Subaru’s EJ, FA, and FB engines share many similarities across models and years, which makes certain swaps straightforward, while others require wiring, ECU, and transmission modifications.
This guide breaks down Subaru engine swap compatibility, offers a complete swap chart, and explains what you need to know before starting your project.
Subaru Engine Swap Compatibility Chart
Subaru EJ-Series Engine Swap
| Engine | Direct Swap Into | Requires Wiring/ECU Mods | Notes |
|---|---|---|---|
| EJ18 | 1993–1996 Impreza | Into 1997–2001 Impreza | Lowest output EJ engine—commonly replaced with EJ22 |
| EJ20 NA (Phase 1) | 1990–1998 Legacy/Impreza | Into 1999–2005 models | Phase 1 intake may need adapting |
| EJ201/202/203 (NA) | 1999–2001 Impreza (EU/JDM) | Into 2002–2005 Impreza | Great budget replacements for EJ25 |
| EJ204 (AVCS NA) | 2000–2007 Legacy/Impreza | Into USDM NA cars (AVCS wiring needed) | Higher compression, better throttle response |
| EJ205 (WRX Turbo) | 2002–2005 WRX | Into 2006–2007 WRX | Swap ECU + immobilizer needed for 06–07 |
| EJ207 (STI Turbo) | 1999–2007 WRX/STI | Into 2008–2014 WRX/STI | AVCS + wiring complexity for later years |
| EJ22 (NA Phase 1) | 1995–1998 Legacy/Impreza | Into 1999–2001 models | Legendary reliability, simple swap |
| EJ22 (Phase 2) | 1999–2001 Legacy/Impreza | Into Phase 1 cars | Intake manifold swap required |
| EJ22T (Turbo) | 1991–1994 Legacy Turbo | Into GC8 Impreza | Closed-deck block perfect for big builds |
| EJ25D (DOHC) | 1996–1999 Legacy/Outback | Into 1999–2004 EJ25 vehicles | Known for head gasket problems—often replaced |
| EJ251 (SOHC) | 1999–2004 Legacy/Forester/Impreza | Into all EJ25 SOHC models | Very common swap base |
| EJ253 (SOHC) | 2005–2012 Legacy/Forester/Impreza | Into EJ251 cars | VVT wiring may differ |
| EJ254 (AVCS NA) | 2006–2009 Legacy (EU/JDM) | Into EJ253 vehicles | Provides AVCS improvements |
| EJ255 (WRX/FXT Turbo) | 2004–2021 WRX/Forester XT | Into 2002–2005 WRX | Needs ECU, intercooler, wiring |
| EJ257 (STI Turbo) | 2004–2021 STI | Into 2004–2014 WRX | Strong block but needs AVCS compatibility |
| EJ30/EG33 (SVX Flat-6) | SVX platform | Into GC8, GD chassis | Heavy custom fabrication |
| EZ30/EZ36 Flat-6 | H6 Outback/Legacy | Into Impreza/WRX chassis | Requires subframe + wiring + radiator mods |
Related Subaru Engine Oil Capacity Chart(For All Models)
Subaru FB-Series Engine Swap
| Engine | Direct Swap Into | Requires Wiring/ECU Mods | Notes |
|---|---|---|---|
| FB16 | 2012–2018 Japanese Impreza | Into FB20 chassis | JDM-only engine; economical |
| FB20 | 2011–2018 Impreza/Crosstrek | Into 2019+ models | Most common FB replacement |
| FB20D (Direct Injection) | 2015–2018 Legacy/Impreza (select markets) | Into FB20 port-injection cars | DI harness complications |
| FB25 (Early) | 2011–2014 Outback/Legacy | Into FB25 (Late) 2015–2019 | Known oil consumption issues |
| FB25 (Updated) | 2015–2019 Outback/Legacy/Forester | Into FB20 cars | Popular displacement upgrade |
| FB25 (Gen 3) | 2020+ Outback/Legacy | Into older FB25 | Not plug & play—CANBUS complexity |
Subaru FA-Series Engine Swap
| Engine | Direct Swap Into | Requires Wiring/ECU Mods | Notes |
|---|---|---|---|
| FA20 NA (BRZ/86) | 2013–2020 BRZ/86 | Into FA20DIT WRX | Very different compression and wiring |
| FA20DIT (Turbo) | 2015–2021 WRX | Into BRZ/86 | Complex swap; not recommended |
| FA24 NA (BRZ 2022+) | 2022+ BRZ/GR86 | Into FA20 BRZ/86 | Needs full ECU and sensor integration |
| FA24DIT (Turbo) | 2020+ Outback XT, Ascent, 2022+ WRX | Into FA20DIT WRX | Enthusiast upgrade but wiring-intensive |
Related Subaru Engine Oil Filter(Top 5 BEST 2025)
Subaru Diesel EE20 Swap
| EE20 (Boxer Diesel) | Direct Swap Into | Notes |
|---|---|---|
| EE20 (2008–2020) | EU/AU diesel Outback, Forester | Rare swap, requires diesel ECU; not allowed in many regions |
Subaru Hybrid Engine Swaps
Hybrid engines use high-voltage systems and are NOT recommended for swaps.
| Engine | Swap Feasibility | Notes |
|---|---|---|
| FB20 + Hybrid Motor | Not recommended | High-voltage safety, battery integration issues |
Impreza Chassis Compatibility
| Chassis | Direct Engine Fits | With Mods | Notes |
|---|---|---|---|
| GC8 (1993–2001) | EJ18, EJ20, EJ22, EJ205 | EJ207, EJ257, EJ30 | Most swap-friendly Subaru platform |
| GD/GG (2002–2007) | EJ205, EJ207, EJ251/253 | EJ255/EJ257 | May need immobilizer matching |
| GR/GV (2008–2014) | EJ255/EJ257 | EJ207 (heavy wiring) | CANBUS complications |
| VA WRX (2015–2021) | FA20DIT | FA24DIT | FA-series only |
| VB WRX (2022+) | FA24DIT | None yet known | Too new for cross-family swaps |
Related 2014 Subaru Forester Oil Type(+Top 5 Best Oil 2025)
Legacy/Outback Chassis Compatibility
| Chassis | Direct Engine Fits | With Mods | Notes |
|---|---|---|---|
| BD/BG (1995–1999) | EJ22, EJ25D | EJ20, EJ30 | Classic EJ swap platform |
| BE/BH (2000–2004) | EJ251, EJ253 | EJ255, EJ257 | Turbo swap possible with exhaust + ECU |
| BL/BP (2005–2009) | EJ253, EJ255 | EJ257 | AVCS wiring differences |
| BM/BR (2010–2014) | FB25 | EZ36, EJ swaps not recommended | Newer electronics |
| BS/BT (2015–2019) | FB25 | FA24 (major work) | Good NA platform |
| BT (2020+) | FB25 Gen 3 | None | CANBUS-heavy |
Forester Chassis Compatibility
| Chassis | Direct Engines | With Mods | Notes |
|---|---|---|---|
| SF (1997–2002) | EJ20, EJ22, EJ25 | EJ205, EJ207 | Very swap friendly |
| SG (2003–2008) | EJ253, EJ255 | EJ257 | WRX/STI swaps popular |
| SH (2009–2013) | EJ253, EJ255 | EJ257 | AVCS wiring |
| SJ (2014–2018) | FB25 | FA20DIT | Requires turbo drivetrain |
| SK (2019–2024) | FB25 | FA24DIT | Not common but possible |
Related Subaru Ascent Engine Oil Capacity(+Best Recommended Oils)
Popular Subaru Engine Swaps Explained
1. EJ25 to EJ22 Swap (Most Common Reliability Swap)
If your EJ25 has head gasket issues, the EJ22 is a legendary replacement. These engines are nearly bulletproof and bolt directly into most EJ25-era Subarus with minimal wiring changes.
2. JDM EJ20 Swap into EJ25 USDM Cars (Cost-Effective Swap)
JDM EJ20 engines are cheap, available, and compatible with many EJ25 cars if you reuse:
- Intake manifold
- Wiring harness
- Sensors
This is one of the most budget-friendly Subaru swaps.
3. EJ205 or EJ207 into Older Imprezas (Performance Upgrade)
WRX and STI turbo engines fit into older GC8 and GD chassis with:
- Turbo ECU
- Boost control solenoids
- Intercooler plumbing
The EJ207 is preferred for its higher rev limit and better internals.
4. FA20DIT into Older WRX (Challenging Swap)
This is rarely done due to:
- Direct injection
- CANBUS electronics
- Different transmissions
It is possible, but usually not cost-effective.
5. FA24 into WRX or Ascent (Modern Upgrade)
The FA24 is Subaru’s most advanced engine, offering strong torque and reliability. However, wiring and ECU complexity make it suitable only for advanced builders.
Related Honda Engine Swap Chart(For All Models)
Engine Swap Compatibility by Chassis
GC8 (1993–2001 Impreza)
Compatible with:
- EJ18
- EJ20
- EJ22
- EJ205
- EJ207
This is one of the easiest swap platforms in Subaru history.
GD/GG (2002–2007 Impreza/WRX)
Compatible with:
- EJ205
- EJ255
- EJ257
- JDM EJ207
Some swaps require ECU reflashing.
GR/GV (2008–2014 WRX/STI)
Compatible with:
- EJ257
- JDM EJ207 (with major wiring)
- EJ255
VA (2015–2021 WRX/STI)
- WRX uses FA20DIT
- STI uses EJ257
- These are not cross-compatible without major wiring and drivetrain changes.
Subaru BRZ/86 Platform
Compatible only with FA20 NA unless undergoing heavy modification.
Related Dodge Charger Engine Swap Compatibility Chart(All Generations)
What to Consider Before a Subaru Engine Swap
1. Wiring Harness Matching
Subaru swaps fail most often due to wiring mismatches. Always verify:
- Sensor compatibility
- Cam/crank trigger patterns
- ECU pinouts
2. Transmission Compatibility
Most EJ engines bolt to most Subaru transmissions, except:
- EZ30/EZ36 six-cylinder
- FA series requires a matching bellhousing
3. Emissions Requirements
Some regions require:
- Same year or newer engine
- Full emissions systems
4. Turbo vs. Non-Turbo Differences
Turbo engines require:
- Stronger fuel pumps
- Intercooling
- Turbo ECU
- Boost control systems
Why Subaru Engines Are Popular for Swaps
Subaru’s boxer engines sit low in the chassis, improve handling, and offer impressive reliability, especially the naturally aspirated EJ series and the turbocharged EJ20/EJ25 variants. Many Subaru enthusiasts also love the modular nature of these engines. Most EJ-series engines share:
- Similar block architecture
- Interchangeable components
- Cross-compatibility with transmissions
- A wide range of aftermarket support
However, newer engines like the FA20/24 and FB20/25 use completely different electronics and mechanical layouts. That means compatibility depends heavily on the generation and engine family.
FAQs
Which Subarus have the same engine?
Many Subarus share engines within the same generation and engine family. For example, the EJ251/EJ253 is shared across the 1999–2012 Impreza, Forester, Legacy, and Outback. The EJ255/EJ257 turbo family is shared across 2004–2021 WRX and STI models.
Newer models like the Outback, Legacy, and Forester from 2011–2019 share the FB25, while the 2015–2021 WRX and 2020+ Outback XT/Ascent share FA-series turbo engines. Subaru tends to use one engine type across multiple models for many years, making swaps common and parts widely compatible.
What years are EJ25 interchangeable?
The EJ25 is interchangeable across many Subarus from 1996 through 2012, but compatibility is split into phases:
- 1996–1999 EJ25D (DOHC) – interchangeable within the same years.
- 1999–2004 EJ251/EJ252 (SOHC Phase 2) – interchangeable with minor sensor/intake swaps.
- 2005–2012 EJ253 (SOHC VVT) – interchangeable mostly within 2005–2012; VVT and emissions equipment must match.
In most cases, an EJ25 from the same phase will swap directly, while cross-phase swaps require swapping intakes, exhaust manifolds, and sometimes cam/crank sensors.
What Subaru parts are interchangeable?
Subaru has excellent cross-compatibility. Interchangeable parts include:
- Engines within the EJ family (EJ18, EJ20, EJ22, EJ25 share block patterns)
- Transmissions across EJ-era Subarus (same bellhousing pattern)
- Suspension components across Impreza, Legacy, and Forester of the same era
- Drivetrain parts like driveshafts and diffs within matching chassis generations
- Interior components like seats and steering wheels across many models
Subaru’s modular design philosophy allows many parts to bolt directly between models of similar years.
Which Subaru engines are interference?
Most modern Subaru engines are interference engines, meaning valves can contact pistons if the timing belt or chain fails. These include:
- EJ25 (all versions)
- EJ20 Turbo (205, 207)
- FA20, FA24 engines
- FB20, FB25 engines
The exceptions are the older non-interference EJ22 engines (1990–1996), which are known for being extremely durable. If you want the least risky Subaru engine, the early EJ22 is the safest bet.
Which Subaru has a Toyota engine?
The Subaru BRZ, Toyota 86, and Scion FR-S share the Subaru-built FA20 (2013–2020) and FA24 (2022+) engines. Although the vehicles are co-developed, Toyota does not supply the engine, Subaru manufactures the boxer engine, while Toyota provides fuel-injection technology (D-4S). So technically, no Subaru model contains a Toyota-built engine, but these models share engineering.
What is the most common problem with Subaru engines?
The most common issue, especially in EJ25 engines from 1996–2012, is head gasket failure. This is caused by:
- Heat buildup
- Cooling system inefficiencies
- Gasket material weaknesses
Other common Subaru engine issues include:
- Oil consumption in early FB engines (2011–2014)
- Ringland failures on turbo EJ255/EJ257 engines under hard use
- Timing belt failures (if not replaced on schedule)
- Rod bearing wear in high-mileage turbo models
