Upgrading your Genesis G70 with a BorgWarner S300SX-E turbocharger is one of the most effective ways to unlock serious horsepower gains without sacrificing reliability. This S300SX-E variant is engineered for high flow efficiency and quick spool, making it a popular choice for enthusiasts looking to push the 3.3L twin-turbo V6 (Lambda II) beyond factory limits. In this expanded guide, we walk you through the entire swap process with precise steps, torque specifications, and pro tips to ensure a clean installation that performs reliably on the street or track.

Understanding the BorgWarner S300SX-E Turbocharger

The BorgWarner S300SX-E is a ball-bearing turbo designed for gasoline and diesel applications demanding up to 650 horsepower. Its billet compressor wheel and extended-tip technology improve efficiency across the boost curve, reducing lag while maintaining top-end flow. For the G70, this turbo is often used as a direct replacement for the smaller factory units, or as part of a larger single-turbo conversion. Key specs include a 61.4mm inducer, 76.6mm exducer, and a 70mm turbine wheel with a 0.91 A/R housing. You can learn more directly from BorgWarner's official site.

Tools and Materials Required

Before you begin, gather the following items. Using the correct tools and quality gaskets prevents leaks and saves hours of rework.

  • Full metric socket and wrench set (8mm–18mm)
  • Torque wrench (3/8” and 1/2” drive)
  • E-Torx sockets (E10, E12, E14)
  • BorgWarner S300SX-E turbocharger kit (including gaskets, oil line adapter, coolant fittings)
  • New OEM or Fel-Pro exhaust manifold gaskets
  • New oil feed and drain gaskets (O-ring or copper)
  • High-temperature silicone sealant (e.g., Permatex Ultra Copper)
  • Shop towels and brake cleaner
  • Safety glasses and gloves
  • Jack and jack stands (or lift)
  • Breaker bar for stubborn bolts
  • Coolant drain pan (capacity 2+ gallons)

Preparation and Safety

Park the G70 on a level surface and allow the engine to cool completely—preferably overnight. Working on a hot turbo can cause burns and damage gaskets. Disconnect the negative battery terminal to prevent electrical shorts. Drain the engine coolant and engine oil into appropriate containers. Having fresh oil and coolant ready for refill is recommended. If your G70 has an aftermarket intercooler or charge pipes, note their routing; you may need to modify them for the larger turbo.

Step 1: Removing the Factory Turbocharger

Disconnect Intake and Exhaust Systems

Begin by removing the factory intake box and air filter assembly. Unbolt the downpipe from the turbo outlet and exhaust manifold. Remove the oxygen sensors carefully to avoid damaging the wires. On the G70, the turbo sits low on the exhaust manifold; you'll need access from both above and below the vehicle.

Disconnect Oil and Coolant Lines

Mark each line before removal—oil feed, oil drain, coolant feed, and coolant return. Use flare nut wrenches to loosen the fittings to avoid rounding them. Be prepared for residual fluid; shop towels are your friend. Remove the oil drain tube by unbolting it from the turbo and the block.

Unbolt the Turbocharger

Support the turbo from underneath if necessary. Remove the two or three bolts securing the turbo to the exhaust manifold (usually E14 torx). Carefully slide the turbo out from the engine bay. Inspect the manifold face for warpage or cracks; clean it thoroughly with a scraper and brake cleaner.

Step 2: Preparing the BorgWarner S300SX-E for Installation

Fit the Oil and Coolant Adapters

The BorgWarner S300SX-E uses standardized ports. You’ll need to install the oil feed adapter (often 1/8 NPT to -4 AN) and the coolant fittings. Apply a small amount of silicone sealant to the threads to prevent leaks. Do not over-torque brass fittings—they crack easily. Use thread tape only on NPT fittings (not on AN). For the oil drain, the S300SX-E requires a -10 or -12 AN fitting; ensure your drain tube or hose matches.

Pre-lube the Turbo

Before installation, pour a few ounces of clean engine oil into the oil feed port and spin the compressor wheel by hand. This pre-lubes the ball bearings and prevents dry starts. Rotate the wheel until oil seeps out of the drain port.

Check Wastegate and Actuator

If your kit includes an external wastegate, set the spring pressure according to your desired boost level (commonly 7–10 psi for break-in). Verify the actuator rod moves freely and install the wastegate flange if required.

Step 3: Installing the BorgWarner S300SX-E

Position and Bolt the Turbo

Lift the S300SX-E into place. Align the turbine inlet with the exhaust manifold outlet. Use new gaskets (copper or multi-layer steel) and apply a thin bead of high-temp silicone around the water ports. Install the bolts hand-tight, then torque to specification: typically 35–40 lb-ft for M10 bolts. Refer to your turbo kit instructions; under-torquing leads to exhaust leaks, over-torquing cracks the housing.

Connect Oil and Coolant Lines

Attach the oil feed line; tighten it to 15–20 lb-ft (or as advised). Install the coolant feed and return lines, ensuring they do not kink. The oil drain line must have a continuous downward slope back to the block—no dips where oil can pool. Use a new O-ring or gasket at the drain port. Double-check all crush washers are in place.

Reattach Intake and Exhaust

Bolt the downpipe to the turbine outlet using a new gasket. Connect the intake piping and charge pipe. If you are upgrading to a larger intercooler, now is the time. Secure all V-band clamps and silicone couplers. Reinstall the oxygen sensors using anti-seize compound on the threads.

Step 4: Final Checks and First Start

Reconnect Battery and Refill Fluids

Reconnect the battery. Refill the engine oil with the recommended 5W-30 (full synthetic). Refill the coolant and bleed the system according to the G70 service manual. Prime the oil system by cranking the engine with the fuel pump fuse removed for about 10 seconds—do this three times. This builds oil pressure before the turbo sees load.

Start and Inspect

Start the engine and let it idle. Listen for any unusual sounds like whistling (exhaust leak) or knocking (pre-ignition). Check all fittings for oil or coolant leaks. Rev the engine gently to 2000–2500 RPM to circulate fluid. Let the engine run until coolant temperature reaches normal operating range. Then shut it off and re-check fluid levels.

Initial Test Drive

Take the G70 on a short drive, keeping boost below 5–7 psi for the first 100 miles to seat the piston rings and break in the turbo bearings. Gradually increase boost after the break-in period. Monitor boost levels, oil pressure, and coolant temperature. Logged data with an OBD-II scanner is invaluable.

Tuning and ECU Considerations

The BorgWarner S300SX-E flows significantly more air than the stock turbos. A custom ECU tune is mandatory to adjust fuel, timing, and boost control. Use a reputable tuning platform such as ECUtek or JB4, and work with a tuner experienced with the G70's Lambda II engine. Without proper tuning, you risk detonation and engine damage. Consider upgrading the fuel pump and injectors if you target over 550 whp. For more community-sourced tuning advice, check the Genesis Owners forum.

Troubleshooting Common Issues

  • Oil leaks at drain fitting: The drain line must have a constant downward slope. If leaking, remove and re-check the gasket and straighten the line.
  • Coolant leak from turbo fittings: Verify all O-rings are seated; use new copper gaskets on banjo bolts.
  • Turbo not spooling: Check for exhaust leaks before the turbine wheel, wastegate stuck open, or boost control solenoid malfunction.
  • Excessive smoke: Could indicate oil seal failure—ensure oil drain isn't restricted, and the crankcase ventilation system is functional.
  • Check engine light: Common after turbo upgrade due to boost pressure deviation. A tune will correct this.

Conclusion

Installing a BorgWarner S300SX-E in your Genesis G70 transforms the driving experience, delivering responsive power and a thrilling growl. By following this guide—focusing on proper preparation, torque specs, and break-in procedures—you set yourself up for a reliable, high-performance build. Always pair the hardware with a professional tune and use quality fluids and gaskets. For sourcing the turbo and supporting parts, visit a trusted retailer such as MAPerformance. Happy boosting.