Subaru EZ36D Specifications
| Engine Model: Subaru EZ36D |
| Engine Type: 4-cycle 6-cylinder DOHC 24-valve liquid-cooled gasoline |
| Total Displacement: 221.4 cu.in (3.63 L) |
| Rated Engine Power: 256 Hp (188 kW) at 6000 rpm |
| Fuel System Type: Multi-point electronic fuel injection |
____________________________________________________________________________________
The Subaru EZ36D embodies a sophisticated evolution of
the flat-six configuration, leveraging advanced engineering to extract
substantial displacement from a compact package. Its all-aluminum construction,
comprising a cylinder block with cast iron liners and aluminum cylinder heads,
contributes to a favorable power-to-weight ratio for a six-cylinder engine of
this capacity.
The double overhead camshaft (DOHC) valvetrain with 24 valves incorporates dual
Active Valve Control System (AVCS) on both intake and exhaust camshafts,
providing continuously variable valve timing across the operating range. The
engine’s most distinctive mechanical feature is the asymmetrical connecting
rods, which are offset to allow a 91.0 mm stroke without increasing the engine’s
width beyond the constraints of the flat-six architecture.
The timing chain system utilizes three separate chains with hydraulic
tensioners, eliminating the periodic replacement intervals associated with
belt-driven designs. The engine produces a broad torque curve well suited to the
weight of Subaru’s larger vehicles, with peak torque available from 4,400 rpm.
Service access presents challenges due to the engine’s width within the engine
bay, particularly for spark plug replacement and front timing cover seal
repairs.
Engine Type: Horizontally opposed 6-cylinder (flat-six), 4-cycle, naturally
aspirated.
Displacement: 3,629 cc (221.4 cu.in).
Bore x Stroke: 92.0 mm x 91.0 mm (3.62 in x 3.58 in).
Compression Ratio: 10.5:1.
Firing Order: 1-6-3-2-5-4.
Maximum Power: 256 hp (188 kW) @ 6,000 rpm.
Maximum Torque: 335 Nm (247 lb-ft) @ 4,400 rpm.
Redline: 6,500 rpm with fuel cut at 6,800 rpm.
Idle Speed: 650 ± 50 rpm.
Fuel Requirement: 87 octane (regular unleaded) per manufacturer specification.
Valvetrain: DOHC, 24 valves (4 valves per cylinder). Dual AVCS (intake and
exhaust camshaft phase control). Chain-driven camshafts.
The cylinder block is constructed from aluminum alloy
with press-fit cast iron cylinder liners, providing a lightweight structure with
durable wear surfaces. The horizontally opposed configuration positions two
banks of three cylinders opposite each other, with the crankshaft located at the
centerline. The block utilizes an open-deck design at the cylinder head
interface, allowing efficient coolant flow around each cylinder bore.
Four main bearings support the crankshaft, with the thrust bearing located at
the number three main bearing position. The block incorporates integrated water
jackets and oil galleries cast into the structure. The asymmetrical connecting
rod design permits the extended 91.0 mm stroke while maintaining the narrow
width characteristic of the flat engine configuration. The engine mounting
points are positioned on the sides of the block, designed for longitudinal
installation in Subaru chassis.
The cylinder heads are manufactured from aluminum
alloy, with separate heads for each cylinder bank. Each head incorporates a DOHC
configuration with the camshafts supported by four bearings per camshaft. The 24
valves are arranged with four valves per cylinder in a pent-roof combustion
chamber design. Dual AVCS systems are integrated into both intake and exhaust
camshafts, providing continuously variable valve timing controlled by hydraulic
actuators.
The system adjusts camshaft phase based on engine speed, load, and coolant
temperature, optimizing volumetric efficiency across the operating range. The
intake valves measure 34.0 mm in diameter, while exhaust valves measure 29.0 mm.
Valve actuation is achieved via direct-acting bucket tappets with hydraulic lash
adjusters, eliminating manual clearance adjustment. Each cylinder head
incorporates triple exhaust ports to improve scavenging and thermal management.
The engine is equipped with a multi-point fuel
injection (MPFI) system. Individual fuel injectors are mounted in the intake
manifold runners, positioned to direct fuel toward the intake valves. The fuel
system operates at a regulated pressure of 3.5 bar (51 psi). An engine control
unit (ECU) manages injection duration, ignition timing, and AVCS operation based
on inputs from sensors including the mass airflow sensor, throttle position
sensor, coolant temperature sensor, camshaft position sensors, crankshaft
position sensor, and oxygen sensors.
The intake manifold is constructed from composite material with tuned runner
lengths optimized for torque production across the engine speed range. The fuel
system incorporates a returnless design, with fuel pressure regulated by a
module mounted on the fuel pump assembly within the fuel tank.
The lubrication system is a pressurized, wet-sump
configuration designed to support the flat-six engine layout. A gear-type oil
pump, mounted to the front of the crankshaft, circulates engine oil through a
full-flow disposable filter and an oil cooler. The oil cooler is of the
water-to-oil type, maintaining oil temperature within operational limits.
Oil galleries within the block and cylinder heads supply pressurized oil to the
crankshaft main bearings, connecting rod bearings, camshaft bearings, AVCS
actuators, and hydraulic lash adjusters. The oil pump incorporates a pressure
relief valve to maintain system pressure within specified limits. The oil sump
is constructed from pressed steel with a baffle system to maintain oil pickup
during cornering. Total oil capacity, including the filter, is 6.0 liters (6.3
qt).
The cooling system is a pressurized, water-cooled
design engineered to manage the thermal output of the 3.6-liter flat-six engine.
A belt-driven water pump, mounted to the front of the engine block, circulates
coolant through the cylinder block, both cylinder heads, and the radiator. The
water pump features a high-flow impeller design to accommodate the cooling
demands of the six-cylinder configuration.
A wax-type thermostat, beginning to open at 82-86°C (180-187°F), regulates
coolant flow to maintain optimal operating temperatures. The cylinder head
gasket design incorporates revised coolant passages to address thermal
distribution concerns present in earlier EZ-series engines. The system utilizes
a cross-flow radiator with an electric cooling fan controlled by the ECU based
on coolant temperature and air conditioning operation. Total coolant capacity is
8.5 liters (9.0 qt).
Ignition System: The EZ36D utilizes a distributor-less
ignition system with individual ignition coils mounted directly over each spark
plug (coil-on-plug configuration). A crankshaft position sensor mounted at the
rear of the engine and camshaft position sensors on each cylinder head provide
timing information to the ECU. Knock sensors mounted on each cylinder bank allow
individual cylinder ignition timing adjustment.
Timing System: The camshafts are driven by three separate timing chains. A
primary chain drives from the crankshaft to an intermediate sprocket mounted
between the cylinder banks. Two secondary chains drive from the intermediate
sprocket to the intake and exhaust camshafts on each cylinder head. Hydraulic
chain tensioners maintain consistent tension. The timing chain system is
designed for the service life of the engine and does not have a scheduled
replacement interval.
AVCS Operation: The Dual AVCS system provides continuously variable valve timing
on both intake and exhaust camshafts. The system operates using engine oil
pressure directed through control valves to advance or retard camshaft phase up
to 35 degrees on the intake side and 25 degrees on the exhaust side. The system
enhances torque at low engine speeds and improves fuel efficiency under partial
throttle conditions.
Emission Control: The engine incorporates a closed-loop emission control system
featuring three-way catalytic converters mounted in the exhaust system, exhaust
gas recirculation (EGR) valve, and positive crankcase ventilation (PCV). Four
oxygen sensors (two upstream, two downstream) provide feedback for closed-loop
air-fuel ratio control and catalytic converter monitoring.
Electrical System: The charging system consists of a 12-volt, 130-150 amp
alternator. The starter motor is a 1.8 kW (2.4 hp) unit.
Dry Weight: 165 kg (364 lb).
Overall Length (from accessory drive to flywheel): 670 mm (26.4 in).
Overall Width: 820 mm (32.3 in).
Overall Height: 590 mm (23.2 in).
Engine Oil Capacity (with filter): 6.0 liters (6.3 qt).
Engine Oil Specification: SAE 5W-30 or 0W-20 meeting API SN or higher.
Engine Oil Pressure (at idle): Minimum 0.8 bar (12 psi).
Engine Oil Pressure (at 3,000 rpm): 3.5-5.0 bar (51-73 psi).
Coolant Capacity: 8.5 liters (9.0 qt).
Coolant Specification: Ethylene glycol-based antifreeze with corrosion
inhibitors.
Spark Plug Type: NGK SILFR6A or equivalent (iridium-tipped).
Spark Plug Gap: 1.0-1.1 mm (0.039-0.043 in).
Spark Plug Replacement Interval: Every 100,000 km (62,000 miles).
Ignition Timing: Controlled by ECU; not adjustable.
Valve Clearance: Not adjustable; maintained by hydraulic lash adjusters.
Timing Chain: Inspect for noise or chain stretch at major service intervals.
Idle Speed: 650 ± 50 rpm.
Fuel Pressure: 3.5 bar (51 psi) nominal.
AVCS Oil Control Valve Resistance: 7-9 ohms at 20°C (68°F).
Compression Pressure: Standard: 12.0-14.0 bar (174-203 psi) at cranking speed.
Compression Pressure: Minimum allowable: 10.0 bar (145 psi).
Compression Pressure: Maximum variation between cylinders: 1.5 bar (22 psi).
Cylinder Head Bolts (M11), Stage 1: 25 Nm (18 lb-ft).
Cylinder Head Bolts (M11), Stage 2: 45 Nm (33 lb-ft).
Main Bearing Cap Bolts, Stage 1: 25 Nm (18 lb-ft).
Main Bearing Cap Bolts, Stage 2: 40 Nm (30 lb-ft).
Main Bearing Cap Bolts, Stage 3: 75 Nm (55 lb-ft).
Connecting Rod Cap Nuts: 20 Nm (15 lb-ft).
Camshaft Bearing Cap Bolts: 15-18 Nm (11-13 lb-ft).
Camshaft Sprocket Bolts (Intake): 90-100 Nm (66-74 lb-ft).
Camshaft Sprocket Bolts (Exhaust): 90-100 Nm (66-74 lb-ft).
Flywheel Bolts: 70-75 Nm (52-55 lb-ft).
Crankshaft Pulley Bolt: 200-220 Nm (148-162 lb-ft).
Intake Manifold Nuts: 20-22 Nm (15-16 lb-ft).
Exhaust Manifold Nuts: 25-30 Nm (18-22 lb-ft).
Spark Plugs: 20-25 Nm (15-18 lb-ft).
Oil Pan Bolts: 10-12 Nm (7-9 lb-ft).
Valve Cover Bolts: 8-10 Nm (6-7 lb-ft).
Timing Chain Tensioner Bolts: 20-25 Nm (15-18 lb-ft).
Timing Chain Guide Bolts: 20-25 Nm (15-18 lb-ft).
Water Pump Bolts: 10-12 Nm (7-9 lb-ft).
AVCS Control Valve Bolts: 20-22 Nm (15-16 lb-ft).
Engine Mount (Bracket to Block): 55-60 Nm (41-44 lb-ft).
Engine Mount (Through Bolt): 70-80 Nm (52-59 lb-ft).
The Subaru EZ36D engine served as the premium
powerplant across Subaru’s larger vehicle platforms throughout its production
life.
Subaru Outback 3.6R: 2010-2019, the EZ36D was offered as the high-output engine
option in the Outback wagon, providing enhanced towing capacity and acceleration
over the four-cylinder variants.
Subaru Legacy 3.6R: 2010-2019, the sedan counterpart to the Outback received the
EZ36D as the top-tier powertrain in markets including North America, Australia,
and select Asian regions.
Subaru Tribeca: 2008-2014, the EZ36D replaced the earlier EZ30R in the Tribeca
crossover SUV, serving as the sole engine option throughout the final years of
this model’s production.
____________________________________________________________________________________
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Industrial Engines Technical Specifications |
| Outboard Engines Technical Specifications |
