The 1999 Mitsubishi Eclipse with a 420a engine can be turbocharged, but it requires careful planning and significant modifications. This guide will help you understand the process, challenges, and potential outcomes of installing a turbo kit on your Eclipse.

Turbo Kit Options

Several turbo kit options are available for the 420a engine:

  • Turbo Specialties T25 Extreme Turbo Kit: Designed specifically for the 1995-1999 Eclipse with the 420a engine.
  • CI Motorsports Full Turbo Kit: Includes a 57 Trim T3 Garrett Turbocharger, cast turbo manifold, and other essential components.
  • Universal T3/T4 turbo kits: Can be adapted to fit the 420a engine with proper modifications.

Engine Considerations

Before installing a turbo kit, consider these important factors:

  • Stock internals: The 420a engine can safely handle up to 8-10 psi of boost with stock internals.
  • Upgraded internals: For higher boost levels and reliability, consider aftermarket pistons and H-Beam rods.
  • Machining: Have your engine block machined and crankshaft reconditioned for better durability.

Essential Modifications

To properly turbocharge your 420a Eclipse, you'll need:

  • Upgraded fuel system (injectors, fuel pump, and fuel pressure regulator)
  • Intercooler and associated piping
  • Blow-off valve
  • Wastegate
  • Engine management system (e.g., Megasquirt ECU)
  • Upgraded radiator and cooling system
  • Stronger clutch and possibly transmission upgrades

Performance Expectations

With proper modifications, a turbocharged 420a can achieve:

  • 200-250 hp at around 8 psi of boost
  • 300-350 hp with significant upgrades and higher boost levels

Keep in mind that reaching higher power levels will require substantial investment and may compromise reliability.

Installation Process

1. Prepare the engine: Ensure your engine is in good condition and consider rebuilding with stronger internals.

2. Install the turbo manifold: Replace the stock exhaust manifold with a turbo manifold.

3. Mount the turbocharger: Attach the turbo to the manifold and connect oil feed and return lines.

4. Install intercooler and piping: Route the intercooler piping and mount the intercooler.

5. Upgrade the fuel system: Install larger injectors, a high-flow fuel pump, and adjust fuel pressure.

6. Add a blow-off valve and wastegate: These components are crucial for proper turbo operation.

7. Install engine management: A standalone ECU or piggyback system is necessary to tune the engine.

8. Upgrade the exhaust: Install a larger diameter downpipe and exhaust system.

Challenges and Considerations

  • Cost: Expect to invest $3,000 to $10,000 or more for a proper turbo setup.
  • Reliability: The 420a engine wasn't designed for forced induction, so longevity may be compromised.
  • Complexity: Turbocharging requires extensive knowledge and often professional installation.
  • Legality: Check local emissions laws, as turbocharging may not be street-legal in some areas.

Conclusion

Turbocharging a 1999 Mitsubishi Eclipse with a 420a engine is possible but challenging. It requires significant investment, careful planning, and a willingness to accept potential reliability issues. For many enthusiasts, it may be more practical to consider a platform that comes turbocharged from the factory, such as the Eclipse GST or GSX models with the 4G63 engine.

FAQs About 1999 Mitsubishi Eclipse 420a Turbo Kits

    • Is it worth turbocharging a 420a Eclipse?
      It depends on your goals and budget. For many, it's more cost-effective to start with a turbocharged model like the GST or GSX.
    • What's the maximum safe boost for a stock 420a engine?
      Generally, 8-10 psi is considered the safe limit for stock internals, but this can vary based on the engine's condition and supporting modifications.
    • Can I install a turbo kit myself?
      While possible, it's recommended to have a professional install the kit due to the complexity and potential for engine damage if done incorrectly.