IAG 800 CNC Pocket Ported AW20 Competition Cylinder Head Package (No Cams Towers Lifters Or Rockers) For 2015-21 WRX

The IAG 800 CNC Pocket Ported Competition Cylinder Heads are designed with the weekend racer in mind. These CNC pocket ported heads provide a significant upgrade in flow over the IAG 600 heads. These heads work great for cars with some race track duty (road, rally, auto-x, drag) and are designed to support up to 800 BHP with supporting mods. These heads include upgraded GSC +1mm Stainless Steel Valves, GSC Viton Valve Stem Seals, Upgraded GSC Valve Guides, Kelford Dual Valve Springs with Titanium Retainers, and OEM Keepers. FA20 Heads are configured differently from their EJ counterparts. In FA20 heads the casting is split into two parts, the "lower" and the "cam towers." As the name suggests, the "Cam Towers" hold the camshafts to the cylinder head. Kelford "A" cams are available with IAG 800 Cylinder Heads. When Kelford cams are chosen we also include new OEM cam towers, rockers, pivots, and valve shim caps.

Each IAG 800 FA20 DIT Cylinder Head Set starts with new OEM castings from Subaru of America. Next, you'll select whether or not you want to include our optional Kelford camshaft package. If selected, these heads will include Kelford "A" camshafts as well as new OEM cam towers, rockers, pivots, and valve shim caps.

The bare castings are visually inspected and the OEM guides are pressed out. The heads are then fixtured into our in-house Centroid 5-axis CNC Machine, one of the most advanced precision engine machining equipment in the world. The Centroid CNC performs a "pocket port" of the area under the valves, enlarging and blending the opening under the valves. 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 porting process the heads are drilled to fit larger 1/2" or 14mm head studs which are commonly used in high horsepower builds. Next, the OEM press-fit freeze plugs are removed, to avoid a common known failure in which they loosen and leak coolant into the engine oil as well as externally. To eliminate this problem each head is tapped and threaded plugs are installed. At this point, GSC Manganese-Bronze valve guides that are shaped to improve airflow are pressed into place then all the new intake and exhaust guides 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 GSC's +1mm valves. The heads decks are then resurfaced using our TS-3000 BlockMate that cuts the aluminum to a smooth even finish. To remove debris and oils from the machining process, the heads are ultrasonically cleaned. Finally, the heads are reassembled using Kelford Dual Cylindrical Valve Springs and Retainers along with GSC Viton stem seals.

Pocket porting is enlarging and blending the area under the valve seat. This is one of the most critical areas to get right in any porting job. Luckily, our Centroid 5 axis cylinder head porting machine gets it perfect every time. The area about 1" under the valve is enlarged and blended to ensure a smooth transition and increase power. The rest of the port is left alone because additional volume is not required at these power levels, and can even hurt velocity if there's not enough airflow.

If you're planning for more power you'll want to select these Kelford "A" camshafts for your IAG 800 Head Package. These cams are perfect for those seeking more power for their modified FA20 WRX. These cams will support up to 800 BHP. Along with the camshafts we'll include all new OEM cam towers, rockers, pivots, and valve shim caps. Finally, we'll take care of setting bench lash using our specially designed fixture. (FINAL LASH SHOULD BE CHECKED AND ADJUSTED ONCE HEADS ARE INSTALLED)

Subaru made some interesting cost-cutting decisions when developing the FA20 cylinder heads. One such measure was the use of pressed in casting or "freeze" plugs on the head castings. These plugs are designed to cover the holes left during the casting process and contain the coolant inside the cylinder head. Unfortunately, the pressed in plugs have a tendency to become loose, and if they pop out you'll have oil and coolant mixing inside your timing cover and causing a huge mess and possibly costing you a new engine. We've developed a solution for this problem which involves carefully threading the opening for the casting plugs and installing new, threaded plugs that wont pop out. This is a must when going for higher horsepower in your FA20 equipped WRX.