Introduction: Why the BorgWarner S300SX Turbo for Your 370Z?

The Nissan 370Z is a formidable platform right out of the factory, but adding forced induction takes it to an entirely new level. The BorgWarner S300SX turbo is a popular choice among enthusiasts because it offers a strong balance of quick spool, reliable power, and excellent top-end performance without overwhelming the stock engine architecture. With a properly sized compressor and turbine wheel, the S300SX can produce anywhere from 500 to 700 wheel horsepower with supporting modifications. This guide covers the complete installation process, from preparation to tuning, and includes expert tips to ensure your turbo upgrade runs smoothly and safely.

Tools and Materials: Full List

Before you begin, gather all necessary components and tools. Missing a single part can halt the entire job. Below is a comprehensive inventory of what you’ll need.

Hardware and Components

  • BorgWarner S300SX Turbo – Choose the correct A/R and wheel combination for your power goals (e.g., S300SX 62mm or 67mm).
  • Turbo manifold (custom or off-the-shelf for VQ37VHR)
  • Downpipe – 3-inch or larger, with provisions for a wastegate
  • Wastegate – Typically a 38mm to 44mm Tial or comparable unit
  • Boost controller – Electronic or manual
  • Intercooler – Front-mount with piping kit for 370Z
  • Turbo oil feed and return lines – AN -4 or -6 stainless steel braided
  • Coolant lines (if turbo is water-cooled)
  • Gaskets and seals for exhaust manifold, turbo, and intercooler connections
  • High-quality synthetic oil and OEM-spec oil filter
  • Engine coolant (Nissan Long Life or equivalent)

Tools

  • Metric socket set (deep and shallow)
  • Torque wrench (ft-lb and in-lb)
  • Ratchet wrenches for tight spaces
  • Jack stands and a hydraulic jack
  • Pickle fork or brake cleaner for gasket removal
  • Thread lock (Loctite 242 or 271)
  • Pliers, wire cutters, zip ties
  • Multimeter for electrical checks
  • Engine lift or hoist (optional but helpful)

Preparation: Setting Up Your Workspace and Vehicle

A well-prepared workspace is half the battle. Secure the car on level ground, engage the parking brake, and use jack stands under the frame rails. Disconnect the negative battery cable and allow the engine to cool completely if it has been running.

  • Remove the engine cover and any cosmetic plastic cowls near the firewall.
  • Drain engine oil by removing the drain plug and oil filter. Catch and dispose of properly.
  • Drain coolant from the radiator petcock and the engine block drain bolt (located on the passenger side block).
  • Remove the intake piping, air filter box, and mass airflow (MAF) sensor housing.
  • Take photos or mark wiring harnesses and vacuum lines to simplify reassembly.

Tip: Cover the open intake ports with clean rags or tape to prevent debris from falling into the engine while you work.

Removing the Stock Exhaust Manifold and Factory Turbo

The 370Z is naturally aspirated from the factory, so there is no stock turbo to remove. Instead, you will be removing the exhaust manifolds (headers) and the exhaust system to make room for the BorgWarner turbo assembly.

  1. Unbolt the exhaust manifold heat shields, if equipped.
  2. Disconnect the oxygen sensors upstream and downstream using a 22mm socket or sensor tool.
  3. Remove the six manifold-to-head bolts for each bank. Some bolts are hidden under heat shields; use a flex-head ratchet.
  4. Support the manifold and wiggle it free from the engine. If stubborn, tap gently with a rubber mallet.
  5. Remove the factory mid-pipe and catalytic converters (if applicable) by unbolting from the Y-pipe.
  6. Clean the cylinder head sealing surfaces with a razor blade and brake cleaner.

Note: Most S300SX kits use a single turbo adapter plate or a twin-scroll manifold. Ensure your manifold clears the steering column and brake master cylinder on the driver side.

Installing the BorgWarner S300SX Turbo: Step-by-Step

Step 1: Mount the Exhaust Manifold

Install the new turbo manifold provided in your kit. Apply a thin coat of anti-seize on the studs and tighten to factory torque specs (typically 25–30 ft-lb for VQ37).

Step 2: Attach the Turbo to the Manifold

Bolt the BorgWarner S300SX directly onto the manifold using the supplied T4 or T3 flange gasket. Torque the retaining nuts in a cross pattern to 30 ft-lb. Verify the compressor outlet is oriented toward the passenger side for intercooler piping.

Step 3: Oil and Coolant Lines

Use a sandwich plate or a crankcase fitting for the oil supply. Connect the feed line to the turbo’s oil inlet (typically top of center housing). Run the oil return line to the oil pan: drill and weld a -10 AN bung into the pan above the oil level. If the turbo is water-cooled, connect coolant lines from the engine’s heater core hoses or thermostat housing.

Step 4: Downpipe and Wastegate Installation

Install the downpipe onto the turbine outlet with a V-band or 3-bolt flange. Mount the wastegate on the manifold or downpipe adapter. Route the wastegate dump tube away from sensitive components. Connect boost reference lines from the compressor housing or intake manifold to the wastegate and boost controller.

Step 5: Intercooler and Piping

Remove the front bumper cover and crash bar to install the intercooler. Use silicone couplers and T-bolt clamps for all joints. Mount the blow-off valve (BOV) on the cold side piping near the throttle body for best response.

Final Electrical and Vacuum Line Connections

Reconnect MAF, intake air temperature (IAT), and crankshaft position sensors. Route boost controller wiring to the cabin. Check all vacuum lines for cracks; use silicone hoses rated for 30 PSI.

  • Install an aftermarket boost gauge (or use the ECU’s signal if tuning via standalone).
  • Connect a wideband oxygen sensor in the downpipe for tuning feedback.
  • Double-check that the wastegate and BOV vacuum lines are not reversed.

Reassembly and Fluid Refill

Reinstall the bumper cover, undertrays, and engine cover. Fill the engine with 5W-30 or 10W-30 synthetic oil (depending on climate). Refill coolant using a funnel and burp the system to remove air pockets. Reconnect the battery negative terminal. Inspect all bolts and clamps for tightness.

Pre-Start Checks and First Start Procedure

  1. Crank the engine with the fuel pump fuse pulled to prime oil to the turbo (about 10 seconds).
  2. Reinsert the fuse and start the engine. Let it idle for 30 seconds, then shut off.
  3. Check for oil and coolant leaks at every connection.
  4. Restart and allow engine to reach operating temperature. Listen for unusual noises from the turbo shaft or wastegate.
  5. Inspect intercooler piping for boost leaks with a smoke tester or pressurized system.

Important: Do not rev the engine above 2,500 RPM until the turbo has been primed and oil pressure is stable.

Breaking In and Testing

Drive the car gently for the first 50–100 miles to seat the turbo bearings and allow the ECU to relearn fuel trims (if using a base tune). Gradually increase boost by adjusting the boost controller. Monitor intake air temperatures and knock readings via a laptop or dash logger. If any symptoms of detonation occur (rattling, high EGT), reduce boost immediately and consult your tuner.

Common Pitfalls and How to Avoid Them

  • Oil starvation: Ensure the feed line has a restrictor (0.060–0.080 inch) for journal bearing turbos like the S300SX. Too much oil pressure can blow seals.
  • Boost creep: Caused by a wastegate that is too small or incorrectly located. Use a 44mm wastegate for high-horsepower builds.
  • Routing clearance: The 370Z engine bay is tight. Test-fit pipes before tightening clamps to avoid rubbing on the chassis.
  • Tuning: A daily-driven turbo Z requires a proper dyno tune or a reliable mail-order calibration. Running rich or lean can destroy the engine.

Choosing the Right Supporting Mods for Your S300SX Build

To maximize the BorgWarner S300SX, consider upgrading the following:

  • Fuel system: 1000cc injectors, in-tank pump with voltage booster, and return-style fuel regulator.
  • Clutch: A twin-disc clutch rated for 600+ ft-lb holds the power.
  • Engine internals: The VQ37VHR is strong to 600 whp, but forged pistons and rods are recommended if chasing 700+.
  • Cooling: Larger radiator and oil cooler maintain temps under sustained boost.

External Resources and Further Reading

Conclusion: Unlock Your 370Z’s Full Potential

Installing a BorgWarner S300SX turbo on your Nissan 370Z is a rewarding project that transforms its drivability. By following this detailed guide—paying close attention to oiling, clearance, and tuning—you’ll create a reliable, high-horsepower street machine. Don’t rush the process; take time to verify each connection and invest in a quality tune. With proper care, your turbocharged 370Z will deliver thrilling acceleration and stand out in any gathering.