IAG 550 EJ25 2.5L Subaru Short Block - 550 BHP

IAG 550 Short Block for 02-14 WRX, 04-21 STI, 04-13 FXT, 05-09 LGT

BUILT FOR BOOST

Designed for modified EJ25 Subarus, the IAG 550 Short Block is a sturdy upgrade that is capable of handling higher cylinder pressures created by increased boost levels. The OEM Subaru connecting rods and pistons (yes, even the STI RA) aren’t strong enough to take on the additional engine load of a larger turbocharger or an increase in boost pressure, which can quickly lead to costly engine failure.

Built for boost, IAG’s 550 Short Block solves this problem by incorporating the use of high performance internal components that can stand up to extra load on the motor, ensuring longevity and reliability in high-performance scenarios.

IAG SPEC H-BEAM FORGED CONNECTING RODS

The IAG 550 Short Block features IAG Spec H-Beam forged connecting rods with ARP2000 rod bolts, along with ACL or King race rod bearings. These structurally optimized connecting rods provide solid support to your high powered EJ25 Subaru engine. Capable of withstanding higher RPM conditions, the ACL and King race rod bearings are a perfect match for this resilient and capable short block.

IAG SPEC JE FORGED PISTONS

To create this high strength short block, IAG teamed up with JE Pistons to create a high performing piston strong enough to match up to the capabilities of the 550 Short Block. With over seventy years of experience in manufacturing ready-to-race forged pistons, JE Pistons has been an invaluable partner in the development of the IAG Spec JE 99.75mm Forged Pistons installed in the IAG 550 Short Block.

These 2618 T6 Alloy high-strength pistons have been specifically designed to support increased cylinder pressures which come with more boost. This is accomplished by using an asymmetrical skirt design instead of the traditional full-round skirt, which also significantly reduces piston weight. Another design attribute of the IAG Spec JE Forged Pistons is the smooth flowing radii on the domes and dishes, which promotes superior flame travel.

The pistons are securely fastened to the rods with .905 x 2.250" x .180" wall carbon steel wrist pins combined with Tru Arc locks.

WHY UPGRADE?

The most common failure point of the OEM Subaru STI EJ257 short blocks are the piston ringlands. The metal ledges on the pistons that hold the compression rings in place can stand up to regular usage, but are susceptible to failure when used in conjunction with modifications. Cracked or broken ringlands often result in increased oil consumption and eventual bearing failure if the oil level is not closely monitored.

While Subaru’s RA block has slightly stronger pistons than the STI EJ257, they are still prone to the same type of failure caused by damaged ringlands.

SUPERIOR DESIGN

The pistons in the OEM Subaru STI EJ257 and the RA blocks continue to be produced using a hypereutectic cast design. This casting method is susceptible to irregularities in both the casting process and the materials used, leading to potential weaknesses in the pistons. This is where the IAG Spec JE Piston comes in; forged from a durable 2618 T6 Alloy with a unique silicone additive, these JE pistons effectively absorb the direct shock and impact of combustion.

Engineered to withstand ringland damage due to detonation and preignition, they feature a higher strength material and have been custom designed to feature thicker ringlands.

BUILT WITH 100% NEW COMPONENTS

Each IAG 550 Short Block starts with brand new EJ25 Subaru 2.5L, 99.75mm stock bore engine case halves, providing a solid foundation for its upgraded components. The case halves are carefully measured and assembled using a new 2017+ Subaru 2.5L nitride treated STI crankshaft, which is matched to ACL or King race main bearings. The IAG 550 Short Block also features IAG Spec H-Beam Connecting Rods with ARP2000 rod bolts, along with ACL or King race rod bearings.

The case halves are sealed with new OEM main case bolts and sealant. Finally, a set of IAG Spec JE 99.75mm Forged Pistons are carefully selected, measured, and installed to finish off the short block.

PROFESSIONALLY ASSEMBLED AND READY TO INSTALL

Our team of certified Subaru specialists at IAG Performance takes great care in assembling each IAG 550 Short Block. These specialists have now built over 13,000 Subaru engines and counting. Equipped with an advanced selection of tooling and state-of-the-art equipment, we guarantee the quality of all our engine blocks. Each block is meticulously crafted and thoroughly checked, ensuring the highest standards of quality assurance.

IAG’s assembled Short Blocks make it easy to upgrade your EJ25 Subaru engine—just leave the technical work to us, and we’ll provide you with a superior short block that’s ready to install.

WE’VE GOT YOU COVERED

While a new OEM block from Subaru doesn't come with a warranty when installed in a different vehicle, IAG Performance supports your purchase with a 12-month or 12,000-mile workmanship warranty for the IAG 550 Short Block. We take that even further to a 24-month, 24,000-mile workmanship warranty when purchased, installed, and tuned at one of our Certified Engine Installation facilities around the country. At IAG Performance, we are committed to your satisfaction and the lasting quality of our products.

Our goal is to deliver a superior product that will last you for miles to come.

IAG 550 SHORT BLOCK INCLUDES

What's Inside:

• Case Halves – Brand new Subaru OEM case halves 99.75mm stock bore
• Pistons – IAG-Spec JE 99.75mm Forged Pistons, Ring Set, .180" Chromoly Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pin)
• Connecting Rods – IAG-Spec H-Beam Rods with ARP2000 rod bolts
• Rod / Main Bearings – ACL or King Race Bearings
• Crankshaft – Standard New Subaru Nitride Treated 2017+ STI Crankshaft
• Case / Main Bolts – Standard FHI Subaru case bolt

Compression Ratio:

• 9.3:1 on D Cylinder Heads (EJ255) w/ OEM Head Gasket
• 8.8:1 on B, V, and W EJ257 Heads w/ OEM Head Gasket
• 9.4:1 on S20 Cylinder Heads without Combustion Mod and with OEM Head Gasket
• 9.0:1 on D Cylinder Heads (EJ255) w/ .039" JE Proseal Head Gasket
• 8.5:1 on B, V, and W EJ257 Heads w/ .039" JE Proseal Head Gasket
• 9.1:1 on S20 Cylinder Heads without Combustion Mod and with .039" JE Proseal Head Gasket

Power Rating:

Power: The IAG 550 Short Block has a power output rating of 550 BHP

Please Note: This item is not eligible for standard ground shipping and must be delivered via freight. 
STOCK NOTICE: This item is built to order and carries a minimum 6-8 week build time.

IMPORTANT DELIVERY NOTE: Your order is shipping Via Truck Freight which requires you to be available at the time of receipt. There is a possibility the trucking company will try to schedule a delivery time with you. At the time of delivery, the driver will hand you the delivery receipt also referred to as the bill of lading, you will use this to notate any damages to the shipment. It is important that you fully inspect the shipment from all sides and notate any dents, punctures or rips in the outside packaging on the delivery receipt. Once you've inspected your shipment from the outside, you will need to open it and check the product in its entirety for damages and notate them if any. If there is no damage sign for the package and enjoy! In the rare case, you do find that your order arrived with damages, it is important you follow these steps. - Do not refuse the product- Document the damages in as much detail as possible on the Bill of Lading
- Take numerous photos from all angles (including packaging)
- Keep the product and contact the shipping company to start the damage claim
- Contact us either by phone or email for the next steps In the situation where the delivery driver is unable to wait for you to open and inspect your product, simply document "driver was unable to wait for inspection." All damage must be noted on the Bill of Lading before signing and initiating a damage claim. If the damage is not notated before signing for the item it is assumed to be in good condition. This will forfeit the ability for a shipping claim and you will not be eligible for refund or replacement.