Introduction

The Mitsubishi 4G63 is one of the most legendary four-cylinder engines ever produced. From its humble roots in the 1980s to its dominance in the Eclipse GSX, Lancer Evolution, and countless drag cars, this cast-iron block has proven time and again that it can handle serious power. Building a 4G63 to produce 650+ horsepower requires careful selection of forged internals, a robust fuel system, and a well-matched turbocharger. But what does that actually cost? In this expanded guide, we’ll break down every component, including the hidden costs of machining, assembly, tuning, and supporting modifications. Whether you are building a street-driven Evo VIII or a weekend warrior Eclipse, this price breakdown will help you budget realistically for a reliable 650+ hp build.

Why the 4G63?

The 4G63 is a 2.0L inline-four engine with a closed-deck iron block, a forged steel crankshaft from the factory, and a robust oiling system. These characteristics make it far more durable than many aluminum-block competitors when pushed to high boost levels. The aftermarket support is massive, with parts ranging from basic bolt-ons to fully billet blocks. For a 650+ hp target, the stock block is still viable when sleeved or reinforced, but most builders opt for a fully forged rotating assembly. The engine’s layout also allows for easy turbo upgrades, and the factory DOHC 16-valve head flows well with porting. To learn more about the 4G63’s history, check out this overview on Wikipedia.

Forged Internals: The Foundation of Reliability

At 650+ hp, stock cast pistons and rods will not survive. Forged internals are non-negotiable. The cost depends on brand, material, and whether you choose a complete rotating assembly or piece together components. Budget for machine work as well—bore honing, decking, and balancing add several hundred dollars.

Forged Pistons

Pistons from brands like Wiseco, CP-Carrillo, and JE Pistons range from $500 to $1,200 for a set of four. For high-boost applications, choose a 2618 aluminum alloy for strength. Note that some pistons come with wrist pins and rings included, while others separate those costs.

Forged Connecting Rods

Rod options include Eagle, Manley, and K1 Technologies. Standard H-beam rods handle 700 hp easily, while billet rods (e.g., R&R, Oliver) can push past 1,000 hp. Expect to pay $400 to $800 for a quality set of rods. For a 650+ hp build, H-beam rods from Manley or Eagle are sufficient and cost-effective.

Forged Crankshaft

The factory 4G63 crank is forged steel and often reusable up to 700 hp. However, many builders upgrade to a better counterweighted design or a knife-edged crank for reduced windage. A new aftermarket forged crank costs between $600 and $1,200. If your stock crank checks out fine, you can save money by having it polished and balanced ($100–$200).

Bearings and Hardware

Do not forget main and rod bearings, thrust washers, and ARP head studs. Bearings from ACL or King cost around $100 to $200. ARP main studs and head studs add another $150 to $300. Including these in your budget is critical for reliability.

Machine Work and Assembly

Machine shop costs vary by region. Typical charges include hot tanking ($50–$100), bore honing ($200–$400), decking ($100–$200), line honing ($150–$300), and crank polish ($50–$100). Balancing the rotating assembly adds $150–$300. Expect to spend $700 to $1,500 on machine work alone.

Upgraded Fuel System: Feeding the Beast

A 650+ hp 4G63 consumes roughly 80–100 lb/hr of fuel (depending on duty cycle and lambda). The stock fuel system will max out well before that. A complete fuel system upgrade includes injectors, pump, regulator, lines, and often a surge tank or fuel cell for drag cars.

Fuel Injectors

High-impedance injectors sized between 1000cc and 1650cc are common. Brands like Injector Dynamics, FIC, and Bosch offer units for $300–$600 for a set of four. For flex-fuel capability, consider ethanol-rated injectors (extra $50–$100).

Fuel Pump and Wiring

A single Walbro 450 lph or AEM 340 lph pump provides enough flow for 650 hp on pump gas. For E85, you may need dual pumps or a larger single like the Walbro 525 or Fuelab. Cost: $150–$400 for the pump, plus a rewire kit ($20–$50). For dual pumps, add a second pump and a Y-block.

Fuel Pressure Regulator and Lines

An adjustable regulator (Aeromotive, Fuelab) runs $100–$250. Upgrade to -6 AN feed and -6 AN return lines for reliable flow. Braided hose and fittings can add $150–$400, depending on how much you fabricate yourself. A fuel rail upgrade ($150–$300) ensures even distribution.

Total Fuel System Estimate

  • Injectors: $300 – $600
  • Fuel pump: $150 – $400
  • Regulator: $100 – $250
  • Lines and fittings: $150 – $400
  • Fuel rail: $150 – $300

Total: $850 – $1,950 (excluding flex-fuel sensor or surge tank).

Turbocharger Selection: Matching Power Goals

The turbo is the heart of reaching 650 hp. A common choice is a Garrett GT3582R (GT35) or a Precision 6466. Both support 650+ hp with proper tuning. A BorgWarner S362 or EFR 7670 are also options. Prices vary by brand and whether you buy new or used.

Turbocharger and Accessories

A new journal-bearing turbo costs $800–$1,200; ball-bearing adds $300–$500. Include a wastegate (Tial 44mm, ~$200–$400), blow-off valve ($100–$250), and turbo manifold. A T3/T4 manifold from STM or Punishment Racing runs $300–$600. Downpipe and wastegate dump tube add $150–$400.

Intercooler and Piping

A front-mount intercooler (bar-and-plate) sized for 650+ hp costs $300–$600. Piping and couplers add $100–$300. If you already have a decent intercooler, you might reuse it, but pressure drop must be considered.

ECU and Tuning: The Brain and the Brawn

Stock ECU can be reflashed up to a point, but standalone ECUs offer full control for high-horsepower builds. Standalone options: AEM Infinity, Haltech Elite, Link G4+ (from $1,200 to $2,500). Alternatively, a flash tune via ECMlink or EcuFlash for DSM Evo VIII/IX can work but requires a flashed ROM and supporting mods.

Tuning Costs

A professional dyno tune typically costs $300–$800, depending on your location and the tuner’s reputation. For standalone, initial setup and idle calibration may cost extra. If you tune yourself, you still need a wideband O2 sensor ($150–$300) and possibly a boost controller.

Additional Electronics

Wideband gauge, boost gauge, oil pressure gauge: $200–$500. A boost controller (manual or electronic) adds $50–$300.

Supporting Mods: Exhaust, Cooling, and Drivetrain

Exhaust System

A 3-inch downpipe and cat-back system reduce backpressure. Stainless steel downpipe: $200–$600. Cat-back: $300–$800. For drag racing, a dump pipe can be added.

Cooling System

At 650 hp, a larger radiator (Koyo, Mishimoto) costs $200–$500. Electric fans and a high-flow water pump add $100–$300. An oil cooler kit is also recommended: $150–$400.

Clutch and Drivetrain

A single-disc clutch rated for 600 ft-lbs (ACT, South Bend) costs $400–$800. A twin-disc clutch for safety margin runs $800–$1,500. Don’t forget flywheel resurfacing or a new lightweight unit ($150–$400). Transmission upgrades: Evo X or DSM gearbox may need reinforcement (gear set: $1,000–$2,500).

Total Cost Breakdown Summary

Below is a consolidated range for a 650+ hp 4G63 build, including typical machine work and supporting mods. Note that labor for assembly and installation (if you don’t do it yourself) can add $2,000–$4,000.

  • Forged rotating assembly (pistons, rods, crank, bearings, hardware): $1,500 – $3,500
  • Machine work: $700 – $1,500
  • Fuel system (injectors, pump, regulator, lines): $850 – $1,950
  • Turbocharger and manifold (with wastegate, BOV, downpipe): $1,500 – $3,500
  • Intercooler and piping: $400 – $900
  • ECU (standalone) and tuning: $1,200 – $2,500
  • Exhaust system: $500 – $1,400
  • Cooling upgrades: $400 – $1,000
  • Clutch and flywheel: $600 – $1,900
  • Gauges, boost controller, wideband: $300 – $800

Estimated total without labor: $7,950 – $18,050. With professional assembly and tune, expect $10,000 – $22,000. These ranges are realistic for a reliable build using quality parts. For more detailed pricing, browse suppliers like MAPerformance, Kiggly Racing, and Import Performance Parts.

Conclusion

Building a 650+ hp 4G63 is a serious financial commitment, but the rewards are immense when done right. By budgeting for forged internals, a high-flow fuel system, a matched turbo, and proper tuning, you create a foundation that can withstand aggressive street driving or track days. Don’t cut corners on machine work or assembly—a poorly built short block will cost you more in the long run. Whether you are aiming for a street monster or a weekend drag car, the 4G63 remains one of the most cost-effective engines to push past the 650 hp mark. Plan carefully, buy quality parts, and enjoy the process of building an iconic powerplant.