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Engine Mechanical (Sti): Specifications Subaru Impreza GH

Mechanical 6 illustrations ~250 words

SPECIFICATION

EngineModel2.5 L
Cylinder arrangementHorizontally opposed, liquid cooled, 4-cylinder, 4-stroke gasoline engine
Valve system mechanismBelt driven, double overhead camshaft, 4-valve/cylinder
Bore x StrokeMm (in)99.5 x 79.0 (3.92 x 3.11)
DisplacementCm 3 (cu in)2,457 (149.94)
Compression ratio8.2
Compression pressure (at 200 - 300 RPM)KPa (Kg/cm 2 , psi)981 - 1,177 (10 - 12,142 - 171)
Number of piston ringsPressure ring: 2, Oil ring: 1
Intake valve timingOpenMax. retardATDC 5°
Min. advanceBTDC 25°
CloseMax. retardABDC 65°
Min. advanceABDC 35°
Exhaust valve timingOpenMax. retardBBDC 32°
Min. advanceBBDC 72°
CloseMax. retardATDC 28°
Min. advanceBTDC 12°
Valve clearanceMm (in)Inspection valueIntake0.20 +0.04 -0.06 (0.0079 +0.0016 -0.0024
Exhaust0.35±0.05 (0.0138±0.0020)
Adjustment valueIntake0.20 +0.01 -0.03 (0.0079 +0.0004 -0.0012 )
Exhaust0.35±0.02 (0.0138±0.0008)
Idle speed (Gear shift lever in neutral position)RPMNo load700±100
A/C ON750±100
Ignition order1 --> 3 --> 2 --> 4
Ignition timingBTDC/RPM15°±10°/700

ENGINE SPECIFICATION

Belt tension adjusterProtrusion of adjuster rodMm (in)5.2 - 6.2 (0.205 - 0.244)
CamshaftBending limitMm (in)0.020 (0.00079)
Cam lobe heightMm (in)IntakeStandard46.55 - 46.65 (1.833 - 1.837)
ExhaustStandard46.75 - 46.85 (1.841 - 1.844)
Cam base circle diameterMm (in)Standard37.0 (1.457)
Journal O.D.Mm (in)FrontStandard37.946 - 37.963 (1.4939 - 1.4946)
Center, rearStandard29.946 - 29.963 (1.1790 - 1.1796)
Oil clearanceMm (in)Standard0.037 - 0.072 (0.0015 - 0.0028)
Thrust clearanceMm (in)Standard0.068 - 0.116 (0.0027 - 0.0047)
Cylinder headWarping limit (Mating surface with cylinder block)Mm (in)0.035 (0.0014)
Grinding limitMm (in)0.3 (0.012)
Standard heightMm (in)127.5 (5.02)
Valve seatSeating angle between valve and valve seat90°
Contacting width between valve and valve seatMm (in)IntakeStandard0.6 - 1.4(0.024 - 0.055)
ExhaustStandard1.2 - 1.8 (0.047 - 0.071)
Valve guideClearance between the valve guide and valve stemMm (in)IntakeStandard0.030 - 0.057 (0.0012 - 0.0022)
ExhaustStandard0.040 - 0.067 (0.0016 - 0.0026)
Inside diameterMm (in)6.000 - 6.012 (0.2362 - 0.2367)
Valve stem outer diametersMm (in)Intake5.955 - 5.970 (0.2344 - 0.2350)
Exhaust5.945 - 5.960 (0.2341 - 0.2346)
Valve guide protrusionMm (in)15.8 - 16.2 (0.622 - 0.638)
ValveHead edge thicknessMm (in)IntakeStandard1.0 - 1.4 (0.039 - 0.055)
ExhaustStandard1.3 - 1.7 (0.051 - 0.067)
Overall lengthMm (in)Intake104.4 (4.110)
Exhaust104.65 (4.1201)
Valve springFree lengthMm (in)53.48 (2.106)
Tension/spring heightN (kgf, lb)/mm (in)Set204.6 - 235.4 (20.86 - 24.00, 46.00 - 52.93)/36.0 (1.417)
Lift363.5 - 401.7 (37.07 - 40.96, 81.73 - 90.32)/26.7 (1.051)
Squareness2.5°, 2.3 mm (0.091 in) or less
Valve lifterOuter diameterMm (in)Standard34.959 - 34.975 (1.3763 - 1.3770)
Valve lifter mating surface inner diameterMm (in)Standard34.994 - 35.016 (1.3777 - 1.3786)
Valve lifter and valve lifter mating surface clearanceMm (in)Standard0.019 - 0.057 (0.0007 - 0.0022)
Cylinder blockWarping limit (Mating surface with cylinder head)Mm (in)0.025 (0.0098)
Grinding limitMm (in)0.1 (0.004)
Standard heightMm (in)201.0 (7.91)
TaperMm (in)Standard0.015 (0.0006)
Out-of-roundnessMm (in)Standard0.010 (0.0004)
Cylinder to piston clearance at 20°C (68°F)Mm (in)Standard0.010 - 0.010 (-0.00039 - 0.00039)
Cylinder inner diameter boring limit (diameter)Mm (in)To 100.005 (3.9372)
PistonPiston grade pointMm (in)38.2 (1.50)
Outer diameterMm (in)StandardA99.505 - 99.515 (3.9175 - 3.9179)
B99.495 - 99.505 (3.9171 - 3.9175)
0.25 (0.0098) OS99.745 - 99.765 (3.9270 - 3.9278)
0.50 (0.0197) OS99.995 - 100.015 (3.9368 - 3.9376)
Piston pinDegree of fitPiston pin must be fitted into position with thumb at 20°C(68°F).
Clearance between piston pin hole and piston pinMm (in)Standard0.004 - 0.008 (0.0002 - 0.0003)
Piston ringPiston ring gapMm (in)Top ringStandard0.23 - 0.28 (0.0091 - 0.0110)
Second ringStandard0.37 - 0.52 (0.015 - 0.0203)
Oil ringStandard0.20 - 0.50 (0.0079 - 0.0197)
Clearance between piston ring and piston ring grooveMm (in)Top ringStandard0.040 - 0.080 (0.0016 - 0.0031)
Second ringStandard0.030 - 0.070 (0.0012 - 0.0028)
Connecting rod and connecting rod bearingBend or twist per 100 mm (3.94 in) in lengthMm (in)Limit0.1 (0.0039)
Thrust clearanceMm (in)Standard0.070 - 0.330 (0.0028 - 0.0130)
Oil clearanceMm (in)Standard0.017 - 0.045 (0.0007 - 0.0018)
Bearing size (Thickness at center)Mm (in)Standard1.490 - 1.502 (0.0587 - 0.0591)
0.03 (0.0012) US1.504 - 1.512 (0.0592 - 0.0595)
0.05 (0.0020) US1.514 - 1.522 (0.0596 - 0.0599)
0.25 (0.0098) US1.614 - 1.622 (0.0635 - 0.0639)
Bushing of small endClearance between piston pin and bushingMm (in)Standard0 - 0.022 (0 - 0.0009)
Crankshaft and crankshaft bearingBending limitMm (in)0.035 (0.0014)
Crank pinOut-of-roundnessMm (in)0.003 (0.0001)
CylindricallyMm (in)0.004 (0.0002)
Grinding limit (dia.)Mm (in)To 51.750 (2.0374)
Crank journalOut-of-roundnessMm (in)0.005 (0.0002)
CylindricallyMm (in)0.006 (0.0002)
Grinding limit (dia.)Mm (in)To 59.758 (2.3527)
Crank pin outer diameterMm (in)Standard51.984 - 52.000 (2.0466 - 2.0472)
0.03 (0.0012) US51.954 - 51.970 (2.0454 - 2.0461)
0.05 (0.0020) US51.934 - 51.950 (2.0447 - 2.0453)
0.25 (0.0098) US51.734 - 51.750 (2.0368 - 2.0374)
Crank journal outer diameterMm (in)Standard59.992 - 60.008 (2.3619 - 2.3625)
0.03 (0.0012) US59.962 - 59.978 (2.3607 - 2.3613)
0.05 (0.0020) US59.942 - 59.958 (2.3599 - 2.3605)
0.25 (0.0098) US59.742 - 59.758 (2.3520 - 2.3527)
Bearing size (Thickness at center)Mm (in)#1, #3Standard1.998 - 2.011 (0.0787 - 0.0792)
0.03 (0.0012) US2.017 - 2.020 (0.0794 - 0.0795)
0.05 (0.0020) US2.027 - 2.030 (0.0798 - 0.0799)
0.25 (0.0098) US2.127 - 2.130 (0.0837 - 0.0839)
#2, #4, #5Standard2.000 - 2.013 (0.0787 - 0.0793)
0.03 (0.0012) US2.019 - 2.022 (0.0795 - 0.0796)
0.05 (0.0020) US2.029 - 2.032 (0.0799 - 0.0800)
0.25 (0.0098) US2.129 - 2.132 (0.0838 - 0.0839)
Thrust clearanceMm (in)Standard0.030 - 0.115 (0.0012 - 0.0045)
Oil clearanceMm (in)Standard0.010 - 0.030 (0.00039 - 0.0012)
NOTE: OS: Oversize US: Undersize
NOTE
OS: Oversize US: Undersize

UNDERSIZE AND OVERSIZE SPECIFICATIONS

Scheme 73

Scheme 73: TIMING BELT

Tightening torque: N.m (kgf-m, ft-lb)

T1: 3.4 (0.3, 2.5)

T2: 5 (0.5, 3.7)

T3: 6.4 (0.7, 4.7)

T4: 9.75 (1.0, 7.2)

T5: 24.5 (2.5, 18.1)

T6: 25 (2.5, 18.4)

T7: 39 (4.0, 28.8)

T8: Refer to INSTALLATION, Cam Sprocket.

T9: Refer to INSTALLATION, Crank Pulley.

Scheme 74

Scheme 74: CYLINDER HEAD AND CAMSHAFT

Tightening torque: N.m (kgf-m, ft-lb)

T1: 6.4 (0.7, 4.7)

T2: 8 (0.8, 5.9)

T3: 10 (1.0, 7.4)

T4: 29 (3.0, 21.4)

T5: Refer to INSTALLATION, Cylinder Head.

T6: Refer to INSTALLATION, Camshaft.

Scheme 75

Scheme 75: CYLINDER HEAD AND VALVE ASSEMBLY

Scheme 76

Scheme 76: CYLINDER BLOCK

Tightening torque: N.m (kgf-m, ft-lb)

T1: 5 (0.5, 3.7)

T2: 6.4 (0.7, 4.7)

T3: 10 (1.0, 7.4)

T4: First 12 (1.2, 8.9)

Second 12 (1.2, 8.9)

T5: 16 (1.6, 11.8)

T6: 25 (2.5, 18.4)

T7: 44 (4.5, 32.5)

T8: 54 (5.5, 39.8)

T9: 69 (7.0, 50.9)

T10: 70 (7.1, 51.6)

T11: Refer to INSTALLATION, Cylinder Block.

Scheme 77

Scheme 77: CRANKSHAFT AND PISTON

Tightening torque: N.m (kgf-m, ft-lb)

T1: 52 (5.3, 38.4)

T2: 72 (7.3, 53.1)

Scheme 78

Scheme 78: ENGINE MOUNTING

Tightening torque: N.m (kgf-m, ft-lb)

T1: 35 (3.6, 25.8)

T2: 42 (4.3, 31.0)

T3: 85 (8.7, 62.7)

Refer to REMOVAL or INSTALLATION for removal and installation procedures of the intake and exhaust valves.

Refer to REMOVAL or INSTALLATION for removal and installation procedures of pistons.

Refer to REMOVAL or INSTALLATION for removal and installation procedures of connecting rod.

Refer to REMOVAL or INSTALLATION for removal and installation procedures of the crankshaft.