Why the HKS GT2835R Is a Benchmark Upgrade for the SR20DET

The SR20DET is one of the most celebrated four-cylinder engines in automotive history, powering iconic platforms like the Nissan Silvia S13, S14, S15, and the 180SX. While the stock turbocharger delivers respectable performance in factory trim, it quickly becomes a bottleneck when you start pushing for higher horsepower numbers. The HKS GT2835R addresses this limitation directly, offering a proven blend of quick spool characteristics and substantial top-end flow capacity. This turbo sits in a sweet spot for street-driven SR20DET builds aiming for the 350–450 wheel horsepower range without sacrificing daily drivability. In this guide, we will walk through every phase of the installation process in detail, covering preparation, mechanical steps, torque specifications, and post-installation considerations. Whether you are working in a home garage or a professional shop, following these steps methodically will help you achieve a reliable, high-performance result.

What You Need Before You Start

Proper preparation is the difference between a straightforward installation and a frustrating weekend of chasing parts. The HKS GT2835R installation is not exceptionally difficult, but it does require attention to detail and a complete set of components. Below is a comprehensive list of parts and tools you should have on hand before turning a single bolt.

Required Parts and Hardware

  • HKS GT2835R turbocharger – Ensure you have the correct version for your SR20DET (typically the GT2835R with a 0.73 or 0.86 A/R turbine housing depending on your power goals)
  • Turbo manifold – A quality top-mount or bottom-mount manifold designed for T3/T4 flange patterns; HKS offers a matching manifold, but many aftermarket options also work
  • Oil feed line – Braided stainless steel line with proper fittings; the GT2835R requires a -4AN feed line
  • Oil drain line – A -10AN drain line is recommended to ensure adequate oil return
  • Coolant lines – Braided or silicone lines for the water-cooled center section
  • Gasket set – Turbo-to-manifold gasket, manifold-to-head gasket, downpipe gasket, and oil return gasket
  • Hardware kit – High-strength bolts, studs, and lock washers for the turbo mounting
  • Intake piping – Silicone couplers, T-bolt clamps, and an intake pipe that matches the GT2835R compressor outlet
  • Downpipe – A 3-inch downpipe with the correct flange to match the turbine outlet
  • Wastegate – The GT2835R can be used with an internal wastegate, but many builds pair it with an external wastegate for better boost control
  • Blow-off valve – Recommended for protecting the compressor wheel and maintaining throttle response
  • Engine oil and coolant – Fresh oil (5W-40 or 10W-40 synthetic depending on climate) and coolant for refilling after installation

Tools and Equipment

  • Socket set – Metric sockets from 8mm to 22mm, including deep sockets
  • Wrench set – Combination wrenches, especially for tight spaces around the turbo
  • Torque wrench – A quality torque wrench capable of reading in Newton-meters (Nm) and foot-pounds (ft-lb)
  • Pry bar – Useful for breaking stubborn exhaust connections
  • Gasket scraper – For cleaning old gasket material off mounting surfaces
  • Jack and jack stands – You will need to lift the vehicle to access the underside
  • Penetrating oil – Such as PB Blaster or WD-40 Specialist, applied to exhaust bolts the night before
  • Silicone sealant – High-temperature RTV silicone for gasket surfaces
  • Shop rags and safety equipment – Gloves, safety glasses, and a fire extinguisher nearby

Take the time to lay out all parts and confirm you have everything. There is nothing worse than getting halfway through the job and realizing you are missing a critical gasket or fitting.

Removing the Factory Turbocharger

Before the HKS GT2835R can go in, the original turbo must come out. This process is straightforward but can be tedious due to tight clearances and heat-seized hardware. Work methodically and do not rush.

Disconnect the Battery and Drain Fluids

Disconnect the negative terminal of the battery first. This eliminates any risk of shorting tools against electrical connections while working near the starter and alternator. Next, drain the engine oil and coolant. Draining the oil prevents messy spills when you disconnect the oil feed and drain lines. Similarly, draining the coolant avoids a flood when you remove the coolant lines from the turbo. You do not need to drain the entire system entirely, but draining the radiator and block makes the job cleaner.

Remove the Intake and Exhaust Systems

Begin by removing the intake piping that connects the air filter to the turbo compressor inlet. Loosen all clamps and set the piping aside. Next, disconnect the intercooler piping from the compressor outlet. If your car has a factory recirculation system, you will also need to disconnect the blow-off valve return hose. On the exhaust side, unbolt the downpipe from the turbine outlet. You will likely need penetrating oil and some leverage to break the nuts free. Support the downpipe as you remove it to avoid stressing the exhaust manifold studs. Finally, remove the oxygen sensor from the downpipe if it is in the way.

Disconnect Oil and Coolant Lines

The oil feed line typically connects to the top of the turbo center section and runs to a supply port on the engine block or head. Use a wrench to loosen the fitting at the turbo and the engine side. Have a catch pan ready, as residual oil will drip out. The oil drain line connects to the bottom of the turbo and runs to the oil pan. Remove the bolts securing the drain line to the turbo and the pan. The coolant lines are similarly routed; disconnect them at the turbo and at the engine block or thermostat housing. Label the fittings if necessary to avoid confusion during reassembly.

Unbolt the Turbo from the Manifold

With all lines disconnected, you can now unbolt the turbo from the exhaust manifold. The turbo is typically held by four or five nuts on studs. Use a deep socket and a breaker bar, as these nuts are often tight and heat-cycled. Once all nuts are removed, carefully lift the turbo off the manifold studs. The turbo is heavy, so support it with one hand while you work the last nut free. Set the old turbo aside and inspect the manifold for cracks or warping while you have access.

Preparing the HKS GT2835R for Installation

Before bolting the new turbo in place, spend time inspecting and preparing it. The GT2835R is a precision component, and taking a few precautions now will save you headaches later.

Inspect the Turbocharger

Remove the turbo from its packaging and inspect it visually for any damage that may have occurred during shipping. Spin the compressor and turbine wheels by hand. They should rotate smoothly without any binding, scraping, or excessive axial play. A small amount of radial play is normal in a new turbo, but there should be no contact between the wheel and the housing. Check the compressor housing and turbine housing for cracks, porosity, or casting flaws. Verify that the wastegate actuator (if using the internal gate) operates freely and holds pressure when tested with a hand pump.

Prepare the Mounting Surfaces

Clean the mating surface on the exhaust manifold thoroughly. Use a gasket scraper to remove any old gasket material, carbon deposits, or rust. Wipe the surface clean with a solvent and allow it to dry. Apply a thin, even layer of high-temperature silicone sealant to both sides of the new turbo-to-manifold gasket. This helps prevent exhaust leaks, which can lead to boost creep and poor performance. Do the same for the manifold-to-head gasket if you are replacing it.

Pre-Lubricate the Turbo

Before installation, you need to pre-lubricate the turbo bearing system. Remove the oil feed line from the turbo center section and pour a small amount of clean engine oil directly into the oil inlet port. Spin the turbo rotor by hand to distribute the oil throughout the bearings. This step is critical because it ensures the bearings are lubricated immediately upon engine startup, preventing dry-start damage. Reattach the oil feed line after pre-lubrication.

Installing the HKS GT2835R Turbocharger

Now you are ready to install the new turbo. Work carefully and torque all fasteners to specification.

Mount the Turbo to the Manifold

Position the new gasket on the manifold studs, then lift the HKS GT2835R into place. Align the turbo mounting holes with the studs and slide it on. You may need to wiggle the turbo slightly or use a rubber mallet to seat it fully. Install the nuts and washers onto the studs. Tighten them gradually in a crisscross pattern to ensure even clamping force. The torque specification for these nuts is typically 30–35 ft-lb (40–47 Nm), but confirm with your manifold manufacturer. Overtightening can warp the mounting flange or break the studs.

Connect the Oil Feed and Drain Lines

Attach the oil feed line to the turbo center section. Use a new crush washer if your fitting requires one. Tighten the fitting securely but do not overtighten; brass or aluminum fittings can crack. Route the line to the engine block supply port and connect it there. Ensure the line is not kinked or touching any hot surfaces. For the oil drain line, attach it to the turbo drain port and the oil pan return fitting. The drain line must slope downward continuously to allow gravity-assisted oil return. Any dips or loops in the drain line can cause oil to back up in the turbo, leading to seal failure. Tighten the drain line bolts to 15–20 ft-lb (20–27 Nm).

Connect the Coolant Lines

Attach the coolant inlet line to the turbo and route it to the engine block or thermostat housing. Connect the coolant outlet line to the turbo and route it to the coolant return port or radiator. Use new clamps and ensure the lines are secure. Bleed any air from the coolant system after filling, as air pockets can cause localized overheating in the turbo center section.

Reattach the Intake and Exhaust Systems

Install the intake piping from the air filter to the compressor inlet. Use silicone couplers and T-bolt clamps for a secure, leak-free connection. Attach the intercooler piping to the compressor outlet. On the exhaust side, install the downpipe to the turbine outlet using a new gasket. Tighten the downpipe bolts to 30–35 ft-lb (40–47 Nm). Verify that the downpipe does not contact the chassis, transmission, or any suspension components. If it does, loosen and reposition it before tightening fully. Install the oxygen sensor into the downpipe bung.

Final Checks Before First Start

With everything mechanically installed, it is time to perform a systematic final inspection. This step prevents simple mistakes from ruining your new turbo.

Verify All Connections

Walk around the engine bay and visually check every connection. Ensure all oil and coolant fittings are tight and free of leaks. Confirm that all intake and exhaust clamps are secure. Check that the wastegate actuator arm is properly attached to the wastegate flapper (if using internal gate) and that it moves freely. Inspect the blow-off valve installation if you added one. Look for any loose tools, rags, or debris that may have been left in the engine bay.

Check Fluid Levels

Refill the engine with fresh oil. The SR20DET typically holds about 4.0 quarts with a filter change, but confirm with your dipstick. Do not overfill. Refill the coolant system with the correct mixture of coolant and distilled water. Bleed the cooling system by running the engine with the radiator cap off and adding coolant until the thermostat opens and air is purged. Top off as needed.

Prime the Oil System

Before starting the engine, you need to prime the oil system to ensure the turbo receives oil immediately. The easiest way is to disable the fuel system (pull the fuel pump fuse or disconnect the injectors) and crank the engine for 10–15 seconds. Watch the oil pressure gauge; you should see pressure build within a few seconds of cranking. If the gauge does not move, stop and investigate before attempting to start the engine. After priming, reconnect the fuel system.

First Start and Break-In Procedure

The first startup is the most critical moment for your new turbo. Follow this procedure to give your GT2835R the best possible start to its service life.

Initial Start and Idle

Start the engine and let it idle. Listen for any unusual noises such as grinding, whistling, or knocking. A small amount of turbo spool noise is normal, but mechanical contact noises indicate a problem. Check for oil and coolant leaks immediately. Let the engine reach operating temperature while monitoring the temperature and oil pressure gauges. If anything looks or sounds wrong, shut the engine down and investigate.

Check for Boost Leaks

Once the engine is warm, perform a simple boost leak check. With the engine running at idle, block the intake opening with a rubber glove or a dedicated boost leak tester. If the intake system holds pressure, the glove will inflate. If you hear air escaping, locate the source and fix it before driving. Boost leaks cause poor throttle response, high intake air temperatures, and can lean out the air-fuel mixture.

Drive and Break-In

After confirming no leaks and stable idle, take the car for a gentle drive. Avoid full-throttle runs for the first 50–100 miles. Vary the engine load and RPM to help the turbo bearings and piston rings seat properly. During this break-in period, monitor boost levels with a quality gauge. The HKS GT2835R with a 0.73 A/R turbine housing typically reaches full boost by 3500–4000 RPM on a well-tuned SR20DET. If boost spikes or creeps, you may need to adjust the wastegate or consider an electronic boost controller.

Tuning Considerations for the HKS GT2835R

Installing a larger turbocharger changes the engine’s airflow characteristics significantly. The factory ECU cannot compensate for the increased flow, so proper engine management is essential.

Fuel System Upgrades

The stock fuel injectors and fuel pump are insufficient for the GT2835R’s flow potential. Upgrading to 550–740 cc injectors and a 255 LPH or larger fuel pump is strongly recommended. Pair these with a rising-rate fuel pressure regulator or a full aftermarket ECU. Without adequate fuel delivery, the engine will run lean under boost, leading to detonation and catastrophic failure.

Engine Management Options

A standalone ECU such as a Haltech, Link, AEM, or Ecumaster is the best choice for extracting full performance from the GT2835R. These systems allow precise control over fuel and ignition timing, as well as boost control if you are using an external wastegate and boost controller. If standalone is not in your budget, a piggyback system like a Nistune or a ROM tune on a factory ECU can work for moderate power levels. Regardless of the system, professional dyno tuning is highly recommended to ensure safe air-fuel ratios and ignition timing across the entire RPM range.

Intercooling and Intake Temperatures

The GT2835R moves a lot of air, and a stock intercooler will struggle to keep intake temperatures under control. Upgrade to a front-mount intercooler with a core size appropriate for your power target. A good rule of thumb is a core measuring at least 24 x 12 x 3 inches for 400+ horsepower builds. Keep the intercooler piping as short and direct as possible to minimize lag.

Common Pitfalls and How to Avoid Them

Even experienced builders make mistakes. Here are the most common issues encountered during an SR20DET turbo upgrade and how to sidestep them.

Oil Drain Line Routing

This is the number one cause of turbo seal failure and oil leaks. The drain line must slope continuously from the turbo to the oil pan without any low spots. If the line is too long or routed incorrectly, oil backs up in the center section and pushes past the seals, causing blue smoke and oil consumption. Use a pre-made drain line kit designed for the GT2835R, or fabricate one with the correct angles.

Insufficient Oil Supply Restriction

The SR20DET oil system delivers high oil pressure, especially when cold. The GT2835R’s journal bearings can be overwhelmed by excessive oil pressure, leading to seal leakage. Many builders install an oil restrictor in the feed line (typically a 0.035” to 0.060” restrictor) to limit oil flow to the turbo. Check HKS’s recommendation for your specific turbo version. If you are unsure, a restrictor with a 0.060” orifice is a safe starting point.

Overtightening Hardware

Aluminum and brass fittings are easily stripped or cracked. Use a torque wrench for all critical fasteners, especially the turbo mounting nuts and oil line fittings. Do not guess torque values. When in doubt, look up the manufacturer’s specification.

Maintenance Tips for Long Turbo Life

Once your GT2835R is installed and tuned, proper maintenance will keep it performing for tens of thousands of miles.

Oil Change Interval

High-performance turbocharged engines place extreme demands on engine oil. Change your oil and filter every 3,000 miles or every 3 months, whichever comes first. Use a high-quality full synthetic oil with a robust additive package. Avoid extended oil change intervals, even if the oil appears clean.

Cool Down Idle

After a hard run, let the engine idle for 30–60 seconds before shutting it off. This allows the turbo to slow down and the oil to circulate, carrying heat away from the bearing housing. A turbo timer can automate this process, but it is not necessary if you develop the habit of a brief cooldown idle.

Inspect Lines and Fittings

Periodically inspect all oil and coolant lines for cracks, chafing, or loose fittings. Vibration and heat cycles can loosen hardware over time. A small leak that goes unnoticed can lead to a large problem quickly. Check the turbo mounting nuts and downpipe bolts for tightness at every oil change.

Performance Expectations with the HKS GT2835R

With a proper installation and tune, the GT2835R transforms the SR20DET into a serious performer. On a stock bottom end SR20DET with supporting mods, expect 350–400 wheel horsepower on pump gas. With forged internals, a larger intercooler, and aggressive tuning, 450–500 wheel horsepower is achievable. Boost response is excellent, with the turbo reaching full boost by 3800 RPM on a well-matched manifold. The power delivery is linear and punchy, making it a joy to drive on both the street and track.

For those looking for even more headroom, the GT2835R can be paired with a larger turbine housing (0.86 A/R) for better top-end flow at the expense of slightly slower spool. This configuration favors cars that see significant track time or high-speed driving.

Wrapping Up the Installation

Installing the HKS GT2835R on an SR20DET is a rewarding project that delivers a dramatic improvement in power and driving experience. The key to success lies in thorough preparation, attention to detail during the mechanical work, and a proper tune that respects the engine’s limits. Take your time with each step, verify your work as you go, and do not cut corners on critical areas like oil line routing and torque specifications. With care and patience, your SR20DET will reward you with reliable, exciting performance for years to come.

For further reading, consult the official HKS product documentation for the GT2835R, and consider joining SR20DET owner forums to learn from the experiences of other builders who have completed this exact upgrade. Resources like HKS Japan’s official site and SR20 Forum offer valuable technical information and community support.