Subaru EJ22T Specifications
| Engine Model: Subaru EJ22T |
| Engine Type: 4-cycle 4-cylinder SOHC 16-valve turbocharged liquid-cooled gasoline |
| Total Displacement: 135 cu.in (2.21 L) |
| Rated Engine Power: 160 Hp (119 kW) at 5600 rpm |
| Fuel System Type: Multi-point electronic fuel injection |
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The Subaru EJ22T is widely regarded as the Holy Grail
of Subaru factory engine blocks, representing a specialized, low-volume
turbocharged powerplant introduced in 1991 that set the foundation for Subaru’s
turbocharged legacy. Developed during the early years of Subaru’s forced
induction program, the EJ22T was engineered with an overbuilt internal structure
that has since achieved legendary status within the automotive community.
The engine is a 2.2-liter, SOHC turbocharged flat-four (boxer) configuration,
distinguished by its fully closed-deck cylinder block - a design feature where
the water jacket does not extend to the top of the cylinders, providing maximum
cylinder wall rigidity and resistance to distortion under high boost pressures.
This closed-deck architecture, combined with factory piston-cooling oil
squirters and a forged crankshaft, gave the EJ22T a level of durability that
later influenced the design of the legendary EJ22G used in the Subaru 22B STi.
The engine features a non-interference valvetrain, a rarity among turbocharged
engines, meaning that valve-to-piston contact does not occur if the timing belt
fails. Produced in limited numbers from 1991 to 1994 exclusively for the Subaru
Legacy Sport Sedan and Legacy Touring Wagon, the EJ22T remains highly sought
after for high-performance builds, with enthusiasts frequently pairing the
robust closed-deck block with more advanced DOHC cylinder heads to create
powerful hybrid engine combinations.
The EJ22T is a four-stroke, water-cooled gasoline engine operating on the
spark-ignition principle. The engine architecture is a horizontally opposed
flat-four (boxer) configuration with a total displacement of 2,212 cc (135.0
cu.in), derived from a bore of 96.9 mm (3.81 in) and a stroke of 75.0 mm (2.95
in). This oversquare design, with bore significantly exceeding stroke, promotes
higher engine speeds and improved volumetric efficiency while maintaining the
low center of gravity characteristic of Subaru’s boxer engine layout. The
compression ratio is set at 8.0:1, a low value selected specifically for
turbocharged operation to reduce the risk of detonation under boost.
The valvetrain utilizes a single overhead camshaft (SOHC) per cylinder bank,
with four valves per cylinder for a total of 16 valves. The camshafts are driven
by a timing belt. The valvetrain incorporates hydraulic lash adjusters (HLAs)
that maintain zero valve clearance throughout the engine’s service life,
eliminating the need for periodic valve clearance adjustments. A critical
feature of the EJ22T is its non-interference design: if the timing belt fails,
the valves do not contact the pistons, preventing catastrophic engine damage.
The firing order for this flat-four engine is 1-3-2-4, with cylinders arranged
with cylinders 1 and 2 on the left bank and cylinders 3 and 4 on the right bank.
Performance outputs for the EJ22T reflect its early 1990s turbocharged
configuration. Maximum power is rated at 119 kW (160 hp) at 5,600 rpm. Maximum
torque is rated at 245 Nm (181 lb-ft) at 2,800 rpm, a low engine speed that
provides strong acceleration from rest. North American market variants were not
equipped with an intercooler, while select Japanese variants received an
air-to-air intercooler. The turbocharger, an IHI RHB5 (VF11) unit, represents
the primary flow restriction in the stock configuration.
The cylinder block is manufactured from cast iron and
features a fully closed-deck design, the defining characteristic of the EJ22T
and the source of its legendary durability. In a closed-deck block, the water
jacket does not extend to the top of the cylinder bores; instead, the area
surrounding the cylinder openings is solid cast iron, providing continuous
support around the entire circumference of each cylinder.
This design eliminates cylinder wall flex (sleeve walk) under high cylinder
pressures, allowing the block to withstand significantly higher boost pressures
than open-deck or semi-closed-deck variants. The cylinder bores are cast
directly into the block and are finished with a plateau honing process that
optimizes oil retention and piston ring sealing.
The block incorporates factory piston-cooling oil squirters, precision nozzles
mounted in the crankcase that direct a stream of engine oil at the underside of
each piston crown. These squirters reduce piston temperatures under high-load
operation, a feature normally reserved for high-performance STi models. The
crankshaft is manufactured from forged steel with a 52 mm rod journal diameter,
providing the strength-to-weight ratio required for sustained turbocharged
operation.
The main bearing caps are manufactured from nodular cast iron and are secured
with four bolts per cap on the center bearings and two bolts per cap on the end
bearings. The cylinder block incorporates the timing belt housing at the front,
including the mounting points for the timing belt tensioner and idler pulleys.
Each cylinder bank is served by a separate aluminum
alloy cylinder head, a design that reduces overall engine weight and improves
thermal conductivity. Each cylinder head houses a single overhead camshaft
supported by five bearing journals. The timing belt drives both camshafts from
the crankshaft, with an automatic hydraulic tensioner maintaining optimal belt
tension.
Each cylinder utilizes four valves - two intake and two exhaust - arranged in a
pent-roof combustion chamber design. The valves are actuated by rocker arms that
incorporate hydraulic lash adjusters (HLAs). The HLAs maintain zero valve
clearance throughout the engine’s service life using engine oil pressure to take
up any slack in the valvetrain, eliminating the need for manual valve
adjustments. The engine is a non-interference design, meaning that the valves do
not extend into the piston travel path at maximum valve lift.
In the event of timing belt failure, the pistons and valves do not make contact,
preventing internal engine damage. The intake valves have a diameter of 36.0 mm
(1.42 in), while the exhaust valves have a diameter of 31.0 mm (1.22 in). The
valve seat inserts are manufactured from sintered metal alloys selected for heat
resistance and wear durability under turbocharged operation. The cylinder head
gaskets are multi-layer steel (MLS) designs, providing robust sealing between
the cast iron block and aluminum heads.
The EJ22T is equipped with a multi-port electronic fuel
injection (MPFI) system controlled by a dedicated engine control unit. Fuel is
delivered from an in-tank pump to a fuel rail mounted on each cylinder head,
distributing fuel to four individually controlled injectors, each mounted in the
intake port directly upstream of the intake valve. The fuel pressure is
regulated by a pressure regulator mounted on the fuel rail, maintaining a
constant pressure differential across the injectors relative to intake manifold
vacuum. The injectors are electrically actuated and are capable of precise fuel
metering based on signals from the ECU.
The ECU monitors crankshaft position, camshaft position, mass air flow, intake
air temperature, coolant temperature, throttle position, boost pressure, and
exhaust oxygen content to calculate injection duration. The fuel system operates
at a pressure of approximately 2.5 bar (36 psi) to 3.0 bar (44 psi) depending on
engine load and operating conditions. North American market variants were not
equipped with an intercooler, while select Japanese variants received an
air-to-air intercooler mounted above the engine.
The lubrication system is a forced-feed, full-flow
filtration design utilizing a gear-type oil pump mounted at the front of the
engine and driven by the crankshaft. The oil pump draws lubricant from the sump
through a strainer and delivers it to the main oil gallery. The system maintains
stable oil pressure across the operating range, with a pressure relief valve
calibrated to open at 5.0 bar (73 psi).
A liquid-to-liquid oil cooler is not fitted in standard configurations, though
the engine design accommodates one for certain applications. The piston-cooling
oil squirters are integrated into the lubrication system, receiving pressurized
oil from the main gallery and directing it toward the piston crowns. The engine
employs a full-flow spin-on oil filter mounted on the engine block. The oil pan
is constructed from stamped steel and has a capacity of 4.5 liters (4.8 US qt)
to 5.0 liters (5.3 US qt) depending on the variant. The engine requires 10W-30,
10W-40, or 5W-30 engine oil meeting API SG or higher specification.
The cooling system is a pressurized, water-cooled
design utilizing a centrifugal water pump driven by the timing belt. The system
maintains engine operating temperature within a range of 80°C to 95°C (176°F to
203°F) under normal conditions. The coolant circuit includes a thermostatic
bypass that facilitates rapid warm-up and reduces internal friction during cold
starts. The water pump is mounted on the front of the engine block and is
serviced in conjunction with timing belt replacement.
The closed-deck cylinder block design, while providing superior structural
rigidity, reduces the volume of coolant surrounding the cylinder bores compared
to open-deck designs, requiring careful thermal management. A cross-flow
radiator with an electric cooling fan supplements the system at low vehicle
speeds and during idle conditions. The total coolant capacity for the engine and
cooling system is 6.0 liters (6.3 US qt) to 7.0 liters (7.4 US qt) depending on
the vehicle application.
Air Intake and Turbocharging: The EJ22T is equipped
with an IHI RHB5 (VF11) turbocharger mounted on a cast iron exhaust manifold.
The VF11 is a small-frame turbocharger with a journal bearing design, providing
rapid spooling characteristics but serving as the primary flow restriction for
power output. The turbocharger incorporates a wastegate for boost pressure
control, with a pneumatic actuator set to provide 0.6 bar (9 psi) of boost
pressure in stock configuration. North American market variants were not
equipped with an intercooler; select Japanese variants received a top-mount
air-to-air intercooler.
Engine Management: The engine is controlled by a Subaru engine control unit
(ECU) that monitors crankshaft position, camshaft position, mass air flow,
intake air temperature, coolant temperature, throttle position, boost pressure,
and exhaust oxygen content. The ECU controls fuel injection duration, ignition
timing, boost pressure, and idle speed control. The ECU calibration is specific
to the EJ22T and differs from naturally aspirated EJ22 variants.
Ignition System: The ignition system is a distributor-based design with a single
ignition coil and distributor mounted on the rear of the left cylinder head. The
distributor is driven by the left bank camshaft. The ignition timing is
controlled by the ECU with a base timing adjustment available through
distributor rotation. The spark plugs are standard resistor-type plugs.
Exhaust System: The exhaust system incorporates a cast iron exhaust manifold
merging into a single turbocharger inlet. A three-way catalytic converter is
positioned downstream of the turbocharger. The system includes an oxygen sensor
positioned before the converter for closed-loop fuel control.
The engine length, measured from the timing belt cover
to the flywheel housing face, is 600 mm (23.6 in). The width, measured across
the cylinder heads at the widest point including the intake manifold and exhaust
manifolds, is 900 mm (35.4 in). The height, measured from the oil pan bottom to
the top of the intake manifold or cylinder head covers, is 600 mm (23.6 in).
The dry weight (without fluids, starter, alternator, or air conditioning
compressor) is 140 kg (309 lb). The fully dressed weight for a vehicle
application, including all accessories, wiring harness, turbocharger, and
fluids, is approximately 165 kg (364 lb). The low height of the boxer engine
configuration contributes to the vehicle’s low center of gravity and handling
characteristics.
The service life of the EJ22T under proper operating
conditions is engineered to exceed 300,000 km (186,000 mi) with regular
maintenance. Oil change intervals are recommended at 5,000 km (3,100 mi) to
7,500 km (4,700 mi) depending on operating conditions and oil quality. The
engine requires engine oil meeting API SG or higher specification in viscosities
of 10W-30, 10W-40, or 5W-30. The presence of piston-cooling oil squirters places
additional demand on the lubrication system, making oil quality and change
intervals critical.
The timing belt is a critical maintenance component. Replacement is mandated at
100,000 km (62,000 mi) or 5 years, whichever occurs first. The water pump should
be replaced concurrently with the timing belt due to its location within the
timing belt drive system. The non-interference design of the engine means that
timing belt failure does not result in valve-to-piston contact, though engine
operation ceases. Replacement of the spark plugs is required every 40,000 km
(25,000 mi).
Replacement of the fuel filter is recommended every 40,000 km (25,000 mi). The
air cleaner element requires replacement every 30,000 km (18,600 mi), with more
frequent servicing in dusty environments. The coolant must be replaced every 4
years or 80,000 km (50,000 mi), using a phosphate-free, long-life coolant
formulation. The accessory drive belt requires inspection at each service
interval, with replacement recommended every 60,000 km (37,000 mi) or sooner if
cracking or wear is evident.
The cylinder head bolts follow a multi-stage angular
torque procedure. The M11 cylinder head bolts receive an initial torque of 30 Nm
(22 lb-ft), followed by a 90-degree angle, and a final 90-degree angle in a
specified sequence. The main bearing cap bolts are torqued to 50 Nm (37 lb-ft)
plus a 60-degree angle. The connecting rod bolts are tightened to 25 Nm (18
lb-ft) plus a 90-degree angle.
The flywheel-to-crankshaft bolts receive a torque of 70 Nm (52 lb-ft) plus a
60-degree angle. The camshaft bearing cap bolts are torqued to 15 Nm (11 lb-ft).
The spark plugs are torqued to 25 Nm (18 lb-ft). The intake manifold bolts are
torqued to 20 Nm (15 lb-ft). The exhaust manifold bolts are torqued to 30 Nm (22
lb-ft). The turbocharger mounting bolts are torqued to 35 Nm (26 lb-ft).
The EJ22T had a limited production run from 1991 to
1994 and was installed exclusively in two Subaru Legacy variants. In North
America, the engine powered the Subaru Legacy Sport Sedan (BC chassis) and the
Subaru Legacy Touring Wagon (BF chassis). These models represented the
high-performance offerings in the Legacy lineup during this period, with the
turbocharged engine providing a significant power advantage over naturally
aspirated variants. The Legacy Sport Sedan featured a sedan body style with
sport-oriented suspension tuning, while the Legacy Touring Wagon offered the
same powertrain in a wagon configuration for buyers requiring additional cargo
capacity.
The EJ22T was not offered in any other Subaru models, including the Impreza, and
was discontinued after the 1994 model year when Subaru transitioned to the EJ20
series turbocharged engines in most markets. The limited production run of four
years, combined with the engine’s durability and the closed-deck block’s
desirability for high-performance builds, has made the EJ22T increasingly
difficult to locate in salvage yards.
The engine remains highly sought after within the Subaru enthusiast community,
where it is frequently used as the foundation for hybrid builds pairing the
closed-deck block with DOHC cylinder heads from EJ20 or EJ257 engines to create
high-power combinations. The EJ22T’s closed-deck architecture, forged
crankshaft, and piston-cooling oil squirters continue to make it one of the most
durable factory engine blocks produced by Subaru.
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