Subaru EJ engine

src: www.speednik.com

The Subaru EJ engine is a series of four-stroke automotive engines manufactured by Subaru. They were introduced in 1989, intended to succeed the previous Subaru EA engine. The EJ series is the mainstay of Subaru's engine line, with all engines of this series being 16-valve horizontal flat-fours, with configurations available for single, or double-overhead camshaft arrangements (SOHC or DOHC). Naturally aspirated and turbocharged versions are available, ranging from 96 to 320 horsepower. These engines are commonly used in light aircraft, kit cars and engine swaps into air-cooled Volkswagens, and are also popular as a swap into the wasserboxer engined Volkswagen T3/Vanagon . Primary engineering on the EJ series was done by Masayuki Kodama, Takemasa Yamada and Shuji Sawafuji of Fuji Heavy Industries, Subaru's parent company.

Video Subaru EJ engine

EJ15

Usage:

• Impreza GC1 series (JDM) - Replaced by Subaru EL engine in 2006 GD, GG, GE & GH series (JDM) Impreza.
• Impreza 93-06 (Latin America)

Specifications

• Displacement:1,493 cc
• Bore: 85.0 mm
• Stroke: 65.8 mm
• Compression Ratio: 9.4:1 - 10.0
• Valvetrain: SOHC, 16 valves
• Fuel Delivery multi point fuel injection

EJ151

• Horsepower: 97 PS (71 kW; 96 bhp) at 6,000 rpm
• Torque: 129.4 N?m (95 lb?ft) at 3,600 rpm

EJ152

• Horsepower: 102 PS (75 kW; 101 bhp) at 5,600 rpm
• Torque: 136.3 N?m (101 lb?ft) at 4,000 rpm

EJ153

• Horsepower: 95 PS (70 kW; 94 bhp) at 5,200 rpm
• Torque: 140.2 N?m (103 lb?ft) at 3,600 rpm

EJ154

• Horsepower: 100 PS (74 kW; 99 bhp) at 5,200 rpm
• Torque: 142.0 N?m (105 lb?ft) at 4,000 rpm

Maps Subaru EJ engine

EJ16

Usage:

• Impreza 93-94 (JDM only) GC4 series
• Impreza 93-06 (Europe & Middle East)
• Impreza 93-97 (Australia)
• Impreza 93-06 (Latin America)

Specifications

• Displacement: 1,597 cc
• Bore: 87.9 mm
• Stroke: 65.8 mm
• Compression Ratio: 9.4:1 - 10.0:1
• Valvetrain: SOHC
• Fuel Delivery mpfi (carburetor in some locations)

EJ16

• Horsepower: 90-98 PS (66-72 kW; 89-97 bhp) at 6,000 rpm
• Torque: 138.3 N?m (102 lb?ft) at 4,500 rpm

src: www.speednik.com

EJ18

Usage:

• Impreza 93-99 GC6 series
• Legacy (except USA) 90-96 BC2, BC3, BD2, BD3, BG3 series
• Isuzu Aska (1990-1993)

Specifications

• Displacement: 
• Bore: 87.9 mm
• Stroke: 75.0 mm
• Compression Ratio: 9.5:1 - 9.7:1
• Valvetrain: SOHC
• Fuel Delivery Carburetor + Distributor (mainly for Latin American and Asian markets) and single point fuel injection

EJ181

• Horsepower: 110 PS (81 kW; 108 bhp) @ 6000 rpm
• Torque: 149.1 N?m (110 lb?ft) @ 3200 rpm

EJ182

• Horsepower: 115 PS (85 kW; 113 bhp) @ 6000 rpm
• Torque: 154.0 N?m (114 lb?ft) @ 4500 rpm

EJ183

• Horsepower: 120 PS (88 kW; 118 bhp) @ 5600 rpm
• Torque: 163.8 N?m (121 lb?ft) @ 3600 rpm

src: upload.wikimedia.org

EJ20

• Bore: 92.0 mm
• Stroke: 75.0 mm

EJ20E SOHC naturally aspirated

• Legacy JDM
  • 1989-1994 125 PS (92 kW) BC - BF series
  • 1993-1999 135 PS (99 kW) BD - BG series( ECU code EURO ,D3 ; Asia 4H)
  • 1998-2004 155 PS (114 kW) BE - BH series( ECU code EURO ,D3 ; Asia 4H)
  • 2003-2009 140 PS (103 kW) BL - BP series

• Europe

• 1991-1999 115 PS (85 kW) BC, BD, BF series

• Impreza JDM
  • 1993-1999 135 PS (99 kW) GC - GF series
  • 2008-current 140 PS (103 kW) GH - GE series

• Europe

• 1994-1999 115 PS (85 kW) GC, GF series

• Isuzu Aska (1990-1993)
  • 1990-1993 125 PS (92 kW)

EJ20D DOHC naturally aspirated

• Legacy JDM
  • 1989-1999 150 PS (110 kW) BC - BF and BD - BG series

EJ202 SOHC naturally aspirated

• Forester JDM SF series, 138 PS (1997 - 2002)

EJ203 SOHC naturally aspirated

• Forester JDM SG series, 140 PS (2003 - 2008)
• Legacy JDM 2.0i BP/BL series, 140 PS (2003 - 2009)

EJ204 DOHC naturally aspirated AVCS

• Legacy B4 TSR JDM BE - BH series
  • 1999-2001 155 PS (114 kW)
• Legacy JDM BL - BP series
  • 2003-2009 190 PS (140 kW)
• Legacy (Europe) BL - BP series
  • 2003-2007 165 PS (121 kW)
• Impreza JDM GC - GF series
  • 1993-1999 155 PS (114 kW)
• Impreza GE - GH series [1]
  • 2007-2011 150 PS (110 kW)
• Forester (Europe) SG Series
  • 2005-2007 155 PS (116 kW)
• Forester JDM SH Series
  • 2008-2011 150 PS (110 kW)
• Exiga JDM YA Series
  • 2008 - 2012 150 PS (110 kW)

EJ20N runs on compressed natural gas

All engines listed below were installed with a turbocharger and an intercooler:

EJ20T

Is not actually a valid code from Subaru, but is mostly used by enthusiasts and mechanics to describe the entire line of turbocharged engines that have been available over time. The practice began with the designation of the USA-spec turbo, commonly referred to as the EJ22T, and the habit of referring to any turbocharged engine as a "T" began. When referring to the EJ20T, one is speaking of one of the following:

EJ20G

EJ20G engines fall into 3 categories:

1. Rocker-style HLA EJ20G usage

• Legacy RS 89-93*Legacy RS-RA 89-93
• Legacy GT 89-93

Power output ranges from 197 bhp (147 kW; 200 PS) @ 6000 rpm and  for the GT to 220 PS (162 kW; 217 bhp) @ 6400 rpm and for the RS versions. Engines can be identified by coil on plug, and with 2 M6 bolts per coil and valve covers with 4CAM 16VALVE and horizontal lines above and below the plug holes. All these engines have the air-to-water intercooler setup (chargecooler) and close deck blocks equipped with piston oil squirters.

2. Bucket-style HLA EJ20G usage

• Impreza WRX 92~96.
• Impreza WRX Wagon 92~96
  • Impreza WRX Wagon AT 96~98
• Subaru Impreza WRX RA 93~96
• EUDM Subaru Impreza Turbo 94~96

This updated type of EJ20G was used in all WRX models since early 1992, cylinder head is equipped with hydraulic lifters compared to the rocker arms used in the previous EJ20G. Pistons in this type of EJ20G are all cast aluminum. Closed-deck engine block equipped with piston oil squirters was used until mid 1994. Followed by Open-deck block equipped with piston oil squirters was used very short period of time, Followed by Open-deck block from 1995 until mid 1996 when the first EJ20K WRX engines came out. The open deck block on all EJ20G could be identified by a smoother surface, and a tab on the right surface of the block halves. The EJ20G continued to be used in the WRX Wagon with an Automatic Transmission from 1996 till 1998 when it was replaced by the EJ205.

3. Shim-under-bucket style EJ20G usage

All EJ20G equipped Impreza WRX STI/STI RA.

Power output ranges from 220 PS @ 6000 rpm and  for the WRX Wagons to 275 PS @ 6500 rpm and for the WRX STI Version II. Engines can be identified by coil on plug with 1 M8 bolt per coil and valve covers with 4CAM 16VALVE and horizontal lines above the plug holes. Generally these engines all have the slanted intercooler. Some engines may not have HLA buckets but solid buckets with shims underneath. These engines also feature lighter valves, the intake valves are marked INKO and the exhaust valves are marked EXKO. The standard HLA valves are I252 and E283 respectively. All WRX Wagon engines and automatic sedan engines came with a TD04 with 90 deg elbow, all manual WRX sedans including STI versions had a TD05 with 90 deg elbow

EJ20K

EJ20K engines fall into 2 categories:

1. Shim-over-bucket style EJ20K usage

• JDM WRX 96~97
• Impreza WRX wagon MT 97~98
• Impreza WRX type RA or R MT 97~98

2. Shim-under-bucket style EJ20K usage

• Impreza WRX sti MT 97~98
• Impreza WRX sti wagon MT 97~98
• Impreza WRX sti type RA or R MT 97~98

Power output is 290 PS @ 6800 RPM for the Japanese versions and 300 PS for the v3 STI with VF23 turbo. These engines can be identified by smooth valve covers, plug leads and a wasted spark coil in the middle of the intake manifold. In addition, the inlet manifold may be bare aluminum for all WRX models and red for all STI models. The engine utilizes an IHI ball-bearing turbo unit. VF22 on the WRX, either a VF23 or VF24 on the STI. These engines have die-cast pistons for all WRX models, STI and STI typeRA/STI type R models shares exactly the same factory forged pistons.

EJ205

This engine series is used for WRX models in the world market outside Japan as of 1999. The Japanese WRX models use the EJ207 from 1999~2001, except the 5-door wagon which also uses the EJ205. After 2001, all WRXs used the EJ205, until 2006 when the USDM WRX model changed engines to the EJ255. The EJ205 has an 8:1-9:1 compression ratio.

To identify an EJ205:

• Coil on plug, except in JDM SF5 forester.
• idle air integrated into throttle body
• inlet under manifold
• open deck block

Usage: Impreza WRX

• 99~01 (JDM Wagon Body only)
• 01~06 (all JDM)
• 02~05 (USDM)
• 04~05 SAAB 9-2X AERO
• 99~06 (all other markets)

Forester Cross Sports, S/tb, STI

• Late 99-01 (9:1 Compression ratio)

NOTE: The Australian Spec MY00 EJ205 does not have coil on plug but can be identified from the VIN of the vehicle (if known) where the 10th digit will be Y (for year 2000) and the 6th Digit will be 8 (for the 2000yr/EJ205)

EJ207

It started its life for the 9/98-8/99 GC8 in Japan, UK, Australia. The EJ207 has an 8.0:1 compression ratio.

To identify a 9/98-9/2000 EJ207 (v5/v6 WRX STI GC8/GF8)

• wasted spark coil pack off center of manifold
• idle air integrated into throttle body
• inlet under manifold
• red or bare aluminum intake manifold
• Open deck block (2001+ are all Semi-closed)
• higher rev limit than ej205
• Version 7 hasAVCS

V7 are single scroll, AVCS, throttle by cable, top-feed injectors, engines. The TGV are deleted from the factory. The factory deletion is incomplete, even on the Spec C and even on the Type RA. The exhaust is compatible all the way to the downpipe to the USDM WRX/Sti. Oxygen sensor is same as USDM EJ205. The oil pan is like the USDM WRX 2.0 The Turbo is the VF30. The ECU has the same number and shape harness plugs as the USDM WRX 2.0. No immobilizer. The engine speed is limited from the factory at 8000 rpm

V8, 9 are twinscroll, AVCS, throttle by cable, topfeed injectors, engines. There are no TGV's, the intake manifold is one piece. The spark plugs are specified one step colder, compared with other Sti. The exhaust is completely different/incompatible with the USDM WRX/Sti, all the way from the header to the downpipe. It can be replaced by a USDM exhaust, the USDM does bolt up to the block. The oil pan is like the USDM Sti. The turbo is a VF37. The ECU has the same number and shape harness plugs as the USDM WRX 2.0 There is no immobilizer for V8 and for some V9. The V9 known so far to not have immobilizer have been early V9 Spec C (revision E engines). The engine speed is limited from the factory at 8000 rpm When compared with the USDM A/C compressor, the JDM Sti is of a different part number and smaller in size. It is possible that the losses while using it are smaller. Many have an additional intake air temperature sensor by the throttle body. Its function has been discussed but not completely clarified. The power steering pump is different. The JDM cars included some Spec C with 13:1 steering rack. The pump remained the same, so it is designed to handle a fast rack. The com protocol is not canbus for any of these. Some of the Sti engines don't come with provision for cruise control. It is next to impossible to tell which had it. The ROM settings are quite different from a V7. The turbo inlet has one less connection in it and most likely is of a larger diameter than the USDM, from the factory. The front Oxygen sensor has been relocated after the turbo, in the downpipe. Different part number 22641AA042. Usage:

• Impreza WRX STi 1998~present (JDM, specifically Homologation models for World Rally Championship)

EJ20X/EJ20Y

Based on the same engine platform; the X designation indicates an automatic package, and the Y designation indicates a manual package. The EJ20X engine was introduced in the 2003 Legacy GT, mated to a five-speed automatic transmission, and the EJ20Y engine was introduced in the 2004 Legacy GT, with a five-speed manual transmission.

The EJ20X and EJ20Y are open deck engines whereby the cylinder walls were supported at the three and nine o'clock positions. It came with an aluminium alloy block with 92.0 mm bores - with cast iron cylinder liners - and a 75.0 mm stroke for a capacity of . with thicker cylinder walls than EJ25 The crankcase for the EJ20X and EJ20Y engines had five main bearings and the flywheel housing was cast with the crankcase for increased rigidity. The EJ20X engine is understood to have a forged crankshaft and connecting rods, but cast aluminium pistons with forged crowns. The EJ20X and EJ20Y engines had an aluminium alloy cylinder head with cross-flow cooling, double overhead camshafts (DOHC) per cylinder bank and four valves per cylinder that were actuated by roller rocker arms.

The EJ20X and EJ20Y engines were equipped with Subaru's 'Dual Active Valve Control System' ('Dual AVCS') which provided variable intake and exhaust valve timing. The Legacy GT, the EJ20X engine was fitted with a twin-scroll IHI VF38 turbocharger; the EJ20Y engine, however, had a larger twin-scroll Mitsubishi TD04 HLA 19T turbocharger. For the revised BL.II Legacy GT, both the EJ20X and EJ20Y had an IHI VF44 turbocharger for the initial 2006 model year, replaced the following year with the IHI VF45.

Both came with a 9.5:1 compression and a fast spooling turbo yields a torque filled performance. (265-280 bhp)

Turbos:

• IHI VF38 (automatic, 03-06)
• Mitsubishi TD04 HLA 19T (manual, 03-06)
• IHI VF44 (manual and automatic, 06MY only)
• IHI VF45 (manual and automatic, 06-09MY)

Usage: EJ20X/EJ20Y

• 03~09 BL and BP Legacy GT

EJ20TT

This may refer to a DOHC Sequential Twin Turbo and intercooled engine (EJ20H/EJ20R/EJ206/EJ208). However, similar to the EJ20T, the term was never used by Subaru. Used from 1994 to 2005 in various iterations listed below. Due to the tight confines of the engine bay, the twin turbo engine was installed in Japanese-spec Legacies only, which were right-hand drive. The Pistons were lighter with a shorter skirt than the WRX EJ20T to allow for higher engine speed.

Specifications

• Displacement: 1,994 cc
• Bore: 92.0 mm
• Stroke: 75.0 mm
• Compression ratio: 8.5:1 - 9.0:1
• Valvetrain: DOHC
• Fuel delivery multi-point sequential fuel injection

EJ20H

Usage:

• 1993-1998 Legacy chassis code BD/BG5 JDM RS, RS-B and GT's (183 kW (249 PS; 245 bhp) manual and automatic) and auto RS-B and GT-B's (190 kW (258 PS; 255 bhp) automatic)

EJ20R

Usage:

• 1996-1998 Legacy chassis code BD/BG5 JDM manual RS-B and GT-Bs (206 kW (280 PS; 276 bhp) Manual)

EJ206

Usage:

• 1998-2003 Legacy chassis code BE5/BH5 JDM GT's, GT-B's and B4's (190 kW (258 PS; 255 bhp)) Transmission: Auto

BH5A - 9.0:1 Compression - "Phase-II", or V5/6 generation.
BH5B - 9.0:1 Compression - "Phase-II", or V5/6 generation.
BH5C - 9.0:1 Compression - "Phase-II", or V5/6 generation.
BH5D - 9.0:1 Compression - "Phase-III", or V7 generation.

EJ208

Usage:

• 1998-2003 Legacy chassis code BE5/BH5 JDM GT's, GT-B's and B4's (206 kW (280 PS; 276 bhp)) Transmission: Manual

BH5A - 8.5:1 Compression - "Phase-II", or V5/6 generation.
BH5B - 8.5:1 Compression - "Phase-II", or V5/6 generation.
BH5C - 9.0:1 Compression - "Phase-II", or V5/6 generation.
BH5D - 9.0:1 Compression - "Phase-III", or V7 generation.

Rev D EJ208's can be considered a totally different motor to the A/B/C's, they run totally different cams, cam pulleys with different timing marks, different crank sprocket with different timing marks, pink  injectors instead of yellow 440's, different intake manifold design. etc.

• A/B have primary VF25 for automatic transmission or VF26 for manual and secondary VF27 turbo's.
• C have primary VF31 and secondary VF32 turbo's.
• D have primary VF33 (46.5 / 9-blade turbine wheel and a  / 6 + 6 blade compressor) and secondary VF32 (exhaust side it uses a 46.5 /  9-blade turbine wheel, teamed with a 52.5 / 10-blade compressor wheel). All secondary turbos are ball bearing and primary turbos are journal bearing.

src: i.ytimg.com

EJ22

Usage:

• Impreza 95-01
• Legacy 90-99, Outback 95-96

Specifications

• Displacement: 
• Bore: 96.9 mm
• Stroke: 75.0 mm
• Compression Ratio: 9.5:1 - 9.7:1
• Valvetrain: SOHC
• Fuel Delivery multi-point fuel injection

EJ221 Naturally Aspirated

• Horsepower: 135 bhp (101 kW; 137 PS) @ 5800 rpm
• Torque: 137 lb?ft (186 N?m) @ 4800 rpm

EJ222 Naturally Aspirated (1999)

• Horsepower: 142 bhp (106 kW; 144 PS) @ 5600 rpm
• Torque: 149 lb?ft (202 N?m) @ 3600 rpm

EJ22 Enhancements and Improvements

Beginning in the 1997 model year, the engine for 1997 Legacy and Impreza models had internal and external changes that yield an approximately 10% increase in power and 3% increase in fuel economy. Accomplishing this involves many factors, one of which is engine friction reduction. The pistons were coated with molybdenum to reduce friction. The thin coating reduces moving friction and reduces cylinder wall scuffing. The piston skirt was reshaped and the piston weight was reduced by approximately 100 grams. Compression ratio was increased to 9.7:1 by reshaping the piston crown. This eliminates the clearance that was available between the piston at TDC and the fully opened valve. Piston pin offset has been changed to (0.020 in). Piston to cylinder wall clearance has been reduced by increasing the piston diameter. Another source of high engine friction is the valve train. Hydraulic lash adjusters (HLAs) are always in contact with the valves. The hydraulic pressure of the lash adjuster must be overcome during operation and during the most critical time of engine start. To overcome this situation and to contribute to the total reduction of friction loss, 1997 and later SOHC engines have solid valve adjusters. The scheduled service of this valve train is set at 100,000 miles (160,000 km). SOHC engines now use an adjustment screw to adjust valve clearance. Engines with the earlier HLA are recommended to use 10W30 or 10W40 oil year-round; 5W30 can be used at very low winter temperatures. The roller rocker cam follower system that was introduced on the  Impreza engines, is installed on all 1996 model year and later engines. The roller assemblies are not serviceable separately, but the rocker arms may be serviced as individual units. The carbon composition head gaskets with integrated o-rings are interchangeable from left to right on 1990 to 1994 NA engines only. Other Engine Modifications ( 1997): The intake manifold has been reshaped to increase the airflow mass and speed, contributing to improved low and mid engine speed operation. Components located on the intake manifold have been relocated as compared to the 1996 models. EGR Solenoid, Purge Control Solenoid, etc. 1999  Phase 2 Engine Enhancements (from endwrench article H-4 and H-6 service): All engine for 1999 are the Phase 2 design. The  Phase 2 engines are a SOHC design, with a newly designed cylinder head. Changes in the Phase 2 engines are as follows:

• the engine and transmission are fastened with six bolts and two studs.
• the thrust bearing has been moved to the number 5 position.
• the oil groove in the number 1 and 3 have been changed to supply additional lubrication to the crank journal.

Additional Phase 2 Engine Features:

• the cylinder head is a two-rocker shaft, solid type valve system with roller followers.
• the valves are positioned at a larger angle than previous model years. The intake valves are positioned 23 degrees off-center with the exhaust valves positioned 20 degrees off-center. Prior model year engines utilized a 15-degree positioning angle.
• head gasket thickness is 0.7 mm (0.03 in).
• the intake rocker arms are marked so they are correctly placed on the rocker shaft when servicing. An IN1 or IN2 will be embossed on each rocker arm. As viewed from the front of the engine the Number 1 intake valve of each cylinder and the number 2 intake valve have an IN1 marked and IN2 marked rocker arm that mates with it. New IN1 rocker arms can also be identified by a Green painted mark on the top of the rocker arm. The IN2 rocker arms have a white mark. Proper positioning is maintained through the use of a wave washer located between the rocker shaft arm and rocker arm shaft support.
• the camshaft is secured to the cylinder head with the camcase. An oil passage in the cylinder head provides the passageway in the camcase with oil that leads to the intake rocker shaft. Oil from the camshaft is collected on the opposite side of the passageway leading to the intake rocker shaft to provide oil to the exhaust rocker shaft.

Note: Cylinder head and camcase must be replaced together (line bored).

• the sparkplug pipe is pressed into the cylinder head and is not serviceable. If it becomes damaged the cylinder head must be replaced. The seals installed onto the ends of the sparkplug pipes seal against the valve covers and should be replaced when the valve cover is removed.
• pistons on the  engines have a 0.5 mm (0.0 in) offset, with the engine having a compression ratio of 10.0 to 1. The horsepower has increased to 142 hp (106 kW) @ 5600 rpm. Maximum torque is 149 lb?ft (202 N?m) @ 3600 rpm.
• camshaft sprockets are constructed of a resin-type material with a metal key pressed into the sprocket for maintaining proper sprocket-to-shaft orientation.

EJ22

135 bhp (101 kW) @ 5800 rpm 140 lb?ft (190 N?m) @ 4800 rpm Australian model - 100 kW (130 hp) @ 6000 rpm 189 N?m (139 ft?lbf) @ 4800 rpm Usage:

• Legacy 89-99 Brighton and L only after 96
• Impreza 93-97-01

EJ22T

Phase one  SOHC Turbo, 163 bhp (122 kW; 165 PS) fully closed deck, oil squirters, no intercooler

• Legacy 1991-1994 (North American-spec). Only several thousand were made with only 600 EJ22T models reaching the United States between 1991-1994. The trim model name for the Turbo Legacy model varied year to year. Approximately half of the models were sedan and half were wagon as well as approximate split between manual and automatic transmission applications.

EJ22G

Phase two closed deck, based on the EJ20K STI engine. Uses identical cylinder heads and turbocharger but with a unique closed deck  crank case. The pistons are factory forged items, the connecting rods are stock. Although being closed deck, the block does not feature oil squirters for piston cooling, opposed to the EJ20 closed deck block and the USDM-only Legacy EJ22T closed deck block.

• Displacement:
• Bore: 96.9 mm
• Stroke: 75.0 mm
• Compression Ratio: 8.0:1
• Valvetrain: DOHC
• Fuel Delivery multi point fuel injection

EJ22G Turbo DOHC

• Horsepower: 280 PS (206 kW; 276 bhp) @ 6000 rpm
• Torque: 362.8 N?m (268 lb?ft) @ 3200 rpm

Usage:

• Impreza STi 22B GC8 series (JDM)

src: jdmracingmotors.com

EJ25

• Displacement: 
• Bore: 99.5 mm
• Stroke: 79.0 mm
• Compression Ratio: 9.5:1 - 10.0:1 Naturally Aspirated
• Compression Ratio: 8.0:1 - 9.5:1 Turbo
• Fuel Delivery EFI

EJ25D

There were two variations of the EJ25D sold in the US market. The engine was introduced in 1996 in the Legacy 2.5GT, LSi, and Legacy Outback. That version of the engine used HLA heads, was recommended to be run on 91 octane fuel, had lower power and torque ratings than the later '97-99 EJ25D, and was only offered with an automatic transmission. In 1997 a revised engine was introduced that used heads with shimmed bucket lifters (versus the HLAs), was designed to run on 87 octane fuel, and was available with either a manual or automatic transmission. Because of the DOHC valve architecture, the spark plugs are more difficult to service in comparison to SOHC variations. The DOHC engines are therefore installed with platinum spark plugs and an extended spark plug service life of 80,000 miles (128,747.5 km). The EJ25D uses smaller rod journals due to the phase 1 EJ25 offset grind crankshaft design, compared to the EJ22 of the same year, and the engines which use a  rod journal. As well, the EJ25D from the 1999 Outback is a one-year only factory hybrid, which uses the phase 2 case halves with an 8 bolt bell housing (as opposed to the 4 bolt bell housing used until 1998), uses a phase 2 crankshaft and rods with rod journals, but retains the same pistons as the 1997-1998 variant to maintain the same compression ratio. The 1996 EJ25D uses different pistons than what was used for 1997-1999, which will increase the compression ratio significantly if combined with 1997-1999 EJ25D heads.

DOHC (1996) - SAE - 155 hp (116 kW) @ 5600 rpm
140 ft?lbf (190 N?m) at 2800 rpm
DOHC (1997-1999) - SAE - 165 hp (123 kW) @ 5600 rpm
162 ft?lbf (220 N?m) at 4000 rpm

Usage

• Impreza 2.5RS 98
• Legacy/Outback 96~99
• Forester 98

EJ251

The EJ251SOHC was the first version of a long line of Single Overhead Cam  engines by Subaru for the US market. The EJ251 was soon replaced by the EJ253 in many models due to its improved cooling to aid in head gasket life and improved engine management and sensors. The EJ251 commonly experienced head gasket failures resulting in interior channel breaches or exterior fluid leaks due to the continued use of a single layer coated gasket first introduced on the EJ25D. Intake volume is calculated by the use of a MAP sensor, unlike the EJ253 which uses a MAF sensor. Compression ratio is 10:1.

Power ISO: 123 kW (165 hp) @ 5600 RPM
226 N?m (167 ft?lbf) @ 4400 rpm

Usage:

• Impreza 2.5RS, 2.5TS 00-03 (US)
• Forester 99-04 (US)
• Legacy 99-01 (US, 4EAT)
• Legacy 99-04 (US)
• Outback 00-01 (US, 4EAT)
• Outback 02-04 (US)
• Baja 03-05 (US)

EJ252

SOHC The EJ252 was only briefly used in North America alongside the EJ251 in the USDM Legacy Outback for the 2000 and 2001 Model Years. They are most commonly found in MY00 Legacy Outbacks manufactured before the end of 1999 while MY00 Legacy Outbacks manufactured in 2000 are rarely designated with EJ252 codes in the VIN. While Subaru has not provided a direct list of revisions between the EJ251 and less common EJ252, there is some degree of information suggesting the EJ252 was simply an alternate version of the EJ251 made to meet California Emissions Standards when the SOHC EJ engines were first introduced in North America. Power output has been reported as ISO 115 kW (156 hp) but is often speculated to share the same specs with the largely identical EJ251. From unofficial analysis, the EJ251 shares the same with block, cams, heads, pistons, connecting rods with the EJ252. The only notable differences confirmed are unique intake manifold and throttle body designs to accommodate the different MAP sensor location and IACV location. Also have different cam and crank sprocket reluctor configuration.

Usage:

• Legacy/Outback 00 - 02 (5MT only)

EJ253

SOHC - 165 hp (121 kW) @ 5600/rpm, 167 ft?lbf (226 N?m) torque @ 4400 rpm. Intake volume is regulated by use of a MAF sensor, unlike the EJ251 which is regulated by a MAP sensor.

I-Active valves (VVL intake side) on 2006 models which have ISO 175 hp (130 kW) @ 5600 rpm, 169 ft?lbf (229 N?m) torque @ 4400 rpm.

PZEV-equipped 2007 and up models have ISO 173 hp (129 kW) @ 5600 rpm, 166 ft?lbf (225 N?m) torque @ 4000 rpm Compression ratio is 10.0:1

• Impreza 2.5RS 99
• Impreza 04-08
• Legacy, Outback (North America) Late 04-12
• Legacy [BL/BP] 03-09 (Europe)
• Legacy [BM/BR] 09-12 (Europe, with 123 kW/167 hp)
• Outback 03-09 (Europe)
• Forester 99 (SF), 05-10 (SG, SH)
• Baja 05+
• Saab 9-2x Linear 05, 06

EJ254

Non Turbo

2005-present - DOHC with 165 hp (123 kW)

Usage:

• Forester 04
• Legacy Lancaster RHD 1999-2003

EJ255

DOHC 16-valve turbo with sodium-filled valves originally designed for North American market, now sees usage in some European Imprezas and Legacies destined for Australia and South Africa. Power 210-265 hp

EJ255 Version 1: Used in the 2005 and 2006 Legacy, as well as the 2004 and 2005 Forester. This engine uses the same shortblock and heads like EJ257 in US 04-06 STI.

EJ255 Version 2: Used in the 2006-2008 WRX, the 2007+ Legacy, and the 2006+ Forester. This is the newer AIS equipped EJ255, which uses a slightly different AB630 shortblock, as well as the AB820 heads. The only difference in the shortblock of this EJ255 and the 04-06 EJ257 is the pistons. They are of nearly the same construction, but have a slightly larger dish volume. Subaru lists the CR at 8.4:1 vs 8.2:1 for the 04-06 STI engine.

Usage in North America:

• Impreza (WRX): 2006-2014
• Forester XT: 2004-2013
• Legacy GT: 2005, 2007-2012
• Outback XT: 2005, 2007-2009
• Baja XT: 2004 - 2006
• SAAB 9-2X: 2006 only

Usage in the rest of the world:

• Legacy/Outback: 2007-present
• Impreza: 2005-present
• Forester: 2005-2010

EJ257

DOHC 16-valve turbo. Originally designed for the North American Impreza STI in 2004 with AVCS and DBW. 2004-2006 STI model used the same shortblock, b25 heads, and valve train as EJ257 in MY2005-2006 Legacy GT and the same block as the 2004-2005 Forester XT. Later years used a revised block, piston and heads. Notably, Dual-AVCS w25 heads appeared in 2008 STI.

Usage:

• US Market Impreza WRX STi MY04~MY07 (300 hp, 293 hp (New SAE standard))
• US Market Impreza WRX STI MY08~MY17 (305 hp (New SAE standard))
• US Market Legacy GT/Ouback XT MY05~06 (250 hp, 250 hp (New SAE standard))
• Asian, European Market Impreza WRX STi 05~present (280 hp, 40 kg/m)

EJ259

Usage: Late 2004 Legacy GT (California Emissions)

src: i.ytimg.com

Other Data

All the EJ series share compatibility and construction similarity and are 16 valved engines. The EJ series started with the EJ15, a  (SOHC) and makes ~90 hp, then the EJ16, a single overhead cam (SOHC). Later followed by the EJ20, a 120 hp  single overhead cam and the EJ22, a 135 hp single overhead cam. The EJ20 turbocharged version was developed with dual overhead cams, as well as non-turbo DOHC engines and DOHC twin-turbos. The EJ18 and EJ20 were most popular in Europe.

The SOHC EJ Subaru boxer engines were non-interference engines through 1995, run by a single timing belt driving both cams (both sides of the engine) and the water pump. Because they are non-interference engines, if the timing belt fails, the engine of the models up to 1995 will not be damaged. The oil pump is driven directly from the crank shaft and the waterpump by the timing belt. All DOHC and 1998-up SOHC EJ engines are interference engines, if the timing belt fails the valves will likely be damaged.

All Subaru EJ engines have a 1-3-2-4 firing order, which, given the longer exhaust runners on cylinders 2 and 4 causes the characteristic "subaru engine sound".

Some of the 2005 and later Subaru vehicle Engines (especially the turbo charged engines) are using CAN bus as their sole Vehicle/Vessel speed input channel. When those ABS Speed signal are removed, the ECU will force the Engine to run in limp home mode. This has posed some challenge for people who try to use the same automotive boxer  and engines on Aerospace application, engine replacement for aged Subaru vehicles, and VW Vanagon modifications, etc.

The following table has details on a few of the commonly modified Subaru engines:

All Spec C are Japanese only  EJ207.

src: www.sunrisejapanese.com

Awards

Subaru Turbo Boxer engine won 'best engine' in the 2.0 to 2.5 litre category in both the 2006 and 2008 International Engine of the Year awards. It also won a place on the list of Ward's 10 Best Engines in 2004 and 2010.

src: i.ytimg.com

Notes

src: sc01.alicdn.com

References

• Subaru Engine Specs and Designations
• http://www.fhi.co.jp/envi/info/pdf/leg_02_08.pdf

Source of the article : Wikipedia