EJ, FA, FB and EZ identify Subaru engine families. Codes such as EJ255 or FA20 narrow the identification, but they do not establish one specification across every year, model and market.
Use the vehicle’s factory records and complete engine type wherever available. For a used or modified engine, verify the actual assembly as well.
This hub covers selected North American engines and separately labeled Japanese performance examples. It is a lookup reference, not a tuning or swap recipe.
Subaru engine families at a glance
| Family | Displacement covered here | Configuration / familiar applications |
|---|---|---|
| EJ | 2.0, 2.2, 2.5 L | Boxer four; NA and turbo. Impreza, WRX, STI, Legacy, Outback, Forester, Baja. |
| EZ | 3.0, 3.6 L | Boxer six; NA. Legacy / Outback six-cylinder models. |
| FA | 2.0, 2.4 L | Boxer four; NA BRZ and turbo WRX configurations. |
| FB | 2.0, 2.5 L | Boxer four; NA Impreza / Forester examples. |
NA = naturally aspirated. DOHC / SOHC = double / single overhead camshaft. AVCS = Subaru’s variable cam timing system; dual AVCS controls intake and exhaust timing. Fuel injection and valve-control equipment must be checked by application.
Quick reference: how to read the tables
The family tables below are the quick reference. Each row identifies a checked factory application, not an entire production range. Years are US model years unless explicitly labeled JDM. Bore × stroke is in millimeters; compression ratios are stock specifications.
EJ family
EJ20, EJ22 and EJ25 are displacement groups within the EJ family. The selected examples show why the variant, heads, fuel system and donor application matter more than an advertised “EJ engine.”
EJ20: US example
| Engine / checked application | Size; bore × stroke | Configuration; compression |
|---|---|---|
| EJ205 — 2002 WRX | 1,994 cc; 92 × 75 | Turbo DOHC; 8.0:1 |
Factory identification and numbers: 2002 Subaru owner manual, 12-3. This EJ205 example is not a specification for every EJ20 turbo.
EJ20 / EJ207: selected JDM examples
| Checked Japanese application | Size; bore × stroke | Configuration; compression |
|---|---|---|
| STI Type RA Spec C — December 2001 catalog | 1,994 cc; 92 × 75 | Turbo DOHC; 8.0:1 |
Subaru’s Japanese Spec C catalog identifies this engine broadly as EJ20. The more specific EJ207 designation and AVCS-equipped GDB A/B/C applications are documented in HKS’s application instructions, p. 1.
Later Japanese STI documentation, such as the 2013 brochure, specification panel, specifies a 2.0-liter dual-AVCS, twin-scroll turbo engine for the STI 6MT. Its 2.5-liter A-Line automatic is a separate application.
Do not transfer those later features to every EJ207. Identify the donor’s applied model/revision, heads, cam-control equipment and turbo/exhaust arrangement. Japanese catalog launch dates are not US model-year designations.
EJ22
| Checked application | Size; bore × stroke | Configuration; compression |
|---|---|---|
| EJ22 family — 2000 Impreza 2.2 | 2,212 cc; 96.9 × 75 | NA SOHC; 10.0:1 |
The 2000 US factory manual, engine specifications supports this example. Earlier EJ22s should not inherit its compression specification automatically.
The EJ22T is the historical 2,212 cc turbo Legacy application listed for 1991–1994 in MAHLE’s North American engine-parts catalog. Its detailed factory compression and revision specifications remain pending verification here; the NA row above does not apply to it.
EJ25: separate NA and turbo variants
All examples in this table are 2,457 cc, 99.5 × 79 mm. Shared displacement and bore/stroke do not establish interchangeable parts.
| Engine | Checked US application | Configuration; compression |
|---|---|---|
| EJ251 | 2002 Impreza 2.5RS | NA SOHC; 10.0:1 |
| EJ253 | 2005 Legacy 2.5i | NA SOHC; 10.0:1 |
| EJ255 | 2004 Forester XT | Turbo DOHC; 8.2:1 |
| EJ255 | 2005 Legacy GT | Turbo DOHC; 8.2:1 |
| EJ255 | 2012 Legacy GT | Turbo DOHC; 9.5:1 |
| EJ257 | 2015 STI | Turbo DOHC; 8.2:1 |
Factory checks: 2002 owner specifications, 2004 Forester SPC-2, 2005 Legacy SPC-2, 2012 Legacy SPC-2, 2015 STI SPC-8.
The two Legacy GT rows demonstrate a real EJ255 application/year difference. EJ255 and EJ257 are not interchangeable labels for one universal turbo short block or complete engine. EJ251 and EJ253 likewise require application-specific heads, controls, emissions equipment and parts verification.
AVCS equipment must be confirmed for the actual turbo EJ revision. For example, Subaru documents dual AVCS on the 2015 North American STI; that does not establish the same system on every earlier EJ257 or EJ255.
EZ family: six-cylinder engines
| Engine / checked US application | Size; bore × stroke | Configuration; compression |
|---|---|---|
| EZ30 — 2005 Outback 3.0R | 3,000 cc as printed; 89.2 × 80 | NA DOHC six; 10.7:1 |
| EZ36 — 2012 Legacy / Outback 3.6R | 3,630 cc; 92 × 91 | NA DOHC six; 10.5:1 |
Factory checks: 2005 Outback SPC-10, 2012 Legacy SPC-2.
EZ30 publication difference: the checked US manual prints 3,000 cc; Subaru’s May 2001 Japanese Lancaster 6 catalog prints 2,999 cc with the same bore/stroke. These are retained as source-specific figures rather than one universal value.
EZ30 revisions also require attention to heads and valve controls. Subaru documents variable valve timing and variable lift for its 2003 Japanese Legacy / Outback 3.0-liter introduction, product-data section. Confirm the exact donor revision before selecting heads, wiring or engine-management parts; “EZ30” alone is insufficient.
FA family: BRZ NA versus WRX turbo
| Engine / checked US application | Size; bore × stroke | Configuration; compression |
|---|---|---|
| FA20 — 2013 BRZ | 2.0 L; 86 × 86 | NA DOHC; 12.5:1 |
| FA20DIT — 2015 WRX | 1,998 cc; 86 × 86 | Turbo DOHC; 10.6:1 |
| FA24 — 2022 BRZ | 2,387 cc; 94 × 86 | NA DOHC; 12.5:1 |
| FA24 turbo — 2022 WRX | 2,387 cc; 94 × 86 | Turbo DOHC; 10.6:1 |
The BRZ examples use direct and port injection. The WRX examples use direct injection turbo configurations. Dual AVCS is documented for these checked applications. “DIT” describes direct injection turbo; it is not proof that two complete engines share parts or controls.
Sources: 2013 BRZ Subaru brochure, specification panel, BRZ factory mechanical manual, FA20 identification, 2015 WRX SPC-2, 2022 BRZ official specifications, 2022 BRZ owner specifications, pp. 380–381, 2022 WRX factory specifications, PDF p. 4.
BRZ and WRX FA20s are different factory configurations. The same caution applies to NA and turbo FA24s, even where displacement and bore/stroke agree.
FB family: generation matters
| Engine / checked US application | Size; bore × stroke | Configuration; compression |
|---|---|---|
| FB20 — 2012 Impreza | 1,995 cc; 84 × 90 | NA DOHC; 10.5:1 |
| FB20 — 2017 Impreza | 1,995 cc; 84 × 90 | NA DOHC; 12.5:1 |
| FB25 — 2014 Forester 2.5i | 2,498 cc; 94 × 90 | NA DOHC; 10.0:1 |
| FB25 — 2019 Forester | 2,498 cc; 94 × 90 | NA DOHC; 12.0:1 |
The earlier examples use manifold/port fuel injection; the later examples use direct injection. The compression change is application-specific, not a rule for every FB20 or FB25.
Factory checks: 2012 Impreza SPC-2 / ID-5, 2017 Impreza owner specifications, 12-3, 2014 Forester SPC-2 / ID-5, 2019 Forester official specifications. The 2019 FB25 designation is cross-checked against Subaru bulletin 02-187-21, p. 3.
What engine is in my Subaru?
- Record the vehicle’s year, model, trim and market. “WRX engine” is not enough.
- Check the VIN against the applicable factory identification section or Subaru parts/service records. This establishes original vehicle information, not proof of a later engine swap.
- Record the applied-model and complete engine-type information from the factory plate/label where fitted. A type such as EJ257AG9LB carries more detail than EJ25. Decode it using that model’s documentation.
- Inspect the engine-type casting and serial stamping using the applicable manual’s location diagram. The serial number and crankcase-half numbers are not interchangeable with the full engine type.
- Cross-check the emissions label and donor paperwork. Confirm heads, fuel injection, cam controls and relevant part numbers where records disagree.
The 2014 Forester identification section, ID-3 onward distinguishes engine-type casting, serial punch mark and model-label information. Subaru’s serial-location guide, p. 2 also identifies the remanufactured short-block tag. Locations and labeling vary; visual resemblance alone is not reliable identification.
Engine code versus actual build configuration
A factory engine code does not prove the current internals of a used or modified engine.
A replacement short block, different heads, pistons or crankshaft, hybrid assembly, built internals, or swapped intake/turbo components may change the actual configuration. Request invoices, part numbers and assembly records; inspect when necessary.
Internals: identify the component
Avoid “forged internals: yes/no.” Verify the crankshaft, connecting rods, pistons, block, heads and valvetrain separately against authoritative documentation for that exact assembly.
This hub makes no blanket claim that STI engines are fully forged, every EJ257/EJ207 is identical, or a family code proves a particular deck design or strength limit.
Commonly confused engines
| Comparison | What to verify |
|---|---|
| EJ255 / EJ257 | Donor year/model, compression, heads, cam controls and assembly part numbers. |
| EJ205 / EJ207 | US WRX versus the documented JDM STI variant; applied-model revision and AVCS hardware. |
| FA20 NA / FA20DIT | BRZ direct-plus-port versus WRX direct-injection turbo configuration. |
| FA24 NA / turbo | BRZ versus WRX fuel/turbo system and compression; equal bore/stroke does not establish interchangeability. |
| EJ251 / EJ253 | Both checked examples are NA SOHC; donor-specific heads, controls, emissions equipment and parts still matter. |
Model-to-engine lookup: checked US examples
These are starting points backed by the sources above, not complete production ranges or proof of the engine currently installed.
| Model / checked year | Original application |
|---|---|
| Impreza 2000 / 2002 / 2012 / 2017 | 2000 2.2: EJ22 family; 2002 2.5RS: EJ251; 2012/2017 2.0: FB20. |
| WRX 2002 / 2015 / 2022 | EJ205 / FA20DIT / FA24 turbo, respectively. |
| STI 2015 | EJ257. Japanese STI examples are listed separately above. |
| Legacy 2005 / 2012 | 2005 2.5i: EJ253; GT in both checked years: EJ255; 2012 3.6R: EZ36. |
| Outback 2005 / 2012 | 2005 3.0R: EZ30; 2012 3.6R: EZ36. These do not cover the four-cylinder trims. |
| Forester 2004 / 2014 / 2019 | 2004 XT: EJ255; 2014 2.5i and 2019: FB25. |
| BRZ 2013 / 2022 | FA20 NA / FA24 NA. |
| Baja 2004 | EJ25 family: 2.5 SOHC NA or 2.5 DOHC turbo. Exact variant suffix still requires verification here. |
The 2004 Baja factory specification sheet verifies those two configurations. The precise Baja suffix is intentionally not inferred from a different model’s identification page.
Related future guides
Detailed references will be linked here when published:
- Subaru EJ20 Engine Guide
- Subaru EJ25 Engine Guide
- Subaru FA20 & FA24 Engine Guide
- Subaru Engine Swap Compatibility Guide
- Subaru Short Block & Cylinder Head Compatibility Guide
- Subaru Turbo Guide
Sources and verification limits
Primary research uses Subaru factory service/owner manuals from the Subaru factory-manual archive, Subaru official specifications and Japanese catalogs. Individual documents are linked beside the relevant tables. Mirrored Subaru publications remain factory-authored documents; HKS and MAHLE are used only for the specific application-identification gaps stated above.
Pending detail includes EJ22T factory compression/revision data, exact Baja variant suffixes, exhaustive EJ207 revisions and application-specific internal construction. No missing specification should be filled by borrowing a value from another market, year or engine with a similar code.