Installing an HKS GT-R Turbo Kit on Your Nissan Skyline

Upgrading your Nissan Skyline with an HKS GT-R turbo kit is one of the most effective ways to unlock serious horsepower and transform the driving character of the car. Whether you own an R32, R33, or R34 Skyline GT-R, the RB26DETT engine responds exceptionally well to a properly matched turbo system. This guide provides a comprehensive, step-by-step walkthrough of the entire installation process, including preparation, removal of the factory turbochargers, fitting the HKS kit, connecting the intercooler and piping, and completing the necessary post-installation checks. The goal is to ensure a reliable, leak-free installation that delivers consistent performance and longevity.

Before you begin, understand that a turbo upgrade of this magnitude typically requires supporting modifications to the fuel system, engine management, and cooling system to realize its full potential and keep the engine safe. This guide assumes you have a basic level of mechanical experience and a properly equipped workshop.

Tools, Materials, and Safety Preparation

Having the right tools on hand prevents frustration and ensures the job is done correctly. Below is a complete list of what you will need. Do not skip safety gear or quality fasteners.

Required Tools

  • Complete socket set (metric, 8–24 mm) including deep sockets and extensions
  • Combination wrenches (metric) and a set of flare nut wrenches for oil lines
  • Torque wrench (range 5–150 Nm or 3.7–110 lb-ft)
  • Screwdrivers (flathead and Phillips)
  • Pry bar and gasket scraper
  • Jack and jack stands (or vehicle lift)
  • Oil drain pan and coolant catch container
  • Shop towels, brake cleaner, and penetrating oil (e.g., WD-40 or PB Blaster)
  • Feeler gauge (for wastegate setup if applicable)
  • Torx and Allen bits (for HKS hardware)

Materials and Consumables

  • HKS GT-R turbo kit (ensure it matches your Skyline model: R32, R33, or R34)
  • New oil (recommended 10W-40 or 5W-30 full synthetic for break-in)
  • New engine coolant (OEM Nissan or equivalent)
  • High-temperature silicone gasket maker or OEM manifold gaskets
  • New copper or aluminum crush washers for oil drain plug and line fittings
  • Thread locker (medium strength, blue Loctite)
  • Zip ties and heat-resistant loom for wiring

Safety Precautions

Critical: Always disconnect the negative battery terminal before working on any electrical or fuel components. Allow the engine to cool completely before draining oil and coolant to avoid burns. Use jack stands rated for the vehicle weight — never rely on a jack alone.

Work in a well-ventilated area and keep a fire extinguisher nearby. Wear mechanic’s gloves and safety glasses when handling coolant and cleaning solvents. The R32–R34 Skyline is a tight engine bay, so be prepared for awkward angles and stubborn fasteners.

Preparation Steps Before Turbo Removal

Proper preparation saves time and prevents mistakes. Follow these steps in order.

  1. Park the vehicle on a flat, level surface and engage the parking brake. Place wheel chocks behind the rear wheels.
  2. Disconnect the battery — negative terminal first, then positive.
  3. Drain the engine oil completely. Remove the oil drain plug (24 mm socket) and the oil filter. Let the oil drain for at least 10 minutes. Replace the drain plug with a new crush washer and hand-tighten only until ready to refill.
  4. Drain the coolant by opening the radiator drain valve (passenger side bottom) and removing the radiator cap. If you plan to reuse the coolant, catch it in a clean container.
  5. Remove the air intake system — including the factory air box, MAF sensor, and intake piping down to the stock turbos. Label any electrical connectors for reinstallation.
  6. Remove the intercooler piping that connects the stock intercooler to the turbos and throttle body. The factory intercooler will also need to come out later to make room for the new HKS unit.

With these items out of the way, you can clearly access the stock turbochargers and their ancillaries.

Removing the Stock Turbochargers

The RB26DETT uses twin-turbochargers in a parallel configuration. Removing them is a systematic process that requires attention to detail, especially around the oil and water lines.

Step 1: Disconnect Oil and Water Lines

  • Using flare nut wrenches, carefully loosen the oil feed lines at the turbocharger and at the block or head. Do not force the fittings — soak them with penetrating oil if necessary.
  • Remove the oil drain lines from the bottom of each turbo. These are usually clamped with rubber hoses; loosen the hose clamps and slide them off. Be careful not to damage the return line connections.
  • Disconnect the water lines (coolant lines) from each turbo. Label which line goes to which port to avoid confusion during reassembly.

Step 2: Unbolt the Exhaust System

  • Remove the downpipes from each turbo by unbolting them from the turbo exhaust outlet and the front pipe/downpipe assembly. You may need to support the exhaust system with a jack or stand.
  • Disconnect the oxygen sensors (O2 sensors) from their wiring harnesses before unbolting the sensors themselves. Keep them safe.

Step 3: Remove the Turbos from the Exhaust Manifolds

  • Starting with the front turbo (driver’s side in RHD / passenger side in LHD), unbolt the turbo from the exhaust manifold. There are typically four bolts securing each turbo to the manifold.
  • Use a torque wrench if possible — record the bolt size and orientation.
  • Gently wiggle the turbo free. If it sticks, use a pry bar between the turbo and manifold, but be careful not to damage the manifold gasket surface.
  • Repeat for the rear turbo (harder to reach — may require removing the heat shield and some intercooler piping brackets).
  • Once both turbos are free, remove them from the engine bay. Inspect the manifold gaskets — they should be replaced regardless.
Pro tip: On an R32 GT-R, the rear turbo can be particularly tight against the firewall. Loosening the engine mounts and tilting the engine slightly forward (engine hoist or jack under the transmission pan) provides invaluable extra clearance.

Installing the HKS GT-R Turbo Kit

With the stock turbos removed, you can now install the HKS kit. This typically includes one or two large turbochargers (e.g., HKS GT-2530, GT-2540, or GT-2835 depending on the kit), an exhaust manifold, wastegates, and all necessary hardware. Follow the specific instructions that come with your kit, but the general procedure below covers typical HKS GT-R turbo installations.

Step 1: Prepare the Engine Mounting Points

  • Clean the exhaust manifold mating surfaces on the cylinder head with a gasket scraper and brake cleaner. Remove any old gasket material or carbon deposits.
  • Install new exhaust manifold gaskets (usually provided in the HKS kit). Apply a thin bead of high-temperature silicone around water ports if the gasket includes them.
  • Replace any studs or nuts that are damaged. Use anti-seize on the manifold studs to ease future removal.

Step 2: Mount the Exhaust Manifold and Turbo

  • Bolting the HKS manifold in place: use the supplied hardware and torque to the manufacturer’s specification (typically 30–40 Nm / 22–30 lb-ft for manifold-to-head bolts). Start from the center bolts and work outward in a cross pattern.
  • Position the new turbocharger onto the manifold. Ensure the oil drain flange is oriented downward (gravity drain). Apply a thin film of oil to the turbo center housing turbine shaft before installation.
  • Secure the turbo to the manifold using the provided bolts. Torque to spec — usually 35–45 Nm / 26–33 lb-ft. Use thread locker on these bolts.
  • Attach the wastegate(s) to the manifold if they are external (common with HKS kits). Use the supplied gasket and springs; set the boost level according to your kit’s recommendation (e.g., 0.8–1.2 bar).

Step 3: Connect Oil and Water Lines

  • Install the new oil feed lines: HKS kits often include -3 or -4 AN braided lines with fittings. Route them away from excessive heat sources. Connect to the block or head oil supply ports, then to the turbo. Torque AN fittings by hand plus a quarter turn with a wrench — do not overtighten.
  • Attach the oil drain line to the turbo’s drain flange. Use a new gasket and secure with supplied bolts (typically M6). The drain line should slope downward to the oil pan without kinks.
  • Connect the water lines (if the HKS turbo has coolant passages). Some larger HKS turbos are oil-only; verify before routing water lines. If coolant lines are present, connect to the engine’s cooling system using the factory quick-disconnects or new adapters.

Step 4: Install Intake Piping and Actuator

  • Fit the intake pipe from the turbo compressor outlet to the intercooler or charge piping. HKS kits usually include silicone hoses and aluminum pipes. Use the provided T-bolt clamps; do not use standard worm-gear clamps as they can cut into silicone hoses.
  • Install the boost control actuator (if internal) or connect the external wastegate reference line. Route a vacuum line from a boost source (e.g., intake manifold) to the wastegate or boost controller.
  • Double-check that all lines are clear of moving parts (fan, belts, steering shaft) and that no sharp edges can chafe the hoses.

Connecting the Intercooler and Piping

A high-flow intercooler is critical for supporting the increased airflow from the HKS turbos. The kit should include a front-mount intercooler (FMIC) or a replacement for the factory side-mounts.

Step 1: Install the Intercooler

  • Remove the factory intercoolers and any mounting brackets. On R32–R34, the FMIC usually mounts behind the front bumper support.
  • Cut or trim the bumper reinforcement if required (most aftermarket FMICs require a small cutout). Use a Dremel or cutoff wheel — measure twice, cut once.
  • Mount the core using the supplied brackets. Ensure it sits level and does not contact the radiator or a/c condenser. Use rubber isolators to prevent metal-on-metal vibration.

Step 2: Route Charge Piping

  • Connect the compressor outlet pipe to the intercooler inlet (cold side). Use silicone couplers and T-bolt clamps.
  • Route the hot side (intercooler outlet to throttle body) piping. HKS kits typically use 2.5” or 3” diameter piping. Ensure gentle bends and no restrictions.
  • Install a blow-off valve (BOV) on the charge piping, preferably near the throttle body. HKS supplies a BOV in the kit. Adjust its spring tension according to boost level.
  • Tighten all clamps securely — but avoid overtightening T-bolt clamps as they can distort the silicone. A good rule: tighten until you feel resistance on the T-bolt nut, then add another quarter turn.

Wastegate Setup, Boost Control, and ECU Considerations

This is a critical area where many installations fail. Incorrect wastegate adjustment or lack of proper engine management can lead to overboost, detonation, and engine failure.

Wastegate Spring and Boost Reference

  • If using an external wastegate, install the spring that matches your target boost pressure (e.g., 0.6 bar for a base boost of ~8.7 psi). Boost reference from the compressor outlet or intake manifold.
  • Connect the wastegate actuator rod to the gate flapper lever; adjust the rod length to achieve a 2–3 mm preload on the wastegate spring. This prevents boost creep.

Engine Management and Tuning

Essential: You cannot install an HKS GT-R turbo kit on a stock ECU without remapping or adding a standalone/piggyback unit. The increased airflow will cause the factory fuel maps to run dangerously lean. Use a solution like the HKS F-CON V Pro, Nistune, or a standalone ECU (e.g., Haltech, LINK, Motec). Have the vehicle professionally tuned on a dyno.

If you are using a stock ECU with a flashable chip (e.g., R34 with Nistune), ensure the tuner has loaded a base map suitable for your turbo size and injectors. Larger injectors (e.g., 700–1000 cc) and a higher-flowing fuel pump (e.g., Walbro 255 lph or higher) are mandatory for anything beyond stock boost.

Final Checks and Reassembly

Before buttoning everything up, perform these critical inspections.

  • Check all fasteners: manifold bolts, turbo bolts, downpipe bolts, wastegate bolts, intercooler mounts. Torque them to specification.
  • Verify oil and water lines: No leaks at any connection. Tighten flare nuts or AN fittings if needed.
  • Inspect intake pipes: Ensure all clamps are tight and no hoses are chafing against the chassis or engine.
  • Reconnect the battery (positive first, then negative). Do not start the engine yet.
  • Refill engine oil with the correct quantity (check dipstick). Use a high-quality oil that meets API SN or better.
  • Refill coolant and bleed the system according to Nissan’s procedure (turn heater to full hot, run engine with radiator cap off until thermostat opens, then burp air).

Reinstall the front bumper, undertray, and any other body panels you removed.

Initial Startup and Testing

The moment of truth — but proceed with caution.

  1. Prime the turbo oil feed: Disable the fuel pump (pull fuse), crank the engine for 10–15 seconds in short bursts until the oil pressure gauge registers pressure. This pushes oil into the turbo center housing before it spins.
  2. Re-enable the fuel pump and start the engine. Let it idle at around 900–1000 rpm. Listen for any metallic noises, scraping, or whistles that indicate a problem.
  3. Check for oil and coolant leaks. If any leak develops, shut off the engine immediately and address it.
  4. After 2–3 minutes of idling, rev the engine gently to 2000–3000 rpm and release. Verify the wastegate opens (you should hear a whoosh or see a boost gauge respond).
  5. Once the engine reaches operating temperature, perform a boost leak test. Use a boost leak tester on the intake pipe and pressurize the system to 1.5x your target boost (e.g., 15 psi for a 10 psi target). Listen and feel for leaks — expect some minor clicks from BOV, but no major hisses. Fix any leaks before driving.

Test Drive and Tuning Log**

Take the car on a quiet road. Gradually increase boost while monitoring wideband AFR, knock, and intake charge temperature. Do not go full throttle until the tuner has verified the fuel map. If you are doing initial driving for a remote tune, record logs with your ECU software and send them to your tuner. Aim for 11.5:1 AFR under full boost and below 2 degrees of knock.

Important: Do not exceed 4000 rpm for the first 100 miles of conservative driving. This allows the piston rings to seat properly and the turbo seals to break in without stress.

Common Installation Pitfalls and How to Avoid Them

  • Oil leaks at the drain line: Most common when the drain line is not routed on a constant downward slope. Support the rubber hose with brackets to prevent sagging.
  • Boost creep: Caused by an incorrectly sized wastegate or flapper. Use an external wastegate with the smallest spring that matches your target. Alternatively, port the turbine housing.
  • Intercooler piping rubbing: Wrap aluminum piping with silicone tape or heat-resistant foam where it contacts the chassis.
  • Faulty O2 sensor after installation: Often due to unplugging during downpipe removal; check the wiring and sensor tip for damage.

Conclusion

Installing an HKS GT-R turbo kit on your Nissan Skyline is a transformative upgrade that significantly raises the power ceiling and driving excitement. By following this detailed step-by-step guide, you can ensure a clean, reliable installation that minimizes the risk of leaks, mechanical issues, and tuning complications. Always remember that the turbocharger itself is only part of the equation — proper fuel delivery, engine management, and tuning are equally critical. Invest in a professional dyno tune and high-quality supporting components, and your Skyline will reward you with an exhilarating yet dependable increase in horsepower for many miles to come.

For further reading and official specifications, consult the HKS official website and the Skyline Owners Club forum. A Nistune tuning platform is recommended for ECU upgrades. If you need sourcing help, RHDJapan stocks genuine HKS parts and turbo kits.