Upgrading the turbocharger on your Lexus IS300 equipped with a 2JZ-GTE swap is one of the most effective ways to unlock serious horsepower. Among the top contenders in the aftermarket turbo world, the Garrett GTX3584RS stands out for its blend of rapid spool, high flow capacity, and proven reliability. This guide dives deep into the benefits, installation steps, supporting modifications, and tuning strategies needed to maximize power with this turbo upgrade on your IS300.

Why Choose the Garrett GTX3584RS for Your 2JZ-GTE Swap?

The GTX3584RS is the next evolution of Garrett’s legendary GT3582R. It uses Garrett’s “GTX” dual ball bearing center housing and a 58mm compressor wheel with a 84mm turbine wheel. For a 2JZ-GTE in an IS300, this turbo offers a near-perfect balance of quick spool and top-end power.

Key Benefits

  • High Power Capacity: The GTX3584RS can support from 600 to 850 wheel horsepower depending on fuel, boost level, and engine build. This makes it suitable for street-driven cars that occasionally see track use.
  • Quick Spool: Thanks to the advanced aerodynamics of the GTX compressor wheel and the lightweight dual ball bearing CHRA, the turbo reaches full boost as low as 4000–4500 RPM on a 2JZ-GTE with proper exhaust manifold sizing.
  • Versatile Tuning Range: The turbo’s broad compressor map allows you to tune for low boost (15–20 psi) for a responsive daily driver or crank up the boost to 30+ psi for drag strip passes.
  • Durability: Garrett’s dual ball bearing design handles high lateral loads and high heat cycles better than traditional journal bearings, extending the life of the turbo under the high-stress conditions of a swapped IS300.
  • Direct Compatibility: Most aftermarket top-mount or bottom-mount manifolds designed for a T3 or T4 flange (with v-band outlet) work with the GTX3584RS, simplifying the swap.

For an IS300 with a 2JZ-GTE, the turbo also complements the car’s relatively light chassis. The power delivery feels linear and controllable, avoiding the “lag then wall” character of larger turbos.

Installation Process for the IS300 2JZ-GTE Swap

Installing the Garrett GTX3584RS requires careful preparation. The process is more involved than a simple bolt-on because the IS300’s engine bay differs from the JZA80 Supra’s, and the 2JZ-GTE swap often uses custom piping. Below is a comprehensive guide.

Tools and Materials Needed

  • Garrett GTX3584RS turbocharger (specify T3/T4 or v-band configuration)
  • Turbo manifold – choose a top-mount or bottom-mount design that clears the IS300’s steering shaft and brake booster. Popular options include GSC, Full-Race, and custom fabricated units.
  • Oil feed and drain lines – use -4AN feed and -10AN drain with proper restrictors for the GTX’s ball bearing CHRA.
  • Water coolant lines – if using water cooling, connect to the engine’s cooling system or run a dedicated pump.
  • Intercooler and piping – a front-mount intercooler (FMIC) with 2.5” to 3” piping is recommended. Account for the IS300’s narrow front end.
  • Wastegate – an external wastegate (e.g., Tial 44mm MVR) is required; the GTX3584RS does not have an internal gate.
  • Blow-off valve – a recirculating or atmospheric BOV is needed.
  • Boost controller (manual or electronic)
  • Downpipe – custom 3” or 3.5” downpipe with v-band to match turbo outlet.
  • ECU tuning solution (standalone like AEM Infinity, Haltech, or Link; or piggyback with a plug-and-play harness for the IS300)
  • Basic tools: wrenches, sockets, torque wrench, gasket scraper, jack stands, etc.

Step-by-Step Installation

  1. Prepare the Car: Safely lift the IS300, drain coolant and oil, and remove the front bumper, intercooler (if stock), and any accessories that will block access to the turbo area.
  2. Remove the Existing Turbo Setup: If you already have a 2JZ-GTE with a stock twin-turbo or a previous single turbo, disconnect all hoses, lines, and bolts. Remove the manifold and turbo as an assembly to avoid damaging threads.
  3. Install the Turbo Manifold: Clean the cylinder head’s exhaust ports and fit a new gasket. Torque the manifold bolts to the manufacturer’s spec (typically 35–40 lb-ft for 2JZ-GTE head). For the IS300 swap, ensure the manifold does not hit the steering rack or firewall. You may need to modify a bottom-mount manifold to clear the IS300’s steering shaft.
  4. Mount the GTX3584RS: Attach the turbo to the manifold with the appropriate gasket or v-band clamp. Apply anti-seize to studs if threaded. Use new copper or aluminum washers for oil feed.
  5. Connect Oil and Coolant Lines: Run a -4AN braided stainless line from the oil filter housing (or a dedicated oil pressure port) to the turbo feed. The drain line must be -10AN and slope downward to the oil pan. If using water cooling, connect to a T-fitting in the heater circuit or a separate pump.
  6. Install Wastegate and Blow-off Valve: Mount the external wastegate on the manifold or a separate screamer pipe. Set the boost pressure reference line to the wastegate and boost controller. Install the BOV on the intercooler piping between the turbo and throttle body.
  7. Fabricate the Downpipe: Use a 3” or 3.5” v-band downpipe that clears the transmission tunnel and subframe. The IS300 swap often requires a custom downpipe because the engine sits further back than a Supra’s. Consider having a muffler shop weld it.
  8. Build the Intercooler Piping: Route 2.5” or 3” intercooler piping from the turbo compressor outlet to the intercooler, then to the throttle body. Use silicone couplers and T-bolt clamps. For the IS300, stay clear of the fan shroud and radiator.
  9. Reinstall Accessories: After all plumbing is secure, refill oil and coolant, check for leaks, and reinstall the front bumper, headlights, etc.

Once mechanically installed, the real work begins: tuning.

Supporting Modifications for Maximum Power

The GTX3584RS can outflow stock supporting systems. To avoid running lean or overheating, upgrade these components in tandem.

Fuel System Upgrades

  • Fuel Injectors: 1000cc to 1600cc injectors are appropriate for pump gas and E85 respectively. Bosch 1600cc or Injector Dynamics ID1050x are popular.
  • Fuel Pump: A single Walbro 450 LPH or a dual pump setup is needed to maintain fuel pressure under high boost. The IS300’s stock pump cannot supply enough volume.
  • Fuel Pressure Regulator: An adjustable FPR using a return-style fuel system is recommended for consistent pressure.

Cooling System

  • Radiator: A larger aluminum radiator (e.g., Mishimoto, PWR) helps manage increased heat from the turbo. The IS300’s stock radiator may struggle.
  • Oil Cooler: A thermostat-controlled oil cooler (25-row or larger) mounted in the front bumper area will keep oil temperatures safe during extended pulls.
  • Intercooler: A bar-and-plate FMIC with a core size around 24” x 12” x 3” supports the GTX3584RS’s airflow. Ensure ducting directs air through the core.

Intake and Exhaust

  • Cold Air Intake: Use a 4” intake pipe with a high-flow filter (e.g., K&N or AEM) positioned in a cooler area of the engine bay.
  • Full Exhaust: A 3” or 3.5” mandrel-bent exhaust from the downpipe back reduces backpressure. Include a high-flow catalytic converter if emissions are a concern.

Transmission and Drivetrain

With high horsepower, the IS300’s stock automatic transmission will fail quickly. A built automatic (e.g., from Boosted Auto or Marlin Crawler) or a manual swap (R154 or CD009) is essential. Upgraded axles and differential (W58 or R200) may also be needed.

Tuning Considerations for the GTX3584RS

Proper tuning is the difference between a reliable 650 hp build and a blown engine. The GTX3584RS responds well to aggressive fuel and spark curves, but the 2JZ-GTE’s handling of boost must be respected.

ECU Choices

  • Standalone ECUs: Units like AEM Infinity 506, Haltech Elite 2500, or Link G4+ are the best options for the IS300 swap. They allow full control over fuel, ignition, boost, and knock sensors.
  • Plug-and-Play Options: Some standalone ECUs come with pre-made harnesses for the IS300 chassis, reducing wiring complexity.

Boost Control Strategy

Use an electronic boost controller (e.g., AEM, Gizzmo, or MAC valve) with a reference pressure source from the compressor cover. For the GTX3584RS, starting at 18–20 psi on pump gas is safe. With E85 and a built engine, boost can climb to 28–32 psi. Log boost pressure and watch for spikes that could cause knock.

Ignition Timing and Fuel Maps

  • Fuel Maps: Target air-fuel ratios of 11.5:1 on pump gas and 12.0:1 on E85 at peak torque, leaning to 12.5:1 at high RPM. Use a wideband O2 sensor for accurate feedback.
  • Ignition Timing: The 2JZ-GTE typically runs 12°–15° base timing at low load and retards to 8°–10° at high boost. Knock sensitivity is high; use quality fuel and add ethanol content for headroom.

Dyno Tuning and Load Testing

Schedule a dyno session with a tuner experienced in 2JZ-GTE and Garrett turbos. Load-based tuning (like using a Mustang dyno) better simulates street conditions. Expect the GTX3584RS to make peak power between 5500 and 7500 RPM. The tuner will also set a conservative boost cut and adjust the knock threshold.

Expected Power Outputs and Comparison

With the GTX3584RS, a properly built 2JZ-GTE in the IS300 can achieve the following (wheel horsepower on a dynojet):

  • Pump Gas (93 octane, 20 psi): 550–600 whp
  • E85 (28 psi, stock head gasket): 650–720 whp
  • Built engine (32 psi, upgraded head studs, cams): 780–850 whp

Compared to the older GT3582R, the GTX3584RS spools 300–500 RPM sooner and makes 20–30 more horsepower at the same boost. It also fits in the same footprints, making it a drop-in replacement on many existing setups. Another popular alternative is the Precision 6266, but the GTX3584RS offers better overall efficiency and Garrett’s aftermarket support.

Reliability and Maintenance

To keep the GTX3584RS performing for years, follow these practices:

  • Oil Change Intervals: Change oil every 2,500–3,000 miles using a high-quality synthetic (5W-30 or 5W-40). The dual ball bearing turbo requires clean oil.
  • Cool Down: After hard driving, let the engine idle for 1–2 minutes to circulate oil through the turbo center section and prevent coking.
  • Check for Leaks: Inspect oil and coolant lines regularly. A small leak can lead to catastrophic failure.
  • Boost Leaks: Use a boost leak tester annually to ensure intercooler piping and couplers are sealed.

Additionally, the IS300’s engine bay lacks the space of a Supra. Keep an eye on heat soak and consider adding a turbo blanket to reduce underhood temperatures.

Final Thoughts

The Garrett GTX3584RS is a mature, high-performing turbo who upgrade transforms an IS300 2JZ-GTE swap into a serious weapon. With the right supporting modifications and a meticulous tune, you can achieve outstanding power without sacrificing daily drivability. Whether you’re aiming for a 650 hp street car or an 850 hp weekend warrior, this turbo delivers consistent results. Plan your build around this turbo, and you’ll enjoy both the spool and the top-end rush on every drive.

For additional references, consult Garrett’s official website for the GTX3584RS product page, see real-world results on SupraForums, and check the Garrett motion site for technical data. Build smart, test on the dyno, and enjoy the boost.