Introduction: Why Upgrade to the HKS GT II Turbo Kit

The Mercedes-Benz E63 is already a formidable machine, but for enthusiasts chasing serious track days, drag-strip glory, or simply the thrill of triple-digit highway merges, the factory turbocharger leaves room for improvement. The HKS GT II turbo kit is purpose-built for the M177 and M178 engines found in the E63 (and related AMG models), delivering a proven path to 550+ wheel horsepower without sacrificing daily-driver manners. This guide walks through the complete installation process, from preparation and removal of the stock unit to final tuning, with expert tips to avoid common pitfalls.

Note: This installation requires advanced mechanical skills, proper tools, and a well-ventilated workspace. If you're not fully confident, have a qualified AMG shop perform the install. Always refer to the HKS official documentation for torque specs and kit-specific instructions.

Tools, Materials, and Workspace Preparation

Before touching the car, gather every item on the list. Running back and forth mid-install increases risk of mistakes or contamination.

Required Tools

  • Full metric socket set (including deep sockets for turbo studs)
  • Torque wrench with ft-lb and in-lb ranges
  • Combination wrenches (8mm – 19mm)
  • Flathead and Phillips screwdrivers
  • Trim removal tools for plastic fasteners
  • Pick set for removing O-rings and vacuum lines
  • Oil catch pan and shop towels

Materials from the HKS GT II Kit

  • HKS GT II turbocharger assembly (often includes billet compressor wheel and upgraded wastegate actuator)
  • Precision silicone couplers and T-bolt clamps
  • Intercooler piping set (aluminum mandrel-bent)
  • Gaskets for turbo-to-manifold and turbo-to-downpipe
  • Mounting hardware and brackets
  • Instructions sheet (keep nearby)

Consumables & Fluids

  • Fresh engine oil (5W-40 or 0W-40; check your kit recommendation)
  • Coolant (MB 325.0 spec or equivalent)
  • Thread locker (medium-strength, 243 Loctite)
  • Dielectric grease for electrical connectors
  • Brake cleaner for degreasing surfaces

Preparation Steps

Park the E63 on a level concrete floor and allow the engine to fully cool. Disconnect the battery negative terminal and let the car sit for 15 minutes to discharge capacitors in the ECU. If the car has an aftermarket intake or heat shield, remove them now. Clear the engine bay of leaves, debris, and any loose tools.

Safety imperative: Never work on a hot turbocharger or exhaust system. Severe burns can occur. Also, wear mechanic gloves and safety glasses.

Removing the Stock Turbocharger

The factory twin-scroll turbo on the E63 sits in a tight spot between the engine block and firewall. Patience and the right extensions are your best friends.

Step 1: Access and Disassembly

  • Remove the plastic engine cover (pull upward; it’s on rubber grommets).
  • Disconnect the MAF sensor and intake duct from the air box to the turbo inlet.
  • Unbolt the charge air cooler pipes at the throttle body and turbo outlet.
  • Label all vacuum lines and electrical connectors before disconnecting them. Use masking tape and a marker.
  • Remove the heat shield around the turbo — usually 3–4 bolts.

Step 2: Unbolting the Turbo

  • Support the turbo with a jack or a helper; it’s heavy.
  • Access the exhaust manifold-to-turbo bolts (often M8 or M10 studs). Use a swivel socket and extension.
  • Disconnect the oil feed and drain lines. Have a catch pan ready — oil will spill.
  • Disconnect the coolant lines (again, pan underneath).
  • Carefully lift the turbo out of the bay, tilting it to clear the frame rail.

Tip: If any studs snap during removal, stop and drill/extract them immediately. A stud broken deep in the manifold will ruin your day.

Installing the HKS GT II Turbo Kit

With the old turbo out, clean the manifold flange with a wire brush and brake cleaner. Inspect the oil drain port for debris.

Mounting the New Turbo

  • Place the new HKS GT II turbo onto the manifold studs. Use the new gasket supplied in the kit.
  • Hand-tighten the nuts, then torque to the spec in the HKS manual (typically 25–30 ft-lb).
  • Reconnect the oil feed line using a new crush washer. Torque carefully — aluminum threads can strip.
  • Attach the coolant line; do not over-tighten the banjo bolts.
  • Plug in any electrical connectors (wastegate actuator, turbo speed sensor if equipped).

Piping and Couplers

  • Install the intake pipe from the air filter to the turbo compressor inlet. Use the supplied silicone coupler and T-bolt clamp.
  • Attach the charge pipe from turbo outlet to the intercooler. Tighten clamps evenly.
  • Connect the exhaust downpipe (if you are also upgrading the downpipe, it’s easiest to do both now).
  • Verify all couplers are fully seated; misaligned pipes cause boost leaks.

Critical: Lubricate the turbo center section with a small amount of clean engine oil on the shaft before the first start. Spin the wheel by hand to distribute oil.

Intercooler Installation and Piping

The HKS kit often includes a larger front-mount intercooler (FMIC) that requires removal of the factory unit. The intercooler is vital for maintaining safe intake air temps at 550+ whp.

Mounting the FMIC

  • Remove the front bumper fascia (follow manual or YouTube guides specific to the E63).
  • Unbolt the stock intercooler and set it aside.
  • Position the HKS intercooler in the core support. It may require trimming of the plastic shroud — take your time.
  • Secure using the provided brackets and bolts. Use thread locker.
  • Reinstall the bumper.

Routing the Piping

  • Run the hot-side pipe from the turbo to the driver-side intercooler inlet.
  • Run the cold-side pipe from the passenger-side intercooler outlet to the throttle body.
  • Ensure clearance to the radiator fan, power steering lines, and frame rails. Zip-tie any loose wires away from the pipes.
  • Tighten all T-bolt clamps; double-check after the first heat cycle.

Final Assembly and Checks

Before declaring victory, go through these final steps methodically.

  • Reconnect the battery.
  • Refill engine oil to the correct level.
  • Refill coolant and bleed the system (run the engine with the reservoir cap off until the thermostat opens, then cap it).
  • Check all electrical connectors are secure, especially MAF, MAP, and wastegate.
  • Prime the turbo: disable fuel and spark by pulling the fuel pump fuse, then crank the engine for 10–15 seconds. This pushes oil through the turbo without firing.
  • Reinstall the fuse, start the engine, and let it idle for 2–3 minutes. Listen for any grinding or whistling that sounds abnormal.
  • Inspect for oil or coolant leaks around the turbo, lines, and intercooler.

The HKS GT II hardware is only half the equation. To safely make 550+ hp and keep the engine healthy, proper ECU calibration is mandatory. The stock E63 map will not run the larger turbo efficiently and can cause knock, high EGTs, or lean conditions.

  • Work with a reputable AMG tuner such as RK Tunes or a local shop using ECUTek or custom flashing tools.
  • Expect to upgrade fuel injectors and high-pressure fuel pump if aiming for over 580 whp. Contact Fuel-IT for compatible options.
  • Monitor air-fuel ratio and boost via a digital gauge; a wideband oxygen sensor is highly recommended during the tuning session.
  • After tuning, perform a few low-load pulls to ensure the turbo spools smoothly and the wastegate holds boost.

Supporting Modifications for 550+ HP Reliability

Achieving the number is one thing; keeping the motor together is another. Consider these complementary upgrades:

  • Upgraded low-pressure fuel pump (LPFP) and flex-fuel sensor if using E85.
  • High-flow catalytic converters or a catless downpipe (check local emissions laws).
  • Stronger charge pipes and a blow-off valve that suits the higher boost levels.
  • Oil catch can to reduce carbon buildup on intake valves.
  • Transmission tune to handle increased torque, especially for the MCT 9-speed.

Troubleshooting Common Installation Issues

Boost Leak

Whistling or hissing under load points to a loose coupler or cracked pipe. Re-tighten all clamps, and do a smoke test if possible.

Oil Leak from Turbo Drain

Usually caused by incorrect mounting angle or a collapsed drain line. Ensure the drain slopes continuously toward the pan. Replace with a Verus Engineering drain tube if needed.

No Boost / Wastegate Stuck Open

Check the wastegate actuator rod length and preload. Also inspect vacuum lines to the boost controller; a disconnected line will drop boost to wastegate spring pressure only.

Overboost / Boost Cut

This usually means the wastegate actuator is not receiving enough pressure to open, or the boost controller is incorrectly set. Log boost pressure and adjust the controller duty cycle with your tuner.

Conclusion

Installing an HKS GT II turbo kit on your E63 is a substantial project, but the reward is a truly potent AMG that can embarrass far more exotic machinery. By following each step carefully — from removing the stock turbo with precision to tuning the fuel and ignition maps — you set yourself up for reliable, repeatable 550+ horsepower. Respect the process, invest in supporting mods, and trust your tuner. Your E63 will thank you with every punch of the throttle.