Before You Begin: Understanding the HKS GT2835PRO Upgrade

Installing the HKS GT2835PRO turbocharger on your SR20DET engine is one of the most effective ways to unlock serious horsepower gains while retaining excellent spool characteristics. This ball-bearing turbo features a twin-scroll divided inlet and a 58mm billet compressor wheel, enabling the SR20DET to produce 350–450 whp on stock displacement with proper supporting mods. However, a successful installation demands careful attention to preparation, torque specifications, and fluid routing. This guide provides the complete step-by-step procedure from removal of the old unit to initial startup tuning.

Tools, Materials, and Safety Gear

Required Tools

  • 1/4″ and 3/8″ drive socket sets with metric extensions (10mm, 12mm, 14mm, 17mm deep sockets)
  • Combination wrenches: 10mm, 12mm, 14mm, 17mm, 19mm
  • Torque wrench (ft-lb and in-lb ranges)
  • Allen key set (for banjo bolts and V-band clamps)
  • Gasket scraper and razor blade (non-marring plastic scraper recommended)
  • Shop towels, brake cleaner, and a catch pan
  • Jack and jack stands (or vehicle lift)
  • Flashlight and mirror for inspecting hard-to-see connections

Materials

  • HKS GT2835PRO turbocharger (part #1401-RS006 or equivalent)
  • New manifold gasket (OEM Nissan or copper MLS style)
  • Turbo-to-downpipe gasket (V-band or 3-bolt depending on kit)
  • Oil supply line kit (HKS recommends -4AN stainless braided)
  • Oil drain line gasket and hose (10mm ID silicone, high-temp)
  • Coolant supply and return lines (pre-bent hard lines or -6AN hose)
  • New copper or aluminum crush washers for all banjo fittings
  • High-temp silicone sealant (RTV for oil pan drain connection)
  • Fresh engine oil (5W‑40 or 10W‑40, break-in oil recommended)
  • New antifreeze/coolant

Safety Gear

  • Safety glasses and gloves
  • Fire extinguisher (rated for fuel and electrical fires)
  • Ventilation fan if working in a closed garage

Preparation: Setting Up for Success

Vehicle Positioning and Electrical Safety

Park the car on a level surface and chock the rear wheels. Disconnect the negative battery terminal and wait five minutes before touching any wiring. For SR20DET engines, the factory battery location can interfere with turbo access; if necessary, loosen the battery tray bolts and move the tray aside. Allow the engine to cool completely – the exhaust manifold and turbo housing will retain heat for hours.

Drain Fluids

Place a drain pan under the engine. Remove the oil drain plug and drain the engine oil. Remove the radiator cap (cold engine only) and open the drain petcock on the bottom of the radiator to drain coolant. The coolant system will need to be refilled later, so consider replacing the thermostat and hoses at this time if they show age.

Removing the Factory Turbocharger

Disconnect Intake and Exhaust Systems

Remove the air intake tube between the MAF sensor and the compressor inlet. Unclip the boost control solenoid and any vacuum lines to the wastegate actuator. Loosen the bolts securing the downpipe to the turbine housing – use penetrating oil on rusted fasteners. Carefully separate the downpipe and support it with a jack stand or strap. Remove the exhaust manifold heat shield (if equipped) by unscrewing the 10mm nuts.

Oil and Coolant Lines

The SR20DET uses a banjo-bolt oil feed from the engine block (typically M12 x 1.5). Use a flare-nut wrench to avoid rounding the fitting. Remove the oil drain line from the turbo center housing and the rubber hose at the oil pan. For the coolant lines, disconnect the two small hoses at the turbo – be ready for residual coolant spillage. Plug the block fittings with rubber caps or clean rags.

Unbolt the Turbo from the Manifold

Support the turbo with one hand while removing the four 12mm nuts securing it to the exhaust manifold. The turbo is heavy; have a helper or a floor jack with a wooden block ready. Lift the turbo straight off the studs and set it aside. Immediately cover the manifold openings with a clean plastic bag to prevent debris entry.

Pro Tip: Take this opportunity to clean the manifold flange surface with a gasket scraper and brake cleaner. Any leftover gasket material will cause exhaust leaks and poor turbo sealing.

Installing the HKS GT2835PRO Turbo

Gasket and Manifold Preparation

Apply a thin layer of high-temp RTV to both sides of the new manifold gasket. Place the gasket over the manifold studs. The HKS GT2835PRO uses a divided inlet; ensure the gasket openings align perfectly with the twin-scroll passages. Do not use stacking multiple gaskets – this can cause misalignment and boost leaks.

Mounting the Turbo to the Manifold

Gently lower the HKS turbo onto the manifold studs. The compressor housing may need to be clocked (rotated) to align with the intercooler piping. HKS provides a clocking guide, but generally the compressor outlet should face the driver side (left) of the engine bay. Hand-tighten the four 12mm nuts in a cross pattern to 33 ft·lb (45 N·m) using a torque wrench. Recheck after the first start.

Oil Feed Line Installation

Connect the oil feed line to the block fitting. HKS recommends a restrictor in the feed line if you are running a ball-bearing turbo – a -3AN restrictor with a 0.8mm orifice is ideal. Attach the other end to the turbo center section using new copper washers on both sides of the banjo fitting. Torque the banjo bolt to 18 ft·lb (24 N·m). Do not overtighten – the aluminum housing can crack.

Oil Drain Line

Connect the oil drain hose from the turbo to the oil pan fitting. The drain line must slope downward at least 20° to ensure proper gravity drainage. Use a 10mm ID high-temp silicone hose and secure with constant-tension clamps. If your pan fitting uses a NPT adapter, apply Teflon tape only to the male threads (do not let tape shred inside the pan).

Coolant Lines

Install the coolant supply line from the engine block to the turbo water jacket. The SR20DET uses a pressurized coolant feed from the thermostat housing; route the hose away from the exhaust manifold. Connect the return line to the water pump inlet or radiator return pipe. Purge air by loosening the highest point fitting before tightening fully.

Intake and Exhaust Reconnection

Intake: Attach the compressor outlet to the intercooler piping using a silicone coupler and T-bolt clamps. Ensure the blow-off valve or bypass valve is correctly plumbed – the HKS GT2835PRO can produce 30+ psi, so a metal BOV is recommended.

Exhaust: Install the downpipe gasket and reattach the downpipe to the turbine housing. The HKS unit uses a 3-bolt V-band or standard 3-bolt pattern – use a new exhaust gasket and torque to 35 ft·lb (47 N·m). Reconnect the oxygen sensor if it was removed.

Final Installation Checks

Leak Prevention

  • Check all banjo bolts and hose clamps for torque and tightness.
  • Inspect the oil drain line for kinks or sharp bends.
  • Verify the wastegate actuator rod is correctly connected and free to move.
  • Spray soapy water on all connections before startup to detect exhaust leaks.

Reconnect Electricals

Reattach the battery negative terminal. Reinstall the MAF sensor, boost control solenoid, and any other harness connectors that were moved. Double-check that no wires are near the hot turbine housing – use heat sleeve if needed.

Priming the Oil System and First Start

Before cranking the engine, you must prime the turbo with oil. Disconnect the fuel pump relay or fuse, then crank the engine for 10 seconds. Watch for oil pressure on the dash gauge. Reconnect the fuel pump and start the engine. Let it idle at 1,500–2,000 RPM for 30 seconds to build oil pressure. Immediately check for leaks at the turbo oil feed and drain. If no leaks, continue idling until the coolant temperature reaches 160°F (71°C) – this ensures the thermostat opens and coolant flows through the turbo.

Critical: Never run the engine without coolant flowing – the water-cooled center housing will overheat and seize the bearings in under 60 seconds.

Testing and Tuning the HKS GT2835PRO

Break-In Procedure

Drive the car gently for the first 100 miles (160 km). Avoid sustained boost above 10 psi. During this break-in, vary the engine speed without exceeding 4,000 RPM. After break-in, perform an oil and filter change. This removes any debris introduced during installation.

Boost and Fuel Tuning

The GT2835PRO with a 0.64 A/R turbine housing typically reaches full boost around 3,200–3,600 RPM on a stock SR20DET. You will need engine management (e.g., Haltech Elite 750 or Nistune) to dial in fuel and timing. Start with a conservative base map. Use a wideband O2 sensor to maintain 11.5–12.0 AFR under boost. If you experience boost creep, verify the wastegate spring rating – HKS sells 7, 10, and 14 psi springs. For more aggressive tuning, consult a professional at Z1 Motorsports or a local SR20 specialist.

Common Mistakes and Troubleshooting

  • Oil leaks at drain connection: Ensure the drain line is not too long or high; the center section must remain below the oil surface in the pan.
  • Coolant leaks at banjo: Replace crush washers each time. Use a torque wrench – 18 ft·lb is maximum.
  • Whistling or chirping under boost: Check for intake leaks between the MAF and turbo. Boost leaks at intercooler couplers also cause similar noises.
  • Over-boosting / boost spikes: Inspect the wastegate actuator for binding; upgrade to an external wastegate if running high boost (22+ psi).
  • Smoke after initial start: Minor smoke is normal as residual assembly lube burns off. Thick blue smoke indicates an oil drain restriction – shut down immediately.

To fully use the GT2835PRO’s airflow capacity, consider these upgrades:

  • 550–800cc fuel injectors (e.g., DeatschWerks)
  • 255 LPH or higher fuel pump (Walbro 450 recommended)
  • Front-mount intercooler with 2.5″ piping
  • 3″ turbo-back exhaust system
  • Upgraded wastegate actuator (if exceeding 14 psi)

Conclusion

Installing the HKS GT2835PRO turbo on your SR20DET is a well-documented path to 350–450 wheel horsepower with excellent drivability. The key to success lies in meticulous preparation – clean surfaces, new gaskets, proper torque, and correct oil/coolant routing. By following the steps outlined here and breaking in the turbo gradually, you will enjoy a reliable and powerful setup. For further details, refer to the official HKS installation manual and join the SR20 Forum community for ongoing support.