Subaru's engine lineup is split across three distinct families with different architectures, strengths, and applications: the EJ series (the classic boxer), the FA series (direct-injection, smaller displacement), and the FB series (naturally aspirated modernization). This guide helps you navigate all three. For a deeper EJ-specific breakdown, see our complete EJ engine family guide.
The EJ series: the classic performance boxer
The EJ family (EJ20, EJ25, EJ205, EJ255, EJ257) ran from the early 1990s through 2021 and covers most of what you'll find in the JDM import market for WRX and STI platforms. Key characteristics: open or semi-closed deck depending on variant, iron-lined aluminum block, and a track record of high-power potential but also head-gasket sensitivity that's well-documented. Pricing from our current inventory: EJ255 at $999–$1,299; EJ257 at approximately $4,899.
The FA series: Subaru's direct-injection turbo
The FA20DIT (2.0L direct-injection turbo) replaced the EJ257 in the 2015+ WRX and also appeared in the BRZ's NA sibling (FA20D). It's a fundamentally different engine than the EJ: aluminum block, direct injection, and a port injection secondary system on later variants. Performance characteristics differ from the EJ — the FA20DIT makes power differently across the rev range, and the aftermarket, while growing, is not as mature as the EJ ecosystem. From our current stock: FA20DIT units at approximately $3,799. The FA24 (2.4L, current WRX) is priced around $4,999.
The FB series: naturally aspirated modernization
The FB25 and FB20 replaced the naturally aspirated EJ25D and EJ20 in mainstream Subaru applications — Impreza, Forester, Outback, Legacy NA. They're modern, direct-injection four-cylinders without a turbo, significantly more efficient than the EJ family they replaced, but not performance-oriented. If you need an NA Subaru engine replacement for a late-model Forester or Outback, the FB series is what you're looking at.
Comparing the three families
| Factor | EJ series | FA series | FB series |
|---|---|---|---|
| Turbo available | Yes (EJ205, EJ207, EJ255, EJ257) | Yes (FA20DIT, FA24) | No (NA only) |
| High-power aftermarket | Mature, decades of development | Growing but less extensive | Minimal performance aftermarket |
| Price range (our stock) | $999–$4,899 | $3,799–$4,999 | Lower (mainstream replacement) |
Frequently asked questions
Should I buy an EJ or FA engine for a 2015+ WRX replacement?
Your 2015+ WRX came with an FA20DIT — the factory-correct replacement is an FA20DIT, which keeps your ECU and drivetrain pairing straightforward. An EJ would require significant supporting modifications to fit your chassis.
Is the EJ family going to be hard to source in coming years?
The EJ ran through 2021 in STI form and was produced in massive numbers, so availability should remain reasonable for many years. Quality and mileage on available units will be the more relevant variable over time than pure scarcity.
What about the BRZ's FA20D?
The BRZ and 86 use a naturally aspirated variant (FA20D) that's tuned differently from the FA20DIT in the WRX. They share the same basic architecture but are not interchangeable without significant work.
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