Introduction

The HPA Motorsports S3 IS38 turbocharger upgrade is one of the most effective bolt-on modifications for the Audi 2.0 TSI/EA888 Gen 3 engine. By swapping the factory IS20 turbo for the larger IS38 found in the Audi S3 and Golf R, you can unlock significant horsepower and torque gains with supporting software. While the installation is straightforward for an experienced DIYer, it requires careful attention to detail, proper tools, and a systematic approach. This comprehensive guide walks you through every step, from preparation to final road testing, ensuring a clean, leak-free installation that delivers reliable performance.

Tools and Materials You Will Need

Before starting, gather all required parts and tools. Missing a critical component mid-job can lead to unnecessary downtime.

  • HPA Motorsports S3 IS38 Turbocharger – The core upgrade. Ensure you have the correct variant for your vehicle model (e.g., transverse or longitudinal engine layout).
  • New gaskets and seals – Turbo-to-manifold gasket, turbo-to-downpipe gasket, intake manifold gasket, and O-rings for oil and coolant lines.
  • Oil and coolant – OEM-spec 5W-40 or 0W-40 oil and G12/G13 coolant (premixed or concentrate with distilled water).
  • Basic hand tools: Metric socket set (8mm, 10mm, 13mm, 15mm, 17mm), combination wrenches, extensions, universal joints, ratchet, and breaker bar.
  • Torque wrench – ⅜” drive (10–60 Nm) and ½” drive (30–200 Nm). Critical for fasteners like turbo mounting bolts.
  • Hex and Torx bits – T25, T30, T40, and hex keys (5mm, 6mm).
  • Pry bar and trim removal tools – For loose hoses and plastic shields.
  • Drain pan, funnel, shop rags, and safety glasses/gloves.

Optional but recommended: a turbocharger installation kit that includes banjo bolts, copper washers, and replacement V-band clamps. A boost leak tester can also help verify the charge system after reassembly.

Preparation and Safety

Park the vehicle on a level surface and allow the engine to cool completely. Disconnect the negative battery terminal to prevent accidental electrical shorts. Raise the front of the car on jack stands (or use a lift) to provide clearance for working underneath. For Haldex-equipped AWD models, ensure the front axle is supported safely.

Drain the engine oil if you plan to replace it during the turbo swap – many enthusiasts do this step first to avoid a double fluid change later. Remove the engine cover by unscrewing the two M6 bolts and gently lifting it off. Also remove any plastic engine splash shields underneath the vehicle.

Step 1: Remove the Air Intake System

Begin by loosening the clamp at the turbo intake elbow and disconnecting the mass airflow (MAF) sensor electrical connector. Unclip the air box lid and remove the entire intake assembly from the air box to the turbo. Set aside the hardware and keep the intake duct free of debris. If your vehicle uses an aftermarket intake, follow the manufacturer’s removal instructions.

Step 2: Disconnect and Drain the Coolant System

Place a drain pan under the radiator’s drain plug (typically on the driver side, bottom corner). Open the plug and allow the coolant to drain. To empty the block, remove the lower coolant hose from the radiator or the water pump. Be careful – coolant may still be hot. After draining, close the drain plug and set the old coolant aside for proper disposal.

Step 3: Remove the Exhaust Downpipe

Access the downpipe from underneath the car. Unbolt the downpipe from the turbo inlet using three M8 nuts (usually 13mm). Disconnect the oxygen sensors (wideband and narrowband) by unclipping their connectors and unthreading them from the downpipe. Remove the downpipe support bracket if equipped, and lower the downpipe out of the vehicle. Newer models may require dropping the subframe slightly or removing the driver side axle for clearance – consult your vehicle’s service manual for specifics.

Step 4: Remove the Factory Turbocharger

With the downpipe out, you have clear access to the turbo. Start by removing the heat shields that surround the turbo – these are typically secured with 8mm or 10mm bolts. Take care not to strip them. Next, disconnect the oil feed line from the top of the turbo (banjo bolt) and the oil drain line from the bottom (two bolts). Collect the copper washers; they should be replaced. Then disconnect the coolant feed and return lines. Plug all open ports with small caps or clean rags to prevent debris entry.

Remove the four M10 bolts securing the turbo to the exhaust manifold. The turbo will be heavy – support it from underneath. Carefully lower the turbo from the engine bay. On some models, you may need to rotate the turbo to clear the manifold studs. Inspect the manifold for cracks or warped surfaces; address any issues before installing the new turbo.

Step 5: Prepare and Install the HPA IS38 Turbocharger

Before mounting, compare the new HPA IS38 turbo to the removed unit. Verify the wastegate actuator preload and that the turbine wheel spins freely. Apply a thin film of anti-seize to the manifold studs to ease future removal. Install a new gasket on the exhaust manifold and carefully position the HPA IS38 turbo onto the studs. Tighten the four mounting nuts in a cross pattern to the specified torque – typically 20–25 Nm (15–18 lb-ft). Using a torque wrench is essential; overtightening can crack the manifold or warp the turbo flange.

Reconnect the oil feed line with new copper washers and tighten the banjo bolt to 25–30 Nm (18–22 lb-ft). Reattach the oil drain line using a new gasket and tighten to 10 Nm (7 lb-ft). Connect the coolant lines similarly. Do not fully tighten the coolant banjo bolts until the lines are properly oriented to avoid kinks. Finally, reinstall the turbo heat shields in reverse order of removal.

Step 6: Reinstall the Exhaust Downpipe

Using a new gasket, attach the downpipe to the turbo outlet. Tighten the three flange nuts to 25 Nm (18 lb-ft). Reconnect the oxygen sensors – apply a small amount of anti-seize to the threads (sensor-safe) and torque to 45 Nm (33 lb-ft). Reinstall the O2 sensor brackets and any support bracing. Ensure the downpipe does not contact the underbody; adjust as needed.

Step 7: Reinstall the Intake System

Attach the intake hose to the turbo inlet elbow and secure the clamp. Reconnect the MAF sensor and any crankcase vent hoses. Ensure the intake filter is clean and properly seated in its housing. For vehicles with a boost pipe (intercooler to throttle body), double-check that all clamps are tight and O-rings are in good condition.

Step 8: Refill Fluids and Bleed the Coolant System

Close the radiator drain plug. Fill the coolant reservoir with the correct mixture (typically 50/50). Leave the radiator cap off temporarily. Start the engine and let it idle with the heater set to maximum. Slowly add coolant until the level stabilizes and the thermostat opens. Burp the system by squeezing the upper radiator hose. Top off as needed. For oil, fill with fresh engine oil through the valve cover cap, using the correct quantity and grade. Start the engine briefly to prime the turbo, then check the oil level and add accordingly.

Step 9: Reconnect Battery and Perform System Checks

Reattach the negative battery terminal. Before starting the engine, visually inspect all connections: turbo bolts, oil/coolant lines, intake clamps, and electrical connectors. Ensure no tools are left in the engine bay. Turn the ignition to the ON position (without starting) and listen for the fuel pump priming – check for any unusual sounds.

Starting the Engine and Initial Break-In

Start the engine and allow it to idle for 3–5 minutes. Listen for unusual noises like whistles (boost leaks) or metallic rattles (contact between turbo and engine). Check for coolant, oil, and exhaust leaks. Rev the engine gently to 2000–3000 rpm to circulate oil through the new turbo bearings. Monitor the coolant temperature gauge and ensure the cooling fan cycles on. If the engine runs rough, there may be air in the coolant system or a vacuum leak.

Post-Installation: Road Test and Data Logging

After confirming no immediate issues, take the vehicle for a short, careful road test. Avoid full throttle until the turbo has been through several heat cycles. Perform a few part-throttle pulls and listen for unusual sounds. Once back, check all fluid levels and look for leaks. If your vehicle is equipped with a performance tuner (e.g., APR, Unitronic, Integrated Engineering), upload the appropriate IS38 calibration. Never operate the IS38 turbo without custom software designed for this hardware – the factory ECU will not supply correct fueling and boost control, risking engine damage.

Use a data logging tool (e.g., VCDS, OBDeleven, JB4) to monitor boost pressure, fuel trims, and exhaust gas temperatures. Target boost levels will vary by tune but typically range from 22–28 psi. If boost spikes or goes into limp mode, inspect for boost leaks or wastegate issues.

For maximum reliability and performance, consider the following modifications alongside the HPA IS38 upgrade:

  • High-pressure fuel pump (HPFP) – To maintain adequate fuel pressure at high boost.
  • Intercooler – The stock intercooler becomes a bottleneck; a direct-fit aftermarket unit reduces intake air temperatures.
  • Spark plugs and coil packs – One step colder plugs and robust coils prevent misfires under increased cylinder pressure.
  • Dual-clutch transmission (DSG) tune – If equipped, to handle higher torque and shift logic.

External Resources

For further technical details and community support, consult the following:

Conclusion

The HPA Motorsports S3 IS38 turbo upgrade is a transformative modification that elevates the driving experience of your Audi. By following this detailed step-by-step guide, you can complete the installation yourself with confidence, avoiding common pitfalls like leaks, misaligned components, or improper torque. Patience during the fluid bleed, careful torque application, and correct engine management tuning are the keys to a successful outcome. Once everything is dialed in, you’ll enjoy a responsive, powerful turbo that makes every day behind the wheel more exciting.