IAG Performance 750 Closed Deck Includes: Case Halves - Subaru Models (Inc. 2002-2021 Subaru WRX / 2004-2021 STI / 2004-2013 Forester)

THE PROBLEM SOLVER

Tackling the prevalent issues faced by modified EJ25 engines, particularly as horsepower levels increase, the IAG 750 Short Block is engineered as a comprehensive solution. Expanding upon the strengths of the IAG 550 block, the IAG 750 incorporates our exclusive closed deck system. This innovative system reinforces and bolsters the cylinder walls, effectively preventing the common problem of cracks induced by heightened cylinder pressures—the foremost concern when pushing horsepower boundaries. Furthermore, featuring 99.75mm JE Forged Pistons, IAG Spec H beam connecting rods, and ACL or King Race bearings, this setup addresses key failure points such as cracked ring lands and spun bearings, ensuring heightened resilience and performance.

CRAFTED WITH 100% NEW COMPONENTS

The foundation of the IAG 750 Short Block begins with fresh Subaru 2.5L engine case halves. Our skilled technicians meticulously machine the assembled case halves using our Haas VF-4SS CNC mill to accommodate the IAG Closed Deck inserts, effectively transforming the block into a solid deck. Subsequently, a set of deck plates is attached, and the short block undergoes precise boring and honing to a diameter of 99.75mm using our in-house Sunnen SV-30 computer-controlled cylinder hone. Leveraging IAG's proprietary honing process, we customize piston-to-wall clearances to ensure smooth and silent operation while minimizing oil consumption. The modified case halves are then assembled with a new 2017+ Subaru 2.5L nitride-treated STI crankshaft and IAG-Spec Tuff H-Beam connecting rods featuring ARP rod bolts. Every IAG Short Block is outfitted with ACL or King Race rod and main bearings, meticulously balanced and blueprinted to meet stringent standards. Finally, the case halves are sealed securely using new OEM main/case bolts and sealant, completing the meticulous construction process.

STRENGTHENED BY CLOSED DECK DESIGN
Our innovative closed deck system significantly reinforces the OEM case halves, providing exceptional strength by supporting the cylinder walls at the top of the case. This crucial process effectively prevents flexing and potential cracking, particularly in areas where the case bolt reliefs are located on the back of the cylinder wall. Throughout the installation procedure, we meticulously machine the assembled case halves using our Haas VF-4SS CNC mill to accommodate the IAG Closed Deck inserts. Once machined, the case undergoes heating in an oven while the specially machined inserts are frozen with liquid nitrogen. These inserts are then precisely pressed into place and machined to achieve a flawless mirror finish. Featuring unique inserts with small passages for essential coolant flow to the deck surface, our closed deck system seamlessly integrates into the block's cooling mechanism. This ensures optimal engine temperature regulation without compromising cooling efficiency, making it suitable for daily driving applications.

BUILT FOR BOOST: FORGED PISTONS
In every IAG 750 Short Block, you'll find IAG Spec JE FSR 99.75mm Forged Pistons. These pistons, made from 2618 T6 Alloy, are meticulously crafted to endure the increased cylinder pressures that come with higher boost levels. Featuring FSR forgings, they effectively reduce mass and friction-induced wear while maintaining robustness. Employing an asymmetrical skirt design rather than the traditional full-round skirt significantly reduces weight without compromising strength. With smooth-flowing radii on the domes and dishes, these pistons promote optimal flame propagation. Ensuring a secure connection to the rods, .905 x 2.250" x .210" wall 9310 steel wrist pins with Tru Arc locks are utilized. These thicker steel wrist pins offer superior support for additional power compared to standard .180" pins.

ALTERNATIVE "HYBRID" PISTONS FOR EJ20 HEADS
Should you intend to pair the IAG 750 Short Block with EJ20 Cylinder Heads, be sure to select the "Hybrid Pistons" option when making your purchase. These specially engineered JE pistons are tailored to enable the use of EJ20 cylinder heads without the need for a chamber matching service on the cylinder heads. This choice is particularly beneficial for international clients who cannot send their cylinder heads for modification. It also proves advantageous for USDM EJ20 owners who opt for 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 Includes:

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