Understanding the G70 Turbo Upgrade

Upgrading the turbocharger on a Genesis G70 is one of the most effective ways to unlock substantial horsepower and torque gains. The factory turbo is designed for a balance of economy and performance, but aftermarket kits from APR and Catalyst Performance push the limits significantly. The APR turbo kit features a billet compressor wheel and a larger turbine housing, while the Catalyst Performance kit complements it with a high-flow downpipe and upgraded wastegate actuator. Together, they create a matched system that supports higher boost levels, improved spool characteristics, and reliable power output. This guide provides a thorough, step-by-step installation process with professional tips to ensure a successful build.

Tools and Materials Needed

Having the correct tools and parts on hand before starting will save hours of frustration. Beyond a basic socket set, you will need specialty items for turbo work. Below is the complete list.

  • Socket set (metric, 3/8” and 1/2” drive) with extensions
  • Torque wrench (1/2” drive, range 20-150 lb-ft)
  • Screwdrivers (flathead and Phillips)
  • Combination wrenches (10mm, 12mm, 13mm, 14mm, 17mm)
  • Engine oil (5W-30 full synthetic, 6 quarts)
  • Coolant (OEM or equivalent G70-specific coolant)
  • APR Turbo Kit (includes turbocharger, gaskets, hardware, oil/coolant lines)
  • Catalyst Performance Kit (includes downpipe, wastegate actuator, gaskets, clamps)
  • Shop towels and degreaser
  • Jack and jack stands
  • Pry bar (for stubborn exhaust connections)
  • Thread-locker (medium strength, e.g. Loctite 242)
  • Vacuum pump or coolant funnel
  • Digital multimeter (optional, for sensor checks)

It is strongly recommended to purchase new turbo gaskets and exhaust manifold studs from the dealership or a trusted supplier. Many aftermarket kits include them, but double-check before beginning.

Preparation Steps

Vehicle Positioning and Safety

Park the G70 on a level concrete surface. Engage the parking brake and chock the rear wheels. Disconnect the negative battery terminal using a 10mm wrench and isolate the cable to prevent accidental contact. This step eliminates the risk of shorting sensors or triggering the fuel pump while working.

Draining Fluids

Place a drain pan under the radiator and open the coolant drain plug (passenger side lower corner) or disconnect the lower radiator hose. Drain the engine oil by removing the oil pan drain plug and the oil filter to allow for a complete drain. Reinstall the drain plug with a new washer after draining. This prevents oil contamination during the turbo swap.

Removing Obstructions

Remove the engine cover (pull upward), the air intake duct, and the air filter box. Unclip the wiring harnesses that run along the upper timing cover. Remove the heatshield covering the turbo. You may also need to unbolt the strut tower brace if equipped. Take photos before disconnecting any vacuum lines to aid reassembly.

Removing the Stock Turbo

Disconnecting Exhaust and Intake

Loosen the V-band clamp connecting the downpipe to the turbo outlet. If the clamp is seized, apply penetrating oil and allow it to soak for five minutes. Next, unbolt the downpipe from the catalytic converter (three 12mm bolts). Disconnect the oxygen sensor connectors and carefully wire them aside. Remove the intake pipe from the turbo inlet — loosen the hose clamp at the compressor housing and the coupler near the air box.

Removing Oil and Coolant Lines

Place a catch pan underneath the turbo area. Using a 13mm flare nut wrench, disconnect the oil feed line from the top of the turbo and the oil return line from the bottom of the block. Coolant lines are secured with 10mm banjo bolts — have a rag ready to catch residual coolant. Cap all open fittings with plastic plugs to prevent debris entry.

Unbolting the Turbo from the Manifold

The stock turbo is mounted to the exhaust manifold with four 13mm bolts. Work from the bottom-up using a socket with a universal joint. Remove the two lower nuts first, then the upper nuts. Support the turbo with one hand as the last bolt is removed. Gently lower the turbo and slide it out between the engine block and frame rail — it requires a bit of twisting. Inspect the manifold surface for cracks or warpage; if damaged, replace the manifold before installing the new turbo.

Installing the APR Turbo Kit

Preparing the New Turbo

Unbox the APR turbo and rotate the compressor wheel by hand — it should spin freely without binding. Compare the part number with the kit contents. Apply a thin film of anti-seize to the threads of the oil feed banjo bolt. Install the supplied oil restrictor if required (follow APR instructions specific to your G70 model year).

Mounting the Turbo to the Manifold

Place a new OEM manifold gasket onto the studs. Lift the APR turbo into position, aligning the oil drain port downward. Hand-tighten the four mounting nuts (M10, 12mm head). Torque them to 35 lb-ft in a cross pattern. Do not over-torque — the cast iron manifold can crack, and the turbo housing may warp.

Connecting Oil and Coolant Lines

Reconnect the oil feed line to the top of the turbo using a new crush washer. Torque the banjo bolt to 18 lb-ft. Attach the oil return line to the turbo drain flange with a new gasket — torque the two Allen bolts to 8 lb-ft. For coolant, connect the feed and return lines to the turbo and block. Use new copper washers on each banjo fitting and torque to 20 lb-ft. Verify all lines are routed away from hot surfaces and secured with factory clips.

Wastegate Actuator Setup

The APR turbo includes a pre-adjusted wastegate actuator. If your kit includes a separate actuator, mount it using the supplied bracket and tighten the rod end so that it just closes the wastegate flapper with zero preload. Secure the locknut at 20 lb-ft. Do not over-extend the rod — it can cause boost creep.

Intake and Exhaust Connections

Attach the intake pipe to the compressor housing, tightening the T-bolt clamp to 6 lb-ft. Install the APR blow-off valve or recirculation valve as per kit instructions. For the exhaust side, use a new V-band gasket and clamp to connect the turbo outlet. Do not fully tighten yet — you will align it when installing the downpipe.

Installing the Catalyst Performance Kit

Downpipe Removal

From underneath the car (safely on jack stands), remove the factory downpipe. Use penetrating oil on the O2 sensor threads, then unscrew sensors using a 22mm O2 socket. The downpipe bolts to the turbo outlet at the top and to the catalytic converter at the bottom (two studs with 14mm nuts). Carefully lower the downpipe — it may need to be rotated to clear the subframe.

Catalyst Performance Downpipe Installation

The Catalyst Performance downpipe is designed for a direct fit with the APR turbo. Apply a small amount of anti-seize to the O2 sensor threads and install them into the provided bungs. Use a new gasket between the downpipe and turbo outlet, then slide the downpipe onto the studs. Hand-tighten the three V-band nuts, then torque to 25 lb-ft in sequence. Attach the lower end to the factory catalytic converter — if the catalyst tubing has a slip-fit, use the supplied clamp and tighten to 40 lb-ft. If you are using a high-flow catted downpipe, ensure the O2 sensor is installed on the post-cat bung. For off-road use downpipes, a spacer or mini-cat may be needed to avoid a check engine light.

Wastegate and Boost Control

If your Catalyst Performance kit includes a boost control solenoid, mount it securely away from heat sources. Run the vacuum hoses as diagrammed — typically one line to the wastegate actuator and one to the turbo compressor housing. Use zip ties to secure hoses from chafing.

Finalizing the Installation

Reassembly and Fluid Fill

Reinstall any components that were removed: heatshields, wiring harness clips, air intake, engine cover. Refill the engine oil — 6 quarts of 5W-30 full synthetic. Start the engine and let it idle for 10 seconds, then check the oil level and top off as needed. For coolant, use a vacuum filler to eliminate air pockets, or fill the expansion tank and run the engine with the heater on full hot until the thermostat opens and bubbles stop. Top off the coolant to the cold fill line.

Leak Check

With the engine running, inspect all oil and coolant connections for drips. Listen for exhaust leaks — a ticking sound near the turbo-to-downpipe joint indicates a gasket leak. Shut off the engine and retorque any loose fittings. After a short test drive, recheck the turbo mounting nuts (hot-torque to specification) and confirm no fluid seepage.

Testing and Tuning

Break-In Procedure

The APR turbo bearings and Catalyst downpipe require a brief break-in period. Drive the vehicle gently for the first 100 miles without sustained boost above 10 psi. Vary engine speed and avoid full-throttle pulls. This allows the seals to seat and prevents oil starvation. During this period, monitor oil pressure and coolant temperature on the instrument cluster.

Data Logging

Use an OBD-II scanner with logging capability (or a dedicated platform like Cobb Accessport) to record boost pressure, air-fuel ratio, and exhaust gas temperature. Ideal peak boost with APR kit and Catalyst downpipe is 22-24 psi on a 93 octane tune. If boost exceeds 25 psi, the wastegate may need adjustment or a boost controller intervention.

Professional Tuning

A turbo swap demands a custom ECU tune to optimize ignition timing, fuel delivery, and boost control. Contact tuning specialists such as Raptor Tuning or LAP3 for a remote calibration specific to this hardware combination. Do not drive the car aggressively on the stock tune — the factory fuel maps will provide excessive fuel enrichment, causing rich misfires and potential catalytic converter damage.

Post-Installation Checks

After tuning, verify that the check engine light remains off. Perform a series of acceleration runs from 0-60 mph and 60-130 mph to confirm performance gains. Typical results with APR turbo and Catalyst downpipe on a Genesis G70 3.3T are 450-480 wheel horsepower with proper fueling. If power falls short, inspect for boost leaks using a smoke tester.

Common Pitfalls and Troubleshooting

  • Oil leak at turbo feed line — Always use new crush washers and torque spec. A weeping banjo bolt is the most common post-install leak.
  • Boost creep (over-boost) — Usually caused by a wastegate actuator that is too short. Adjust rod length to provide more preload. Ensure the wastegate flapper is fully seated.
  • Exhaust rattle — The downpipe may contact the subframe if not properly aligned. Loosen the V-band and reposition before final tightening.
  • Check engine light P0420 — Catalyst efficiency code. Install a 90-degree O2 sensor spacer on the downstream sensor, or use a mini-cat adapter.
  • Turbo lag — Verify the intake system is sealed. A pre-turbo leak reduces spool performance. Also check that the blow-off valve is not leaking at idle.

Conclusion

Installing the APR turbo kit paired with the Catalyst Performance downpipe transforms the Genesis G70 into a genuine high-performance machine. The process is demanding but achievable for a skilled DIYer with mechanical aptitude and the right tools. By following this expanded guide — from proper fluid draining to torque specifications and tuning — you ensure reliability and maximum power. The result is a responsive, powerful G70 that pulls hard to redline and delivers an exhilarating driving experience every day. For further reading, consult the official APR product page and Catalyst Performance support site for updated instructions and firmware.