The Subaru EJ20G is a 1,994 cc, flat-four petrol engine produced between 1992 and 1996. It features a DOHC 16-valve configuration with multi-point fuel injection (MPFI) and sequential twin-turbocharging, delivering 164 kW (223 PS) in high-output STI applications. Developed as the performance flagship of Subaru's EJ series, it was engineered for rally-bred road cars including the Impreza WRX STI GC8, combining compact packaging with strong torque delivery.
Fitted exclusively to high-performance variants such as the Impreza WRX Type RA and STI, the EJ20G was designed for enthusiasts seeking maximum power within Japan's horsepower agreement limits. Emissions compliance was achieved through oxygen sensor feedback control and catalytic converters, allowing most units to meet Japanese Domestic Market (JDM) emissions standards, with Euro 2 compliance in limited export builds.
One documented reliability concern is head gasket degradation under prolonged thermal stress, highlighted in Subaru Service Information Bulletin SSB-93-018. This issue is often associated with coolant system neglect or aggressive driving cycles. In 1994, Subaru revised the cylinder head bolt torque sequence and introduced updated gasket materials to improve sealing integrity.
Production years 1992–1994 meet JDM emissions standards; 1995–1996 export models comply with Euro 2 (VCA UK Type Approval #VCA/EMS/1703).
The Subaru EJ20G is a 1,994 cc flat-four turbocharged engine engineered for high-performance applications (1992–1996). It combines Subaru's horizontally-opposed layout with sequential twin-turbocharging to deliver rapid boost response and broad power delivery. Designed primarily for JDM use, it balances motorsport-derived performance with street drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,994 cc | |
| Fuel type | Petrol | |
| Configuration | Flat-4, DOHC, 16-valve | |
| Aspiration | Twin-turbocharged (sequential) | |
| Bore × stroke | 86.0 mm × 86.0 mm | |
| Power output | 164 kW (223 PS) @ 6,500 rpm | |
| Torque | 309 Nm @ 5,000 rpm | |
| Fuel system | Multi-point fuel injection (MPFI) | |
| Emissions standard | JDM Standard (pre-1995); Euro 2 (export models) | |
| Compression ratio | 8.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | IHI VF22 (primary), IHI VF23 (secondary) | |
| Timing system | Belt-driven (front-mounted) | |
| Oil type | SAE 10W-40 (API SH) | |
| Dry weight | 138 kg |
The twin-turbocharged flat-four layout provides exceptional balance and low center of gravity ideal for all-wheel-drive dynamics but requires strict maintenance to sustain longevity. SAE 10W-40 oil meeting API SH specifications is recommended for optimal lifter and camshaft lubrication. Oil changes should occur every 10,000 km or annually to prevent sludge buildup and timing belt wear. The interference design means valve damage will occur if the timing belt fails. Valve clearance adjustments are required every 30,000 km using feeler gauges per factory procedure. Sequential turbo operation demands regular inspection of actuator solenoids and vacuum lines to maintain boost transition smoothness.
Oil Specs: Requires API SH-rated 10W-40 oil (Subaru SIB SSB-93-018). Compatible with ILSAC GF-2 requirements.
Emissions: Euro 2 certification applies only to post-1995 export models (VCA Type Approval #VCA/EMS/1703). JDM variants meet domestic Japanese emissions.
Power Ratings: Measured under JIS D 1001 standards. Output achieved with 100 RON fuel and optimal ignition timing (Subaru TIS Doc. A20GPERF).
Subaru Technical Information System (TIS): Docs A20GEJ, A20GFUEL, A20TIMING
VCA Type Approval Database (VCA/EMS/1703)
JIS D 1001: Internal combustion engine — Test code
The Subaru EJ20G was used exclusively in high-performance Impreza WRX STI platforms (GC8 chassis) with longitudinal mounting and symmetrical all-wheel drive. This engine received platform-specific adaptations-reinforced block castings in the STI Version II and revised intake manifolds in the Type RA-and from 1994 the updated STI Rev. F models adopted improved head gaskets and oil squirters, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-left cylinder block near the exhaust manifold (Subaru TIS A20GID01). The 4th digit of the VIN indicates engine family ('E' for EJ series). Pre-1994 models have silver valve covers with ribbed rocker housings; post-1994 units use black valve covers with revised fastener layouts. Critical differentiation from EJ20K: EJ20G has sequential twin-turbos and different ECU calibration. Service parts require production date verification - head gaskets and oil pans for pre-1994 models are incompatible with later revisions due to internal cooling passage updates (Subaru SIB SSB-93-018).
The EJ20G's primary reliability risk is head gasket failure on high-mileage engines, with elevated incidence in vehicles subjected to sustained high-load operation. Internal Subaru engineering reports noted increased gasket blowout rates beyond 150,000 km, while UK DVSA field data shows a notable share of coolant contamination failures linked to degraded seals. Extended track use and delayed maintenance increase thermal stress, making coolant quality and flush intervals critical.
Analysis derived from Subaru technical bulletins (1992-1996) and UK DVSA failure statistics (1995-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about SUBARU EJ20G.
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