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Stage 3 EJ25 Closed Deck Case - 1/2" H.S.M. 99.75mm Bore & Hone

JGJS_IAG-ENG-1813
In stock
Engine Long Block
$3,850.97
IAG's Closed Deck converted case halves were created to be the most affordable and cost-effective short...
Size Guide
$3,850.97

Stage 3 EJ25 Closed Deck Case - 1/2" H.S.M. 99.75mm Bore & Hone
IAG's Closed Deck converted case halves were created to be the most affordable and cost-effective short block modification for EJ25 Subaru turbo engines. The deck surface is machined to accept specially CNC'd cast inserts that strengthen the weakest point of the OEM case at the upper sleeve. The case halves are then CNC drilled and tapped to accept 1/2 inch head studs that greatly reduce headgasket failure during high cylinder pressure scenarios. The case is bored and honed to 99.75mm in our Sunnen SV-10 that allows you to set a piston to wall clearance tighter for a quieter engine. IAG's Closed Deck is suitable for street or race use. The factory Subaru EJ25 case is referred to as a semi-open (or semi-closed) deck. The block is essentially an open deck with 3 narrow supports tying in the main case to the tops of the sleeves. This feature was a slight improvement over the EJ20 case, which was a completely open deck with no support. The purpose of the deck supports is to keep the sleeve from moving. While conceptually this is an improvement, the reality is that it simply isn't enough for a high horsepower Subaru. The weakest point of the sleeve is still left open and unaddressed. Our machining process converts the semi-open deck to a complete closed deck. This design features the use of cast insert material that closely matches the metallurgy of the aluminum case material in a factory Subaru EJ engine block. By using a similar cast material, we ensure that during expansion and contraction the materials grow and shrink at similar rates, which is vital for maintaining roundness within the top of the bore. The outer inserts are machined from 3/4 inch cast material and the inner inserts from 1-inch cast material. Once the deck is surfaced, the result is a true 1/2 inch finished outer insert thickness and true 3/4 inch finished inner insert thickness. The IAG Closed Deck conversion is performed 100% in-house by our engineers and experts using state-of-the-art equipment.
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