuel
distribution across the piston bowl.
Valve seats are manufactured from heat-resistant alloy steel, and valve
guides are press-fitted into the head. The valvetrain incorporates
hydraulic lash adjusters and roller finger followers, eliminating the
need for periodic valve clearance adjustments. The hollow camshafts are
driven from the rear of the engine by a gear train, reducing front-end
accessory complexity. The intake ports are designed as high-swirl
passages to improve air-fuel mixing at low engine speeds when the
supercharger is active.
The fuel system is a high-pressure common rail (HPCR) direct injection
design using a Bosch common rail architecture. A gear-type electric lift
pump draws fuel from the tank and delivers it to a high-pressure pump
driven by the engine gear train. The high-pressure pump pressurizes fuel
to a maximum of 1800 bar (26,100 psi) and supplies the common rail
accumulator mounted on the cylinder head. The rail distributes fuel to
six solenoid-type injectors.
The engine management system (EMS) controls injection timing, duration,
and pressure based on engine load, speed, coolant temperature, and boost
pressure. The EMS commands multiple injection events per cycle: pilot
injection for noise reduction, main injection for power, and
post-injection for exhaust temperature management. A primary fuel filter
with an integrated water separator is installed between the lift pump
and the high-pressure pump. A secondary spin-on fuel filter is mounted
on the engine.
The lubrication system is a forced-feed, pressurized design using a
gear-type oil pump mounted on the front of the crankshaft. The pump
draws oil from a pressed steel oil pan through a suction strainer. Oil
passes through a full-flow spin-on oil filter with an integral bypass
valve. From the filter, oil enters the main oil gallery. The gallery
supplies the five main bearings, connecting rod bearings, camshaft
bearings, and the turbocharger bearing housing.
A piston cooling system is integrated, featuring oil jets directed at
the underside of each piston crown. These jets operate continuously to
manage thermal loads from the supercharger and turbocharger under high
power output. A centrifugal oil separator or closed crankcase
ventilation (CCV) filter is mounted on the cylinder head cover to return
oil mist to the sump while routing blow-by gases to the intake system.
The oil pan includes a drain plug and a dipstick for level measurement.
The cooling system is a dual-circuit, thermostat-controlled freshwater
(closed) cooling system with a seawater (raw water) cooling circuit. The
freshwater circuit uses a centrifugal water pump driven by the front
accessory belt. The pump circulates coolant through the cylinder block,
cylinder head, and the freshwater side of the charge air cooler
(aftercooler). A thermostat housing on the cylinder head controls flow
to the heat exchanger.
The seawater circuit uses a flexible impeller-type pump mounted on the
front of the engine. Seawater is drawn through a strainer and seacock,
then circulated through the heat exchanger, the seawater side of the
charge air cooler, and the oil cooler. The heat exchanger is a
shell-and-tube design mounted on top of the engine. The charge air
cooler is an integrated seawater-aftercooled unit that reduces intake
air temperature after the turbocharger. A coolant expansion tank with a
pressure cap rated at 0.7-1.0 bar (10-15 psi) accommodates thermal
expansion.
Intake and Dual Charging: A belt-driven Roots-type mechanical
supercharger is mounted on the side of the cylinder block. A
pneumatically or electrically actuated clutch engages the supercharger
at low engine speeds (below approximately 2000 rpm). The supercharger
provides immediate boost pressure for rapid acceleration and planing. An
exhaust gas turbocharger (wastegate or fixed geometry) takes over at
higher engine speeds. A bypass valve divests the supercharger once the
turbocharger delivers sufficient boost. The combined air stream passes
through the seawater-aftercooled charge air cooler before entering the
intake manifold.
Exhaust System: The exhaust manifold is a single-piece cast iron
component collecting gases from all six cylinders. Gases pass through
the turbocharger turbine housing, then through a water-cooled exhaust
elbow where seawater is injected for cooling and silencing. The wet
exhaust system discharges through a gooseneck fitting to prevent
siphoning.
Engine Management (EVC): The engine is fully integrated with the Volvo
Penta Electronic Vessel Control (EVC) system. A dedicated ECU
communicates via CAN bus with the electronic shift and throttle (EST)
levers, the helm display, and the vessel management system. The EVC
provides functions including cruise control, low-speed maneuvering
(trolling mode), engine synchronization for twin installations, and
comprehensive diagnostics with alarm functions.
Overall Length (without accessories): 1310 mm (51.6 in) from front
pulley to flywheel housing.
Overall Width (max, including supercharger): 870 mm (34.3 in).
Overall Height (max, including charge air cooler): 880 mm (34.6 in).
Dry Weight (engine only, without gearbox or drive): 580 kg (1279 lb).
Dry Weight (with DPH sterndrive): 810 kg (1786 lb).
Weight (IPS450 pod drive system): 1015 kg (2238 lb) inclusive of engine
and pod unit.
Engine Oil Capacity (with filter): 13.0 liters (13.7 qt) for standard
oil pan. Deep sump option holds 16.0 liters (16.9 qt). Engine Oil
Specification: Volvo Penta VDS-4.5 or API CJ-4. SAE 15W-40 for normal
operation; SAE 5W-40 or 0W-40 for cold-water environments below 5°C
(41°F). Oil Change Interval: 200 hours or 12 months, whichever arrives
first. Heavy-duty commercial use (patrol, pilot boats) requires 100-hour
intervals. Oil Filter Change Interval: Every 200 hours (with each oil
change).
Fuel Filter (Primary) Change Interval: 200 hours or 12 months. Fuel
Filter (Secondary) Change Interval: 200 hours or 12 months. Idle Speed
Adjustment: Not user-adjustable; controlled by EVC. Drive Belt Tension
(accessory belt): Automatic tensioner - no adjustment. Engine Anodes
(zinc): Inspect every 100-200 hours; replace when 50% consumed. Anodes
are located on the heat exchanger, charge air cooler, and gearbox.
Coolant Capacity (Freshwater Circuit): 12.0 liters (12.7 qt). Coolant
Specification: Ethylene glycol-based antifreeze, silicate-free, meeting
Volvo Penta specification. Coolant Change Interval: 500 hours or 2
years. Seawater Pump Impeller Change Interval: 200 hours or 12 months.
Inspect earlier in sandy or silty water conditions. Supercharger Clutch
Inspection: Every 500 hours. Valve Clearance: Hydraulic lash adjusters -
no periodic adjustment required.
Cylinder Head Bolts (Stage 1): 40 Nm (30 lb-ft).
Cylinder Head Bolts (Stage 2): 120 Nm (89 lb-ft).
Main Bearing Cap Bolts (Stage 1): 60 Nm (44 lb-ft).
Main Bearing Cap Bolts (Stage 2): 120 Nm (89 lb-ft).
Connecting Rod Cap Nuts (Stage 1): 30 Nm (22 lb-ft).
Connecting Rod Cap Nuts (Stage 2): 60 Nm (44 lb-ft).
Flywheel Bolts: 120 Nm (89 lb-ft).
Crankshaft Pulley Bolt: 350 Nm (258 lb-ft).
Camshaft Bearing Cap Bolts: 20 Nm (15 lb-ft).
Rocker Arm Shaft Bolts: 25 Nm (18 lb-ft).
Intake Manifold Bolts: 25 Nm (18 lb-ft).
Exhaust Manifold Nuts: 45 Nm (33 lb-ft).
Injector Clamp Bolts: 12 Nm (9 lb-ft).
Fuel Rail Mounting Bolts: 25 Nm (18 lb-ft).
Water Pump Mounting Bolts (Freshwater): 25 Nm (18 lb-ft).
Seawater Pump Mounting Bolts: 20 Nm (15 lb-ft).
Heat Exchanger Cover Bolts: 15 Nm (11 lb-ft).
Charge Air Cooler Mounting Bolts: 25 Nm (18 lb-ft).
Leisure Sport Cruisers: The D6-350 is extremely popular in planing hull
boats between 30 and 45 feet (9-14 m). Specific models include the Targa
35 and Targa 38 from Finnmaster, the Windy 37 Grand Mistral, and the
Galeon 330.
Flybridge Yachts: Used in smaller flybridge configurations such as the
Nimbus 380 Flybridge and similar vessels requiring rapid planing from a
350 hp single or twin installation.
Commercial Patrol Boats: Installed in fast patrol vessels, customs
interceptors, and police launches. The dual-charging system provides
immediate acceleration for pursuit maneuvers.
Pilot Boats: Marine pilot transfer vessels utilize the D6-350 for its
reliability and rapid response when maneuvering alongside large ships.
Rescue Craft: Search and rescue (SAR) vessels from manufacturers
including Ribcraft and Zodiac Milpro use this engine in rigid inflatable
boat (RIB) configurations.
DPH Sterndrive Configuration: The engine paired with the DPH Aquamatic
sterndrive is used in sports cruisers and day boats where
maneuverability and shallow-water operation are required.
IPS450 Pod Drive Configuration: The engine integrated with the Inboard
Performance System (IPS450) is used in larger yachts and commercial
vessels seeking improved fuel efficiency and joystick docking control.
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