About the Cosworth EJ257 Crate Engine

In 2004, Subaru and Cosworth teamed up to push the former's high-performance engines to the next level. In 2008, Cosworth started to introduce its version of Subaru's engines into the market, including this Cosworth EJ257 crate engine for sale. Ready to breathe new life into your vehicle, this engine is a testament to Cosworth's legendary engineering and has proven its worth on roads, tracks, and tests time and time again. With a roar-like exhaust note, this EJ257 crate engine is for anyone who possesses enthusiasm for automotive building or anyone looking to enhance their Subaru's driving experience.

Seize this opportunity to own a piece of motorsport history and let your car's true potential be realized. Whether you're searching for "cosworth subaru engine," "cosworth ej257," "ej257 crate engine," or "ej257 for sale," this is the right listing for you.

Important Configuration Clarification

The live product page description states the engine type as "Inline-4" , this is incorrect. The Cosworth EJ257 is a flat-4 (horizontally opposed) boxer engine, NOT an inline-4. The cylinders are arranged horizontally in two banks of two, with each bank facing outward to opposite sides of the vehicle. This is Subaru's signature engine configuration, preserved in the Cosworth performance build.

The Subaru and Cosworth Partnership: A Brief History

The Cosworth EJ257 is the result of one of the most significant performance engine partnerships in modern automotive history:

2004: Subaru and Cosworth establish performance partnership. Cosworth, the legendary British engineering firm with Formula 1 heritage, brings its high-performance engine building expertise to Subaru's already-respected EJ-series turbocharged boxer engines.

• 2008: Cosworth introduces its performance EJ257 variants to market. These engines feature Cosworth's full performance build treatment.
• 2008-2015: Peak production years for Cosworth-built Subaru engines, with multiple build specifications offered (Stage 1, Stage 2, Stage 3, race builds).
• 2015+: Cosworth EJ257 builds continue through authorized rebuilders and specialty shops using Cosworth components.

Cosworth's heritage includes the Ford-Cosworth DFV (the most successful Formula 1 engine of the 1970s), engines for Lotus, McLaren, and many championship-winning racing programs. When Cosworth engineers the EJ257, the result is an engine built to a higher standard than factory production.

What Makes the Cosworth EJ257 Special

The Cosworth EJ257 takes the stock Subaru EJ257 (already a performance engine producing 305 HP in stock WRX STI tune) and upgrades it comprehensively:

Closed-Deck Aluminum Block , The Critical Upgrade

The single most important Cosworth upgrade is replacing the stock EJ257's open-deck aluminum block with a closed-deck block:

Why this matters: The open-deck design is the most well-known weakness limiting the EJ257's power potential. Under high boost, the open-deck cylinders can deform, causing head gasket failures, lost compression, and ultimately catastrophic engine failure.

Closed-deck advantage: The closed-deck design provides full structural support to the cylinder walls, dramatically increasing rigidity under high boost pressure. This is the foundation that allows all the other Cosworth upgrades to deliver reliable power.

Forged Internal Rotating Assembly

• Forged Crankshaft: Much stronger than the stock cast crankshaft, capable of handling significantly higher torque loads
• Forged H-Beam Connecting Rods: Cosworth's own H-beam design eliminates the stock rod as a failure point at high boost. Stock EJ257 rods typically limit safe power to ~400 HP; Cosworth rods support 600+ HP

Forged Pistons: Typically Cosworth's own piston design with optimized ring lands, skirt geometry, and crown shape for forced induction. Stock cast pistons are the most common EJ257 failure point (ringland failures) , Cosworth forged pistons address this

Supporting Performance Components

• Performance Bearings: Upgraded main and rod bearings for high-RPM operation
• Upgraded Oil Pump: Higher capacity for sustained high-RPM and high-boost operation
• Multi-Layer Steel Head Gaskets: Superior to stock for high-boost applications, less prone to failure
• Performance Valve Springs: On some Cosworth builds, allowing higher RPM operation
• CNC Ported Heads: On higher-spec Cosworth builds (Stage 2.5 and above)

Power Output and Build Levels

Cosworth EJ257 builds typically come in several specifications:

• The available engine at this listing (330-350 HP, 330-340 lb-ft per live spec) matches a Cosworth Stage 1 to Stage 2 build level , an excellent street/track build with strong reliability and significant performance gains over stock.

Vehicle Applications

The Cosworth EJ257 direct fits all generations of the Subaru WRX STI:

The Cosworth EJ257 is also used in performance engine swap projects (Forester XT, Legacy GT, Impreza non-STI applications) where buyers want STI-level or beyond performance.

Why Choose the Cosworth EJ257 Over Stock EJ257?

The Cosworth EJ257 isn't just a performance upgrade , it's a fundamentally more durable and capable engine. For any serious WRX STI build pursuing 350+ HP reliably, starting with a Cosworth EJ257 saves time and money vs building from a stock EJ257.

Common Cosworth EJ257 Service Items (Honest Disclosure)

The Cosworth EJ257 addresses most stock EJ257 weaknesses but has its own considerations:

• Premium Fuel Mandatory: 91 octane minimum, 93 octane strongly recommended for full output. Some Cosworth builds (Stage 2.5 and above) may require race fuel for advertised power.
• Oil Quality Critical: Use full synthetic, preferably racing-grade oil. Cosworth's tighter tolerances and higher operating loads require quality lubrication.
• More Frequent Oil Changes: 3,000-5,000 mile intervals recommended (vs Subaru's 6,000-7,500 mile standard interval).
• Turbocharger Service: Cosworth builds typically use upgraded turbos , verify turbo condition and consider preventive service at high mileage.
• Tuning Required: Cosworth EJ257 engines require proper tuning. Never run a Cosworth EJ257 on stock ECU programming , the tune assumes performance internals and supporting modifications.
• Cold Start Behavior: Cosworth's tighter ring tolerances may produce slightly more cold-start smoke until oil temperature reaches operating range , normal behavior, not a defect.
• Heat Management: Aggressive use (track days, sustained high boost) requires excellent cooling system maintenance.

Why Choose a Used Cosworth EJ257 Engine?

• Cost savings vs new ($4,999 used vs $12,000-20,000 new Cosworth crate engine)
• Forged internals already done , no need to build a stock EJ257 ($5,000-8,000 in parts + labor)
• Closed-deck block , addressing the EJ257's primary weakness
• Direct OEM fit for all WRX STI generations
• Performance heritage , Cosworth engineering and Subaru rally legacy
• Significant power gains over stock EJ257
• Headroom for further mods , supports 500+ HP with appropriate supporting modifications

Here at Vaz Auto Solutions, you'll find this Cosworth EJ257 crate engine for sale at the most reasonable price possible, with Cosworth build verified (forged internals, closed-deck block), all 4 cylinders compression tested, turbocharger condition verified, AVCS function tested, and complete inspection.

Vehicle Compatibility

Direct Fit:

Condition and Inspection

• Cosworth build verified (forged internals, closed-deck block, Cosworth-specific components)
• Closed-deck aluminum block confirmed (the critical Cosworth upgrade)
• Forged crankshaft verified
• Forged connecting rods verified
• Forged pistons verified

All 4 cylinders compression tested (Cosworth builds typically show higher cylinder pressures than stock)

Oil pressure verified at idle and operating speed

• Turbocharger condition verified (including shaft play, oil seals, bearing condition)
• Wastegate operation verified
• AVCS variable valve timing function tested (intake AND exhaust)
• Performance valvetrain components inspected (valve springs, retainers)
• Multi-layer steel head gaskets verified
• CNC head porting verified where applicable (Stage 2.5+ builds)
• Upgraded oil pump verified
• Spark plug condition documented (4 iridium / NGK race plugs)
• Coil-on-plug function verified
• Coolant system function verified
• Cosworth build documentation reviewed where available
• Miles from donor vehicle documented where available
• Cosworth build verified (forged internals, closed-deck block)
• All 4 cylinders compression tested
• Turbocharger condition verified
• Closed-deck block inspection (the critical Cosworth upgrade)
• Forged internal components verified (crank, rods, pistons)
• AVCS variable valve timing tested
• Performance valvetrain inspection
• Multi-layer steel head gaskets verified
• Cosworth build documentation reviewed where available
• Cross-reference assistance across WRX STI generations
• WRX STI performance build consultation
• Cosworth supporting modifications guidance
• Free freight pallet delivery to all 50 states
• 15 day replacement warranty on internal defects
• Subaru and Cosworth performance specialist support team