The Ultimate EJ257 Long Block Buyer's Guide

Push a stock EJ257 past its limit and it will fail. Usually at the ringlands, usually at the worst time. A long block is the fix: the bottom end and the heads, built and matched as one unit, sized for the power you actually plan to make.

If you're planning a serious power upgrade for your Subaru, this guide covers what a long block is, how to match the internals to your power goal, and what else has to be right for the engine to live.

Key takeaways

• Plan your power level first. Your horsepower goal decides the internals. Stock parts hold to about 350 whp. Forged internals past that. A built block with forged internals for serious builds over 500 whp.
• Budget for the whole system, not just the block. Turbo, fuel, cooling, clutch, and a custom tune all cost money. The engine is one line item.
• Clean installation protects the engine. After a failure, every part that carried the old oil gets cleaned or replaced. No exceptions.

What is an EJ257 long block?

A long block is a nearly complete engine: the short block plus the cylinder heads, assembled and bolted together. Inside are the crankshaft, connecting rods, pistons, rings, and bearings. On top are finished heads with valves, springs, and camshafts. A quality build also includes new gaskets, seals, and hardware throughout.

You still add the external parts — intake, turbo, timing components, accessories. What you don't do is the most sensitive assembly work yourself.

Long block vs. short block

A short block is the bottom half only: block, crank, rods, pistons. A long block adds the heads and valvetrain, assembled to spec.

If your heads are in good shape and you plan to reuse them, a short block can be enough. If the heads are tired, damaged, or unproven, a long block removes that variable. Both halves are built to work together. That is the point of Crawford Performance long blocks.

The machine work matters

Parts alone don't make an engine. The machining does.

Boring cuts each cylinder to the exact size for the new pistons, perfectly round and straight. Honing follows, leaving a cross-hatch pattern in the cylinder walls. That pattern holds a film of oil so the rings seal. A good seal means compression, and compression means power. Balancing the rotating assembly removes vibration at high RPM, which protects bearings and extends engine life.

Skip any of the three and the parts don't matter.

Forged internals: when you need them

The factory cast pistons and rods are fine at stock power. They are the weak point past it. The piston ringlands — the grooves that hold the rings — crack first when cylinder pressure climbs.

Forged pistons and rods are formed under extreme pressure. The metal is denser and stronger, and it holds up to the heat and pressure of a high-output engine. Stronger wrist pins and high-load main and rod bearings belong in the same conversation. Piston coatings — friction-reducing on the skirts, heat-reflecting on the crowns — are a further option on some builds.

The rule is simple. Past 350 whp, forged pistons. Past 400 whp, forged rods too.

Which Subarus use the EJ257?

The EJ257 long block is best known as the WRX STI engine, in US cars from 2004 to 2021. The same 2.5L turbo family also powered the Forester XT (2004–2013), Legacy GT (2005–2012), and Outback XT (2005–2009). That makes the EJ257 a popular swap into those cars, with the same upgrade path as the STI.

Plan the power level first

Set your power goals for the EJ257 before you order anything. The goal decides the internals, the supporting parts, and the budget. Build for a number, not a feeling.

350 whp: the reliable daily driver

A stock EJ257 can live at 350 whp with a professional custom tune. Treat that as the ceiling for factory internals, not a starting point. The ringlands are the limit.

400 whp: forged internals required

Past 350 whp, forged pistons are mandatory. Pair them with forged rods. At this level the stock rotating assembly is a countdown.

500+ whp: the block has to be built

At 500 whp and beyond, the block itself needs help. In a stock open-deck block, the tops of the cylinder walls stand free. Under high boost they can flex and crack. Crawford builds those motors on the factory semi-closed deck case with forged internals — its top tier is rated at 720+ bhp without a closed-deck conversion. The bores stay round under pressure, the rings keep sealing, and the head gasket keeps its clamp. The internals and the clearances decide whether 500 whp is reliable — not a deck conversion.

OEM+ or fully built?

Replacement-spec builds follow the factory design and improve on it: blueprinted assembly, stronger pistons, careful clearances. They suit daily drivers and street cars in the 350–450 whp range.

Fully built engines are for 500 whp and up: the strongest rods and pistons available in a built block, every clearance set for hard use. That is the track-car path, and it costs like one.

Neither is better. Match the build to the goal and the budget. The Crawford Performance Long Blocks range covers both.

Why Crawford

Crawford Performance builds EJ engines by hand, and every engine ships with a build sheet. The company's engines have a proven racing legacy, including the Gymkhana Subarus. Racing doesn't forgive weak assembly. Neither do we.

Read the build sheet

Before you buy any long block, from anyone, ask for the build sheet. It lists every component: pistons, rods, bearings, head studs, with brands and specifications. It is the single source of truth for what is inside the engine.

A builder who won't show you one has told you what you need to know.

No core charge

Crawford builds on brand-new OEM blocks only. There is no core charge, no core return, and no used block at the start of your build. You are not paying a deposit on your old engine, and you are not waiting on anyone to inspect it.

What the warranty covers

Crawford long blocks carry a 12-month / 12,000-mile limited warranty against defects in materials and workmanship.

The conditions are plain: professional installation, a professional custom tune, a clean oil system, and the break-in procedure followed — including the first oil analysis. Skip the break-in or the oil analysis and the warranty is void. The warranty covers the engine. It does not cover the shortcuts around it.

Before the engine goes in

If your old engine failed, assume the oil system is contaminated. A failure sends metal through every part the oil touches. Run those parts on a new engine and the new engine fails the same way.

Replace the oil pan, oil pickup tube, oil cooler, and AVCS cam gears at minimum. Flush or replace everything else in the oil circuit. Use new gaskets, seals, and head studs. Torque everything to factory specification. Prime the oil system before the first start.

More detail here: Best Practices for a Reliable Installation.

Supporting mods

The engine cannot do the job alone. Essential mods for every power target include a turbo sized to the goal, a higher-flowing fuel pump and larger injectors, an intercooler that can hold the intake temperatures down, a free-flowing exhaust, and cooling upgrades — radiator and oil cooler — to shed the extra heat. The clutch has to hold the torque. None of this is optional at the power levels above.

Tuning is not optional

A built engine on a stock tune, or an off-the-shelf map, is a failure waiting for a date. Those maps were written for a stock engine with stock parts. Your engine is neither.

Get a professional custom tune for your exact combination of parts before the car is driven hard. The tune sets air-fuel ratio, ignition timing, and boost for your engine, with the safety margins it needs. This is the last step of the build, not an afterthought.

Shipping

Crawford-built long blocks ship free, freight, insured. Confirm delivery details when you order — an engine is not a parcel, and somebody needs to be there to receive it.

Break-in

Your engine ships with a break-in spec sheet. Follow it exactly.

The numbers: oil changes at 500 and 1,500 miles. Keep engine speed between 2,000 and 4,500 RPM and vary it — no sustained cruising, no full-throttle pulls. Do not exceed 80% of your target boost until break-in is complete.

The first oil analysis is mandatory — it is part of the warranty terms, and it is how a problem gets caught while it is still cheap.

Break-in is where ring seal and bearing life are decided. There are no shortcuts that end well.

What it costs

The power target sets the price. A replacement-spec long block costs the least. Forged internals add cost. A fully built motor adds more. At the top of the range, the Ken Block EJ257 Long Block is built for extreme use, and priced like it.

Then budget the rest of the system: turbo, fuel, cooling, clutch, tune. A long block is a larger upfront cost than a short block, and it often ends cheaper — the heads arrive assembled, which removes labor and removes a source of errors.

Custom builds take longer than shelf configurations. Say your timeline when you order, and plan the car around it.

Oiling hardware for the build

Crawford stocks the Killer B Motorsport oiling parts these builds call for: the EJ25 Ultimate Oil Pickup at $149.00, the EJ20/EJ25 Performance Baffle at $87.00 — or the pickup and baffle combo at $219.00 — and the High Performance Cast Oil Pan at $549.00. The full line is in the Killer B Motorsport collection.

Frequently asked questions

Why a long block instead of a rebuild or a short block? A long block arrives assembled, with the heads matched and torqued to the block. That removes the most error-prone work from your garage and cuts labor time. A short block is the right call when your heads are known-good. A long block is the right call when they aren't, or when you want the whole core built as one system.

Are forged internals worth it if I'm not chasing big power yet? Under 350 whp, stock-style internals are enough. If there is any chance you will want more later, build the foundation now. Forged pistons and rods installed the first time cost far less than pulling the engine and doing it twice.

What must be replaced after my old engine failed? Everything that shared oil with it. At minimum: oil pan, oil pickup tube, oil cooler, and AVCS cam gears. Flush or replace the rest of the oil circuit. Debris left behind will destroy a new engine.

Can I install a long block myself? An experienced mechanic with the right tools and a clean workspace can. We recommend a professional installation. Small mistakes in this job have large price tags, and the warranty requires professional installation.

What voids the warranty? No custom tune. A contaminated oil system. A skipped break-in or a skipped first oil analysis. Improper installation. The warranty protects you from defects in the engine. It does not protect the engine from the build around it.

Related articles

• The Ultimate Built Subaru EJ25 Long Block Guide
• EJ257 Short Block: The Ultimate Buyer's Guide
• New Subaru OEM EJ257 Short Block Engine Part #10103AC870

Questions about a build: (855) 677-8243.

Complete the Build: Oil Control and Break-In

A fresh motor lives or dies on oil control and break-in. A Crawford air oil separator keeps oil out of the intake, and the first fills run on Motul break-in oil — oil changes at 500 and 1,500 miles, per the Crawford break-in spec.

The full EJ25 picture is in the EJ25 built long block buyer's guide.