Paxman Valenta (Y3J) Technical Specification

This page gives engine data and the technical specification of Valenta engines for marine propulsion applications, as extracted from Paxman Publication PD 015 (Revised January 1990). Specifications, power ratings and optional equipment for Valentas built for other applications, such as marine auxiliaries and rail traction, obviously differ from those shown below. However, the information below provides a useful guide to the key features of the Valenta range of engines, regardless of application.

A brief history of the Valenta's development can be found on the page Paxman Diesels since 1934.

Owners and operators of Valenta engines should not rely on the information given here (see Disclaimer) but seek the correct information about their particular engine(s) from MAN Diesel & Turbo UK Ltd, the current owners of the Paxman business, at their Colchester Business Unit.

Paxman Valenta
Marine Propulsion Diesel Engines
695 - 3655 kW brake (943 - 4970 ps, 930 - 4900 bhp)

Number of cylinders6, 8, 12, 16 and 18
Bore and stroke197mm x 216mm, 7·75in x 8·5in
Cycle4 stroke
Configuration60° Vee (in line - 6 cylinder)
Compression ratio13:1 (12·4:1 Maximum rated engines)
Operating speed range600 - 1640 rev/min
Idling speed600 rev/min
Mean piston speed: 1500 rev/min10·8m/s, 2125ft/min
Mean piston speed: 1200 rev/min8·64m/s, 1700ft/min
Direction of rotationAnti-clockwise on flywheel end
Combustion systemDirect injection
Thread system: EngineMetric
Thread system: ConnectionsMating flanges supplied drilled for metric fasteners
Starting systems: Electric178mm, 7in (2 motors on 12, 16 and 18 cylinder)
Starting systems: TypeBendix or axial
Starting systems: Voltage24 - other voltages available
Alternator continuous output1400 watts
Air motor: High pressure24·1 bar, 350 lbf/in² (2 motors on 12, 16 and 18 cylinder)
Air motor: Low pressure10·35 bar, 150 lbf/in² (1 motor)
Air receiver capacity: 6 & 8 cylinder0·317m³, 11·2ft³
Air receiver capacity: 12, 16 & 18 cyl0·660m³, 23·4ft³
Air compressorDiesel driven 0·425m³/min, 15ft³/min free air
Hydraulic motor207 bar, 3000 lbf/in² (2 motors on 16 and 18 cylinder)
Basic governor series1100 (Regulateurs Europa)
FuelB.S. 2869: 1988 Class A1 and A2 and ASTM D-975-88 Nos. 1 & 2-D with cetane No. 45.
Lubricating oilS.A.E. 30 or 40 (according to duty) heavy-duty oil to MIL-L-2104E specification should be employed with a TBN of 9 for engines running on fuels stated above.
CAPACITIES, m³, gallons
Number of cylinders68121618
Sump0·241 530·164 360·241 530·300 660·341 75
Water jacket0·218 480·18 400·29 640·36 800·378 85
Intercooler0·014 30·021 4·50·027 60·042 90·027 6
Fresh water: Outlet76 3127 5127 5127 5127 5
Fresh water: Inlet76 3127 5127 5127 5127 5
Sea waterWater flow should not exceed 1·8m/s, 6ft/s
Air intercooler76 3·076 3·076 3·076 3·076 3·0
Fuel13 0·519 0·7519 0·7519 0·7519 0·75
Oil64 2·564 2·564 2·576 3·076 3·0
Air25 1·025 1·033 1·538 1·538 1·5
Exhaust pipe and silencer305 12·0356 14·0406 16·0457 18·0508 20·0


HOUSING The housing is manufactured either from a high grade casting or fabricated from steel castings and plate (8, 12, 16, and 18 cylinder). The whole structure is fully stress relieved before machining. The underslung crankshaft is carried in main bearing caps located against side thrust by fitting faces. Lateral bolts screwed into the caps through the housing skirt and a longitudinal beam bolted to the underside of the bearing caps increase the rigidity of this assembly. The housing carries wet type steel cylinder liners, surmounted by individual cylinder heads. The underside of the housing is enclosed by a sheet metal oil sump complying with classification societies requirements of pitch and roll.

CRANKSHAFT AND MAIN BEARINGS The forged steel nitride hardened shaft is carried in prefinished main bearings of the steel shell type, lined with tin aluminium, requiring no hand fitting. It is located by rings at the drive end of the engines. The crankshaft is flanged at the drive end for the attachment of the flywheel and driven machinery by set bolts, the drive being taken by driving pins. An additional bearing is provided to support the input end of driven machinery. A viscous torsional vibration damper (two on 16 and 18 cylinder engines) is bolted to the flange at the free end of the crankshaft. The drive for the camshaft, governor, injection, oil and water pumps is from a train of hardened gears located at the drive end of the engine. Eight cylinder engines have a gear driven secondary balancing system. Eighteen cylinder engines have a gear driven primary balancing system and primary balance weights on the crankshaft are fitted to all engines. The free-end cover is machined to S.A.E. No. 2 dimensions for the attachment of power take-off drives, etc.

CONNECTING RODS AND BEARINGS Fork and blade connecting rods (vee form engines) are machined from steel stampings. A one-piece rod is fitted to 6 cylinder engines. A large end block attached to the forked rod houses a replaceable steel back, tin aluminium lined bearing, which runs on the crankpin. A lead bronze lined shell in the blade rod runs on a nitride hardened outer surface on the large end block. The joint faces of the bearing block and blade rod are serrated for location purposes. The rods and bearing block are drilled for lubrication of the small ends and for piston cooling.

PISTONS Aluminium alloy oil cooled pistons are each fitted with three compression and one oil control ring above the fully floating gudgeon pin which is located by circlips. The top pressure ring is fitted in an "Alfin" bonded cast iron ring groove insert.

CYLINDER HEADS, VALVE GEAR AND LINERS Single unit cast iron cylinder heads with drilled passages giving optimum water flow around the valve seats, are fully interchangeable, and house two inlet and two exhaust valves seating on replaceable inserts and a central injector. The valves are operated by one push rod and rocker per two valves, a bridge piece actuating each pair of valves. The valve gear is fully enclosed by easily removable covers; the injector is enclosed by the valve cover, but the inlet pipe is sleeved to prevent leakage into the lubricating oil system. Hard chrome plated wet type liners of seamless steel tube flanged at the head end, carry copper plated steel rings above and below the flange for sealing against gas and water leakage; the lower end of the liner is sealed by two rubber rings. Water transfer from the housing jacket to the head is by ferrules sealed by rubber rings. The waterside surface of the liner is protected by chromium plating.

CAMSHAFT AND DRIVE The camshaft is located in a trough formed by the two banks of cylinders (vee form engines) or at the side (in line engines). It is gear driven from the crankshaft and runs in pressure lubricated bearings. A separate tappet housing for each line of cylinders is fitted above the camshaft and contains roller type cam followers for operating the tubular push rods; return springs maintain constant engagement of each cam roller with its cam.

FUEL INJECTION EQUIPMENT Lucas single unit fuel injection pumps are operated by camshafts running in aluminium cambox housings, which are located on the sides of the engine and are grouped below the air inlet manifolds. The fuel injection pump camshafts are lubricated from the engine system with a metered supply to the pump plungers. Fuel feed and injection pumps are driven from the gear train at the drive end. The fuel system includes a fuel reservoir and air vessel. The combustion system employs direct injection of fuel by a central multi-hole injector into an open toroidal cavity in the top of the piston. Short pipes, of equal length, are fitted between the pumps and injectors.

GOVERNOR, DRIVE AND CONTROLS A standard Regulateurs Europa 1100 series governor, driven from the engine gear train is located at the drive end of the engine. The governor is of the centrifugal weight type, operating through a hydraulic servo-mechanism and controls the effective stroke of the injection pump plungers through a system of rods and levers. Precision self-aligning spherical bearings are employed at the control rod ends and bearing points to minimise friction and lost motion. The governor is available for remote control (mechanical, electrical, hydraulic and pneumatic).

PRESSURE CHARGING One water-cooled exhaust gas driven turbo-blower is located at the free end (6 cylinder) or above the vee of 8, 12, 16 and 18 cylinder engines. Two turbo-blowers are fitted to lower rated engines. Water-cooled exhaust manifolds are fitted within the vee of vee form engines.

AIR INTERCOOLERS The intercooler(s) for cooling the air for aspiration from the turboblower(s) is mounted at the free end of the engine. Water from the sea water circuit is the cooling medium. On higher rated engines air for aspiration passes through a heater unit which is mounted between the intercooler and the air manifolds. This unit is heated by engine jacket water the flow of which is controlled to give the optimum manifold air temperature when starting up and at low load running. Gunmetal waterboxes, naval brass tube plates and copper nickel tubes are standard materials used.

LUBRICATION One engine-driven gear type lubricating oil pump (two in parallel - 12 and 16 cylinder engines, triple-rotor type - 18 cylinder engines) is housed inside the sump at the drive end of the engines. This pump supplies high-pressure oil to all bearings points in the engine (including water pump) via full flow filters, and to the built-on oil coolers. Pressure is controlled by a single spring-loaded relief valve.

COOLING Fresh water is circulated through the engine, oil cooler (6 cylinder engines), exhaust manifold jackets and turbo-blower cooling system with controlled flow round the injectors and valve seats, by a single pump fitted at the free end of the engine and driven from the drive end gear train by a tubular shaft. Outlets from the engine are brought together to provide a common inlet to a thermostatic control valve mounted above and attached to the pump.

OIL COOLERS Engine mounted tubular oil coolers, one per engine, are fresh water cooled (6 cylinder engines). Sea water cooling is employed for other sizes of engine. Gunmetal waterboxes, aluminium alloy cylinders and copper-nickel tubes are standard materials used. For sea water cooled systems a control valve operated by a temperature sensitive thermostat is fitted in the oil circuit.

EXHAUST Cooled exhaust system brought to a single outlet from turbo-blower(s). Flexible pipes, "Y" piece (18 cylinder engines) and absorption type silencers can be supplied.

CRANKCASE EXPLOSION DOORS These are fitted to all engines.

Air Oil wetted panel type filters (2 per turbo-blower) mounted on trunking attached to the turbo-blower inlet casing. A circular oil wetted filter attached to the turbo-blower is fitted to 6 cylinder engines. For engines operating in high ambient temperatures, air for aspiration should be trunked from outside the engine room.
Fuel Oil Single element fuel oil filters are fitted to all engines. A coalescer is supplied for independent mounting in the vessel (see Optional Equipment).
Lubricating Oil Single element, full-flow filters are inserted in the pressure circuit for mounting adjacent to the engine (see Optional Equipment).

FUEL FEED PUMP A fuel feed pump is fitted to all engines. The suction lift of the pump should not exceed 1830mm, 72in.

FLYWHEEL Flywheels can be coupled to any type of driven equipment.

OVERSPEED Built-in overspeed shutdown equipment is fitted.

INSTRUMENTS These are supplied loose for mounting adjacent to the engine. Thermometers graduated in Centigrade and Fahrenheit for measuring the coolant and lubricating oil temperatures: oil pressure gauge calibrated in bar and lbf/in2 and an electrically driven tachometer. Exhaust pyrometers for measuring before turbine temperatures and a revolution indicator driven by a tacho-generator are fitted. Duplicate sets of instruments for mounting in the wheelhouse or in the engineer's control cubicle can be supplied.
When it is required to measure the outlet temperatures of the exhaust from individual cylinders in addition to the above, complete instrumentation can be supplied at extra cost.

INSTRUCTION AND SPARE PARTS MANUALS A comprehensive Instruction Manual and fully illustrated Spare Parts List are supplied with each engine.

TESTING Engines are brake tested to a standard schedule when power and speed stops are set and sealed; additional tests are undertaken to customer's requirements. Engine Test Certificates are supplied with each engine.


HEAT EXCHANGER A standard range of stack type tubular coolers with gunmetal waterboxes, aluminium cylinders and aluminium brass tubes for independent mounting in the vessel, is available to cover the complete engine range and sea water temperatures up to 32°C. Coolers with copper nickel tubes can be provided.

SEA WATER PUMP A centrifugal, self-priming sea water pump with gunmetal body and impeller and stainless steel shaft is driven by endless belts from the engine free-end pulley.

BILGE PUMP This is of similar design to the sea water pump. Piping is supplied with the pump for connecting the sea and bilge pumps together to ensure that the latter runs "wet" when in service.

PRIMING PUMP A hand-operated lubricating oil priming pump piped to the engine is supplied for priming the engine and for sump emptying purposes.

Fuel Oil
 A duplex filter with changeover valve can be supplied at extra cost, if specified or when engines are built to classification societies requirements.
Lubricating Oil A duplex filter with changeover valve can be supplied at extra cost, if specified or when engines are built to classification societies' requirements.

STARTING Air, electric or hydraulic starter motors may be employed. Air receivers and diesel driven air compressor sets with exhaust silencer, unloading and relief valves can be supplied. Batteries for starting engines should be located not more than 3660mm, 144in from the motor(s). Suitable cables can be supplied to carry the starting current. Where batteries are installed at a distance in excess of the above the engine manufacturer should be consulted. An independent hydraulic starting system can also be supplied.
An engine-driven battery charging alternator can be supplied with control board and ammeter and integral wiring. Enclosures for control gear can be supplied to obviate radio interference. For engines with higher power output and lower compression ratio, a preheating system to warm the engine before start can be supplied. This is in the form of a module comprising a heater tank, complete with heaters and a circulating pump.

COLD STARTING Start Pilot equipment can be supplied to assist starting when the temperature of the engine room falls below 7°C. A pump unit driven by a 24V electric motor connected to nozzles through which a quantity of low ignition fuel is sprayed into the air manifold whilst the engine is motored. A compressed air operated system is also available.

EXHAUST SILENCERS A silencer of the absorption or spark arrester dry type is available. Both types of silencer are designed to give a good degree of silencing where there is a minimum space for installation. They are suitable for use in all applications where super-critical silencing is not required.
A single silencer is provided for all engines and standard lengths of flexible piping can be supplied. Pipe sizes are suitable for lengths up to 15m, 600in. Silencers and piping can be lagged.

FREE END DRIVES Pulleys can be provided at the free end of the crankshaft to drive water and hydraulic pumps, alternators, etc., by means of endless belts.

Fresh Water and Lubrication Systems
 Should these systems fail, pressure and temperature sensitive switches complete electric circuits to visual and audible alarms.

SUMPS Tapered, sheet metal marine type sumps are fitted to meet installation design angles, operational trim and classification societies' requirements of pitch and roll.

MOUNTING A four-point resilient mounting system is normally employed.

COUPLING A flexible coupling is fitted between the engine and gearbox. This coupling gives a very high degree of damping to torsional vibrations.

SPARES The Company can supply spares to meet operator's or classification societies' requirements.

TOOLS AND SPARES Standard tools are supplied for normal maintenance routine. A selected set of spares is also supplied.

A short description of the standard Regulateurs Europa governor fitted to Paxman engines and the main provisions of governing requirements of the major classification societies are given below. Other makes of governor can be fitted.
1100 Series This has a quick-response flyweight spring speed measuring device followed by a hydraulic servo-mechanism to provide the necessary controlling forces. It is completely self-contained, with its own oil reservoir, oil pump, relief valve and hydraulic accumulator. An oil-damped flexible coupling is inserted between the governor drive shaft and flyweight. The hydraulic stabilisation system now incorporates a non-linear action which gives an extremely large stability margin, rapid recovery and minimal transients. New features which can be incorporated are fuel limitation in response to boost pressure and/or set and running speeds.
Governing requirement Transient speed changes to meet classification societies' rules should not exceed 15% when full load is suddenly taken off, but for 1100 series governors this change should not exceed 9% in practice. Governors fitted to Paxman engines are set to a permanent speed droop of 6% unless otherwise required. For more than one engine mechanically coupled through a common gearbox a maximum variation between any two engines is set so as not to exceed 0.25%.

Hand Control
 Simple hand-control wheel built into Regulateurs Europa 1103 governor.
Mechanical Lever provided on side of Regulateurs Europa 1101 governor for connection by a rod and lever system or by cable to the control cubicle or gearbox interlock unit.
Electrical Infinitely variable electrically operated Regulateurs Europa 1114 governors are eminently suitable for the control of high-speed craft, speed setting is by linear differential transducer load control system and dual d.c. solenoids. They are normally used in conjunction with a Regulateurs Europa Control system.
Pneumatic Control over complete engine speed range with Regulateurs Europa 1104 governors. Modulated air pressure 0·69 to 4·1 bar (10 to 60 lbf/in²) or 0·27 to 6·1 bar (3 to 88lbf/in²) for continental control systems is usually employed. Controls can be fitted to limit acceleration of the engine. Manual over-ride speed setting is also available to meet classification requirements.
Controls for controllable pitch propellers Governors with load control (hydraulic or electric) are available which incorporate the above type of control systems for use with this type of propeller.
Torque Limitation When vessels are heavily loaded and the hull becomes fouled in service, limitation of engine output is necessary to prevent overloading the engine. Regulateurs Europa 1100 series governors incorporating a control system which restricts engine output over the engine speed range, are fitted to engines powering high-speed craft. Engine output has been devised to give maximum service life with minimum restriction to the ship's operating mode.
Speed Droop The droop of all 1100 series governors can be adjusted by a calibrated dial type control from 0 (isochronous) to 10%. The speed droop of propulsion engines is usually set at 6%.
Shut-down All engines can be shut down by means of a solenoid valve built into the governor. The supply voltage can be either 24, 32, 48, 110 or 200 volts d.c. A pneumatic shut-down device is also available.
Coupled engines (Engines in multiple driving one propeller) governors can be provided with built-in transducers for remote indication of engine fuel rack position, to assist manual load control. Alternatively, complete automatic pneumatic or electronic load sharing systems can be supplied.

GEARBOX The Company can supply all types of transmission to suit both fixed and variable pitch propellers.
Standard lightweight Zahnradfabrik gearboxes are included in the standard schedule of dimensions and weights.
Oil filters and coolers suitable for sea water cooling, are built onto these gearboxes, the cooling medium being water from the sea water circuit. Stern gear can be supplied to suit each application.
Manoeuvrability of high-speed craft can be improved by the use of two-speed marine gears. Lightweight gearboxes matched to Paxman engines are available as are vee drive gears, which enable engines to be positioned aft in the vessel, giving additional flexibility in engine room layout and improved vessel performance.

GEARBOX CONTROLS Interlocking of engine speed with forward and reverse gearbox control eliminates heavy loading on the engine, gearbox and shafting when changing from "Ahead" to "Astern" and vice versa. The type of control and linkage between engine, gearbox and bridge varies with the make of the gearbox fitted and the vessel in which the equipment is installed. For patrol and specialist high-speed craft an integrated electric or pneumatic system operated by a command lever is used to simulate the functional requirements for the engagement and disengagement of clutches for ahead and astern running, increase and decrease of engine speed, selection of maximum ratings with suitable delays built into the system to safeguard engine and gearbox during these operations. Over-ride levers are fitted at the gearbox and engine when electric or pneumatic controls are fitted for emergency purposes, an additional mechanical remote control system with gearbox interlock can also be fitted for this purpose.

AUTOMATIC CONTROL EQUIPMENT Automation of many of the ship's services is a recognised operational requirement.
Reduction in engine room staff necessitates the provision of automatic control equipment for starting and stopping sequences and for watch-keeping on voyage or in port.
The Company, in collaboration with their associates Regulateurs Europa can, through their wide experience derived from the successful operation of auto-controlled sets, put forward marinised equipment assembled from standard units to meet specific requirements with the built-in protection of essential operating services.
Functions which can be automated are:
Start and stop of propulsion and auxiliary diesel engines, increase and decrease of engine speed, manoeuvring—ahead, neutral and astern operations of gearboxes, engagement and disengagement of clutches and propeller shaft brakes, control of variable pitch propellers.
The opening and closing of sea cocks, starting of air compressors, selection of air bottles, fuel and lubricating oil filtering and centrifuging, engine protection and warning equipment. Automatic load-sharing and synchronising of auxiliary generating sets.

DIESEL-ELECTRIC PROPULSION Diesel-electric drive has a number of important advantages over direct drive particularly when applied to work boats with cyclic operating procedure, e.g. trawlers, dredgers, tugs, harbour cranes and similar craft. Of prime importance is the ability to shut-down one or more sets when a low power cycle is in operation, e.g., trawling or dredging, whereas on passage or when maximum power is required, all sets are available. A further consideration is that all the ship's services, heating, lighting, electrical equipment, etc., can be powered by the main engines without recourse to separate auxiliary sets.


Fast patrol craft
High speed yachts
Fast pleasure craft
similar applications
Short range ferries
Cruising yachts
Pleasure craft
Long range patrol craft
Some short range fishing vessels
similar applications
Vessels with unlimited operating range and/or unrestricted continuous operation
Long range fishing vessels
Deep sea ferries
similar applications

i) Catamarans, S.E.S., Hydrofoils and SWATH can all fall within the above categories and therefore reference should be made to the rating definition.
ii) CODAD, CODOG and CODLAG systems etc can also fall within the above categories and therefore reference should be made to the rating definition.


The maximum rating is available for 30 minutes in each period of six hours operation at or below the continuous rating. If this time is exceeded it may be necessary to reduce the overhaul periods.
The intermittent rating is available for one hour in each period of six hours operation at or below the continuous rating. If this time is exceeded it may be necessary to reduce the overhaul periods.
The continuous rating is available for operating periods normally associated with high speed craft.

The intermittent rating is available for 6 hours in each 24 hours of operation at or below the continuous rating. If this time is exceeded it may be necessary to reduce the overhaul periods.
Total operating hours at the intermittent rating should not exceed 10 percent of total hours in the period up to major overhaul.
The continuous rating is unrestricted.

MARINE PROPULSION — CATEGORY 'C' The continuous rating is unrestricted.

6L 830
8V 1110
12V 1970
16V 2625
18V 2955

Environmental Conditions for Propulsion Engines
All ratings in the foregoing tables are based on an ambient air temperature and seawater temperature not exceeding 27°C, Barometric pressure 1 bar. Derating should be to ISO 3046.

1. All data is for guidance purposes and is subject to confirmation.
2. It may be possible to increase speeds and outputs in some of the categories after full consideration of the operating profile.

Page updated: 31 DEC 2011