JE Pistons FSR Forged Piston Kit for 2001-2007 Mitsubishi Evo 4G63 85.5mm - 297051

JE Pistons | Mitsubishi 4G63 | Evo VII-IX | 85.5mm Forged Pistons | 8.5:1 Compression | FSR | Set of 4

Building a Mitsubishi Evolution that can handle a more demanding turbo setup? The JE Pistons Forged Piston Kit, part number 297051, gives the legendary 4G63 engine a serious foundation for increased boost, aggressive street driving, and motorsport applications. Whether you're rebuilding an Evo after piston damage or preparing a fresh short block for a larger turbocharger, these American-made 2618 forged aluminum pistons provide the strength and ductility needed for high-cylinder-pressure performance builds.

Designed for the 4G63 engine used in Evolution VII, VIII, and IX applications, this set features an 85.50mm bore, 8.5:1 nominal compression ratio, -13.30cc dished crown, and JE's lightweight Forged Side Relief (FSR) design. Accumulator grooves help manage pressure between the piston rings, while precision pin fitting, smooth crown finishing, and coated skirts address important concerns in a hard-working turbo engine. JE Pro Seal rings, steel wrist pins, and retaining locks are included for a complete four-cylinder piston package.

Key Features & Specifications:

Kit Includes:

• 4 x JE Pistons 2618 Forged Aluminum FSR Pistons

• JE Pro Seal Premium Piston Ring Set

• 4 x Case-Hardened Steel Wrist Pins

• Wrist Pin Retaining Locks

About the JE Pistons Mitsubishi 4G63 Forged Piston Kit

Build Your Evo for the Next Level

The Mitsubishi 4G63 has a long history in turbocharged performance, from quick street cars to time attack and drag racing builds. But when you're increasing boost and asking more from the engine, the piston package needs to match those goals.

JE's forged 2618 aluminum pistons offer a performance-oriented alternative to factory-style internals. Their construction is designed for the elevated combustion pressures encountered in properly engineered high-output turbocharged engines.

This kit's 8.5:1 nominal compression ratio and -13.30cc dished crown provide an established configuration for the intended 4G63 cylinder head and engine geometry. The 85.50mm bore makes it suitable for blocks that have been prepared for a 0.50mm overbore.

Lightweight Forged Side Relief Design

JE's proprietary FSR forging reduces skirt width to help minimize friction and excess reciprocating weight. The design also accommodates shorter wrist pins, reducing unnecessary mass while maintaining a forged structure suited to demanding performance operation.

At an average of 312 grams per piston, this design provides a lightweight foundation for a performance 4G63 rotating assembly.

Accumulator Grooves and Smooth Crown Finish

Under heavy boost, combustion gases can build pressure between the top and second piston rings. JE's accumulator groove provides additional space for these gases, helping limit ring flutter and maintain consistent top-ring sealing.

The smooth crown finish removes sharp edges around the piston crown and valve relief areas. This helps reduce stress concentrations and potential hot spots, both important considerations when building a turbocharged engine exposed to elevated cylinder temperatures.

Skirt Coating and Precision Pin Fit

JE's skirt coating is designed to reduce friction and wear against the cylinder walls while helping limit operating noise. This is especially useful for a street-driven performance engine using forged 2618 pistons.

The precision-honed wrist pin bores help establish controlled pin-to-piston clearance. JE identifies typical pin-fit clearances of 0.0003 to 0.0010 inches, with final measurements determined during engine assembly.

With JE Pro Seal rings, case-hardened steel wrist pins, and retaining locks included, this kit provides the key piston components needed for a properly prepared Evo short block.

Fitment & Installation Notes:

• 2001-2007 Mitsubishi Lancer Evolution VII-IX: 4G63 turbocharged engine applications using the 22mm wrist pin configuration.

• Mitsubishi 4G63 DOHC Turbo: Designed for compatible 4G63 cylinder head and rotating assembly configurations.

• Required Finished Bore: 85.50mm.

• Overbore: +0.50mm compared with the standard 85.00mm 4G63 bore.

• Compression Ratio: Nominal 8.5:1 for the specified engine geometry. Actual assembled compression depends on chamber volume, head gasket thickness, and deck clearance.

• Piston Configuration: -13.30cc dished crown with 1.367-inch compression height.

• Wrist Pin Requirement: 0.866-inch (22mm nominal) wrist pin.

• Connecting Rod Compatibility: Verify rod length and small-end fit before assembly.

• Engine Machining: Finish cylinder bores for the required 85.50mm bore and JE's specified piston-to-wall clearance.

• Piston Ring Installation: Check and adjust ring end gaps for the intended fuel, boost level, and operating conditions.

• Valve Clearance: Verify piston-to-valve clearance when assembling the engine, especially with aftermarket camshafts or modified cylinder heads.

• Engine Calibration: Fuel delivery, ignition timing, boost control, and ECU tuning must match the completed performance build.

• Horsepower Rating: No specific horsepower limit is published for this piston kit. Engine capability depends on the complete rotating assembly, supporting components, and calibration.

Whether you're rebuilding a damaged Evolution engine or putting together a stronger 4G63 for a serious turbocharger upgrade, the JE Pistons 297051 kit combines forged 2618 construction, lightweight FSR design, enhanced ring control, and friction-reducing features in a complete four-piston package.