RallySport Direct now carries highly sought-after high-performance upgrades and accessories brought to you by IAG Performance.
This is the IAG Performance Stage 5 Cylinder Head Package With Combustion Chamber Mod.
These heads utilize a CNC porting program for the S20 heads that have been developed over the past 5 years, and they have been tested on the most successful high-horsepower Subarus. These begin as brand new S20 head castings directly from Subaru Of America, where they are visually inspected and then fixtures at IAG's in-house Centroid 5-axis CNC machine which is considered to be of the most advanced piece of precision engine machining equipment available worldwide.
Centroid 5-Axis CNC machined in-house at IAG
The Centroid ports the intake and hard to reach exhaust "dog-leg" port runners
Everything starts with brand new Subaru S20 head castings that are visually inspected
The Centroid 5-Axis offers consistent port results that are hard to achieve by hand
COMBUSTION CHAMBER MODIFICATION
Once the Centroid completes the port process the heads receive the combustion chamber modification
The shapes of the chamber are machined to reduce compression and to improve the burn path
The heads then undergo a cam clearance machining process that removes material from the lifter area where large duration cam profiles are known to contact the castings
Short after, the heads are drilled to fit larger 1/2" or 14mm head studs which are commonly used in high-horsepower builds
COMPONENTS AND MACHINING PROCESS
The OEM guides get pressed out
Installed are Ferrea Copper / Bronze valve guides that offer greater heat dissipation and lubricity properties
The intake and exhaust guides are then diamond-honed
The heads are fixtured with IAG's Serdi 3.0 Valve Guide And Seat Machine
All intake and exhaust seats are cut with a multi-angle valve job that suits the flow characteristics of Ferrea Comp Plus +1mm valves
The head decks are resurfaced using IAG's TS-3000 BlockMate that cuts the aluminum to a smooth even finish
The heads are then ultrasonically cleaned to remove debris and oil from the machining process
(2) Brand new Subaru S20 cylinder head castings
(8) Ferrea 37mm (+1mm) Comp Plus intake valves
(8) Ferrea 33mm (+1mm) Comp Plus exhaust valves
(16) Ferrea Dual Valve Springs with Titanium Retainers
(16) Ferrea Copper / Bronze Valve Guides
(16) Ferrea 6mm intake and exhaust valve stem seals
IAG Performance CNC porting
Multi-angle valve job
Drilling for compatibility for 1/2" or 14mm head studs
Note: Workmanship/parts warranty will only be available for professionally installed cylinder heads.