Installing a Precision turbocharger on your Nissan GT-R represents one of the most effective ways to increase horsepower and torque, but the installation process itself demands meticulous attention to detail. A poorly executed installation can lead to boost leaks, oil contamination, or even turbo failure. Whether you are swapping the factory twin-turbos for a Precision single-turbo conversion or upgrading to a pair of Precision units, following proven best practices ensures reliable performance and longevity. This guide covers everything from preparation and tool selection through final tuning and common mistakes to avoid.

Preparation Before Installation

Proper preparation is the foundation of a successful turbo installation. Rushing this phase increases the risk of damaging components or making errors that require rework.

Selecting the Correct Precision Turbo Model

Precision offers several turbo families suitable for the GT-R’s VR38DETT engine, including the 6266 (great for quick spool and 700–800 hp), 6466 (mid-range power up to 900 hp), and 6766 (for higher horsepower goals). For twin-turbo setups, two smaller units (such as the 5862) are common. Verify compatibility with your GT-R model year, as later models have different intake and exhaust flange configurations. Always cross-check the turbo specs against your engine management system’s capability and fuel system capacity.

Gathering Tools and Equipment

Beyond a standard socket set, a GT-R turbo installation requires specialized tools. Prepare the following:

  • Metric socket set (6 – 19 mm) with deep sockets and extensions
  • Torque wrench (split-beam recommended) capable of 10–100 ft-lb
  • Line wrench set (flare nut wrench) for oil and coolant fittings
  • Crow’s foot attachments to reach tight fittings
  • Pick set for removing o-rings and gaskets
  • Digital caliper to measure thread pitch on banjo bolts
  • Oil primer pump or pre-luber (critical for dry starts)
  • Vacuum pump for leak-checking after assembly
  • Boost leak tester (can be fabricated from PVC parts)
  • Trim removal tools for interior panels if routing wideband wiring

Do not rely on worn or damaged tools. Torque wrenches should be recalibrated annually.

Workspace and Safety Preparation

Pneumatic impact tools and engine oil create a slippery environment. Clean your workspace thoroughly and ensure adequate lighting. Disconnect the negative battery terminal before beginning any electrical or fuel system work. Place fender covers and floor mats to protect the paint and carpet. Have a fire extinguisher rated for gas and oil fires nearby.

Also inspect your Precision turbo before installation. Check the compressor wheel for damage, spin the bearing to ensure smooth rotation, and verify that the oil restrictor (if included) is appropriate for your oil pressure. Precision recommends using their supplied gaskets and fasteners; do not substitute with generic hardware.

Removing the Factory Turbochargers

Removing the factory turbos on an R35 GT-R is a labor-intensive process that often requires removing the entire exhaust manifold assembly, intercooler piping, and several auxiliary components. Work slowly and label everything.

Draining Fluids and Disconnecting Systems

Start by draining the engine oil and coolant to prevent spills when disconnecting lines. Remove the air intake tract and mass airflow (MAF) sensors. Unplug the O2 sensors and wideband sensors from the downpipes. For twin-turbo cars, the factory turbos sit tightly between the exhaust manifold and the catalytic converters. You will need to unbolt the front and rear downpipes, separate the mid-pipe, and support the exhaust assembly.

Removing the Intake and Exhaust Components

Detach the intercooler piping, throttle body boots, and the factory recirculating bypass valve hoses. For a single turbo conversion, you will also be removing the factory Y-pipe and installing an intake manifold compatible with a single throttle body (if you are switching from the factory dual-throttle setup). On a twin upgrade, the intercooler piping remains largely stock but may need modification for larger compressor outlets.

Unbolt the exhaust manifold heat shields. The factory manifold nuts are prone to seizing; use penetrating oil and allow it to soak for 15–20 minutes. Once the manifold is free, carefully pull the factory turbochargers out together with the manifolds. Be mindful of the oil drain tubes and coolant hoses—if they are brittle, replace them prophylactically.

Cleaning Mounting Surfaces

With the turbos removed, clean the manifold flange surfaces using a plastic scraper and brake cleaner. Any leftover gasket material or carbon deposits will cause boost leaks. Chase the threads on the manifold studs and replace any that show corrosion. On the VR38, the studs for the manifold-to-turbo flange are a common failure point; upgrade to ARP studs if available.

Installing the Precision Turbo

Precision turbo installation requires careful alignment, proper gaskets, and exact torque specifications. Do not reuse old gaskets—always install fresh Precision-supplied gaskets.

Mounting the Turbo and Torquing Fasteners

Position the new Precision turbo onto the exhaust manifold or the custom turbo manifold (if converting to single). Hand-tighten the fasteners in a cross pattern, then torque to 80 ft-lb for the manifold-to-turbo bolts (check your specific kit instructions). For the oil drain flange, use a new gasket and torque to 35 ft-lb. Use a small amount of anti-seize on the threads if the hardware is stainless steel.

For a twin-turbo setup, repeat the process for the second turbo, paying attention to mirrored orientation. Precision provides specific fitting kits for GT-R twin applications that include braided oil feed lines and -10 AN drain line fittings. Ensure the drain line slopes downward from the turbo to the oil pan without any dips that could trap oil.

Oil and Coolant Line Routing

Precision turbos often use a -4 AN supply line and a -10 AN drain line for oil. For water-cooled models, connect the coolant lines using a -6 AN fitting. Always use a pre-filter (a small inline screen) on the oil supply line to protect the journal bearings from debris. Route oil lines away from the exhaust manifold and turbo housing to avoid heat soaking. Secure lines with cushioned clamps to prevent vibration fatigue.

Prime the turbo bearing before first start-up by either filling the oil feed line with clean engine oil or using a pressure oil pre-luber connected to the oil pressure sender port. Rotating the compressor wheel by hand while priming helps distribute oil throughout the bearing.

Post-Installation Checks and Initial Start-Up

After the turbo is installed, verify every connection before adding fluids or starting the engine.

  • Check for overtightening: Re-check all fasteners with the torque wrench; overtorqued aluminum fittings can split.
  • Pressure test the oil system: Block the drain line and apply 10–15 psi of air to the oil fill port to verify no external leaks.
  • Coolant system test: Fill with coolant and pressurize the system to 15 psi. Look for drips at the coolant line fittings.
  • Boost leak test: Cap the intake pipe at the MAF, pressurize the system to 20 psi, and listen for hissing. Soapy water at every joint reveals leaks.
  • Check wastegate actuator: Ensure the wastegate arm is correctly adjusted to maintain your target boost level. Precision’s external wastegate should be set to a spring pressure appropriate for your power goal.
  • Inspect turbo clearance: Rotate the compressor wheel by hand—it should spin freely without rubbing against the housing.

When starting the engine for the first time, disable the fuel injectors (unplug the fuse or use the tuning software) and crank the engine for 10–15 seconds to build oil pressure. Reconnect the injectors and start the engine. Let it idle for several minutes while monitoring oil pressure, coolant temperature, and boost gauge reading (should show vacuum at idle). Listen for any unusual whining or scraping sounds.

Tuning for Maximum Performance

Installing a Precision turbo without proper tuning is dangerous. The increased airflow requires recalibrating fuel maps, ignition timing, and boost control strategies.

Fuel System Considerations

Stock GT-R fuel injectors and pump are quickly overwhelmed. For Precision turbo upgrades, upgrade to 1,300 cc/min injectors or larger and a fuel pump capable of flowing 300 lph or more. A fuel pressure regulator set to 43.5 psi (base pressure) is common. For flex-fuel tuning, add a fuel alcohol content sensor.

Selecting a Tuning Platform

The three most reputable tuning platforms for the R35 GT-R are ECUTek, Cobb Tuning Accessport, and Haltech Elite for standalone engine management. ECUTek is the industry standard for high-horsepower GT-Rs, offering direct flash of the factory ECU. Cobb’s Accessport is simpler but less flexible for extreme power levels. For single turbo conversions, a plug-and-play standalone like Haltech is often necessary to control the whole engine.

Work with a tuner experienced in Precision turbocharged VR38 engines. Provide them with logs of boost pressure, air-fuel ratio, and exhaust gas temperature during the first few pulls. Expect the tuning process to require several revisions to dial in timing and boost spikes.

Common Pitfalls to Avoid

Avoid these frequent mistakes that can ruin your Precision turbo installation:

  • Incorrect oil restrictor selection: Precision turbos require a specific oil restrictor (0.040 to 0.060 inch orifice) depending on idle oil pressure. Too much oil flow causes the bearing to hydraulic lock, leading to seal leakage. Confirm the restrictor part number with Precision’s tech support.
  • Neglecting crankcase ventilation: The GT-R’s PCV system can pressurize the crankcase at high boost, forcing oil into the turbo drain. Upgrade to a properly vented catch can setup.
  • Reusing V-band clamps: V-band clamps wear and can slip under high exhaust pressure. Always install new clamps when changing turbos.
  • Routing the wastegate dump tube too close to the downpipe: Heat can warp adjacent components. Leave at least ½ inch of air gap around all hot-side pipes.
  • Skipping the post-install alignment: Use a straightedge to ensure the turbo mounting flange sits parallel to the manifold. A misaligned flange can crack the turbine housing.
  • Forgetting to bleed the coolant system: Air pockets can cause hot spots and damage the water-cooled turbo bearings. Use a vacuum fill tool to eliminate air.

Conclusion

Installing a Precision turbo on your Nissan GT-R can elevate the car’s performance to incredible levels, but it requires the same precision that Precision builds into their turbos. From careful preparation and correct tool selection to meticulous line routing and professional tuning, every step matters. By following the best practices outlined in this guide—and avoiding the common shortcuts that lead to failures—you can enjoy reliable, high-horsepower operation for thousands of miles. For additional resources, consult the official Precision Turbo website for application-specific installation manuals and tech bulletins.