IAG PerformanceIAG Stage 4 Tuff EJ20 Subaru Closed Deck Short Block for 02-05 WRX.

IAG Stage 4 Tuff Subaru EJ20 Closed Deck Short Block. The IAG Stage 4 Tuff Short Block starts with brand new Subaru 2.0L engine case halves. IAG machines the case halves assembled together in our Haas VF-4SS CNC mill 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 Stage 4 Tuff case is then drilled and tapped to accept 14mm head studs that combined with the IAG Fire-Lock head gasket set greatly reduces head gasket failure during high cylinder pressure scenarios. Next, the short block is Deck Plate bored and honed to 92.5mm in our in-house Sunnen SV-30 the most advanced automotive cylinder hone available. IAG's in-house honing process is able to set custom piston to wall clearances to best fit your needs. The modified case halves are then assembled using a new Subaru 2.0L WRX crankshaft with improved oil passages that is matched to ACL or King race main bearings. Custom IAG TRI-BEAM +2mm connecting rods by Manley and ARP 625+ rod bolts are utilized along with ACL or King race rod bearings. The case halves are sealed with new OEM main/case bolts and sealant (upgrading to ARP mains requires line honing). Finally, IAG-Spec 92.5mm JE FSR 2618 Forged Pistons with electroless nickel plated tops and ring area as well as upgraded .250" / .906" H13 wrist pins are added to finish the Stage 4 Plus block.