IAG 750 EJ25 Subaru Closed Deck Short Block - 750 BHP

IAG 750 Closed Deck Short Block for 02-14 WRX, 04-21 STI, 05-09 LGT, 04-13 FXT

THE PROBLEM SOLVER

The IAG 750 Short Block is designed to solve the majority of common problems which plague modified EJ25 engines, especially at higher horsepower levels. The IAG 750 short block builds off the IAG 550 block's strengths by adding IAG’s proprietary closed deck system. This system strengthens and supports the cylinder walls to prevent cracks which can occur with increased cylinder pressures (one of the most common issues when increasing horsepower).

The IAG 750 also features 99.75mm JE Forged Pistons and IAG-Spec Tuff H-Beam connecting rods, along with ACL or King Race bearings. Together, these components strengthen typical EJ25 failure points such as cracked ringlands and spun bearings to provide a more reliable foundation for high-boost builds.

BUILT WITH 100% NEW COMPONENTS

Each IAG 750 Short Block starts with brand new Subaru 2.5L engine case halves. The assembled case halves are machined in-house to accept IAG Closed Deck inserts, transforming the block into a solid deck. Next, deck plates are installed and the short block is bored and honed to 99.75mm using IAG’s in-house honing process, which allows custom piston-to-wall clearances for quiet operation and reduced oil consumption.

The modified case halves are assembled using a new 2017+ Subaru 2.5L nitride-treated STI crankshaft and IAG-Spec Tuff H-Beam connecting rods with ARP rod bolts. IAG short blocks feature ACL or King Race rod and main bearings, are balanced and blueprinted, and are sealed with new OEM main/case bolts and sealant for a clean, ready-to-install foundation.

CLOSED DECK FOR EXTRA STRENGTH

IAG’s unique closed deck system significantly increases the strength of the OEM case halves by supporting the cylinder walls at the top of the case. This support helps prevent flexing and possible cracking where the case bolt reliefs are cut into the back of the cylinder wall.

During installation, the assembled case halves are machined to accept the IAG Closed Deck inserts. The case is heated while the inserts are frozen, then the inserts are pressed into place and finished to a precise, mirror-like surface. The inserts also incorporate small passages to allow necessary coolant flow to the deck surface, helping maintain cooling performance for street and daily-driven applications.

FORGED PISTONS, DESIGNED FOR BOOST

Each IAG 750 Short Block features IAG-Spec JE FSR 99.75mm forged pistons. These 2618 T6 Alloy high-strength pistons are designed to support increased cylinder pressures that come with higher boost. FSR forgings reduce mass and friction wear without sacrificing strength by using an asymmetrical skirt design instead of a traditional full-round skirt, significantly reducing piston weight.

Featuring smooth flowing radii on the domes and dishes, the design promotes excellent flame travel. The pistons are secured to the rods with .905 x 2.250" x .210" wall 9310 steel wrist pins and Tru Arc locks. The thicker .210" pins provide additional support over standard .180" pins for higher power applications.

OPTIONAL "HYBRID" PISTONS FOR EJ20 HEADS

If you plan to use the IAG 750 Short Block with EJ20 cylinder heads, select the “Hybrid Pistons” option. These specially designed JE pistons allow the use of EJ20 heads without requiring a chamber matching service. This is a great option for international clients who cannot send cylinder heads in for modification, and it also works well for EJ20 owners who prefer to run a 2.5L short block.

The 9.5:1 compression JE FSR piston set includes .905 x 2.250 straight wall carbon steel wrist pins with Tru Arc locks, along with a complete ring set.

IAG 750 CLOSED DECK SHORT BLOCK INCLUDES

What's Inside:

• Case Halves – Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 99.75mm
• Pistons – IAG-Spec JE FSR 99.75mm 2618 Forged Pistons, Ring Set, .210" 9310 Steel Wrist Pins, Clips (Perfect Skirt Coating and Offset Wrist Pins)
• Connecting Rods – IAG-Spec Tuff H-Beam / 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 bolts

Compression Ratio:

• 9.5:1 on D Cylinder EJ255 Heads w/ OEM Head Gasket
• 8.9:1 on B, V and W EJ257 Heads w/ OEM Head Gasket
• 9.6:1 on S20 Heads without Combustion Chamber Mod and with OEM Head Gasket
• 9.1:1 on D Cylinder EJ255 Heads w/ .039" JE Proseal Head Gasket
• 8.6:1 on B, V and W EJ257 Heads w/ .039" JE Proseal Head Gasket
• 9.2:1 on S20 Heads without Combustion Chamber Mod and with .039" JE Proseal Head Gasket

Power Rating:

Power: The IAG 750 Short Block has a power output rating of 750 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.