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IAG : Performance 550 2.5L Long Block Engine w/Street Heads - (EJ25)

IAG : Performance 550 2.5L Long Block Engine w/Street Heads - (EJ25)

Regular price $18,999.95 AUD
Regular price $22,174.00 AUD Sale price $18,999.95 AUD
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The IAG 550 Long Block has a power output rating of 550BHP.


The IAG Performance Hand-Built 550 Subaru EJ25 Long Block Packages are a complete, valve cover to valve cover, crate engine. These long block engines offer significant ease of installation for customers seeking a complete "drop-in" engine package for their Subaru WRX, STI, Forester XT or Legacy GT. The Long Blocks feature a combination of our proven IAG 550 Performance Short Block and IAG 550 Cylinder Head package, along with other race-proven components to complete the assembly. When paired with our Long Block Installation Packages, you have a true plug-and-play solution to get you back on the road, FAST! All components included are BRAND NEW and there is NEVER A CORE CHARGE required.


The IAG 550 package is ideal for clients looking for a long block engine package to support up to 550 BHP applications. The IAG 550 long block features our highly popular IAG 550 Short Block that utilizes a brand new EJ25 Subaru case, 99.5mm IAG-Spec JE forged pistons, IAG Spec H-Beam connecting rods and OEM STI Crank. The block is then paired up with our IAG 550 Cylinder Head Package which features Subaru WRX STI OEM cylinder head castings and GSC valvetrain components. To complete the package, we add an 11mm ARP 2000 head stud set and all required gaskets for the final valve cover-to-valve cover assembly.


Each IAG 550 Short Block starts with brand new EJ25 Subaru 2.5L, 99.5mm stock bore engine case halves as standard. The case haves are carefullly measured and assembled using a new 2017+ Subaru 2.5L nitride treated STI crankshaft, which is matched to ACL or King race main bearings. The IAG 550 Short Block features IAG Spec H-Beam Connecting Rods with ARP2000 rod bolts, 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 carefully selected, measured, and installed to finish off the short block.


The IAG 550 Short Block is designed for modified EJ25 Subarus that need a stronger short block to support increased cylinder pressures created by additional boost pressure. The IAG 550 short block features IAG Spec H-Beam forged connecting rods. The upgraded connecting rods and race bearings are able to support additional engine load produced by larger turbochargers or increased boost which the OEM STI rods found in the Stock short blocks cannot support reliably.


Each IAG 550 Short Block features IAG Spec JE 99.5mm Forged Pistons. These 2618 T6 Alloy high-strength pistons have been specifically designed to support increased cylinder pressures which come with more boost. This is accomplished by using an asymmetrical skirt design instead of the traditional full-round skirt, also this reduces weight significantly. 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 .180" wall carbon steel wrist pins with Tru Arc locks.


The IAG 550 Cylinder Heads are designed to function as an entry-level replacement for stock OEM heads. If your engine has suffered a catastrophic failure which requires replacement of your cylinder heads, or if you don't have OEM heads to start with, the IAG 550 Cylinder Heads are a perfect solution. These heads also work great for cars with basic bolt-on parts up to 550 BHP. These heads include upgraded GSC standard size valves, GSC Viton Valve Stem Seals, IAG Stage 1 Valve Springs with Titanium Retainers, and OEM Keepers. GSC S1 Camshafts are available with OEM valve lifter buckets.


Each IAG 550 Cylinder Head Set starts with new OEM castings from Subaru of America. The first step is to select your Year and Model of vehicle so that we may provide you with the right castings to fit your project. Next, you'll select whether or not you want to include our optional GSC camshaft package. If selected, these heads will include new GSC S1 Camshafts and OEM Lifter Buckets for valve adjustment.

The bare castings are visually inspected and then fixtured into our in-house Centroid 5-axis CNC Machine. In the Centroid, the heads undergo a cam clearance machining process which removes material from the lifter area where larger lift and duration cam profiles are known to contact the castings. (Just in case you want to go bigger later.) Then the heads are fixtured in our Newen Valve Guide and Seat Machine to cut all intake and exhaust seats with a multi-angle valve job that suits the flow characteristics of GSC's standard size 36mm Intake and 32mm Exhaust valves. At this point, the heads' decks are resurfaced using our TS-3000 BlockMate, which cuts the aluminum to a smooth, even finish. Next, the heads are ultrasonically cleaned to remove debris and oils from the machining process. Finally, the heads are reassembled using GSC Stainless Intake and Exhaust Valves, GSC Viton stem seals, IAG-Stage 1 Valve Springs with Titanium Retainers, and OEM Valve Keepers.


The included GSC Power-Division billet S1 camshafts for your IAG 550 Head Package will not drop any low end power, and will create more power and torque across the entire RPM range. These are perfect for stock frame upgraded turbos or up to 500 WHP upgrades. Along with the camshafts we'll include all new OEM valve lifter buckets and set final lash.


We stand behind every hand-built engine we produce. IAG's Standard Long Block Workmanship Warranty covers your long block for 12 months or 12,000 miles. 



IAG 550 EJ25 Short Block:

  • 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 -¬†IAG Spec H-Beam Rods w/ ARP2000 Rod Bolts
  • Rod / Main Bearings -¬†ACL or King Bearings
  • Crankshaft -¬†Standard New Subaru Nitride Treated 2017+ STI Crankshaft
  • Case / Main Bolts -¬†Standard FHI Subaru case bolts

IAG 550 Cylinder Heads:

  • Heads -¬†Brand New Subaru OEM WRX STI Cylinder Head Castings
  • Intake Valves -¬†GSC 36mm (Standard) Intake Valves
  • Exhaust Valves -¬†GSC 32mm (Standard) Exhaust Valves
  • Springs / Retainers -¬†GSC Valve Springs & Titanium Retainers
  • Guides -¬†OEM Valve Guides
  • Valve Seals -¬†GSC Valve Stem Seals
  • Lifters -¬†OEM Lifter Buckets
  • Camshafts -¬†GSC Stage 1 Billet Camshafts
  • Multi-Angle Valve Job
  • Machined Cam Lobe Clearance
  • Resurface
  • Ultrasonic Cleaning
  • Final Lash

Gaskets, Hardware & Accessories:

  • Head Studs -¬†ARP 2000 11mm Set
  • Head Gaskets -¬†OEM
  • Valve Cover Gaskets -¬†OEM
  • Cam Seals -¬†OEM
  • Valve Covers -¬†OEM
  • Wrist Pin Seal, Rear Main Seal & Separator Kit
  • Crankshaft Woodruff Key


Vehicle Fitment:

Additional hardware may be required to install this long block to the following vehicles, including but no limited to ECU, Sensors, Ancillaries, Covers, Pumps etc.

  • 1999-2014 Subaru WRX
  • 1999-2021 Subaru STI
  • 1997-2013 Subaru Forester XT
  • 2004-2009 Subaru Liberty GT
  • 2004-2009 Subaru Outback XT
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