IAG Stage 4 Cylinder Head Package w/ Combustion Chamber Mod Includes GSC S2 Camshafts

RallySport Direct now carries highly sought-after high-performance upgrades and accessories brought to you by IAG Performance. 

 

This is the IAG Performance Stage 4 CNC Ported Heads With +1MM GSC Valves And GSC Billet S2 Camshafts 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. 

 

FEATURES:

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 GSC Manganese-Bronze valve guides that are shaped to improve airflow

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 GSC's +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

The heads are then reassembled using GSC Billet S2 camshafts

 

INCLUDES:

(2) Brand new Subaru S20 cylinder head castings

(8) GSC 37mm (+1mm) intake valves

(8) GSC 33mm (+1mm) SuperAlloy exhaust valves

(16) GSC Beehive springs and retainers

(16) GSC Manganese-Bronze valve guides

(16) GSC valve stem seals

(16) OEM lifter buckets

GSV Billet S2 Camshafts

IAG Performance CNC porting

Multi-angle valve job

Drilling for compatibility for 1/2" or 14mm head studs

Cam clearancing

Resurface

Ultrasonic cleaning

Bench lashed

 

GSC BILLET S2 CAMSHAFT FEATURES:

272-degree intake/exhaust duration

234-degree intake/exhaust duration @ 0.040

Intake/exhaust peak lift 10.25mm

Intake center-line - 110 degrees

Exhaust center-line 115 degrees

Note: Workmanship/parts warranty will only be available for professionally installed cylinder heads