- EJ15:1.5 Litre SOHC
Usage:
Impreza (JDM only, though often seen in gray market exports to eastern Europe and Russia.) - EJ16:1.6 Litre SOHC, 90 hp @ 5600 rpm.
Usage:
Impreza 93-94 (JDM only)
Impreza 93-06 (Europe & Middle East) - EJ18:1.8 Litre SOHC 110 hp @ 5600 rpm.
Usage:
Impreza 93-96
Legacy (non-USDM) 90-96 - EJ20:2.0 Litre SOHC or DOHC
- EJ20T
This is not actually a valid code from Subaru, but is mostly used by enthusiasts (and can be seen in such context on webforums such as NASIOC)& also mechanics to describe the entire line of 2.0 litre turbocharged engines that have been available over time. When referring to the EJ20T, one is speaking of one of the following: - EJ20G
EJ20G fall in to 2 categories -early engines 1989-9/1996 -late wagon and automatic sedans from 9/1996 and later
to identify an early EJ20G
Coil on plug
Divorced idle air controller
Upturned inlet in turbo
Air to water or slated intercooler
Late model EJ20Gs are the same general design as the EJ20K
Usage:
Legacy RS 89-93
Legacy RS-RA 89-93
Legacy GT 89-93
Impreza WRX 92~96
Impreza WRX Wagon 92~98
Impreza WRX STi 94~96 - EJ20K
to identify an EJ20K
Wasted spark coil pack on center of manifold
Inlet under manifold
Divorced idle air controller
Usage:
Impreza WRX & STi 9/96~9/98 - EJ205
This engine series is used for non-Japanese marketed WRX models in the world market 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 use the EJ205. to identify an EJ205:
Coil on plug
idle air integrated into throttle body
Usage: Impreza WRX 99~current - EJ207
to identify an 9/99-9/2000 EJ207
Wasted spark coil pack off center of manifold
Inlet under manifold
Red manifold
Usage:
Impreza WRX STi 9/98~00 (JDM, specifically Homologation models for World_Rally_Championship) - EJ20TT
This can refer to one of the 2.0 Litre DOHC Sequential Twin Turbo and intercooled engines (EJ20H/EJ20R), used in specialty Legacy's. Yet like EJ20T, it is not actually a valid code used by Subaru themselves.
Usage:
Legacy GT & B4 (JDM) - EJ20H
Usage:
Legacy BD/BG5 JDM GT's (183 kW manual & auto) and GTB's (190 kW auto) - EJ20R
Usage:
Legacy BD/BG5 JDM RSB and GTB's (205 kW Manual)
B4 Legacy 280bhp - EJ22:2.2 Litre SOHC
Subaru EJ22
Usage:
Impreza 95-01
Legacy 90-99 
EJ22E
2.2 litre:135 bhp @ 5800 rpm 140 ft·lbf @ 4800 rpm
Australian model - 100kW @ 6000 rpm 189Nm @ 4800 rpm
Usage:
Legacy 89-96
Liberty 89-96- EJ22T
2.2 Litre SOHC Turbo, no intercooler
Also known affectionately by enthusiasts as Subaru's bulletproof engine.
Legacy 89-94 (USDM only from 1991) - EJ22K
Usage:
Impreza WRX STi 22B (JDM) - EJ25:2.5 Litre,EJ251
The EJ251 is a 2.5 L (2457 cc) Horizontally Opposed SOHC Engine with a bore of 99.5 mm and a stroke of 79.0 mm. Compression ration is 10.0: 1. Firing order is 1 - 3 - 2 - 4.
121kW and 226Nm
Usage:
Impreza RS 00-05 (US)
Impreza Outback 00-05 (US)
Forester 00-05
Outback 00-05 (US) - EJ252
SOHC
Usage:
Legacy 00 - EJ253
SOHC - 165 HP @ 5600 RPM RPM, 166 .lb-ft torque @ 4000 RPM
Impreza 99/05+
Legacy 00+
Forester 99/05+
Baja 05+ - EJ25D
DOHC - 125kW @ 6000 RPM 238Nm at 2800
Usage
Impreza 98
Legacy 96~99
Forester 98~99 - EJ25E
SOHC 16 valve
Usage:
Impreza RS 99~01
Forester 99~00
Legacy 00~01 - EJ255
2.5 litre DOHC AVCS turbocharged, 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.
Usage in North America:
Impreza: 2006 - present
Forester: 2004 - present
Legacy: 2005 - present
Baja: 2004 - 2006
Usage in the rest of the world:
Legacy: 2005 - present
Impreza: 2006 - present - EJ257
DOHC 16 valve turbo
Usage:
US Market Impreza WRX STi MY04~present (300 hp)
Asian, European Market Impreza WRX STi 05~present (280 hp, 40KGh/m)
An unexpected contract with Subaru, the automobile branch of Fuji Heavy Industries, brought substantial monetary backing and additionally an exclusive "works" engine for free. The Japanese took over 51% of Coloni formula, paid the debts and supported the new alliance with a brand new, unique engine. It was a flat-12 engine which in fact was penned by Carlo Chiti. Chiti's Motori Moderni company at Novara had supplied V6 Turbo engines for the Minardi Formula One team from 1985 to 1987, and in 1988 Chiti had penned a normally aspirated V12 engine that attracted Subaru. In late 1988, the Japanese commissioned Chiti to design a new Formula One engine with a "flat" layout - as used in their road cars - that was ready in the Summer of 1989. The engine - now with a Subaru badge - was tested in a Minardi M188 chassis but due to a severe lack of power Minardi very soon lost interest. After a few months of searching, Subaru found the Coloni team. Eventually, the "Subaru Coloni" Team was founded with Enzo Coloni staying on board as the man for operational business.
By the beginning of 1990, the "Subaru" flat engine was not producing more than 500 bhp, so the Coloni Subaru was by far the least competitive machine regularly competing in Formula One in 1990. Subaru and Chiti agreed to build a new V12 engine for Summer 1990 together with a completely new chassis, but in the meantime the flat engine should be used by the "Coloni Subaru" Team in a carry-over chassis. Early in 1990, a handful of Enzo Coloni's mechanics worked on a single C3 and tried to put the Subaru engine in it. The work was not done until the day the FIA started shipping the Formula One material to Phoenix. In the pits at Phoenix, the car was assembled for the very first time, and a short private "practice" took place on a parking area of an American supermarket. On prequalification day of Phoenix the world saw Coloni's "new" model C3B which wore a white, red and green livery. Without an airbox but with wide, long sidepods, it looked like a tank, was overweight by 300 pounds and nearly impossible to handle. Neither at Phoenix nor at any other event, did Bertrand Gachot, Coloni's new driver, manage to prequalify the car. As the season went on, improvements were few and results stayed nowhere. Meanwhile, no success could be seen at Coloni's plant in Perugia where obviously nobody worked seriously on a new car. In May, Enzo Coloni was sacked by Subaru, but no improvement came. In June, the Japanese company withdrew completely and sold the team back to Enzo Coloni, debt free, but with no sponsors and no engines. By the German Grand Prix Coloni had arranged a supply of Cosworth engines, prepared by Langford & Peck. An improved car also appeared in Germany. The "new" Coloni C3C was simply a 1989 C3 with minor changes in aerodynamics. The car was quicker, but not enough to achieve any serious results. Gachot was usually able to prequalify his car, but the "main" qualification was still out of reach. By the end of the season, Coloni had not taken part in a single Grand Prix.Subaru 2.5-liter Turbo Boxer Engine won 'best engine' in the 2.0-2.5 litre category in the 2006 International Engine of the Year awards.
