The IAG 1150 Short Block is designed for those who plan to drag race their high horsepower Subarus regularly. While still a streetable block, the IAG 1150 is designed for the track. This block includes additional features to further strengthen the OEM case halves including Stage 4 Closed Decking and pinned mains secured with ARP case hardware. Our record-setting "Fire-Lock" Head Gasket system and 14mm head studs are used to ensure a tight seal even in extreme conditions. The IAG 1150 Short Block features IAG Spec "Tri-Beam" +2mm forged connecting rods. An IAG Spec Billet Crankshaft is used to support additional oiling and prevent main bearing distortion. The upgraded block, billet crank, connecting rods, race bearings, and forged pistons are able to support additional engine load produced by the largest turbochargers and the most demanding uses including competition drag racing.

Every IAG Short Block is built with 100% new components. The modified case halves are assembled using an IAG-Spec Billet crankshaft that is matched to ACL or King race main bearings. Custom IAG TRI-BEAM +2mm connecting rods with ARP 625+ rod bolts are utilized, along with ACL or King race rod bearings. The case halves are sealed with OEM sealant and ARP main bolts. The IAG-Spec 99.75mm Custom Forged Pistons with .250" / .927" wrist pins as well as electroless nickel plated tops and ring area are chosen to finish the Stage 4 Extreme Short Block.

The IAG 1150 Short Block starts with brand new Subaru 2.5L EJ25 engine case halves. The case halves are split and the main webs are CNC machined in our Haas VF-4SS CNC mill for 9.5mm pins to reduce distortion and movement of the case in extreme conditions. The case halves are then reassembled and IAG machines the case 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 for our new Fire-Lock™ head gasket solution that is loosely derived from diesel technology where a counterbore step is machined around each cylinder bore allowing specially sized fire rings to drop into the machined area and head gasket bores. The IAG 1150 case is CNC drilled and tapped to fit 14mm head studs. Utilizing the new Fire-Lock™ gasket solution, along with larger IAG / ARP 14mm head studs, nuts, and washers reduce the chances of the heads lifting under extreme boost conditions. The short block is then Deck Plate bored and honed to 99.75mm in our in-house Sunnen SV-30 cylinder hone. IAG's in-house honing process is able to set custom piston to wall clearances to ensure performance an reliability.

The IAG 1150 Short Block uses our strongest pistons ever - The IAG-Spec 99.75mm Custom Forged Pistons with .250" / .927" wrist pins feature electroless nickel plated tops and ring area. IAG's custom pistons feature a lightweight design while increasing strength where you need it and are designed to work exclusively with the IAG +2mm Tri-Beam connecting rods. The wrist pin is short and is made from strong H13 tool steel. The pin piers are profiled to increase pin boss strut. Finally, IAG's pistons feature a 25% larger oil ring for reduced oil consumption and added gas ports that aid ring sealing in high boost conditions.

The IAG 1150 CNC Ported Drag Cylinder Heads are designed for drag racing and competition. These fully CNC ported heads provide a significant upgrade in long term performance over the IAG 950 heads. These heads work great for cars where getting the most power with maximum reliability is the goal. The IAG 1150 heads are the best heads available for high-horsepower drag racing. They are designed to support up to 1150 BHP with supporting mods. These heads include upgraded Ferrea Comp Plus Valves, GSC Viton Valve Stem Seals, Upgraded GSC Valve Guides, Ferrea Dual Drag Valve Springs with Titanium Retainers, and Ferrea Keepers. GSC S2 or S3 Camshafts are available with OEM valve lifter buckets.

Each IAG 1150 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 S2 or S3 Camshafts and OEM Lifter Buckets for valve adjustment.

This IAG 1150 fully CNC ported head package starts with brand new WRX STI OEM head castings directly from Subaru of America. The bare castings are visually inspected then fixtured into our in-house Centroid 5-axis CNC Machine. The Centroid CNC ports the intake and hard to reach exhaust "dog-leg" port runner. The benefit of CNC porting is not only an efficient way of machining the heads it also offers consistent port results that are hard to achieve by hand. Once the Centroid completes the port process the heads undergo a cam clearance machining process that removes material from the lifter area where large duration cam profiles are known to contact the castings. Shortly after the heads are drilled to fit larger 1/2" or 14mm head studs, which are commonly used in high horsepower builds. Next, the OEM guides are pressed out and replaced in favor of GSC Manganese-Bronze valve guides that are shaped to improve airflow. Once all the new intake and exhaust guides are in place they are diamond-honed in our honing station. The heads are then 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 Ferrea's +1mm 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 Ferrea Drag Springs and Retainers along with Ferrea Viton stem seals.

Cylinder head porting has been around since the invention of the internal combustion engine. It can be done by hand with a die grinder and some cartridge rolls, and a seasoned professional can likely get a good result that way. Unfortunately, doing porting this way requires a lot of experience and care. One slip of the die grinder can ruin your cylinder head. This is where CNC porting comes in. Using our Centroid 5 axis CNC porting machine we can achieve the same results every time we put a set of heads into the machine. Every cylinder head comes out exactly the same and uses our race-proven, computer controlled, CNC porting program to guarantee results.

To get the most out of these heads you'll want to select the GSC Power-Division billet S2 camshafts for your IAG 1150 Head Package. These cams are built to suit the higher horsepower these heads will support. With a power range of 500 WHP and up, you need some additional supporting mods to utilize the true potential of the S2s. Our IAG 1150 Short Block, an upgraded turbocharger and fuel system, and a quality engine management system are key.

If you're targeting maximum power over 1000 whp and willing to give up some low end drivability, the GSC S3 cams are the way to go. PLEASE NOTE THAT THESE CAMS REQUIRE A STANDALONE ECU AND MAY NOT FUNCTION CORRECTLY WHEN AVCS IS USED. Along with the camshafts we'll include all new OEM valve lifter buckets and set valve lash so the engine will be ready to install and run.