Introduction: Why the HKS GTIII 3580R for Your A45?

The Mercedes-AMG A45 (W176 and subsequent generations) is already a performance powerhouse from the factory, but its turbocharged 2.0-liter M133 engine has significant untapped potential. Upgrading to the HKS GTIII 3580R turbocharger is one of the most effective ways to increase both horsepower and torque while maintaining drivability. This direct-bolt-on unit is designed specifically for the M133 platform, offering improved flow characteristics, faster spool, and higher boost ceilings compared to the stock turbo. With the right supporting modifications and tuning, owners have seen gains of 80–120 wheel horsepower, pushing the A45 well past the 450–500 hp mark.

This guide provides a comprehensive, step-by-step walkthrough for installing the HKS GTIII 3580R on your A45. Whether you’re an experienced DIY mechanic or a shop professional, following these instructions carefully will help you avoid common pitfalls and ensure a reliable, high-performance upgrade. Before you begin, understand that this installation requires moderate mechanical skill, a clean workspace, and proper tools. Always refer to the latest manufacturer specifications and torque values.

For official product information, visit the HKS GTIII 3580R product page. For community-specific guidance, forums like MBWorld and A45/M133 owner groups are invaluable resources.

Tools, Materials, and Safety Preparations

A successful turbo swap begins with having everything on hand. Rushing to find a missing tool mid-install leads to mistakes and wasted time. Below is a detailed list of required items along with safety and workspace preparations.

Required Tools

  • Socket set – Metric sizes, including 8mm, 10mm, 12mm, 14mm, and 17mm; deep sockets and swivel joints help access tight bolts.
  • Torque wrench – A quality 3/8" or 1/2" drive click-type wrench covering 10–80 Nm ranges.
  • Combination wrenches – Open-end and box-end in the same metric sizes.
  • E-torx socket set – Many engine and turbo bolts are E-torx (e.g., E10, E12, E14).
  • Flathead and Phillips screwdrivers – For clamps, electrical connectors, and pry points.
  • Trim removal tools – Non-marring plastic tools for removing hoses and covers.
  • Pick set – For removing o-rings and tight hoses.
  • Brake cleaner and shop towels – For cleaning sealing surfaces.
  • Penetrating oil – Soak stubborn bolts (especially downpipe studs) the night before.
  • Jack and jack stands or vehicle lift – Working under the car is necessary for downpipe and lower connections.

Materials and Parts

  • HKS GTIII 3580R turbocharger kit – Includes turbo, gaskets, and fitting hardware. Verify contents against the kit list.
  • Replacement gaskets – Turbo-to-manifold, turbo-to-downpipe, and oil/coolant line o-rings. HKS supplies some, but it’s wise to have additional OEM or quality aftermarket gaskets.
  • High-temperature silicone sealant – For oil pan or block sealing if needed; use one rated for 500°F+.
  • New oil and oil filter – 5W-40 full synthetic recommended for modified turbo engines. Change oil after initial startup.
  • Premium coolant – Mercedes-Benz blue coolant or equivalent, pre-mixed.
  • Boost gauge (optional but recommended) – To monitor turbo performance post-install. Many A45 owners use a P3 gauge or app-based logging.
  • Intercooler piping and couplers – The HKS turbo may require upgraded silicone hoses; check compatibility with your existing intake and intercooler system.

Safety and Workspace

Work in a well-ventilated area. Disconnect the negative battery terminal before any electrical disconnection. Allow the engine to cool completely if it has been running. Wear safety glasses and gloves when handling coolant, oil, and gasket residue. Use jack stands rated for the vehicle’s weight; never rely on a jack alone. Have a fire extinguisher nearby, and keep a parts tray or labeled bags to avoid losing fasteners.

Preparation Steps Before Removal

Proper preparation prevents damage and speeds up the removal process.

Drain Engine Oil and Coolant

Drain the engine oil from the oil pan; the turbo oil feed line will be disconnected, and you want to minimize spills and contamination. Also drain the cooling system at the radiator petcock or by removing the lower radiator hose. This reduces the chance of coolant entering the exhaust system when you disconnect the turbo coolant lines. Capture fluids in approved containers and dispose of according to local regulations.

Remove Air Intake System and Cover Components

Remove the engine cover, intake air box, and intake tube up to the turbo inlet. This gives you clearance to the turbo area. Remove the intercooler-to-throttle body pipe if it blocks access. On the A45, the front bumper cover may need to be partially removed or loosened for intercooler piping access later, but for turbo removal you only need top access.

Disconnect Sensors and Wiring

Label and disconnect all electrical connectors attached to the stock turbo: the boost solenoid, wastegate position sensor (if equipped), and any exhaust gas temperature probes. Carefully unclip the wiring loom that runs along the valve cover. A small flathead screwdriver helps release the locking tabs.

Step 1: Removing the Factory Turbocharger

With preparation complete, you can now remove the original turbo. Take your time to avoid stripping bolts or damaging adjacent components.

Remove Intake Manifold and Throttle Body

The intake manifold sits directly above the turbo and must be removed for access. Unbolt the throttle body from the manifold first (four bolts). Then undo the manifold mounting bolts (typically 8mm or E-torx). Lift the manifold off carefully; the gasket may stick. Clean the manifold sealing surface and inspect for any dirt that could fall into the engine ports. Cover the open intake ports with a clean rag.

Disconnect Downpipe

From underneath the vehicle, remove the exhaust downpipe from the turbo outlet. The bolts on the V-band clamp or flange are often rusted; spray with penetrating oil before attempting. Use a six-point socket to avoid rounding. If the downpipe does not separate easily, gently pry with a bar, but be careful not to damage the turbo or downpipe flange. Once loose, support the downpipe with a jack or strap to remove it completely.

Remove Oil and Coolant Lines

The stock turbo has a steel oil feed line from the engine block and a return line to the oil pan. The coolant lines are typically rubber hoses with spring clamps. Have a drain pan ready. Disconnect the coolant hoses first; some coolant will spill. Then undo the oil feed line banjo bolt (use a wrench on both sides to avoid twisting the line). The return line is usually a flexible hose clamped to a pipe; release the clamp and slide it off. Plug or cap the openings to prevent debris ingress.

Unbolt and Extract the Turbo

The turbo is secured to the exhaust manifold by four or five studs with nuts. Working from above and below, remove these nuts. A wobble extension and universal joint are helpful for the lower ones. Once all nuts are off, carefully wiggle the turbo free from the manifold. It may be stuck due to carbon buildup; gently tap with a rubber mallet around the flange. Lift the turbo out through the top of the engine bay. Be mindful of the wastegate actuator linkage; it may snag. Remove the old manifold gasket and clean the manifold surface.

Tip: Inspect the oil return port on the block or oil pan for any sludge. Clean if necessary to ensure unimpeded oil flow to the new turbo.

Step 2: Installing the HKS GTIII 3580R Turbocharger

Now the exciting part: fitment of the new HKS unit. The HKS GTIII 3580R is designed as a direct replacement, but attention to detail is critical.

Prep the Manifold and Turbo

Clean the exhaust manifold sealing surface with a wire brush and brake cleaner. Install a new manifold gasket. If your HKS kit does not include a manifold gasket, purchase an OEM gasket from Mercedes (part number A 276 142 01 80 or equivalent). Lightly coat both sides with high-temp copper spray for a better seal.

Examine the new turbo: check the compressor wheel for free spin, and verify that the wastegate actuator moves smoothly. If you have a shop air source, pressurize the actuator to see when it opens and ensure it matches the spring pressure (typically around 8–10 psi for the HKS unit). Some owners opt to adjust the actuator preload for higher boost targets later.

Position and Bolt the Turbo

Carefully lower the HKS GTIII 3580R onto the manifold studs. Use a few drops of penetrating oil on the studs to ease tightening. Hand-tighten the nuts first, then torque to the manufacturer specification (check the HKS manual; typically 25–30 Nm). A torque wrench and crow’s foot may be needed for the lower nuts. Do not over-tighten – the flange can warp.

Connect Oil and Coolant Lines

The HKS turbo uses the same connections as the stock unit, but it’s wise to upgrade the oil feed line to a braided stainless steel line for durability. The kit may include adapters. Use new copper washers on banjo bolts. Tighten the oil feed bolt to 20–22 Nm. For the coolant lines, use new o-rings at the turbo connections. Secure with factory-style spring clamps or worm-gear clamps; avoid over-tightening that can collapse the liner in silicone hoses. Verify the oil return hose is clean and not kinked. Route it gently back to the oil pan.

Note on oil restrictors: The HKS GTIII 3580R does not typically require an external oil restrictor if using a properly sized feed line (around -3 AN). Consult the kit instruction to confirm; excessive oil pressure can cause seal failure.

Reconnect Downpipe and Electrical

Attach the downpipe to the turbo outlet with a new gasket. If your downpipe uses a V-band, clean the mating surfaces and lubricate the clamp teeth. Torque the clamp nut to spec. Reconnect any exhaust sensors and wiring that were removed. Double-check that no wires are touching the turbo housing; use zip ties to secure them away from the heat shield area.

Step 3: Connecting the Intake and Intercooler System

The HKS GTIII 3580R has a larger compressor outlet and inlet than stock. Your intercooler piping and intake must match.

Install Intercooler Piping

If you are using the factory intercooler, you may need an adapter or silicone reducer to fit the larger turbo outlet. It is strongly recommended to upgrade to a larger front-mount intercooler (FMIC) with 2.5” or 2.75” piping to realize the full potential of this turbo. HKS provides a pipe kit for some applications; otherwise, source quality silicone couplers with T-bolt clamps. Ensure all connections are aligned and tensioned evenly to prevent blow-off under boost.

Connect the Intake System

The turbo inlet requires a 4” to 3.5” or 4” to 4” coupler, depending on your air filter setup. Many A45 owners use an aftermarket cold air intake with a large conical filter. Ensure the filter has a heat shield to avoid ingesting hot engine bay air. Test-fit the intake tube before final tightening; it must not rub against the chassis or other components.

Reinstall Intake Manifold

Before reinstalling the intake manifold, inspect the throttle body gasket and clean both surfaces. Reinstall the manifold with new gaskets and torque to spec (typically 10–12 Nm in a criss-cross pattern). Reconnect the throttle body and all vacuum lines. This is a good time to replace any brittle vacuum hoses with silicone.

Step 4: Fuel System and Tuning Considerations

Upgrading the turbo without proper fuel and ECU support is dangerous. The HKS GTIII 3580R moves significantly more air, requiring a revised air/fuel ratio and boost pressure curve. This step is often overlooked by novice installers, leading to engine damage.

Fuel Pump and Injectors

The stock A45 fuel system can support modest power increases, but at 450+ hp, the factory high-pressure fuel pump (HPFP) and injectors may max out. Consider upgrading to a Nitro or Autotech HPFP and larger fuel injectors (e.g., 380cc or more) if your power goals exceed 470 hp. Consult with your tuner to see if these are required for your specific target.

ECU Remapping

You cannot run the HKS turbo on a stock tune. The wastegate duty cycle, fuel maps, ignition timing, and boost control all need recalibration. Work with a reputable tuner who has experience with the M133 engine and HKS turbos. Options include mail-order tunes (like Eurocharged, DME Tuning, or custom software) or a dyno tuning session. A fully custom dyno tune is ideal for extracting maximum safe power and ensuring drivability.

For more insight into tuning the M133, see resources like DME Tuning or community guides on Club CL86 (A45 subsection).

Boost Control

The HKS turbo typically comes with an electronic boost controller solenoid or you can use the factory solenoid if re-mapped. A manual boost controller is not recommended due to the need for precise control. Ensure your tune incorporates proper boost ramping to avoid torque spikes that can break the transmission or driveline.

Step 5: Final Checks, Filling Fluids, and Initial Start-Up

Before turning the key, methodically verify every connection.

Leak Check and Bolt Re-torque

Inspect all turbo, downpipe, intercooler, and intake clamps. Torque each fastener to spec. Use a boost leak tester (a simple PVC cap with an air fitting) to pressurize the intake system to 15–20 psi and listen for hissing. Fix any leaks. Also check oil and coolant line connections for tightness.

Prime the Oil System

To prevent a dry start that can damage the new turbo bearings, disable the fuel pump (pull the fuse or relay) and crank the engine for 15–20 seconds in short bursts until the oil pressure light goes out. Reconnect the fuel pump, then fill the cooling system. Start the engine and let it idle; immediately check for oil or coolant leaks. The turbo will emit a faint burning smell for the first few minutes as assembly lube burns off – this is normal.

Monitor and Adjust

During the first drive, keep the RPM below 4000 and vary the load while watching the boost gauge. The wastegate should open at the target spring pressure. Listen for unusual rattles or whistles. After a short 10-minute drive at moderate speeds, check oil level and top up coolant. Re-torque the downpipe clamp after two heat cycles. Schedule an oil change after 500 miles to flush out any break-in debris.

Conclusion

Installing the HKS GTIII 3580R on your A45 is a substantial upgrade that transforms the car’s acceleration and top-end power. When done correctly with proper tuning and supporting modifications, this turbo can deliver a reliable increase of 100–130 horsepower over stock. The key to success lies in meticulous preparation, careful torque control, and professional ECU calibration.

Remember that the turbo is only one part of a high-performance system. Complement it with a suitable intercooler, upgraded fueling, and a high-flow exhaust for maximum gains. With the right approach, your A45 will become a formidable street and track performer. For further details on turbo selection and tuning, refer to HKS’s official turbo lineup and consult with your local performance shop that specializes in Mercedes-AMG platforms.