Mitsubishi S6E Specifications
| Engine Model: Mitsubishi S6E |
| Engine Type: 4-cycle inline 6-cylinder naturally aspirated liquid-cooled diesel |
| Total Displacement: 238.8 cu.in (3.91 L) |
| Rated Engine Power: 107 Hp (80 kW) at 2500 rpm |
| Fuel System Type: Indirect fuel injection |
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The Mitsubishi S6E is a substantial
six-cylinder inline diesel engine, engineered for heavy-duty industrial
applications demanding smooth, reliable power and exceptional
durability. This 3.913-liter, naturally aspirated power plant utilizes
an indirect injection combustion system with a swirl pre-combustion
chamber, prioritizing smooth operation, reduced mechanical noise, and
excellent cold-start characteristics over ultimate fuel efficiency. Its
square bore and stroke design contributes to a balanced mechanical
layout and a broad, accessible torque curve.
The six-cylinder configuration provides inherent primary and secondary
mechanical balance, resulting in remarkably low vibration levels, a
feature highly valued in stationary power generation and large material
handling equipment. Constructed with a heavily reinforced cast iron
block and a gear-driven camshaft, the S6E is designed for long service
intervals and straightforward maintenance, establishing it as a
dependable workhorse in continuous-duty and high-cycle applications.
Manufacturer: Mitsubishi Heavy Industries, Ltd.
Engine Model: S6E.
Engine Type: 4-cycle, water-cooled, vertical inline, indirect injection
diesel.
Aspiration: Naturally aspirated.
Emission Compliance: Manufactured prior to modern emission protocols;
conforms to historical industrial engine standards.
Management System: Mechanical fuel injection with mechanical governor.
Number of Cylinders: 6.
Bore: 94 mm (3.701 in).
Stroke: 94 mm (3.701 in).
Displacement: 3.913 L (3913 cc) (238.8 cu in).
Compression Ratio: 19:1.
Firing Order: 1-5-3-6-2-4.
Rotation Direction: Counter-clockwise when viewed from the flywheel
side.
Maximum Gross Power Output: 80 kW (107 hp) at 2,500 rpm.
Maximum Gross Torque: Approximately 294 Nm (217 lb-ft) at 1,600 rpm.
Rated Speed: 2,500 rpm for industrial applications; 1,500 or 1,800 rpm
for constant-speed generator duty. Idle Speed: 650-750 rpm.
The cylinder block is a massive, deeply ribbed casting manufactured from
high-grade gray iron. It features an extended deep-skirt design that
reaches well below the crankshaft centerline, creating an exceptionally
rigid foundation that effectively damps vibration and resists flexing
under load. The cylinder bores are precision-machined and honed directly
into the block material. The crankshaft is a forged steel component,
supported by seven main bearings.
This seven-main-bearing support system is critical for maintaining
precise alignment and minimal deflection of the long crankshaft,
ensuring smooth operation and contributing directly to extended bearing
and seal life. Connecting rods are forged steel, fitted with replaceable
precision bearing shells at the crankpin end. The piston pin is a
press-fit in the connecting rod small end. Pistons are aluminum alloy,
designed with a specific crown profile compatible with the indirect
injection swirl chamber system. The piston ring pack consists of two
compression rings and one oil control ring.
A single-piece cast iron cylinder head is utilized, secured to the block
with a multitude of high-tensile studs and nuts. The head accommodates
one intake and one exhaust valve per cylinder. Valve seat inserts are
manufactured from hardened, heat-resistant alloy to ensure longevity.
The valve train operates on an overhead valve (OHV) principle, with the
camshaft positioned in the cylinder block.
The camshaft is gear-driven from the crankshaft, a robust and
maintenance-free timing drive system. The camshaft actuates the valves
via solid pushrods and rocker arms. Rocker arms are mounted on a
stationary shaft fastened to the cylinder head. Valve clearance is set
and maintained by a screw and locknut adjustment on each rocker arm. The
cylinder head incorporates the indirect injection pre-combustion (swirl)
chamber for each cylinder, which houses a glow plug for cold starting
assistance.
The engine employs a mechanical, inline pump-line-nozzle fuel injection
system. Core components include a mechanical fuel lift pump, a
six-element inline injection pump, high-pressure fuel lines, and
pintle-type injectors. The injection pump is a large jerk-pump design,
driven by the engine's gear train. It supplies fuel at high pressure to
nozzles that discharge into the pre-combustion swirl chamber.
A mechanical centrifugal governor, integral to the injection pump,
regulates engine speed by controlling the position of the fuel rack. The
system is calibrated for consistent fuel delivery. Fuel filtration is
provided by a primary sedimentor/water separator and a secondary fine
filter, both essential for protecting the precision components of the
injection pump and injectors from contamination and water.
Lubrication is provided by a high-capacity, forced-feed, full-flow wet
sump system. A gear-type oil pump, driven directly from the crankshaft,
draws oil from the sump through a large-diameter pickup tube equipped
with a robust strainer screen. Pressurized oil is routed through a
full-flow, spin-on or canister-type oil filter. After filtration, oil
enters the main oil gallery in the block, supplying the crankshaft main
and connecting rod bearings, the camshaft bearings, and the valve gear
via internal passages and hollow pushrods.
The system is engineered for high flow to ensure adequate lubrication
and cooling of all internal bearings across the long cylinder block. The
specified engine oil is API CC, CD, or CF grade. Total oil capacity,
including the filter, is 12.0 liters (12.7 US qt). The oil pan is a
heavy-duty stamped steel or cast iron component.
Cooling is managed by a pressurized, pump-circulated liquid system. A
centrifugal water pump, driven by a V-belt from the crankshaft pulley,
provides coolant circulation. System operating temperature is regulated
by a wax-pellet type thermostat. Heat rejection occurs via a large
tube-and-fin radiator; the cooling fan is mounted on the engine and is
V-belt driven.
The substantial displacement and six-cylinder format generate
considerable heat, necessitating a high-capacity cooling system. The
cooling system requires a mixture of ethylene-glycol antifreeze and
clean water. A 50/50 mixture is standard for corrosion protection and
freeze resistance. Total cooling system capacity is 14.0 liters (14.8 US
qt) for the engine side, excluding the radiator and external hose
volume.
| Intake and Exhaust Systems |
Intake System: Consists of an air cleaner and a cast iron or aluminum
intake manifold. Exhaust System: Comprises an exhaust manifold and
downpipe connecting to the equipment's exhaust silencer.
Electrical System: Operates on a 12V or 24V system, with 24V being
common for industrial starters. A corresponding starter motor and
alternator are fitted. The engine incorporates a glow plug system for
each cylinder, controlled by a key-switch or timer module for cold
starting. An electric stop solenoid or manual cable acts on the
injection pump rack.
Length (Front Face of Block to Flywheel Housing): 1,120 mm (44.09 in).
Width (Overall): 610 mm (24.02 in).
Height (Overall, from sump to valve cover): 725 mm (28.54 in).
Dry Weight (with standard accessories): 360 kg (794 lb).
Engine Oil Change: Every 250 operating hours. Oil Filter Replacement:
Every oil change (250 hours). Fuel Filter Replacement: Service sediment
bowl daily; replace secondary filter element every 500 hours. Air
Cleaner Element Service: Clean or replace based on environment; inspect
regularly. Valve Clearance Adjustment: Check and adjust every 500
operating hours.
Coolant Replacement: Drain, flush, and refill every 2,000 operating
hours or every two years. Fan Belt Tension Check/Adjustment: Inspect and
adjust tension every 250 hours; replace at signs of wear or cracking.
Fuel Injection System Inspection: Have injection pressure and spray
pattern checked by a specialist every 1,500 hours.
Cylinder Head Nuts: Tighten in the specified multi-step crisscross
sequence to a final torque of 118-127 Nm (87-94 lb-ft). Main Bearing Cap
Bolts: 108-118 Nm (80-87 lb-ft).
Connecting Rod Cap Bolts: 88-98 Nm (65-72 lb-ft).
Flywheel to Crankshaft Bolts: 118-127 Nm (87-94 lb-ft).
Fuel Injector Holder: 59-69 Nm (44-51 lb-ft).
Glow Plugs: 15-20 Nm (11-15 lb-ft).
Oil Pan Drain Plug: 59-69 Nm (44-51 lb-ft).
Oil Filter Canister/Cartridge: Follow manufacturer's specification;
generally hand-tight plus 3/4 to 1 turn after gasket contact.
The Mitsubishi S6E engine was deployed in large, heavy-duty industrial
equipment where its smooth power delivery and robustness were essential.
Common applications include: Heavy-Duty Forklifts: Powers large
container handlers, and high-capacity forklifts (15-25 ton range) from
Mitsubishi, Kalmar, and Fantuzzi. Generator Sets: A prime mover for
industrial and prime power generator sets in the 50-80 kVA power range.
Industrial Pumps: Drives large-volume pumps for firefighting, mining
dewatering, and major irrigation projects.
Compressors: Used as the diesel driver for large industrial
reciprocating and screw-type air compressors. Construction Equipment:
Found in larger vibratory rollers, drilling rigs, and older mid-sized
excavators. Marine Applications: Served as a propulsion engine for small
tugboats, fishing vessels, and workboats, and as a generator drive on
larger vessels. Railroad and Mining: Used in some railcar applications
and stationary mining equipment.
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