Understanding Turbochargers and the 2G Eclipse Engine Options

Turbocharging is one of the most effective ways to increase horsepower without replacing the entire engine. The second-generation Mitsubishi Eclipse (1995–1999) came with two distinct engine options: the 4G63 (turbocharged in the GSX and GST trims) and the 420A (naturally aspirated in the RS and GS trims). While both can be upgraded, the approach differs significantly.

The 4G63 iron block is legendary for its strength and can handle substantial boost on stock internals. The 420A, derived from the Chrysler Neon, has a weaker bottom end and requires more careful tuning and lower boost levels. Understanding your engine’s capabilities is the first step toward a safe and reliable 60‑hp gain.

Why 60 HP for Under $2,500?

For a 2G Eclipse, adding 60 horsepower is a realistic and cost‑effective goal. A well‑designed budget turbo kit can achieve this without pushing the engine to its limits. The key is to select components that match your power target—overspending on a massive turbo wastes money, while undersizing leaves performance on the table. By focusing on essentials like the turbocharger, manifold, intercooler, and fuel management, you can hit the 60‑hp mark for less than $2,500.

Choosing the Right Turbo Kit for Your Engine

4G63 Turbo Models (GSX / GST)

If you already own a factory turbo 4G63, a simple “upgrade” kit that replaces the stock TD04 or small 16G with a larger unit (e.g., an Evo III 16G or a Garrett GT28) can easily add 60 hp. Many kits include everything needed: turbo, manifold, wastegate, and oil lines. Popular options:

  • Evo III 16G Kit – Direct bolt‑on, good for 300–350 hp with supporting mods.
  • FP (Forced Performance) 68HTA – Excellent spool and mid‑range power.
  • Holset H1C/HX35 – Budget‑friendly if you can fabricate or adapt.

420A Non‑Turbo Models (RS / GS)

The 420A requires a full conversion kit. Because it never came turbocharged, you’ll need an exhaust manifold, oil pan with drain provision, a turbocharger, intercooler, and engine management. Budget kits from brands like Hahn Racecraft or JMF Racing target 200–220 hp, which is a 60‑60‑hp bump over stock. Expect to spend extra on a missing oil return line or custom downpipe.

Key Components in a Kit

  • Turbocharger – Journal bearing is cheaper; ball bearing spools faster but costs more.
  • Exhaust Manifold – Cast iron is durable; tubular stainless steel offers better flow but can crack.
  • Intercooler and Piping – A front‑mount intercooler (FMIC) 24x12x3 inches is sufficient for 60 hp. Avoid cheap Chinese cores with thin fins.
  • Wastegate – External (38 mm or 44 mm) for better boost control; internal wastegates save money.
  • Oil Feed and Return Lines – Use stainless braided lines with proper restrictors for journal bearing turbos.
  • Blow‑Off Valve (BOV) – Recirculating type for the 4G63; atmospheric for 420A with proper tuning.

Preparation and Supporting Mods

Simply bolting on a turbo without addressing supporting systems invites failure. Before installation, ensure these areas are ready:

Fuel System Upgrades

More air requires more fuel. For a 60‑hp gain, upgrading the fuel pump and injectors is mandatory:

  • Fuel Pump: A Walbro 255 lph or equivalent is recommended for both 4G63 and 420A builds. It ensures adequate flow at higher boost.
  • Injectors: 450 cc injectors are fine for 4G63s at low boost. For the 420A, 550 cc high‑impedance injectors are a common upgrade.
  • Adjustable Fuel Pressure Regulator (AFPR): Helps set base pressure accurately with a bigger pump.

Cooling and Oil System

A turbocharged engine runs hotter. Consider a thicker radiator (e.g., Mishimoto) and an oil cooler to maintain safe temperatures. For the 4G63, the oil filter housing has a water‑cooled oil cooler; verify it’s not blocked. For the 420A, an aftermarket oil cooler sandwich plate is simple to install.

Exhaust and Intake

You’ll need a free‑flowing exhaust (2.5‑inch minimum) and a re‑routed intake pipe. Avoid restrictive crush‑bent pipes; mandrel‑bent tubing is far better.

Step‑by‑Step Installation Process

This overview assumes a basic mechanical skill level. Always consult your kit’s specific instructions. Here are the critical steps, with extra detail for the 420A conversion.

Step 1: Disconnect Battery and Drain Fluids

Safety first. Remove the negative terminal and drain engine oil and coolant (if you’re touching coolant lines). For the 420A, remove the intake manifold and exhaust manifold completely.

Step 2: Install the Turbo Manifold and Turbocharger

Clean the cylinder head surface. Use new manifold gaskets and torque bolts to spec (typically 30–35 ft‑lb for 4G63 cast iron, less for tubular). Mount the turbo to the manifold with supplied gaskets. Tighten the turbo’s mounting nuts evenly.

Step 3: Connect Oil Feed and Return Lines

For the 4G63, the oil feed can be sourced from the filter housing or head. For the 420A, you must drill and tap the oil pan for the return line, or use an oil return adapter that replaces the oil pan plug. The oil feed should come from the oil pressure sender port on the engine block; use a restrictor fitting if required. Run the return line with a gentle slope back to the pan—no kinks.

Step 4: Install the Intercooler and Piping

Mount the FMIC behind the front bumper. Trim the bumper support if necessary. Route the hot side piping from the turbo compressor outlet to the intercooler, and the cold side from the intercooler to the throttle body. Use silicone couplers and T‑bolt clamps. Ensure no rubbing against the radiator or fan.

Step 5: Install Wastegate and Blow‑Off Valve

External wastegate: weld the flapper to the downpipe or run a separate dump tube. Internal wastegate: just connect the actuator arm to the swing valve. Mount the BOV on the cold side piping, recirculating for the 4G63 (if using stock MAS) or vented for speed density setups.

Step 6: Reinstall Intake Manifold and Connect Vacuum Lines

For the 4G63, the intake manifold stays put, but you might need to reroute vacuum lines for the BOV and wastegate. For the 420A, the intake manifold must be reinstalled with new gaskets after you’ve modified the throttle body opening for the intercooler piping. Connect a vacuum line from the intake manifold to the wastegate (for boost reference) and the BOV.

Step 7: Electrical and Final Checks

Reconnect the battery. Verify all bolts are torqued, no oil leaks, and coolant lines are secure. Start the engine and check for idle stability. Listen for any unusual noises. Inspect all couplers for boost leaks using a cheap boost leak tester.

Tuning and Calibration

Without proper tuning, your turbo kit could detonate and destroy the engine. For a 60‑hp increase, you have several options:

ECU Options

  • ECU Flash (for 4G63): Using software like ECMlink (formerly DSMlink) allows you to adjust fuel and timing maps. It’s the most popular and capable solution for the 4G63.
  • Piggyback Fuel Controller: Units like the AEM F/IC or SAFC (Super Air Fuel Controller) work for both engines but are less precise than a full standalone. They are cost‑effective for low boost.
  • Standalone ECU: Offer highest control, but cost $1,000+ and require professional tuning. Haltech and AEM are common.

Whichever route you take, set your boost to about 8–10 psi for the 4G63 and 6–8 psi for the 420A to safely reach the 60‑hp target. Always monitor your air‑fuel ratio; a wideband O2 sensor is non‑negotiable.

Boost Controller and Wideband

A manual boost controller (MBC) is cheap and reliable for fixed boost. An electronic boost controller (EBC) allows on‑the‑fly adjustment and is easier to dial in. Pair it with a wideband gauge (e.g., AEM X‑Series) to keep air‑fuel ratios between 11.5:1 and 12.0:1 under boost.

Common Pitfalls and Troubleshooting

  • Boost Leaks: The most frequent issue. Use a boost leak tester at 15 psi. Listen for hissing around couplers, throttle body, and injector seals.
  • Oil Leaks: Often from the drain line if it’s too small or has sharp bends. Ensure the drain is at least -10 AN (or 3/8″ inner diameter) and slopes downward.
  • Fuel Starvation: If the fuel pump can’t keep up, the wideband will show lean conditions. Upgrade to a 255 lph pump and rewire it with a relay.
  • Overheating: A missing fan shroud or clogged radiator reduces cooling after adding the FMIC. Consider an electric fan upgrade.
  • Knock or Detonation: Caused by too much timing or too little octane. Use at least 93 octane fuel and pull timing with your ECU tune until knock sensor readings are safe.

Maintenance and Longevity

After installing your turbo kit, you must adopt a stricter maintenance schedule:

  • Oil Changes: Every 3,000 miles with high‑quality synthetic oil (5W‑30 or 10W‑40). Turbo bearings hate dirty oil.
  • Spark Plugs: Use copper plugs gapped to 0.028–0.030 inches for boosted applications. Iridium or platinum may foul if you run rich.
  • Coolant Flush: Every two years. Turbocharged engines generate more heat; keep your coolant fresh.
  • Boost Leak Check: Every oil change. Rubber couplers degrade over time.

The 2G Eclipse platform is well‑supported by the aftermarket community. Reliable information and parts are easy to find on forums like DSMTuners and vendors such as ExtremePSI. For fuel system upgrades, consult Racetronix for plug‑and‑play pump kits.

Conclusion

Installing a turbo kit on your 2G Eclipse can deliver 60 horsepower for under $2,500 if you choose the right components and prepare the vehicle properly. Whether you’re working with a 4G63 or a 420A, attention to detail during installation and tuning is critical. A properly set‑up turbo kit transforms the Eclipse’s driving experience without breaking the bank. With patience, the right tools, and a solid understanding of forced induction, you’ll enjoy a reliable, fast car that punches above its weight class.