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The JE Pistons Ultra Series piston kit for Subaru EJ257 STI brings premium racing features to your performance engine build. Forged in the USA from 2618 aluminum, Ultra Series pistons combine application-specific engineering with thermal barrier crown coating, coated skirts, lateral gas ports, and high-strength 9310 alloy wrist pins. The crown coating helps manage heat at the piston, while the skirt coating reduces friction and wear. Lateral gas ports support top-ring sealing under demanding cylinder pressures, and the FSR forging keeps the design focused on strength and reduced reciprocating weight. Supplied with piston rings, this kit provides a complete set of four pistons for a serious street, track, or competition engine.
| Specification | Details |
|---|---|
| Brand | JE Pistons |
| Manufacturer Part Number | 361327 |
| Series | JE Ultra Series |
| Engine Application | Subaru EJ257 STI |
| Cylinder Head | EJ257 STI |
| Bore Diameter | 99.52 mm |
| Compression Ratio | 8.5:1 |
| Compression Height | 1.209 in. |
| Piston Material | Forged 2618 Aluminum |
| Piston Quantity | 4 |
| Forging Type | FSR (Forged Side Relief) |
| Piston Head Type | Dish |
| Piston Volume | -16.50 cc |
| Average Piston Weight | 425 g |
| Piston Ring Set Included | Yes |
| Top Compression Ring Thickness | 0.0475 in. |
| Second Compression 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 Outer 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 |
| Connecting Rod Length | 5.138 in. |
| Engine Stroke | 3.110 in. |
| Intake Valve Relief Depth | 0.230 in. |
| Intake Valve Relief Diameter | 1.550 in. |
| Exhaust Valve Relief Depth | 0.230 in. |
| Exhaust Valve Relief Diameter | 1.550 in. |
| Intake Valve Relief Angle | 22° |
| Exhaust Valve Relief Angle | 22° |
| Accumulator Groove | Yes |
| Precision Pin Fit | Yes |
| Skirt Coating | Yes |
| Lateral Gas Ports | Yes |
| Thermal Barrier Crown Coating | Yes |
| Manufacturing Location | USA |
