The EJ20 and EJ25 are both members of Subaru’s EJ-series of flat-four (boxer) engines. The EJ20 displaces 2.0 liters and the EJ25 displaces 2.5 liters. In the US, the early turbocharged WRX used a 2.0 L EJ20 variant, while later WRX models and the STI used turbocharged EJ25 variants.
EJ25 vs EJ20 at a glance
| EJ20 | EJ25 | |
|---|---|---|
| Engine family | Subaru EJ-series | Subaru EJ-series |
| Layout | Horizontally opposed four-cylinder | Horizontally opposed four-cylinder |
| Displacement | 2.0 L | 2.5 L |
| US turbocharged use | WRX, roughly 2002 to 2005 | WRX roughly 2006 to 2014 (EJ255); STI (EJ257) |
| Wider use | Turbo versions widely used in markets outside the US | Turbo and non-turbo versions across many US Subaru models |
What is the difference between the EJ20 and EJ25?
The headline difference is displacement. The EJ25 has a larger bore and a longer stroke than the EJ20, which gives it about half a liter more swept volume. Both share the EJ family’s basic architecture: an aluminum block, a flat-four layout, and many naturally aspirated and turbocharged versions over the years. Because there are so many sub-variants, the full engine code (for example EJ205, EJ255 or EJ257) tells you far more than the family name alone.
Which WRX and STI models used which engine?
- US WRX, about 2002 to 2005: turbocharged 2.0 L EJ20 variant (EJ205).
- US WRX, about 2006 to 2014: turbocharged 2.5 L EJ25 variant (EJ255).
- US WRX STI: turbocharged 2.5 L EJ25 variant (EJ257) throughout its run in the US.
- Other markets: turbocharged EJ20 engines were used widely in WRX, STI and other Subaru models sold outside the US.
From the 2015 model year the US WRX moved to the newer FA-series engine, while the STI kept the EJ257. If you are deciding between the two 2.5 L turbo engines, see EJ255 vs EJ257.
Can you swap an EJ25 block for an EJ20 block?
Not directly. Even though they belong to the same family, the blocks are not interchangeable without changing other parts, and the supporting hardware, engine management and calibration depend on the exact engine code and vehicle. Treat any change from one displacement to the other as a project that needs planning with a specialist, not a bolt-in replacement.
Our EJ25 short blocks and long blocks list the vehicles and model years they fit in each listing, so compare those against your car before ordering. Some listings include early WRX years that left the factory with the 2.0 L engine; ask a specialist what else that application requires.
Does deck design matter?
For high-boost builds, how the block’s cylinder deck is supported is often discussed alongside displacement. Several of the EJ25 blocks we list are closed-deck designs. Our guide to closed deck vs open deck explains what that means for EJ and FA blocks.
Where to shop
Browse Subaru EJ25 and EJ257 short blocks and long blocks, or see engine and related parts by car under Subaru WRX and STI parts.
More guides: what is a boxer engine? · EJ25 problems.
Shipping is a flat $80.00 per order to US addresses, with 15-day free returns. Questions? Ask a parts specialist.