Unlocking the Full Potential of Your SW20 with an HKS Turbo Kit

The Toyota MR2 SW20 is already a nimble, mid-engine legend, but adding forced induction from a trusted name like HKS transforms it into a serious performance machine. An HKS Turbo Kit provides a well-engineered path to significant horsepower gains without the guesswork of piecing together mismatched parts. This guide walks you through a complete installation, covering everything from workspace preparation to the first test drive. Whether you are a seasoned DIY mechanic or a dedicated enthusiast, following these detailed steps will help you achieve a reliable, high-output build that honors the SW20's engineering heritage.

Before you begin, understand that turbocharging an engine increases thermal and mechanical stress. Proper installation, quality components, and attention to detail are essential for long-term reliability. The HKS kit is designed to integrate with the SW20’s 3S-GTE engine, offering a significant upgrade over the stock turbo setup. Expect gains in the range of 50–80 wheel horsepower depending on boost settings and supporting modifications. This guide assumes you have intermediate mechanical skills and access to a well-equipped garage. If you encounter steps beyond your comfort zone, consult a professional tuner or performance shop.

Tools, Parts, and Preparations: Setting Up for Success

What You'll Need: The Complete Checklist

A successful installation starts with gathering every tool and component beforehand. Missing a single part halfway through the job can derail your day. Use the following list to ensure you have everything on hand.

HKS Turbo Kit Contents

  • HKS turbocharger (typically a GT3037S or similar, depending on the kit version)
  • Cast or tubular exhaust manifold
  • Oil feed and return lines with fittings
  • Intercooler core and piping (hot and cold side)
  • Wastegate actuator
  • Blow-off valve
  • Gaskets, O-rings, and hardware
  • Instruction manual (keep it handy for torque specs and routing)

Tools and Consumables

  • Metric socket set (8mm to 19mm) with extensions and universal joints
  • Torque wrench (ft-lb and in-lb ranges)
  • Combination wrenches, screwdrivers, pliers, and wire cutters
  • Jack and jack stands (or lift) – you will be under the vehicle
  • Drain pan, funnel, and rags
  • Fresh engine oil (5W-30 or as recommended for your climate)
  • Coolant (Toyota Red or equivalent)
  • Thread locker (blue Loctite) and anti-seize compound
  • Shop towels, cleaning solvent, and a wire brush
  • Safety glasses, mechanic gloves, and fire extinguisher

Safety First: Prep Your Workspace and Vehicle

Choose a clean, well-ventilated area with ample lighting. Disconnect the negative battery terminal and secure the cable away from the post. Place the vehicle on level ground, engage the parking brake, and chock the rear wheels. If you plan to work underneath, use jack stands rated for the vehicle’s weight – never rely solely on a hydraulic jack. Allow the engine to cool completely before starting any disassembly; hot exhaust components can cause severe burns.

Take reference photos of the engine bay from multiple angles. These images will be invaluable when routing hoses and wiring harnesses later. Label any connectors or vacuum lines you disconnect with painter’s tape and a marker. This small step saves hours of frustration during reassembly.

Step-by-Step Installation: From Stock to HKS Turbocharged

1. Draining Fluids and Initial Disassembly

Place a drain pan under the coolant drain plug on the radiator (or lower radiator hose) and drain the coolant. Then remove the oil drain plug and drain the engine oil. Replace the drain plug with a new crush washer and tighten to spec. Removing these fluids reduces mess when you disconnect hoses and lines. Next, remove the engine undercover (if equipped) to access the oil pan and turbo area.

Remove the air intake duct, air filter box, and all intercooler piping connected to the stock turbo. Unplug the oxygen sensor(s), knock sensor, and any other connectors near the turbocharger. Carefully detach the coolant hoses from the stock turbo unit – expect some residual fluid to spill. If your SW20 has an aftermarket boost controller or gauges, disconnect those lines as well.

2. Removing the Stock Turbo and Exhaust Manifold

The stock turbo on the 3S-GTE is mounted to the exhaust manifold at the rear of the engine. Access is tight but manageable. Remove the heat shield(s) covering the manifold and turbo. Unbolt the downpipe from the turbo outlet and separate it from the exhaust system. You may need to remove the rear engine mount bracket to free the downpipe. Support the turbo while unbolting the oil feed and return lines. Be careful with the banjo bolts – they have copper washers that can deform.

Once the lines are loose, remove the four (or eight) nuts securing the turbo to the manifold. Lift the turbo away. Now unbolt the manifold from the cylinder head. Work in a reverse sequence, loosening nuts gradually to avoid warping. Remove the manifold and discard the old gasket. Clean the mounting surface on the cylinder head with a scraper and solvent, ensuring no old gasket material remains. Any debris can cause a vacuum leak.

3. Installing the HKS Exhaust Manifold and Turbocharger

Apply a thin coat of anti-seize to the manifold studs and threads (if using a cast manifold). Place a new manifold gasket onto the studs, then position the HKS manifold. Tighten the nuts in a crisscross pattern to the manufacturer’s specified torque (typically 32–38 ft-lb). Do not overtighten – the manifold can crack under thermal expansion.

Now mount the HKS turbocharger to the manifold using the supplied gasket and hardware. Tighten the mounting nuts evenly. Attach the oil feed line to the turbo center housing (banjo bolt with new washers). Connect the oil return line to the block fitting – ensure the line has a gentle downward slope to drain properly. If the HKS kit uses a braided stainless steel line, check for kinks. Torque the banjo bolts to spec (about 25–30 ft-lb). Next, connect the coolant lines. Some HKS kits use a water-cooled center section; route the hoses to the engine coolant pipes or radiator as per the instructions. Secure all hoses with clamps.

4. Installing the Intercooler and Piping

Position the HKS intercooler in the front bumper or side vent location (kit-specific). The SW20 engine bay is tight, so the intercooler is usually mounted in the front trunk area. Remove the plastic bin tray to access the mounting points. Bolt the intercooler to existing brackets or drill new holes if necessary. Install the cold pipe from the turbo outlet to the intercooler inlet, and the hot pipe from the intercooler outlet to the throttle body. Use silicone couplers and T-bolt clamps for a secure, leak-free fit. Tighten all clamps snugly, but avoid stripping the threads. If the kit includes a blow-off valve, mount it on the hot pipe and connect a vacuum line to the intake manifold.

5. Reconnecting Ancillary Components

Reattach the oxygen sensor(s) to the downpipe (if the HKS downpipe has a bung). Install the HKS wastegate actuator – connect the control rod to the wastegate arm and adjust preload per the manual. Route the vacuum line from the actuator to a boost source. If you are using the stock ECU, consider an HKS FCD (Fuel Cut Defencer) to prevent fuel cut under boost. Wire it according to the instructions. Reconnect all electrical connectors, ensuring they are clean and sealed. Install the intake filter onto the turbo inlet.

6. Refilling Fluids and Rechecking Everything

Pour fresh coolant into the radiator until full, then run the engine with the radiator cap off to burp air. Top off as needed. Refill the engine with the recommended volume of oil (typically 4.5–5 quarts with a new turbo). Check the oil level on the dipstick. Reconnect the battery negative terminal. Before starting, verify that all bolts, clamps, and connections are tight. Double-check that no tools or rags are left in the engine bay.

Post-Installation Testing and Tuning

Start-Up and Leak Check

Start the engine and let it idle. Listen for unusual metallic sounds or hissing. Check for oil and coolant leaks around the turbo, manifold, and lines. If you see drips, shut off the engine and address them immediately. Check the oil pressure gauge – it should rise within a few seconds. Let the engine come to normal operating temperature, watching the temperature gauge. If it climbs too high, check coolant flow and bleed air again. Perform a boost leak test using a homemade adapter (PVC cap with a Schrader valve) and a hand pump. Pressurize the intake system to 10 psi and listen for leaks. Repair any hissing sounds by tightening clamps or replacing couplers.

Initial Drive and Break-In

Take the car on a short, gentle drive (< 5 miles) keeping boost below 5 psi and RPM under 3500. This allows the turbo bearings and seals to seat. Return to the shop and re-check fluid levels, bolt torque on the manifold and downpipe (they may loosen after thermal cycling). For the next 500 miles, vary engine speed but avoid sustained high load. An oil change after the first 100 miles is cheap insurance against debris flushed from the new turbo. After break-in, you can increase boost to the kit’s recommended level (usually 7–14 psi) using a boost controller if desired.

Performance Monitoring and Future Upgrades

Invest in a wideband air/fuel ratio gauge and a boost gauge to monitor engine health. The stock ECU has some adjustability, but for maximum power and safety, consider a standalone ECU or piggyback system such as the HKS F-CON or AEM Infinity. Professional tuning is strongly recommended when increasing boost beyond kit baseline. With proper tuning, an HKS turbo kit on the SW20 can produce 350–400 crank horsepower while remaining reliable.

Conclusion: A Thrilling Upgrade Delivered with Care

Installing an HKS Turbo Kit in your SW20 is a rewarding project that unlocks the true sporting character of the MR2. By following this detailed guide, you have replaced a restrictive stock system with precision-engineered components that flow more air, generate more boost, and deliver exhilarating performance. The key to long-term satisfaction lies in thorough preparation, meticulous installation, and disciplined break-in. Maintain the car with regular oil changes (every 3,000 miles or sooner if tracking) and inspect turbo hoses and clamps periodically. Your newly turbocharged SW20 is now a force to be reckoned with – enjoy the enhanced power and the unmistakable sound of a properly tuned HKS turbo spooling behind your seat.

For further reading and community support, explore these resources: