Introduction: Why the Garrett GTX3584RS for Your A90 Supra?

The A90 Supra, powered by the BMW B58 engine, has quickly become a benchmark for modern turbocharged performance. Its factory twin-scroll turbocharger delivers responsive power, but enthusiasts seeking serious horsepower quickly turn to upgraded turbochargers. The Garrett GTX3584RS is a favorite choice, thanks to its advanced airfoil technology, dual ball bearing core, and ability to support up to 850 horsepower with proper supporting mods and tuning.

This expanded guide takes you beyond the basic steps, providing detailed torque specifications, wiring tips, and real-world installation experience. Whether you are a seasoned mechanic or a dedicated DIYer, following this guide will help you avoid common pitfalls and achieve a clean, reliable installation. We recommend reading through the entire guide before touching a single bolt.

Tools and Materials Needed

A complete tool list ensures you do not get stuck halfway through the job. Quality tools save time and prevent damage to fasteners and components.

Required Parts

  • Garrett GTX3584RS Turbocharger (Garrett part # 877258-5001S). Confirm you have the correct oil drain flange and water line adapters for the A90.
  • Turbo Manifold – Stock manifold can be reused but may need port matching for the larger turbine inlet. A billet twin-scroll manifold is recommended for maximum spool.
  • Oil Feed Line Kit – Use a full-flo (AN-4 or -6) with a restrictor if the turbo requires it. Always check Garrett’s oil inlet size.
  • Oil Return Line – Must be an AN-10 or larger with a free drain path. Avoid kinks.
  • Water Lines – Coolant hoses for the GTX3584RS’s water-cooled center housing. Use high-temp silicone or OEM-quality hoses.
  • Intercooler Piping Kit – You will need a custom charge pipe to match the compressor outlet (usually 4” to 3” reducer). A high-flow intercooler is strongly recommended.
  • Exhaust Components – Downpipe with V-band connection compatible with the GTX turbine housing. A 3.5” or 4” downpipe helps prevent backpressure.
  • Wastegate and Boost Controller – The GTX3584RS typically uses an external wastegate (44mm or 45mm) and a quality electronic boost controller like a BoostFactory or AEM.
  • Gaskets & Seals – Turbo-to-manifold gasket, V-band gaskets, oil drain gasket, and all exhaust flange gaskets.
  • Fasteners – High-strength bolts (10.9 or 12.9 grade) for manifold-to-turbo, and new lock washers.

Essential Tools

  • 3/8” and 1/2” drive socket sets (metric, 10mm-19mm)
  • Torque wrench (0-150 ft-lb range)
  • Combination wrenches
  • Pry bar (for stubborn bolts)
  • Hex/Torx bits (for stock turbo flange bolts)
  • Oil filter removal tool
  • Coolant vacuum filler (optional but handy)
  • Safety glasses, gloves, and shop rags
  • Jack and jack stands (or lift)
  • Borescope (for checking oil drain routing)

Preparation Steps

Preparation is where most installations succeed or fail. A clean, organized workspace and proper safety measures make the work smoother.

  • Park on level ground and engage the parking brake. Disconnect the battery negative terminal.
  • Remove the engine cover (plastic cover) and the front bumper cover if you plan to access the intercooler area.
  • Drain engine oil and coolant. Remove the oil filter and drain plug. For coolant, locate the lower radiator hose drain valve or remove the block drain plug (B58 engine). Dispose of fluids properly.
  • Remove air intake system – Take out the factory airbox, MAF sensor (keep in a safe place), and intake tube to the turbo inlet.
  • Remove the downpipe if still stock. It is easier to access turbo removal with the downpipe out of the way.
  • Inspect the V-band and wastegate on the stock turbo – note orientation for reference during reassembly.

Pro tip: Label every connector and hose with tape and a marker. The A90 Supra’s tight engine bay is unforgiving if you forget a vacuum line connection.

Removing the Stock Turbo

Work carefully to avoid damaging the manifold studs or surrounding components.

  1. Disconnect the wastegate actuator rod (if stock internal wastegate). Use a small pry bar or needle-nose pliers to remove the e-clip.
  2. Unplug the electrical connectors on the wastegate and any boost pressure sensors nearby.
  3. Remove the intake pipe from the compressor inlet. There is often a nylon coupling that can be stubborn – twist while pulling.
  4. Loosen and remove the exhaust flange bolts connecting the turbo to the downpipe. Use penetrating oil if rusted.
  5. Unfasten the turbo-to-manifold bolts. There are typically four M8 bolts. Some may be accessed from underneath with a long extension.
  6. Gently lift the stock turbo out of the engine bay. Watch for oil or coolant droplets from the lines. Place on a clean workbench.
  7. Remove the oil feed line and water lines from the turbo if they are not already disconnected. Discard old crush washers.

Inspect the manifold for cracks or carbon buildup. If you are upgrading the manifold, now is the time to install it. Thoroughly clean the manifold gasket surface with a razor blade and brake cleaner.

Installing the Garrett GTX3584RS Turbo

This step demands attention to detail. Follow torque specs (approximate, based on typical fasteners).

  • Prepare the manifold – Install the new gasket (use OEM or copper gasket) onto the exhaust manifold. Do not use RTV near exhaust gaskets.
  • Attach the turbo – Lift the GTX3584RS into position, aligning the turbine inlet with the manifold. Fit the V-band or bolted flange depending on your manifold. Torque bolts to 30 ft-lb for M8 (or as per manufacturer).
  • Install wastegate – If using an external wastegate, bolt it to the turbine housing or manifold port. Connect the actuator arm to the gate. Torque wastegate flange bolts to 18 ft-lb.
  • Oil feed and return – Connect the oil feed line to the turbo’s center housing using new copper washers. Torque to 10-12 ft-lb. For the oil drain, use a high-temp O-ring or gasket. The drain line must slope downward to the oil pan – avoid any low spots where oil can pool.
  • Water lines – Attach the coolant hoses to the turbo. Use constant-tension clamps. Route hoses away from the downpipe to avoid heat damage.
  • Boost control lines – Connect the pressure source (compressor housing or intake manifold) to the boost controller, then to the wastegate. Use silicone hose and secure with zip ties.

Important: Prime the oil system before first start. Remove the spark plugs, disable the fuel pump relay, and crank the engine for 10 seconds several times. This sends oil to the new turbo’s bearings without combustion.

Connecting Intercooler and Exhaust Components

With the turbo secured, you must integrate it with the rest of the intake and exhaust system.

  • Compressor outlet – Attach the charge pipe to the 4” outlet. Use a high-quality silicone coupler and T-bolt clamps. The intercooler inlet should match the pipe diameter.
  • Intercooler piping – Install a larger intercooler if still factory. The GTX3584RS moves much more air, and the stock unit becomes a bottleneck. Use 3” aluminium piping with welded bead locks.
  • Downpipe connection – The GTX turbine outlet is usually a V-band. Install a matching downpipe with a 3.5” or 4” stainless steel tube and a high-flow cat (if required for emissions). Torque the V-band clamp to 50-60 ft-lb.
  • Exhaust front pipe – Connect the downpipe to the rest of the exhaust system. Use a new gasket and spring bolts to allow for thermal expansion.
  • Intake system – Mount an air filter (pod style) on the turbo inlet, or fabricate an intake pipe to the factory airbox location. Make sure the MAF sensor is properly installed in the intake pipe if you are retaining it (for speed density tuning, it may be removed).

Check all couplers and V-bands for alignment. Overtightening couplers can damage the silicone, so use a torque of 5-6 Nm (for T-bolt clamps).

Final Steps and Testing

Before starting, double-check every connection – especially oil and coolant lines.

  • Refill engine fluids – Use high-quality synthetic engine oil (5W-30 or 5W-40) and fill to the correct level. Refill coolant and bleed air by idling with the radiator cap off until the thermostat opens.
  • Reconnect battery and inspect for loose grounds or exposed wires.
  • First start – Start the engine and let it idle for 2-3 minutes. Listen for any unusual sounds (whistling, metal grinding). Watch the oil pressure gauge – it should rise quickly.
  • Leak check – Spray soapy water on all oil, coolant, and intake connections. Look for bubbles. For boost leaks, use a smoke tester or pressure tester (20 psi max).
  • Test boost control – Do a cautious test drive. Start with low boost (7-10 psi) to verify wastegate behavior. If using an electronic boost controller, follow the manufacturer’s setup procedure.

Important: Do not go to full throttle until the engine has been tuned on a dyno or by a reputable tuner. The GTX3584RS requires a custom ECU calibration to match fuel, ignition, and boost targets.

Tuning and Performance Considerations

Installing the GTX3584RS is only half the battle. The A90 Supra’s stock ECU can adapt to some changes, but a larger turbo demands a complete recalibration. Here is what you need:

  • ECU tune – Use a flash tune via BootMod3, MHD, or ECUtek. Many tuners offer OTS maps for GTX3584RS on 93 octane or E85.
  • Fuel system upgrades – At 600+ hp, you will need larger fuel injectors (e.g., 1000cc+) and an LPFP upgrade or port injection.
  • Boost targets – Typical street tune: 22-24 psi on 93 octane, 28-30 psi on E85. Spool time will be around 3800-4200 RPM with the stock manifold; a twinscroll manifold can drop spool 300-500 RPM.
  • Cooling – Upgraded intercooler (e.g., VRSF, CSF) and oil cooler are highly recommended for sustained performance.

For more details, check Garrett’s official B58 upgrade guide and community dyno threads on SupraMKV.com for real-world power numbers.

Conclusion

The Garrett GTX3584RS transforms the A90 Supra into a true high-horsepower machine. While the installation process is straightforward with careful planning, do not underestimate the importance of clean oil routing, proper wastegate setup, and professional tuning. This guide has given you the steps to perform a safe, reliable install, but if you lack experience with turbo swaps, consider enlisting a qualified shop. When done right, the result is an exhilarating driving experience that rivals far more expensive sports cars.

For additional resources, see Garrett Motion official website for technical specs, and TuningTech FS for a complete installation kit that simplifies the process.