IAG Performance 550 Short Block Includes: Case Halves - Subaru Models (Inc. 2002-2021 Subaru WRX / 2004-2021 STI / 2004-2013 Forester)

CRAFTED FOR RESILIENCE

Specifically designed to meet the demands of modified EJ25 Subarus seeking increased strength in the short block to endure elevated cylinder pressures from added boost, the IAG 550 Short Block excels in performance. Featuring IAG Spec H-Beam forged connecting rods, this short block incorporates enhanced elements, such as race bearings, adept at accommodating the heightened engine load resulting from larger turbochargers or heightened boost levels—demands that surpass the reliable capabilities of the OEM STI rods found in standard short blocks.

ASSEMBLED USING 100% FRESH COMPONENTS

The IAG 550 Short Block commences with entirely new EJ25 Subaru 2.5L engine case halves, maintaining a standard 99.5mm stock bore. These case halves undergo precise measurement and assembly procedures, incorporating a newly introduced 2017+ Subaru 2.5L nitride-treated STI crankshaft, meticulously matched with ACL or King race main bearings. Featuring IAG Spec H-Beam Connecting Rods with ARP2000 rod bolts, accompanied by ACL or King race rod bearings, this short block is meticulously sealed with new OEM main case bolts and sealant. Bringing the assembly to completion, IAG Spec JE 99.5mm Forged Pistons are thoughtfully selected, measured, and expertly installed.

FORGED PISTONS TAILORED FOR BOOST

The IAG 550 Short Block stands out with its inclusion of IAG Spec JE 99.5mm Forged Pistons. Crafted from 2618 T6 Alloy, these high-strength pistons are purposefully designed to endure heightened cylinder pressures associated with increased boost. The unique asymmetrical skirt design, departing from the conventional full-round skirt, not only provides strength but also significantly reduces weight. Featuring smooth-flowing radii on the domes and dishes, this design enhances flame travel. The connection between pistons and rods is secured by .905 x 2.250" x .180" wall carbon steel wrist pins equipped with Tru Arc locks, ensuring reliable performance in boosted conditions.

IAG 550 Short Block Includes:

• Case Halves -Brand new Subaru OEM case halves 99.5mm stock bore
• Pistons -IAG-Spec JE 99.5mm 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