IAG Stage 1 Short Block
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.
Stage 1 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 Steel Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pin)
- Connecting Rods - Early OEM (Stronger Style) STI rods
- Rod / Main Bearings - ACL or King Bearings
- Crankshaft - Standard New Subaru Nitride Treated 2017+ STI Crankshaft
- Case / Main Bolts - Standard FHI Subaru case bolts
Additional Options Available:
- IAG Oil Pickup - Upgraded oil pickup featuring heavy gauge steel tubing, 2 point bracket & mesh filter - $129.99
- IAG Oil Baffle - Upgraded oil control baffle and windage tray - $199.99
- IAG Oil Pickup & Baffle Set - Upgraded oil pickup, oil control baffle, and windage tray - $299.99
- Hardware / Seals - OEM cover and seal kit - $105.99
Power: The IAG Stage 1 Short Block has a power output rating of 500BHP.
*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.
Oil Pickup / Oil Control Baffle / Windage Tray Options:
The IAG Performance Subaru WRX / STI oil pickup was designed by Tigwerks to replace the OEM EJ25 oil pickup, which is prone to failure. It’s a well-known fact that the OEM oil pickups often crack and fail which, in most cases, destroys your engine from lack of oil pressure. To avoid the cracking failures seen in the OEM oil pickup tubes, the Tigwerks oil pickup is manufactured from heavy-gauge steel tubing that is 3x thicker than OEM. Additionally, it features a flange machined from 3/8” 1018 CR steel to mate with the block, sealed with a Viton O-ring. The integrated heavy-duty mounting bracket uses two mounting points rather than the OEM single mounting point. Furthermore, the oil pickup features a formed bottom with an OEM style mesh screen for proper filtration. The TIG-welded oil pickup's increased material thickness, matched with the two-point heavy-duty mounting bracket, helps ensure that it does not fatigue and fail over time like an OEM unit.
The IAG Oil Control Baffle and Windage Tray System is designed to limit potential blow-by and prevent oil starvation in your Subaru’s WRX / STI EJ engine during high rpm and high g-force driving. Through the use of Viton one-way flapper valves on our baffle and louvers in our windage tray, oil is prevented from reentering the upper crankcase area and is directed down into the oil pan to ensure plentiful supply to the oil pickup. IAG’s integrated two-piece Oil Control Baffle and Windage Tray System is designed to work with our own oil pickup, as well as other oil pickups*. The baffle fits neatly in the engine crankcase area, allowing normal installation of the OEM oil pan and popular aftermarket pans*.
Oil Pickup & Baffle Install Notes
EJ20 Subaru WRX engines require EJ25 oil pans for fitment
- IAG oil pickup spacer (Part# IAG-ENG-2081SP) is required when using IAG oil pickup with Killer B Oil Pan.
- *Does not work with Moroso oil pans or pickups
Hardware / Seal Option:
planning on reusing your original short block service plugs and covers?
IAG offers a simple comprehensive cover and seal kit that includes (1)
Rear main seal, (3) OEM wrist pin plugs, (3) OEM wrist pin plug washers,
(1) OEM separator cover, (6) OEM separator cover bolts, (1) OEM wrist
pin service cover, (1) OEM wrist pin service cover O-ring and (2) OEM
wrist pin service cover screws. *If you are reusing your original wrist
pin service plugs and covers always replace the (3) OEM wrist pin plug
washers and (1) wrist pin service cover O-ring before installing a short
block to avoid potential leaks. *Never reuse a rear main seal on a new
Please review the PDF document below regarding installation, break-in procedures and warranty information.
WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer and reproductive harm. For more information, visit www.P65Warnings.ca.gov.