Subaru EE20 Specifications
| Engine Model: Subaru EE20 |
| Engine Type: 4-cycle 4-cylinder DOHC 16-valve turbocharged liquid-cooled diesel |
| Total Displacement: 121.9 cu.in (1.99 L) |
| Rated Engine Power: 145-148 Hp (108-110 kW) at 3600 rpm |
| Fuel System Type: Common rail direct injection |
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The Subaru EE20 is distinguished by its horizontally
opposed architecture, which delivers exceptional smoothness and a lower center
of gravity compared to conventional diesel engines. The engine utilizes a square
bore and stroke dimension of 86.0 mm by 86.0 mm, a configuration that
facilitates balanced combustion characteristics and high specific output.
A DOHC 16-valve valvetrain, driven by a timing chain, actuates the valves, while
a common rail direct injection system operating at up to 1,800 bar supplies fuel
to the combustion chambers. A variable geometry turbocharger (VGT) provides
boost pressure across a broad engine speed range, enabling peak torque of 350 Nm
from as low as 1,600 rpm. The EE20’s compact dimensions are achieved through an
all-aluminum construction for both the cylinder block and cylinder heads, a
departure from the cast iron blocks common in diesel engines.
Early Euro 4 variants were noted for specific reliability concerns, particularly
regarding crankshaft integrity and bearing durability, issues that were
addressed through manufacturing revisions in later Euro 5 and Euro 6 versions.
The engine’s emissions system incorporates a diesel oxidation catalyst (DOC) and
a diesel particulate filter (DPF), with later variants adding selective
catalytic reduction (SCR) for Euro 6 compliance.
Engine Type: Horizontally opposed 4-cylinder (boxer), turbocharged diesel.
Displacement: 1,998 cc (121.9 cu.in).
Bore: 86.0 mm (3.39 in).
Stroke: 86.0 mm (3.39 in).
Compression Ratio: 16.0:1 (early Euro 4 variants).
Compression Ratio: 15.2:1 (later Euro 5/Euro 6 variants).
Fuel System: Common rail direct injection.
Firing Order: 1-3-2-4 (horizontally opposed layout).
Max Power: 108-110 kW (145-148 hp) @ 3,600 rpm.
Max Torque: 350 Nm (258 lb-ft) @ 1,600-2,400 rpm.
Redline: 4,800 rpm.
Engine Management System: Denso or Bosch common rail system with integrated ECU.
The cylinder block is constructed from aluminum alloy
with cast iron cylinder liners, a design choice that reduces overall engine
weight while providing the wear resistance required for diesel operation. The
horizontally opposed layout places two cylinders on each side of the crankshaft
centerline, with the pistons moving in opposing directions. This configuration
inherently cancels primary and secondary vibrational forces, eliminating the
need for external balance shafts.
The block is an open-deck design, with the cylinder liners supported by the
aluminum structure. The crankcase is integrated into the block casting, with
five main bearing caps secured by bolts. The block incorporates oil galleries
for piston cooling jets, which spray oil onto the undersides of the pistons to
manage the elevated thermal loads of diesel combustion. The engine’s compact
width, enabled by the opposed configuration, allows for a low hood profile and
contributes to the vehicle’s low center of gravity.
The cylinder heads are separate castings in aluminum
alloy for the left and right cylinder banks, each covering two cylinders. The
DOHC valvetrain utilizes a timing chain arrangement that drives both cylinder
heads from a central drive sprocket on the crankshaft.
Four valves per cylinder are arranged in a pent-roof combustion chamber, with
the valves actuated by roller rocker arms and hydraulic lash adjusters,
eliminating manual valve clearance maintenance. The combustion chamber is
specifically designed for diesel direct injection, with a centrally mounted
injector position and a swirl-inducing bowl in the piston crown.
Valves: 16 total (8 intake, 8 exhaust)
Intake Valve Diameter: 30.0 mm (1.18 in)
Exhaust Valve Diameter: 26.0 mm (1.02 in)
Valve Stem Diameter: 6.0 mm (0.24 in) for both intake and exhaust
Valve Seat Material: High-strength sintered alloy for exhaust seats
The intake and exhaust camshafts are equipped with variable valve timing (VVT)
on later variants to improve low-end torque and reduce emissions. The cylinder
head gasket is a multi-layer steel (MLS) design specific to the aluminum block
and head combination, accommodating differential thermal expansion.
The fuel system is a common rail direct injection
system supplied by Denso or Bosch, depending on the production period and
market. A high-pressure fuel pump, driven by the timing chain system, draws fuel
from the tank and pressurizes it to a maximum of 1,800 bar. This pressurized
fuel is stored in a common rail accumulator mounted on the engine. From the
rail, fuel is delivered to solenoid or piezoelectric injectors that are
centrally positioned within each cylinder.
The injection strategy employs multiple injection events per combustion cycle -
including pilot injection, main injection, and post-injection - to control
combustion noise, reduce particulate formation, and facilitate DPF regeneration.
The system utilizes a fuel cooler and a water-in-fuel sensor to protect the
high-pressure components. A fuel return system routes excess fuel back to the
tank, aiding in fuel temperature management.
The lubrication system is a pressurized, wet-sump
design with a variable-displacement oil pump that adjusts output based on engine
speed and load to reduce parasitic losses. The pump is chain-driven from the
crankshaft and mounted within the front cover assembly.
Oil is drawn from a baffled aluminum oil pan designed to maintain pickup under
lateral acceleration. A full-flow, spin-on oil filter with an integrated bypass
valve is mounted externally on the engine block. The system supplies oil to the
crankshaft main and connecting rod bearings, the piston cooling jets, the
camshaft bearings and VVT actuators, and the turbocharger bearing cartridge.
Oil Capacity (including filter): 5.1-5.4 liters (5.4-5.7 US qt)
Oil Pressure at Idle: Minimum 100 kPa (14.5 psi)
Oil Pressure at 3,000 rpm: 350-500 kPa (50.8-72.5 psi)
Recommended Oil Viscosity: 5W-30 or 0W-30, meeting ACEA C2 or C3 low-SAPS
Oil Pump Type: Variable-displacement vane-type
The cooling system is a pressurized, closed-loop design
with a belt-driven water pump mounted to the front of the engine. The
horizontally opposed configuration requires a complex coolant circuit that
circulates fluid through both cylinder banks. Coolant flows from the radiator
through the pump, into the cylinder block passages surrounding each bank, then
upward through the cylinder heads, and returns to the radiator through a
thermostat housing.
A wax-type thermostat with an integrated heating element is controlled by the
ECU to manage warm-up times and maintain optimal combustion temperatures. The
system utilizes a cross-flow radiator with an electric cooling fan. An
additional electric auxiliary water pump is fitted on some variants to provide
circulation after engine shutdown, preventing heat soak in the turbocharger.
Turbocharging System: A variable geometry turbocharger
(VGT) manufactured by IHI or Mitsubishi provides boost pressure. The VGT
mechanism adjusts the angle of the turbine vanes to optimize exhaust gas flow
across a wide range of engine speeds, enabling rapid boost response at low rpm
while preventing over-speed at high rpm. Boost pressure is managed by the ECU
via a vacuum-actuated or electronically controlled mechanism.
Intake System: A plastic intake manifold with integrated swirl valves controls
air movement into the cylinders. The swirl valves are closed at low engine
speeds to promote air turbulence for better fuel mixing with the direct
injection charge. A charge air cooler (intercooler) of the air-to-air type
reduces intake air temperature after compression.
Exhaust and Emissions System: The exhaust aftertreatment system consists of
multiple stages. Downstream of the turbocharger, exhaust gases pass through a
diesel oxidation catalyst (DOC) to oxidize hydrocarbons and carbon monoxide. A
diesel particulate filter (DPF) traps soot particles; periodic regeneration
events elevate exhaust temperatures to burn off accumulated soot. For Euro 6
variants, a selective catalytic reduction (SCR) system with AdBlue injection is
added to reduce nitrogen oxide (NOx) emissions.
Glow Plug System: The engine utilizes ceramic glow plugs for rapid cold-start
performance. The glow plugs reach operating temperature within seconds, allowing
reliable starting in low ambient temperatures without extended preheating.
Emissions Control: The engine incorporates a high-pressure exhaust gas
recirculation (EGR) system, which routes cooled exhaust gases back to the intake
manifold to reduce combustion temperatures and limit NOx formation. The EGR
valve is electronically controlled, and the cooler is integrated into the engine
cooling circuit.
Overall Length: 570 mm (22.4 in)
Overall Width: 780 mm (30.7 in)
Overall Height: 600 mm (23.6 in)
Dry Weight (complete engine): 130 kg (287 lb) without ancillary systems.
Dry Weight (complete engine): 145 kg (320 lb) with turbocharger, intake,
exhaust, alternator, and starter motor.
0Valve Clearance: Hydraulic lash adjusters - no manual
adjustment required. Timing Chain: Chain-driven with hydraulic tensioner.
Inspection interval of 150,000 km (93,000 mi). No scheduled replacement
interval. Fuel Filter Replacement Interval: 30,000 km (18,600 mi). Glow Plug
Inspection: Every 60,000 km (37,000 mi).
Engine Oil Change Interval: 10,000 km (6,200 mi) or 12 months with low-SAPS
synthetic oil. Shorter intervals are strongly advised for vehicles used
primarily in urban driving or with frequent interrupted DPF regeneration cycles.
Oil Filter Replacement: With every oil change.
DPF Regeneration: Automatic regeneration occurs under normal highway driving
conditions. Forced regeneration is required if DPF warning indicators are
activated. Interruption of a regeneration cycle can lead to oil dilution with
diesel fuel. Coolant Replacement Interval: 100,000 km (62,000 mi) or 5 years,
then every 50,000 km (31,000 mi). Accessory Drive Belt Replacement Interval:
60,000 km (37,000 mi) or 4 years.
Cylinder Head Bolts: 30 Nm (22 lb-ft) in sequence
Connecting Rod Cap Bolts: 25 Nm (18 lb-ft)
Main Bearing Cap Bolts: 35 Nm (26 lb-ft)
Camshaft Bearing Cap Bolts: 22 Nm (16 lb-ft)
Intake Manifold Bolts: 20 Nm (15 lb-ft)
Exhaust Manifold Nuts: 25 Nm (18 lb-ft)
Injector Clamping Bolts: 25 Nm (18 lb-ft)
Glow Plugs: 15 Nm (11 lb-ft)
Oil Filter: 18 Nm (13 lb-ft)
Oil Drain Plug: 35 Nm (26 lb-ft)
Crankshaft Pulley Bolt: 50 Nm (37 lb-ft)
Flywheel/Flexplate Bolts: 70 Nm (52 lb-ft)
The Subaru EE20 engine was offered across the core
Subaru model range in European, Australian, and select Asian markets from 2008
until the discontinuation of diesel-powered passenger cars in 2018.
Subaru Legacy / Liberty (BM, BR): The EE20 was the sole diesel offering for the
fifth-generation Legacy sedan and wagon, marketed as the 2.0D. Production
spanned 2008 to 2014 for this generation, with the engine continuing in the
sixth-generation (BN, BS) from 2014 to 2018.
Subaru Outback (BR, BS): The Outback received the EE20 as the diesel option
across both the fourth-generation (BR) and fifth-generation (BS) platforms,
providing a diesel alternative to the gasoline H4 and H6 engines. Production
covered 2008 to 2018.
Subaru Forester (SH, SJ): The third-generation (SH) Forester introduced the EE20
in 2008, offering a diesel variant for European markets. The fourth-generation
(SJ) Forester continued with the EE20 until 2018, when diesel production ceased.
Subaru Impreza (GE, GH, GJ): The Impreza received the EE20 in its five-door
hatchback body style for European markets from 2009. The XV crossover variant,
derived from the Impreza platform, also utilized the EE20 from its introduction.
Subaru XV (GP): The first-generation XV, marketed as a standalone model, was
offered with the EE20 in European and Australian markets throughout its
production run from 2012 to 2017.
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