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. IAG's custom pistons feature a lightweight design while increasing strength where you need it and are designed to work exclusively with the IAG +2mm Tri-Beam connecting rods. The wrist pin is short and is made from H13 tool steel and the pin piers are profiled to increase pin boss strut. IAG's pistons feature a 25% larger oil ring for reduced oil consumption and added gas ports that aid ring sealing in high boost conditions.
Stage 4 Tuff Closed Deck Includes:
- Case Halves -Converted to Closed Deck using brand new Subaru OEM case halves, bored and honed to 92.5mm.
- Fire-Lock -IAG Fire-Lock receiver groove machining, latest solution to prevent head gasket failure on high horsepower and high boost Subaru's - *IAG Fire-Lock head gaskets required
- Head Studs -Machine case to fit 14mm head studs - *Head studs sold separately
- Pistons -IAG-Spec JE FSR 92.5mm 2618 Forged Pistons, Electroless Nickel Plated Tops & Ring area, Ring Set, .250" / .906" H13 Wrist Pins, Clips, (Perfect Skirt Coating and Offset Wrist Pins)
- Connecting Rods -IAG-Spec Tri-Beam +2mm w/ ARP 625+ Rod Bolts.
- Rod / Main Bearings -ACL or King Race bearings.
- Crankshaft -New Subaru 2.0L EJ20 Crankshaft with improved oil passages.
- Case / Main Bolts -Standard FHI Subaru case bolts.
Additional Options Available:
- Head Studs -IAG / ARP Spec 14mm head studs, nuts, and washers
- Head Gaskets -IAG Fire-Lock .051" Head Gaskets with IAG-Spec Alloy Ring Set* Required for use with this short block
- Oil Pump -Subaru JDM High Volume Oil Pump, or Subaru 11mm Oil Pump
- IAG Oil Pickup - Upgraded oil pickup featuring heavy gauge steel tubing, 2 point bracket & mesh filter
- IAG Oil Baffle - Upgraded oil control baffle and windage tray
- IAG Oil Pickup & Baffle Set - Upgraded oil pickup, oil control baffle, and windage tray
- Hardware / Seal Option -(Wrist pin plugs, washers, separator cover, bolts, etc. In case you don't want to transfer from the original engine).
Head Gasket Required:
- *IAG Fire-Lock .051" Head Gaskets with IAG-Spec Alloy Ring Set* PN# IAG-ENG-1745
Power: The IAG Stage 4 Tuff Short Block has a power output rating of 1000BHP.
*All IAG short blocks are balanced and blueprinted.
Oil Pickup & Pan Packages:
IAG offers a number of oil pickup, pan, baffle and windage tray options to help you complete your engine build. When utilizing our Oil Pickup with an EJ20 it requires a 2.5L EJ25 oil pan and dipstick for fitment.
About the V2 Oil Pickup:
It's well-known that the OEM oil pickups often crack and fail which in most cases destroys your engine from lack of oil pressure. To avoid the cracking failures seen in the OEM oil pickup tubes, IAG’s oil pickup is manufactured from heavy-gauge steel tubing that is 2x thicker than OEM. It features a machined 3/8" stainless steel flange, which mates to the block with a Viton O-ring. The integrated heavy-duty stainless steel mounting bracket uses two mounting points rather than the OEM single mounting point. Furthermore, the oil pickup features a formed bottom with an OEM style mesh screen for proper filtration. The TIG-welded oil pickup increased material thickness matched with the two-point heavy-duty mounting bracket helps ensure it does not fatigue and fail over time like an OEM unit.
The IAG V2 Oil Pickup is available separately or in one of two types of packages. The first package bundles the pickup with our windage tray and oil control baffle, enabling you to utilize a EJ25 pan of your liking. The second package includes our V2 Oil Pickup along with a Street or Competition Series Baffle and Windage Tray combined with our new Oil Pan.
About The Pans:
IAG's cast aluminum and CNC machined oil pans suit a wide range of street and track applications with fitment for a larger variety of popular headers in mind, while still increasing oil capacity up to 30% over OEM.
The pans incorporate cooling fins to dissipate heat from the oil as air passes over them. The included oil drain plug is integrated into the lower cooling fins at the absolute bottom of the pan to ensure all the waste oil is removed during maintenance changes. The pan is also threaded with 1/8th inch NPT port to accept many popular oil temperature sensors. 1/8th inch NPT plug is also included in the event that the sensor port is not used.
The upper flange mounting surface is CNC machined for better hardware fitment and features a sealing O-ring for easier installation and removal. Furthermore, the pan is designed to use the included OEM style Viton dipstick o-rings with a unique chamfer to aid in the installation of the dipstick.
About Street Series Oil Baffle
Internally, the pan includes our integrated, stainless steel, Street Series Oil Baffle that is designed to prevent oil inside the pan from sloshing around and creating cavitation, which can lead to oil starvation. The baffle is engineered to be removable for future upgrades and easy cleaning.
About Competition Series Oil Baffle
The IAG Competition Series Oil Baffle is designed to limit potential blow-by and prevent oil starvation in your Subaru's WRX / STI EJ engine during high rpm and high g-force driving. The Competition Series Baffle should be used in vehicles that will see track time, however, it is acceptable to run this baffle on the street as well. The Comp Series baffle is configured with Viton one-way flapper valves which hold oil in the area closest to the pickup. Combining the baffle with the louvers in our windage tray, oil is prevented from reentering the upper crankcase area and is directed down into the oil pan to ensure plentiful supply to the oil pickup.
About The Windage Tray:
The job of the windage tray is to help direct oil from the upper crankcase down into the lower crankcase and oil pan area. Manufactured from stainless steel, precision-formed louvers direct oil downwards and help to prevent oil that is draining from the cylinder heads in the lower crankcase area from sloshing upwards into the path of the crankshaft and connecting rods, thus reducing aeration.
Oil Pickup & Baffle Install Notes
- EJ20 Subaru WRX engines require EJ25 STI oil pans and dipstick for fitment
- IAG oil pickup spacer (Part# IAG-ENG-2081SP) is required when using IAG oil pickup with Killer B Oil Pan.
- *Does not work with Moroso oil pans or pickups
Hardware / Seal Option:
Not planning on reusing your original short block service plugs and covers? IAG offers a simple comprehensive cover and seal kit that includes (1) Rear main seal, (3) OEM wrist pin plugs, (3) OEM wrist pin plug washers, (1) OEM separator cover, (6) OEM separator cover bolts, (1) OEM wrist pin service cover, (1) OEM wrist pin service cover O-ring and (2) OEM wrist pin service cover screws. *If you are reusing your original wrist pin service plugs and covers always replace the (3) OEM wrist pin plug washers and (1) wrist pin service cover O-ring before installing a short block to avoid potential leaks. *Never reuse a rear main seal on a new short block.
Please review the PDF document below regarding installation, break-in procedures and warranty information.
PDF Closed Deck Install Guide for 1/2" & 14mm Head Studs
PDF After Sale Document - Contains Shipping, Engine Care and Warranty Information