Engine Specs Specification (Engine Mechanical (H4Dotc 2.5L Dohc Turbo) : General Description)
Engine Specs Specification (Engine Mechanical (H4Dotc 2.5L Dohc Turbo) : General Description)
Engine Specs Specification (Engine Mechanical (H4Dotc 2.5L Dohc Turbo) : General Description)
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2010 Subaru Impreza 2.5L Eng WRX STi
1Search™ Print Date: 17/01/2017
ENGINE SPECS
SPECIFICATION [ ENGINE MECHANICAL (H4DOTC 2.5L DOHC TURBO) : General
Description ]
SPECIFICATION CHART
Model 2.5 L
Horizontally
opposed, liquid
Cylinder arrangement cooled, 4cylinder,
4stroke gasoline
engine
Belt driven, double
Valve system mechanism overhead camshaft,
4valve/cylinder
99.5 x 79.0 (3.92 x
Bore x Stroke mm (in)
3.11)
Compression ratio 8.4
kPa
981 1,177 (10
Compression pressure (at 200 300 RPM) (kg/cm2 ,
12, 142 171)
psi)
Pressure ring: 2, Oil
Number of piston rings
ring: 1
Max. retard ATDC 5°
Open Min.
BTDC 35°
advance
Intake valve timing
Max. retard ABDC 65°
Engine Close Min.
ABDC 25°
advance
Open BBDC 55°
Exhaust valve timing
Close ATDC 5°
0.20+0040.06
Intake (0.0079+000160.0024
Inspection )
value
0.35±0.05
Exhaust
mm (0.0138±0.0020)
Valve clearance
(in) 0.20+0010.03
Intake (0.0079+000040.0012
Adjustment
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value )
0.35±0.02
Exhaust
(0.0138±0.0008)
No load 700±100
Idling speed (at "P" or "N" position on
AT model, or neutral position on MT RPM AT model: 825±100
model) A/C ON
MT model: 800±100
Ignition order 1 → 3 → 2 → 4
AT model: 17°
±10°/700
Ignition timing BTDC/RPM
MT model: 12°
±10°/700
Belt tension 5.2 6.2 (0.205
Protrusion of adjuster rod mm (in)
adjuster 0.244)
46.55 46.65
Intake Standard
(1.833 1.837)
Cam lobe height mm (in)
46.75 46.85
Exhaust Standard
(1.841 1.844)
Camshaft 37.946 37.963
Front
(1.4939 1.4946)
Journal O.D. mm (in) Standard
Center, 29.946 29.963
rear (1.1790 1.1796)
0.037 0.072
Oil clearance mm (in) Standard
(0.0015 0.0028)
0.068 0.116
Thrust clearance mm (in) Standard
(0.0027 0.0047)
Warping limit (Mating surface with cylinder
mm (in) 0.035 (0.0014)
block)
Cylinder head
Grinding limit mm (in) 0.3 (0.012)
Seating angle between valve and valve seat 90°
0.6 1.4 (0.024
Intake Standard
Valve seat Contacting width between 0.055)
mm (in)
valve and valve seat 1.2 1.8 (0.047
Exhaust Standard
0.071)
0.030 0.057
Intake
Clearance between the (0.0012 0.0022)
mm (in) Standard
valve and valve stem 0.040 0.067
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Exhaust (0.0016 0.0026)
6.000 6.012
Inside diameter mm (in)
Valve guide (0.2362 0.2367)
5.955 5.970
Intake
Valve stem outer (0.2344 0.2350)
mm (in)
diameters 5.945 5.960
Exhaust
(0.2341 0.2346)
15.8 16.2 (0.622
Valve guide protrusion mm (in) 0.638)
1.0 1.4 (0.039
Intake Standard
0.055)
Head edge thickness mm (in)
1.3 1.7 (0.051
Valve Exhaust Standard
0.067)
Intake 104.4 (4.110)
Overall length mm (in)
Exhaust 104.65 (4.1201)
205 235 (20.9
Set 24.0, 46.1
52.8)/36.0 (1.417)
Tension/spring height N (kgf, lb)/mm (in)
Valve spring 426 490 (43.4
Lift 50.0, 95.8
110)/26.50 (1.043)
2.5°, 2.1 mm (0.083
Squareness
in) or less
34.959 34.975
Outer diameter mm (in) Standard
(1.3763 1.3770)
Valve lifter mating surface inner 34.994 35.016
Valve lifter mm (in) Standard
diameter (1.3777 1.3786)
Valve lifter and valve lifter mating 0.019 0.057
mm (in) Standard
surface clearance (0.0007 0.0022)
Warping limit (Mating surface with cylinder
mm (in) 0.025 (0.0098)
head)
0.010 0.010
Cylinder to piston clearance at 20°C
mm (in) Standard (0.00039
(68°F)
0.00039)
To 100.005
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99.505 99.515
A
(3.9175 3.9179)
Standard
99.495 99.505
B
Piston (3.9171 3.9175)
Outer diameter mm (in)
99.745 99.765
0.25 (0.0098) OS
(3.9270 3.9278)
99.995 100.015
0.50 (0.0197) OS
(3.9368 3.9376)
Piston pin must be
fitted into position
Degree of fit
with thumb at 20°C
Piston pin (68°F).
Clearance between piston hole and 0.004 0.008
mm (in) Standard
piston pin (0.0002 0.0003)
0.20 0.25 (0.0079
Top ring Standard
0.0098)
Second 0.37 0.52 (0.015
Piston ring gap mm (in) Standard
ring 0.0203)
0.20 0.50 (0.0079
Piston ring Oil ring Standard
0.0197)
0.040 0.080
Clearance between piston Top ring Standard
(0.0016 0.0031)
ring and piston ring mm (in)
groove Second 0.030 0.070
Standard
ring (0.0012 0.0028)
Bend or twist per 100 mm (3.94 in) in
mm (in) Limit 0.10 (0.0039)
length
0.070 0.330
Thrust clearance mm (in) Standard
(0.0028 0.0130)
0.017 0.045
Oil clearance mm (in) Standard
(0.0007 0.0018)
Connecting rod
1.490 1.502
and connecting Standard
(0.0587 0.0591)
rod bearing
1.504 1.512
0.03 (0.0012) US
Bearing size (Thickness at (0.0592 0.0595)
mm (in)
center) 1.514 1.522
0.05 (0.0020) US
(0.0596 0.0599)
1.614 1.622
0.25 (0.0098) US
(0.0635 0.0639)
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51.984 52.000
Standard
(2.0466 2.0472)
51.954 51.970
0.03 (0.0012) US
(2.0454 2.0461)
Crank pin outer diameter mm (in)
51.934 51.950
0.05 (0.0020) US
(2.0447 2.0453)
51.734 51.750
0.25 (0.0098) US
(2.0368 2.0374)
59.992 60.008
Standard
(2.3619 2.3625)
59.962 59.978
0.03 (0.0012) US
Crank journal outer (2.3607 2.3613)
mm (in)
diameter
59.942 59.958
Crankshaft and 0.05 (0.0020) US
(2.3599 2.3605)
crankshaft bearing
59.742 59.758
0.25 (0.0098) US
(2.3520 2.3527)
1.998 2.011
Standard
(0.0787 0.0792)
2.017 2.020
0.03 (0.0012) US
(0.0794 0.0795)
#1, #3
2.027 2.030
0.05 (0.0020) US
(0.0798 0.0799)
2.127 2.130
Bearing size 0.25 (0.0098) US
mm (0.0837 0.0839)
(Thickness at
(in) 2.000 2.013
center) Standard
(0.0787 0.0793)
2.019 2.022
0.03 (0.0012) US
(0.0795 0.0796)
#2, #4, #5
2.029 2.032
0.05 (0.0020) US
(0.0799 0.0800)
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2.129 2.132
0.25 (0.0098) US
(0.0838 0.0839)
0.030 0.115
Thrust clearance mm (in) Standard
(0.0012 0.0045)
0.010 0.030
Oil clearance mm (in) Standard
(0.0004 0.0012)
NOTE: OS: Oversize US: Undersize
SPECIFICATION [ ENGINE MECHANICAL : Connecting Rod ]
Refer to REMOVAL or INSTALLATION for removal and installation procedures of connecting rod.
SPECIFICATION [ ENGINE MECHANICAL (H4DOTC 2.5L DOHC TURBO) : Intake And
Exhaust Valve ]
Refer to "Cylinder Head" for removal and installation procedures of the intake and exhaust valves.
Ref. to REMOVAL , Cylinder Head. Ref. to INSTALLATION , Cylinder Head.
SPECIFICATION [ ENGINE MECHANICAL : Intake And Exhaust Valve ]
Refer to REMOVAL or INSTALLATION for removal and installation procedures of the intake and
exhaust valves.
SPECIFICATION [ ENGINE MECHANICAL (H4DOTC 2.5L DOHC TURBO) :
Crankshaft ]
Refer to "Cylinder Block" for removal and installation procedures of the crankshaft. Ref. to REMOVAL ,
Cylinder Block. Ref. to INSTALLATION , Cylinder Block.
SPECIFICATION [ 2.5 L Turbo Engine (FROM '10MY) ]
The following shows the comparison between new and existing engines.
New engine Existing engine
Longitudinallypositioned, Longitudinallypositioned,
Engine
horizontally opposed 4cylinder horizontally opposed 4cylinder
Total displacement cm3
2, 457 (149.93) 2, 457 (149.93)
(cu in)
Maximum output kW
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Maximum torque N.m
350 (35.7, 258)/2, 000 to 5, 200 327 (33.3, 241)/3, 600
(kgfm, ftlb)/rpm
SPECIFICATION [ ENGINE MECHANICAL (H4DOTC 2.5L DOHC TURBO) : Piston ]
Refer to "Cylinder Block" for removal and installation procedures of pistons. Ref. to REMOVAL ,
Cylinder Block. Ref. to INSTALLATION , Cylinder Block.
SPECIFICATION [ ENGINE MECHANICAL : General Description ]
ENGINE SPECIFICATION
Model 2.5 L
Horizontally opposed, liquid cooled, 4
Cylinder arrangement
cylinder, 4stroke gasoline engine
Belt driven, double overhead camshaft, 4
Valve system mechanism
valve/cylinder
Compression ratio 8.2
KPa
Compression pressure (at 200
(Kg/cm2 , 981 1,177 (10 12,142 171)
300 RPM)
psi)
Number of piston rings Pressure ring: 2, Oil ring: 1
Max. retard ATDC 5°
Open Min.
BTDC 25°
advance
Intake valve timing
Max. retard ABDC 65°
Engine Close Min.
ABDC 35°
advance
Max. retard BBDC 32°
Open Min.
BBDC 72°
advance
Exhaust valve timing
Max. retard ATDC 28°
Close Min.
BTDC 12°
advance
Ignition order
Ignition timing BTDC/RPM 1 → 3 → 2 → 4
15°±10°/700
UNDERSIZE AND OVERSIZE SPECIFICATIONS
46.55 46.65 (1.833
Intake Standard
mm 1.837)
Cam lobe height
(in) 46.75 46.85 (1.841
Exhaust Standard
1.844)
Camshaft 37.946 37.963 (1.4939
Front Standard
mm 1.4946)
Journal O.D.
(in) Center, 29.946 29.963 (1.1790
Standard
rear 1.1796)
0.037 0.072 (0.0015
Oil clearance mm (in) Standard
0.0028)
0.068 0.116 (0.0027
Thrust clearance mm (in) Standard
0.0047)
Warping limit (Mating surface with cylinder
mm (in) 0.035 (0.0014)
block)
Cylinder head
Grinding limit mm (in) 0.3 (0.012)
Seating angle between valve and valve seat 90°
0.030 0.057 (0.0012
Intake Standard
Clearance between the mm 0.0022)
valve guide and valve stem (in) 0.040 0.067 (0.0016
Exhaust Standard
0.0026)
6.000 6.012 (0.2362
Inside diameter mm (in)
0.2367)
Valve guide
5.955 5.970 (0.2344
Intake
0.2350)
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Valve stem outer diameters mm
(in) 5.945 5.960 (0.2341
Exhaust 0.2346)
15.8 16.2 (0.622
Valve guide protrusion mm (in)
0.638)
204.6 235.4 (20.86
Set 24.00, 46.00
N (kgf, lb)/mm 52.93)/36.0 (1.417)
Tension/spring height
Valve spring (in) 363.5 401.7 (37.07
Lift 40.96, 81.73
90.32)/26.7 (1.051)
2.5°, 2.3 mm (0.091 in)
Squareness
or less
34.959 34.975 (1.3763
Outer diameter mm (in) Standard
1.3770)
Valve lifter mating surface inner 34.994 35.016 (1.3777
Valve lifter mm (in) Standard
diameter 1.3786)
Valve lifter and valve lifter mating 0.019 0.057 (0.0007
mm (in) Standard
surface clearance 0.0022)
Warping limit (Mating surface with cylinder
mm (in) 0.025 (0.0098)
head)
Cylinder to piston clearance at 0.010 0.010 (0.00039
mm (in) Standard
20°C (68°F) 0.00039)
Cylinder inner diameter boring limit
mm (in) To 100.005 (3.9372)
(diameter)
99.505 99.515 (3.9175
A
3.9179)
Standard
99.495 99.505 (3.9171
Piston mm B
Outer diameter 3.9175)
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99.995 100.015
0.50 (0.0197) OS
(3.9368 3.9376)
Piston pin must be fitted
Degree of fit into position with thumb
at 20°C(68°F).
Piston pin
Clearance between piston pin 0.004 0.008 (0.0002
mm (in) Standard
hole and piston pin 0.0003)
0.23 0.28 (0.0091
Top ring Standard
0.0110)
mm Second 0.37 0.52 (0.015
Piston ring gap Standard
(in) ring 0.0203)
0.20 0.50 (0.0079
Piston ring Oil ring Standard
0.0197)
0.040 0.080 (0.0016
Top ring Standard
Clearance between piston mm 0.0031)
ring and piston ring groove (in) Second 0.030 0.070 (0.0012
Standard
ring 0.0028)
Bend or twist per 100 mm (3.94
mm (in) Limit 0.1 (0.0039)
in) in length
0.070 0.330 (0.0028
Thrust clearance mm (in) Standard
0.0130)
0.017 0.045 (0.0007
Oil clearance mm (in) Standard
0.0018)
Connecting rod and
1.490 1.502 (0.0587
connecting rod Standard
0.0591)
bearing
1.504 1.512 (0.0592
0.03 (0.0012) US
Bearing size (Thickness at mm 0.0595)
center) (in) 1.514 1.522 (0.0596
0.05 (0.0020) US
0.0599)
1.614 1.622 (0.0635
0.25 (0.0098) US
0.0639)
Clearance between piston pin
Bushing of small end mm (in) Standard 0 0.022 (0 0.0009)
and bushing
Outof
mm (in) 0.003 (0.0001)
roundness
Grinding limit
mm (in) To 51.750 (2.0374)
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(dia.)
Outof
mm (in) 0.005 (0.0002)
roundness
Crank journal Cylindrically mm (in) 0.006 (0.0002)
Grinding limit
mm (in) To 59.758 (2.3527)
(dia.) 51.984 52.000 (2.0466
Standard
2.0472)
51.954 51.970 (2.0454
0.03 (0.0012) US
mm 2.0461)
Crank pin outer diameter
(in)
51.934 51.950 (2.0447
0.05 (0.0020) US
2.0453)
51.734 51.750 (2.0368
0.25 (0.0098) US
2.0374)
59.992 60.008 (2.3619
Standard
2.3625)
59.962 59.978 (2.3607
0.03 (0.0012) US
Crank journal outer mm 2.3613)
Crankshaft and
crankshaft bearing diameter (in) 59.942 59.958 (2.3599
0.05 (0.0020) US
2.3605)
59.742 59.758 (2.3520
0.25 (0.0098) US
2.3527)
1.998 2.011 (0.0787
Standard
0.0792)
2.017 2.020 (0.0794
0.03 (0.0012) US
#1, 0.0795)
#3 2.027 2.030 (0.0798
0.05 (0.0020) US
0.0799)
2.127 2.130 (0.0837
0.25 (0.0098) US
Bearing size mm 0.0839)
(Thickness at center) (in) 2.000 2.013 (0.0787
Standard
0.0793)
2.019 2.022 (0.0795
#2, 0.03 (0.0012) US
0.0796)
#4,
#5 2.029 2.032 (0.0799
0.05 (0.0020) US
0.0800)
2.129 2.132 (0.0838
0.25 (0.0098) US
0.0839)
0.030 0.115 (0.0012
Thrust clearance mm (in) Standard
0.0045)
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NOTE: OS: Oversize
US: Undersize
SPECIFICATION [ ENGINE MECHANICAL : Crankshaft ]
Refer to REMOVAL or INSTALLATION for removal and installation procedures of the crankshaft.
SPECIFICATION [ ENGINE MECHANICAL (H4DOTC 2.5L DOHC TURBO) :
Connecting Rod ]
Refer to "Cylinder Block" for removal and installation procedures of connecting rod. Ref. to
REMOVAL , Cylinder Block. Ref. to INSTALLATION , Cylinder Block.
SPECIFICATION [ ENGINE MECHANICAL : Piston ]
Refer to REMOVAL or INSTALLATION for removal and installation procedures of pistons.
SPECIFICATIONS INDEX
IMPREZA STi SPECIFICATIONS INDEX
System Specification/Procedure
Air Conditioning
Service SPECIFICATION
Torque COMPONENT
Axle Shaft Nut (Front) 162 Ft.lb (22.4 kgfm, 220 N.m)
Axle Shaft Nut (Rear) 140 Ft.lb (19.4 kgfm, 190 N.m)
Battery NA
Brakes
Bleeding Sequence AIR BLEEDING
Disc/Drum Brakes SPECIFICATION
Torque See applicable COMPONENT for
torque specifications.
Charging
Generator SPECIFICATION
Torque COMPONENT
Drive Belts
Belt Routing & Adjustment VBELT
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Engine Cooling
General Service Specifications SPECIFICATION
Radiator Cap Pressure 1418 psi (.951.25 kg/cm2 )
Standard 73.6 103.0 kPa (0.75 1.05
kg/cm2 , 11 15 psi)
Service Limit 63.6 kPa (0.65 kg/cm2 , 9 psi)
Thermostat R & I THERMOSTAT
Water Pump R & I WATER PUMP
Engine Mechanical
Compression
Standard 981 1,177 kPa (10 12 kgf/cm2 ,
142 171 psi
Difference 49 kPa (0.5 kgf/cm2 , 7 psi) or
Between Cylinders less
Oil Pressure SPECIFICATION
Overhaul SPECIFICATION
Torque See applicable COMPONENT for
torque specifications.
Fluid Specifications See FLUIDS under MAINTENANCE tab.
Flywheel/Flex Plate (Drive Plate) Torque 72 N.m (53.1 Ftlb)
Fuel System
Fuel Pressure Test Procedure FUEL PRESSURE
Fuel Filter Location InTank Type
Ignition
Firing Order & Cylinder Identification FIRING ORDER & CYLINDER
IDENTIFICATION
Ignition Wires (Resistance) NA
Ignition Wires (Routing) NA
Spark Plug SPARK PLUG
Starting
Starter
Starter SPECIFICATION
Torque 37 Ft.lb (5.1 kgfm, 50 N.m)
Wheel Alignment
Adjustment Specifications
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Front SPECIFICATION
Rear SPECIFICATION
Torque
Front COMPONENT
Rear COMPONENT
Wheel & Tire
Wheel Lug Nut Torque 73.8 Ft.lb (9.1 kgfm, 100 N.m)
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