IAG Subaru Performance Engine Packages
Here is a list of the most common blocks (but not limited to) to get you thinking about your next performance upgrade.
IAG Stage 3 Upgrade
The IAG Stage 3 Extreme Short Block starts with brand new Subaru 2.5L engine case halves.
IAG machines the case halves assembled together in our Haas VF-4SS CNC mill to accept the IAG CLOSED Deck Inserts that transform the block into a solid deck.
The unique inserts feature small passages that allow needed coolant flow to the deck surface. The case halves are then CNC machined with o-ring receiver grooves around the bore surface as well as drilled and tapped to accept larger 1/2" head studs that aids in preventing cylinder heads from lifting in high boost applications.
Next, the short block is Deck Plate bored and honed to 99.75mm in our in-house Sunnen SV-30 the most advanced automotive cylinder hone available. IAG‘s in-house honing process is able to set custom piston to wall clearances to best fit your needs. The modified case halves are then assembled using a new 2017+ Subaru 2.5L nitride treated STI crankshaft that is matched to ACL or King race main bearings. Manley Turbo Tuff Tri-Beam connecting rods and ARP rod bolts are utilized along with ACL or King race rod bearings.
The case halves are sealed with new OEM main/case bolts and sealant (upgrade to ARP mains and line hone service a la carte). IAG-Spec JE FSR 99.75mm Forged Pistons are chosen to finish the Stage 3 Extreme short block.
Stage 3 Extreme Closed Deck Includes:
Case Halves - Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 99.75mm.
O-Ringing - Machine and O-Ringed Deck Surface
Head Studs - Machine case to fit 1/2" head studs - *Head studs sold separately
Pistons - IAG-Spec JE FSR 99.75mm 2618 Forged Pistons, Ring Set, .180" Chromoly wrist pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins)
Connecting Rods - Manley Turbo Tuff Tri-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.
Additional Options Available:
Head Studs - IAG Performance 1/2" head stud set manufactured by ARP - $499.99
Oil Pump - Subaru JDM 12mm High Volume Oil Pump - $219 or 11mm Subaru Oil Pump - $199.95
IAG Oil Pickup - Upgraded oil pickup featuring heavy gauge steel tubing, 2 point bracket & mesh filter - $129.99
Head Gaskets - JE Pro Seal .039" Head Gaskets - (PN# SB1001-039 for D25 & B25 Heads, PN# SB1003-039 for V25, W25 & N25 Heads)
Hardware / Seal Option - $105.99 (Wrist pin plugs, washers, separator cover, bolts, etc. In case you don’t want to transfer from the original engine).
Compression Ratio:
8.5:1 on D Cylinder Heads (EJ255)
8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.
Head Gasket Recommendations:
*IAG Recommends JE Pro Seal .039 inch head gaskets
JE PN# SB1001-039 are for use with S20, B25 & D25 Cylinder Head Castings (2004-06 STI, 06-14 WRX, 04-13 FXT, 05-12 LGT, 02-05 WRX)
JE PN# SB1003-039 are for use with V25, W25 & N25 Cylinder Head Casting (2007-19 STI)
Power: The IAG Stage 3 Extreme Short Block has a power output rating of 800BHP.
IAG Stage 2 Upgrade
The IAG Stage 2 Short Block is designed for modified EJ25 Subaru's that need a beefed-up performance short block.
The IAG Stage 2 short block builds off the Stage 1's strengths by adding IAG Spec H-Beam forged connecting rods. The upgraded rods and bearings are able to support additional engine load produced by larger turbochargers that the OEM STI rods cannot support reliably.
Each IAG Stage 2 Short Block starts with new Subaru 2.5L 99.5mm stock bore EJ25 engine case halves as standard. The short block is measured and assembled using a new 2017+ Subaru 2.5L nitride treated STI crankshaft that is matched to ACL or King race main bearings. IAG-Spec H-Beam rods and ARP2000 rod bolts are utilized along with ACL or King race rod bearings.
The case halves are sealed with new OEM main case bolts and sealant. Finally, IAG-Spec JE 99.5mm Forged Pistons are spec'd and installed finishing off the short block.
Stage 2 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 bolts
Power: The IAG Stage 2 Short Block has a power output rating of 575BHP.
*All IAG Short Blocks are balanced and blueprinted.
Compression Ratio: 8.5:1 on D Cylinder Heads (EJ255)
Compression Ratio: 8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.
IAG Stage 1 Upgrade
The IAG Stage 1 Short Block is perfect for lightly modified EJ25 Subaru's that need a basic and reliable performance short block.
Subaru turbo engines are commonly known for piston ring land failures and if gone unchecked lead to rod knock and total engine failure due to oil starvation from blow by. IAG's Stage 1 Short Block includes upgraded forged pistons along with performance main and rod bearings that replace the OEM components that are prone to common failure on Stage 2 and up vehicles.
Each IAG Stage 1 Short Block starts with a new Subaru 2.5L 99.5mm bore EJ25 engine case halves as standard. The short block is measured and assembled using a new 2017+ Nitride Treated Subaru 2.5L STI crankshaft that is matched to ACL or King main bearings. Early style OEM STI rods are utilized along with ACL or King rod bearings.
The case halves are sealed with new OEM case bolts and sealant. Finally, 99.5mm IAG-Spec JE Forged Pistons are spec'd and installed finishing off the short block.
Power: The IAG Stage 1 Short Block has a power output rating of 475BHP.
*All IAG short blocks are balanced and blueprinted.
Compression Ratio: 8.5:1 on D Cylinder Heads (EJ255)
Compression Ratio: 8.2:1 on B, V and W EJ257 Heads with standard thickness gasket.
All information is represented from IAG performance.