Garrett T67 Turbocharger Swap Guide for the 3000GT VR4

Few platforms respond to forced induction upgrades as well as the Mitsubishi 3000GT VR4. With its all-wheel-drive chassis, 3.0-liter DOHC V6, and twin-turbo architecture, the VR4 was a technological flagship in the early 1990s. Yet for enthusiasts chasing serious power, the factory twin-turbo setup quickly becomes a bottleneck. Replacing the restrictive stock turbos with a single Garrett T67 turbocharger is one of the most transformative upgrades you can make. That shift from a parallel twin-turbo layout to a larger single turbo improves airflow, reduces under-hood complexity, and simplifies the induction path. This guide covers every step of swapping to a Garrett T67 on your 3000GT VR4, from selection and preparation through installation, tuning, and testing.

Why Choose the Garrett T67 for Your 3000GT VR4

The Garrett T67 is part of Garrett Motion's GTX and T-Series lineup, widely respected for delivering high flow capacity with responsive spool characteristics. On the 3000GT VR4, the T67 sits in a sweet spot: it supports power targets from 500 to 700 wheel horsepower without the lag associated with larger frames. The T67 is available in several A/R (area/radius) housing options; a 0.68 A/R turbine housing offers quicker spool for street-driven cars, while a 0.82 A/R housing provides better top-end flow for race-oriented builds.

Key characteristics of the Garrett T67 that make it ideal for this swap include:

  • Compressor wheel designed for up to 67 lb/min airflow, sufficient for 700+ hp with proper fueling and tuning.
  • Dual ball-bearing center section for reduced friction, faster spool, and improved oil flow tolerance.
  • Cast stainless steel turbine housing that resists cracking under high exhaust gas temperatures.
  • Compact footprint relative to its flow capacity, easing fitment in the VR4's tight engine bay.
  • Extensive aftermarket support for service parts, rebuild kits, and custom compressor housings.

When you swap from the stock twin turbos to a single T67, you eliminate the factory crossover piping and reduce the number of gaskets, oil lines, and vacuum lines. This simplification improves reliability while making room for a larger intercooler and intake plumbing.

Tools, Materials, and Parts List

Before you begin, assemble everything you need. Scrambling for missing parts mid-job on a 3000GT VR4 can stall a project for days. The following list covers all tools and consumables required for the swap.

Tools

  • 3/8-inch and 1/2-inch drive socket set (metric, 8mm-19mm)
  • Combination wrench set (metric, 10mm-17mm)
  • Torque wrench capable of 10-80 ft-lb
  • Flathead and Phillips screwdrivers
  • Pliers (standard and snap-ring)
  • Gasket scraper and razor blade
  • Jack and jack stands or lift
  • Drain pan for coolant and oil
  • Shop towels and brake cleaner
  • Threadlocker (blue, medium strength)
  • Vacuum line diagram or reference photos of the stock engine bay

Parts and Materials

  • Garrett T67 turbocharger with your chosen A/R turbine housing
  • Turbocharger installation kit (includes gaskets, crush washers, and hardware)
  • Oil feed line kit (stainless braided with AN fittings, if possible)
  • Oil drain line with correct flange to match the T67 center section
  • Coolant feed and return lines (if water-cooled version)
  • Wastegate assembly (external wastegate is strongly recommended with the T67)
  • Downpipe with T3/T4 flange or custom V-band flange to match the housing
  • Intake piping with appropriate couplers and T-bolt clamps
  • Intercooler and pipework rated for 700+ hp
  • Fuel injectors (minimum 1000cc, preferably 1200cc or larger)
  • Fuel pump (Walbro 450 or equivalent high-flow unit)
  • ECU tuning solution (standalone or flash-based with custom mapping)
  • Boost controller (manual boost controller or electronic solenoid)
  • Coolant and engine oil (high-quality full synthetic)

If you are ordering the T67 as a complete assembly, confirm whether the wastegate is included. Many T67 packages ship with a wastegate port on the turbine housing, but you may need to source the gate and spring separately.

Preparation and Preliminary Steps

Proper preparation prevents damage to your VR4's engine and reduces downtime. Start these steps at least one day before the actual turbo swap.

Disconnect the Battery and Drain Fluids

Remove the negative battery terminal and secure it away from the post. Drain the engine oil and coolant into approved containers. The 3000GT VR4 holds roughly 5.5 quarts of oil and about 10 liters of coolant. Removing both fluids prevents contamination when you disconnect oil and coolant lines from the turbos.

Remove Obstructions

Clear access to the turbocharger area by removing the engine cover, intercooler ducting, and the intake air box and intake pipe. For the VR4, you will also need to remove the factory throttle body elbow and the upper intercooler pipe. Use reference photos or labels for vacuum lines attached to the stock turbos; some of these will be repurposed for the single-turbo setup.

Inspect for Existing Damage

With the intercooler piping and intake removed, inspect the factory turbos for shaft play, oil leaks, or cracked housings. If the stock turbos already have significant wear, you are making the right decision to swap them out. Check the oil drain passages in the block for sludge; if the drain is restricted, clean it thoroughly before installing the new T67.

Removing the Factory Twin Turbochargers

The stock VR4 twin-turbo setup involves two small turbos mounted on either side of the engine. Removing them requires patience, as access to bolts is often tight.

Disconnect Intake and Exhaust Plumbing

Remove the Y-pipe connecting the turbos to the intercooler. Disconnect the downpipes from each turbo's exhaust outlet. On the 3000GT VR4, the front turbo is easier to reach, while the rear turbo requires removing the heat shield and, in some cases, the alternator for clearance.

Disconnect Oil and Coolant Lines

Each factory turbo has an oil feed, oil drain, and coolant lines. Use a line wrench on the banjo bolts to avoid rounding the hex. Be prepared for residual fluid to drip after draining. Label each line so you know which is feed and which is return.

Unbolt the Turbos from the Exhaust Manifolds

The stock turbos mount to cast iron exhaust manifolds with three or four bolts each. Break the bolts loose with penetrating oil if they are rusted. Once the bolts are removed, lift each turbo out of the engine bay. It helps to rotate the engine slightly to improve access to the rear turbo bolts.

Installing the Garrett T67 Turbocharger

With the stock turbos removed, you will see the open manifold flanges and the now-empty space in the engine bay. Installing the T67 requires a clean slate.

Prepare the Mounting Surface

Clean the exhaust manifold flanges where the turbos were mounted. If you are using a single-turbo adapter plate or a new manifold designed for the T67, mount that first. Many aftermarket manifold options for the 3000GT VR4 use T3 or T4 flange patterns. The T67 typically uses a T3 divided or T4 divided flange. Use new gaskets and apply threadlocker to the manifold-to-head bolts.

Mount the T67 Turbocharger

Position the T67 onto the manifold or adapter flange. Apply a thin film of anti-seize to the mounting studs. Tighten the nuts in a crisscross pattern to the torque specification provided by Garrett (typically 35-45 ft-lb for T3/T4 flanges). Do not overtighten, as the cast housing can distort.

Connect Oil and Coolant Lines

Use the T67's oil feed port on top of the center section. The oil drain is typically on the bottom. Install the oil feed line with a restrictor if specified by the turbo's documentation; dual ball-bearing cartridge turbos often require a restrictor to prevent seal damage. Connect the coolant feed and return lines if your T67 variant includes water cooling. Use new crush washers on all banjo fittings and torque to 15-20 ft-lb. The oil drain line should slope continuously downward to the block's drain port; any dip can cause oil pooling and seal failure.

Install the Wastegate

Mount your external wastegate to the appropriate port on the turbine housing or manifold. Use a gasket and ensure the wastegate spring matches your target boost level. For a street-driven VR4, a spring rating of 10-14 psi is common; you will add boost with a boost controller later.

Attach Intake and Exhaust Piping

Connect the downpipe to the T67's exhaust outlet. A 3-inch mandrel-bent downpipe is recommended to reduce backpressure. For the intake side, route a large-diameter pipe from the air filter to the T67 compressor inlet. On the charge side, route the intercooler piping from the compressor outlet to the intercooler, then from the intercooler to the throttle body. Use silicone couplers and T-bolt clamps for a leak-free seal.

Supporting Modifications for a Successful Swap

Bolting on a Garrett T67 without upgrading the supporting systems will result in a dangerous lean condition or driveline damage. The 3000GT VR4 demands a holistic system approach once you exceed the factory power level.

Fuel System Upgrades

The stock fuel pump and injectors cannot supply enough fuel for the T67's airflow. Install a high-flow fuel pump such as a Walbro 450 or a brushless return-style pump. Upgrade injectors to at least 1000cc for pump gas applications and 1200cc or larger if you plan to use E85. The fuel pressure regulator should be adjustable, and hardwiring the pump is recommended to avoid voltage drop.

Intercooling

The T67 moves significantly more air than the stock turbos. A larger front-mount intercooler with a 25x10x3 inch core or larger is necessary to keep charge air temperatures under control. Ensure the pipe routing is as direct as possible with minimal bends.

Exhaust System

A free-flowing exhaust is mandatory. A 3-inch turbo-back exhaust system with a good catalytic converter (or test pipe for off-road use) drops backpressure and allows the T67 to spool properly.

Engine Management and Tuning

The stock ECU cannot compensate for a 500+ hp turbocharger. You need a standalone ECU such as a Haltech, AEM Infinity, or a flash-able ECU like ECMLink with custom tuning. A good tune not only optimizes power but also protects the engine from detonation and lean spikes. Plan for professional dyno tuning after the installation.

Tuning and Calibration After the Upgrade

After the hardware is installed, the calibration phase determines whether the swap succeeds or fails. Start with a base map provided by your tuner or ECU manufacturer.

Base Map and Initial Start

Load the base map onto your standalone ECU. Set injector sizing, fuel pressure, and timing tables conservatively. For the first start, set the boost level low, around 7-10 psi. Start the engine and check for immediate fuel and ignition sync. Listen for any air leaks at the intake and intercooler connections. Do not rev the engine above 3000 RPM until the tune is verified.

Boost Control Strategy

With an external wastegate, you can adjust boost by changing the spring or using a boost controller. A manual boost controller works reliably for 10-20 psi, while a electronic boost controller allows you to tune boost by gear. For the T67 on the 3000GT VR4, most street setups run 18-22 psi on pump gas and up to 30 psi on race fuel or E85.

Fuel and Timing Tuning

On a dyno, your tuner will dial in the air-fuel ratio to 11.5:1 for pump gas and 12.0:1 for E85 under boost. Timing is mapped to avoid knock; the 3.0L 6G72 engine responds well to moderate timing advance with intercooling. Expect peak power around 5500-6500 RPM with the T67.

Testing, Break-In, and Verification

After tuning, verify the installation before driving aggressively.

Leak Testing

Pressurize the intake system to 20 psi with a boost leak tester. Listen for hissing at couplers, throttle body gaskets, and the intercooler. Fix any leaks immediately. Also check the oil and coolant fittings with the engine running at idle for at least 10 minutes.

Road Test

Take the VR4 on a gentle road drive for 15-20 miles. Avoid hard boost until the engine is fully warmed. Monitor oil pressure, coolant temperature, and boost pressure. Look for smoke from the exhaust, which could indicate a turbo seal issue or a poor oil drain.

Subsequent Checks

After the first drive, let the engine cool and re-torque the turbo mounting bolts and downpipe fasteners. Check the oil drain connection for seepage. Some break-in of the turbo seats is normal; if you see minor oil residue at the compressor outlet after 500 miles, clean the piping and monitor. If the smoke persists, investigate the oil drain slope and the crankcase ventilation system.

Common Issues and Troubleshooting

Even a well-planned T67 swap can encounter issues. Recognizing them early reduces the chance of damage.

Oil Leaks from the Turbo Center Section

Most post-install oil leaks on the T67 come from the oil drain being too small or having a trap. Verify the drain line is -10 AN or larger and has a continuous downward slope. If the drain is correct, the issue may be excessive crankcase pressure; check the PCV system for blockage.

Boost Creep with External Wastegate

If boost continues to rise above the wastegate spring rating, the wastegate port may be too small or positioned poorly. Some T67 housings have a small wastegate port; opening the port slightly or using a larger wastegate gate orifice can help. Also verify that the wastegate actuator is receiving full manifold pressure.

Surge under Part-Throttle

Compressor surge occurs when the throttle is partially closed but the turbo is still producing high pressure. This can be mitigated by recirculating a blow-off valve, tuning the boost controller for smoother spool, or using a larger compressor housing with a properly matched A/R.

Fitment Clearance Issues

The T67 is larger than the stock turbos. You may need to massage the firewall heat shield or relocate the alternator slightly. If the intake piping hits the hood, consider a shorter intake path or a different air filter placement. Test fit all components before final tightening.

Performance Expectations and Real-World Results

A properly tuned 3000GT VR4 with a Garrett T67 should produce 500-600 wheel horsepower on pump gas and more than 700 wheel horsepower on E85 or race fuel. The power delivery differs from the stock twins: the T67 provides a strong mid-range pull rather than the sharp peak of the smaller factory turbos. Spool time on a T67 with a 0.68 A/R housing typically reaches full boost around 3800-4200 RPM, depending on exhaust system backpressure and intake restrictions.

The trade-off for this power is a slightly later spool than the stock twins, but the top-end airflow more than compensates. For a street-driven car that sees track days, the T67 offers a balanced profile. For a drag-focused build, a larger turbo like a T76 may be more appropriate, but the T67 remains the most popular single-turbo upgrade for the VR4 for good reason.

Next Steps and Additional Resources

Completing a Garrett T67 swap on your 3000GT VR4 is a substantial project that rewards careful planning and execution. The results are a deeper power band, reduced engine bay clutter, and a reliable platform for high horsepower. If you want to dive deeper into specific aspects of the build, the following resources provide valuable information.

  • Garrett Motion Official Website – Specifications, technical drawings, and product data for the T67 and all Garrett turbochargers.
  • 3SX Performance – Specialized parts and kits for 3000GT VR4 turbo upgrades, including adapters and piping for single-turbo conversions.
  • ECMLink – Comprehensive tuning support and forums for 3000GT VR4 engine management.
  • 3Si.org / 3000GT/Stealth Forum – Active community with build threads, dyno results, and troubleshooting advice specific to single-turbo swaps.
  • Stealth 316 Technical Reference – In-depth technical articles on 3000GT VR4 modifications, including turbo upgrades and fuel system changes.

The Garrett T67 turbocharger swap remains one of the most effective performance upgrades for the 3000GT VR4. With proper preparation, quality parts, and a thorough tune, your VR4 will deliver a driving experience that honors the potential Mitsubishi built into the platform. Proceed methodically, respect the torque specs, and enjoy the transformation.