The 4G63 Engine: A Brief Overview

The Mitsubishi 4G63 is a turbocharged inline-four engine that powered the Eclipse, Talon, and Galant VR-4 throughout the 1990s. Its cast iron block and aluminum DOHC head provide a sturdy foundation that responds exceptionally well to modification. Two main variants exist: the 6-bolt (1989–1992.5) and the 7-bolt (1992.5–1999). The 6-bolt is preferred for its more robust thrust bearing and larger connecting rod bolts, but both can be built to 500 hp with the right components.

Why High-Strength Internals Matter at 500 hp

Stock 4G63 internals were designed for around 195–210 hp from the factory. Once you push past 350–400 hp, the factory cast pistons and powder-metal connecting rods become a weak link. The rod bolts stretch, the pistons crack at the ring lands, and the wrist pins may gall. Upgrading to forged internals from reputable brands like Crower and Wiseco addresses every one of these failure points. Forged 4340 steel rods and forged pistons are significantly stronger, can handle higher cylinder pressures, and offer better heat dissipation. A 500 hp goal is well within the safe range of a properly built bottom end.

Crower Components for the 4G63

Connecting Rods

Crower offers both I-beam and H-beam connecting rods forged from 4340 chromoly steel. For a 500 hp build, the H-beam design provides maximum strength under high boost and high rpm. Each rod is finished with ARP 2000 or L19 bolts to prevent stretch at elevated power levels. Crower rods are precision weight-matched and feature a 1.89 inch big end journal and 0.827 inch wrist pin bore. These rods are a direct replacement for 6-bolt and 7-bolt engines, requiring no machining.

Camshafts

To support 500 hp, you need camshafts that allow the engine to breathe at higher rpm. Crower’s 4G63 cam profiles range from a mild Stage 2 (272° duration, 0.449” lift) to an aggressive Stage 4 (280° duration, 0.467” lift). For a streetable 500 hp car on a moderate turbo, Stage 2 or Stage 3 cams are ideal. They provide excellent mid-range torque without sacrificing idle quality. Crower also offers billet cam blanks for custom grinds.

Valvesprings and Retainers

High-lift cams require stiffer valve springs to prevent valve float at high rpm. Crower’s valve springs for the 4G63 offer seating pressures around 100–120 lbs and open pressures approaching 300 lbs. Paired with titanium retainers from Crower, this valvetrain can safely rev to 8,500 rpm. The retainers reduce reciprocating mass, increasing reliability and response.

Rocker Arms and Lifters

Although not always necessary at 500 hp, upgrading to Crower’s billet rocker arms provides additional strength if you plan to spin the engine past 8,000 rpm. Crower also offers heavy-duty lash adjusters (lifters) to ensure consistent valvetrain geometry under high load.

External link: Crower 4G63 connecting rods and camshafts

Wiseco Pistons and Rings

Forged Pistons

Wiseco pistons for the 4G63 are forged from 2618 aluminum alloy, which offers excellent fatigue resistance at high temperatures and boost levels. For a 500 hp build, a 9.0:1 compression ratio with a shallow dish works well with pump gas and moderate boost (25–30 psi). Wiseco’s piston skirts feature a proprietary anti-friction coating that reduces scuffing during cold starts. The pistons come with premium 9310 steel wrist pins and spiral locks to retain the pins securely.

Piston Rings

Wiseco’s ring sets are available in ductile iron or stainless steel. For a 500 hp daily driver, the ductile iron top ring with a moly inlay reduces cylinder wall wear and offers great sealing. The second ring is a ductile iron low-tension design that minimizes blow-by. Wiseco rings are file-to-fit, allowing the builder to set the exact gap needed for high-boost applications (typically 0.022–0.024” top ring gap for nitrous or high boost).

Complete Piston Kits

Wiseco sells complete piston kits that include pistons, rings, wrist pins, and locks. For a 4G63, the kit part numbers vary by bore (standard 0.020, 0.040 oversize) and compression ratio. Ordering a complete kit eliminates guesswork and ensures all components are balanced and match the required specifications.

External link: Wiseco 4G63 piston look-up

Building the Short Block for 500 hp

Block Preparation

A clean and well-machined block is critical. The deck surface must be flat (preferably within 0.001”) and the bore should be honed to a 45-degree crosshatch. Many builders recommend torque-plate honing to simulate the distortion caused by the main studs and head studs. A 0.040” overbore is common for 4G63 builds, giving a final displacement of about 2.1 liters. The main bearing saddles must be aligned and the crank needs to be micro-polished or replaced with a forged aftermarket unit for extra safety.

Crank and Bearings

For 500 hp, the factory nodular iron crankshaft is usually sufficient if it is shot-peened and polished. However, if you plan to rev past 7,500 rpm or run more than 500 hp in the future, upgrading to a forged crank is wise. Use King or ACL race bearings with proper clearances: 0.0020–0.0025” for mains and 0.0025–0.0030” for rods.

Oil System Upgrades

Stock oil pumps can fail at high rpm. Installing a 4G63 oil pump gear set from OEM or aftermarket (like a factory 3-eclipse 1990 style) and a shimmed oil pressure relief valve prevents starvation. A larger capacity oil pan, such as a modified 4G63 pan with baffles and a windage tray, keeps oil around the pickup during hard acceleration.

Balance Shaft Considerations

Many builders eliminate the balance shafts on the 4G63 to reduce rotating mass and simplify maintenance. A balance shaft eliminator kit replaces the shafts with a stubby oil pump gear. This saves weight and eliminates a common failure point. The engine will vibrate slightly more, but the trade-off is negligible for a performance build.

Supporting Modifications for the 500 hp Goal

Turbocharger Selection

To reach 500 hp, you need a turbo that flows enough air. Popular choices for the 4G63 include the FP Green, BorgWarner S257 SX-E, Garrett GT3582R, and the Precision 5858. A turbo with a 63–68 mm inducer wheel and a T3 or T4 turbine housing will spool quickly on a 2.0 liter engine while delivering the necessary mass flow. Consider a divided housing and twin-scroll manifold to improve spool and reduce lag.

Fuel System

A Walbro 450 lph fuel pump, 1000–1300 cc/min injectors (e.g., FIC 1200 or Injector Dynamics 1000), and an adjustable fuel pressure regulator are the minimum for 500 hp. All fuel lines should be -6AN or larger. Use ethanol blends (E85) if available, as they provide greater knock resistance and allow more timing advance.

Intercooler and Piping

An efficient intercooler is essential. A front mount with a core size around 24x12x3” and 2.5–3” piping keeps intake air temperatures low. Use a blow-off valve that vents to atmosphere correctly with mass air flow (or switch to speed density tuning).

Engine Management and Tuning

Stock ECUs can be flashed with aftermarket chips, but a standalone ECU like ECMLink (for DSM ECUs), AEM Infinity, or Link G4+ provides full control. Professional dyno tuning is non-negotiable for a 500 hp build. Tuning should be performed by an experienced calibrator who knows 4G63 fuel and ignition maps.

External link: ECMLink – Popular 4G63 tuning software

Installation Tips and Common Mistakes

Critical Assembly Steps

  • Cleanliness: Degrease the block, oil passages, and all components before assembly. Use a thread chaser to clean bolt holes.
  • Torque to Spec: Use a quality torque wrench. Main cap bolts should be tightened in sequence to 58–65 ft-lbs (factory spec) or to ARP specifications if using studs. Always use moly lube on ARP bolts.
  • Ring End Gap: Set top ring gap per the piston manufacturer’s recommendation. For forced induction, a larger gap (0.022–0.024”) prevents ring butting at high cylinder pressure.
  • Bearing Clearances: Check rod and main bearing clearance with plastigauge. Adjust with different bearing shells as necessary. A tight clearance (0.0020”) reduces noise but risks seizure; slightly looser (0.0030”) is safer for high rpm.
  • Valve-to-Piston Clearance: With high-lift cams, clay-test the clearance. You need at least 0.080” exhaust and 0.100” intake clearance.

Break-In Procedure

After assembly, the engine must be broken in properly. Start the engine and let it idle at 2,000–2,500 rpm for 20 minutes with varying throttle. Use a break-in oil without friction modifiers. Avoid prolonged idling. After the first heat cycle, change oil and filter. Then drive the car under varying load for 500 miles before increasing boost. This seats the rings and settles the bearings.

Common Mistakes to Avoid

  • Not cleaning the oil galleys: Metal shavings from machining can ruin bearings within minutes.
  • Incorrect head stud torque: Follow the tightening sequence and re-torque after the first heat cycle.
  • Using stock head bolts: For 500 hp, ARP head studs are mandatory to prevent head lift.
  • Neglecting the valve train: Stock hydraulic lifters can pump up at high rpm. Upgrade to Crower adjustable lash lifters or a solid lift conversion.

External link: DSMtuners 500 hp 4G63 build list and discussion

Conclusion: Reap the Rewards

Building a 500 hp Mitsubishi 4G63 for your Eclipse is a rewarding project that transforms the car into a serious performer. The combination of Crower connecting rods and camshafts with Wiseco pistons and rings delivers the strength and reliability needed to handle that power level daily. By also upgrading the turbo, fuel system, and tuning, you create a well-balanced package that pulls hard on the street or at the track. Proper assembly and break-in ensure the engine will last for thousands of miles of high-boost enjoyment.

Remember that every component works in harmony—choose quality parts, take your time with clearances, and invest in a professional tune. With Crower and Wiseco internals, your 4G63 Eclipse can reliably achieve the 500 hp goal and become a true DSM legend.

External links: Wiseco Pistons Official Site | Crower Cams & Rods