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The JE Pistons Ultra Series forged piston kit for Subaru EJ257 STI engines combines 2618 aluminum construction with premium features for demanding performance builds. A thermal barrier crown coating helps manage combustion heat, while the skirt coating reduces friction and wear along the cylinder wall. Lateral gas ports and an accumulator groove support ring sealing, and the 9310 steel wrist pins add strength where cylinder pressure places high loads on the assembly. Built around JE's Forged Side Relief (FSR) architecture, these pistons bring a focused combination of material strength, surface treatments, and application-specific dimensions to your engine build. Supplied as a set of four with piston rings included.
| Specification | Details |
|---|---|
| Brand | JE Pistons |
| Manufacturer Part Number | 361329 |
| SKU | JEP361329 |
| UPC | 193564036803 |
| Series | JE Ultra Series |
| Engine Application | Subaru EJ257 STI engines |
| Engine | EJ Series |
| Cylinder Head | EJ257 STI |
| Compression Ratio | 8.5:1 |
| Connecting Rod Length | 5.138 in |
| Engine Stroke | 3.110 in |
| Engine Displacement | 2457 cc |
| Vehicle Make | Subaru |
| Engine Type | Internal Combustion |
| Bore Diameter | 100.00 mm |
| Compression Height | 1.209 in |
| Piston Material | Forged 2618 Aluminum |
| Piston Quantity | 4 |
| Piston Design | Forged Side Relief (FSR) |
| Piston Crown | Dished |
| Piston Volume | -17.30 cc |
| Average Piston Weight | 430 g |
| Piston Rings Included | Yes |
| Associated Part Number | JG4901-3937 |
| Top Ring Thickness | 0.0475 in |
| Second Ring Thickness | 0.0480 in |
| Oil Ring Thickness | 0.0995 in |
| Top Ring Groove Width | 0.04750 in |
| Second Ring Groove Width | 0.04800 in |
| Oil Ring Groove Width | 0.09950 in |
| Wrist Pin Diameter | 0.905 in |
| Wrist Pin Length | 2.250 in |
| Wrist Pin Wall Thickness | 0.210 in |
| Wrist Pin Material | 9310 Nickel Carbon Steel Alloy |
| Piston-to-Wall Clearance | 0.0040 in |
| Intake Valve Relief Diameter | 1.550 in |
| Intake Valve Relief Depth | 0.230 in |
| Intake Valve Relief Angle | 22° |
| Exhaust Valve Relief Diameter | 1.550 in |
| Exhaust Valve Relief Depth | 0.230 in |
| Exhaust Valve Relief Angle | 22° |
| 3D Undercrown Milling | No |
| Accumulator Groove | Yes |
| Anodized Top Ring Groove | No |
| Combo 2 | No |
| Contact Reduction | No |
| Double Pin Oilers | No |
| DVGP | No |
| Economy Undercrown Milling | No |
| EN Plating | No |
| Gas Distribution | No |
| Lateral Gas Ports | Yes |
| Milled Undercrown | No |
| Precision Pin Fit | Yes |
| Skirt Coating | Yes |
| Smooth Crown Finish | No |
| Thermal Crown | Yes |
| Tuff Skirt | No |
| Ultra Dome | No |
| Ultra Groove | No |
| Ultra Groove with Gas Port | No |
| Vertical Gas Ports | No |
| Product Type | Engine Piston Kit |
| Product Market | Sport Compact |
| Industry | Automotive |
| Country of Manufacture | USA |
