Introduction

The A90 Toyota Supra, powered by the BMW B58 engine, has become a favorite platform for enthusiasts seeking serious horsepower. The AMS Alpha 9 turbo kit is engineered to push this engine beyond its factory limits, delivering a significant increase in both peak power and usable mid-range torque. This upgrade is not for the faint of heart—it requires meticulous installation to ensure reliability and performance. Below you’ll find a comprehensive, step-by-step breakdown of the installation process, including critical details often overlooked in basic guides. Whether you are a seasoned mechanic or a dedicated DIYer, these instructions will help you achieve a factory-quality install that stays safe and strong for thousands of miles.

Tools and Materials Needed

Before starting, assemble all necessary tools and components. Missing a critical tool mid-install can cause delays or mistakes.

  • AMS Alpha 9 Turbo Kit – verify all components are present against the included checklist
  • Socket set – metric sizes 8mm through 19mm, plus a 3/8” drive for tight spaces
  • Torque wrench – capable of measuring in inch-pounds and foot-pounds (range 10–150 ft-lb recommended)
  • Screwdrivers – flathead and Phillips, magnetic tip helps with dropped bolts
  • Combination wrenches – 10mm, 12mm, 13mm, 14mm, 17mm, 19mm
  • Jack and jack stands – minimum 3-ton capacity, with rubber pads to protect the chassis
  • Coolant – BMW-approved phosphate-free coolant (e.g., BMW NALCOOL 2000) or equivalent
  • Engine oil – 5W-30 or 0W-40 meeting BMW LL-01 specs
  • Shop towels and brake cleaner for degreasing gasket surfaces
  • Safety glasses and mechanic gloves
  • Optional but helpful: ¼” drive ratchet set, swivel sockets, LED work light, telescoping mirror for inspecting rear turbo bolts

Preparation Steps

Proper preparation minimizes risk of damage and ensures a clean workspace.

  • Park the vehicle on a level concrete floor and engage the parking brake. Place wheel chocks behind the rear tires.
  • Disconnect the negative battery terminal to avoid accidental short circuits or triggering the fuel pump while working.
  • Raise the front of the car using a jack at the center front crossmember, then place jack stands under the designated front lift points (not the radiator support). The car should sit at a comfortable working height.
  • Drain the coolant by opening the radiator drain plug and removing the lower radiator hose. Drain the engine oil after warming the engine (if it has been run recently). Replace the drain plug with a new crush washer.
  • Remove the engine cover, air intake box, and any sound deadening panels. Label connectors and hoses with masking tape to avoid confusion during reassembly.

Understanding the AMS Alpha 9 Turbo Kit

Before diving into the mechanical work, take a moment to familiarize yourself with the kit’s design. The AMS Alpha 9 features a billet compressor wheel and a journal-bearing center section optimized for quick spool and sustained high-rpm flow. It replaces the stock single-scroll turbo with a larger turbine housing and a custom cast exhaust manifold that improves flow balance between cylinders. The kit also includes reinforced oil and coolant lines, a new downpipe with high-flow catalytic converter (or a catless option for track use), and all necessary gaskets and fasteners. Understanding each component’s role will help you identify potential issues during installation.

Removing the Stock Turbo

Removing the factory turbo requires patience and attention to detail. Rushing can lead to broken bolts or damaged wiring.

  1. Remove the intake manifold – Undo the eight bolts holding the manifold to the cylinder head. Carefully disconnect the throttle body electrical connector, the charge air temperature sensor, and the crankcase ventilation hose. Set the manifold aside on a clean surface.
  2. Disconnect coolant and oil lines – The stock turbo uses banjo fittings for oil feed and drain, and spring clips for coolant hoses. Use a flare nut wrench to avoid rounding the banjo bolts. Have shop towels ready to catch residual fluid. Cap the lines to prevent debris ingress.
  3. Remove the exhaust downpipe – Reach under the car and unbolt the downpipe from the turbo outlet (four bolts) and from the exhaust cat-back (two bolts). It may be necessary to loosen the cat-back mounts to shift the exhaust pipe out of the way.
  4. Unbolt the turbo from the manifold – The stock turbo is held by four nuts on studs. Use a deep socket with a universal joint to reach the lower rear nut. Carefully lift the turbo off the studs and out of the engine bay. If it hangs, check for any remaining hose or wiring attachments.
  5. Inspect and clean – With the turbo removed, clean the exhaust manifold mating surface thoroughly. Use a razor scraper and brake cleaner. Inspect the studs for damage; replace any that are bent or stripped.

Installing the AMS Alpha 9 Turbo Kit

Now the new turbo goes in. Follow the AMS instructions precisely, but note these critical points.

  1. Install the new exhaust manifold (if provided as part of the kit) – Apply a thin layer of high-temperature anti-seize to the manifold studs. Tighten the manifold nuts in a crisscross pattern to the specified torque (typically 25–30 ft-lb).
  2. Mount the turbo onto the manifold – Use the supplied gasket between the turbo and manifold. Ensure the turbo sits flat before tightening the retaining bolts. Torque to 35–40 ft-lb per AMS specs.
  3. Reconnect oil and coolant lines – Use only the hardware included in the kit. The oil feed line often requires a new banjo bolt with a restrictor – do not reuse the stock part. Tighten banjo bolts to 18–22 ft-lb. Coolant line clamps should be rated for high-pressure and temperature; use a plier-style clamp tool to secure them.
  4. Install the new intake manifold – Apply a light coat of silicone spray to the manifold gasket to hold it in place during installation. Torque the manifold bolts to 10–12 ft-lb working from the center outward. Reconnect all sensors and hoses: throttle body, MAP sensor, PCV hoses, and intake air temperature sensor. Verify that the harness clips are fully seated.

Connecting the Exhaust and Intake Systems

Proper connection of the exhaust and intake is crucial for performance and avoiding boost leaks.

  • Attach the downpipe – Use the provided gasket and nuts. Snug them evenly, then torque to 40–45 ft-lb. Support the downpipe with a bracket if included; do not allow it to hang on the turbo flange.
  • Route the intake piping – The AMS kit includes a new air filter and charge pipes. Secure all couplers with T-bolt clamps tightened to 5–6 ft-lb (do not overtighten, as it can cut the silicone). Position the filter in a cool, clean area away from the radiator fan.
  • Check clearance – Rotate the blades of the turbo by hand to ensure there is no rubbing. Spin the compressor wheel – it should rotate freely with slight resistance. If it binds, loosen the compressor housing bolts and re-center it.
  • Install the wastegate actuator – The Alpha 9 kit uses an external wastegate. Mount it securely using the supplied bracket and adjust the rod length so that the gate opens as per the manufacturer’s recommendation (typically 1 mm of preload). Use a pressure source to verify operation.

Final Steps and Testing

The mechanical installation is complete, but the job isn't over yet. Follow these steps for a safe first start and initial testing.

  1. Reinstall any removed components – The radiator fan shroud, belly pans, splash shields, and engine cover. Ensure no tools or rags are left in the engine bay.
  2. Refill fluids – Add coolant and oil. Use a vacuum filler if possible to avoid air pockets in the turbo cooling circuit. Crank the engine with the fuel pump fuse removed for 10 seconds to prime the oil system before starting.
  3. Reconnect the battery and verify all electrical connectors are latched.
  4. Initial start – The engine will likely run roughly due to the new injectors or tune requirements. Let it idle for 2–3 minutes, then check for oil leaks around the turbo oil feed and drain, coolant leaks, and any exhaust smoke.
  5. Boost leak test – Use a boost leak tester (pressurize the intake system to 20 psi) and listen for hissing. Fix any leaks before driving.
  6. Road test – Drive gently for the first few miles, monitoring coolant temperature and oil pressure. Gradually increase load while watching the wideband air/fuel ratio. If the car is not tuned for the Alpha 9, do not exceed light throttle until a proper calibration is loaded.

Common Pitfalls and Troubleshooting

Even experienced installers can run into issues. Here are the most common problems and how to avoid them.

  • Gasket leaks at the turbo-to-manifold joint – Always use a new gasket and clean the mating surfaces with a razor. Overtightening can warp the flange – stick to the torque spec.
  • Wastegate actuator interference – The external gate may hit the engine block or frame rail. Test-fit the actuator before finalizing all hardware. A 1” spacer can sometimes provide clearance.
  • Coolant line kinking – The AMS braided lines are more flexible than stock, but routing them around the block can still pinch. Use silicone hose protectors or zip ties to keep lines away from sharp edges.
  • Sensor connectivity – After reinstalling the intake manifold, double-check that the throttle body is fully plugged in and the wiring harness is not strained. A loose MAP sensor will cause a check engine light and poor drivability.

Post-Installation Break-In and Tuning Requirements

Installing a larger turbo without a tune is dangerous. The AMS Alpha 9 kit is intended for use with a custom ECU calibration, typically via ECUtek or MHD on the B58. Immediately after installation, drive the car to a tuning shop on a low-boost map (if available) or a safe base calibration provided by AMS. Do not boost the engine until the tune is finalized. Break-in of the turbo is straightforward: vary the engine speed for the first 500 miles, avoiding constant high load and extended periods of full throttle. Change the oil and filter after the break-in period to remove any debris that may have accumulated.

For more tuning resources, consult a professional such as Pure Tuning or the ECUtek website for a list of authorized tuners.

Conclusion

The AMS Alpha 9 turbo kit transforms the A90 Supra from a capable grand tourer into a true track-capable weapon. The installation described here is a multi-step process that rewards careful attention to detail. While this guide covers the major steps, always reference the official AMS Performance manual for torque values and specific kit variations. If at any point you feel uncertain about a step, consult a professional installer. A correctly installed Alpha 9 will provide years of thrilling, reliable performance.