Upgrading your Toyota MR2’s intercooler is one of the most effective modifications for unlocking the full potential of its turbocharged engine. A high-flow, bar-and-plate intercooler like the Greddy Trust unit replaces the restrictive factory unit, reducing intake air temperatures (IAT) and increasing air density. This directly translates into higher horsepower, improved throttle response, and greater engine safety under boost. In this comprehensive guide, we’ll walk through every phase of the installation, from preparation to final tuning considerations, ensuring you achieve a leak-free, performance-optimized upgrade.

Why Upgrade to a Greddy Trust Intercooler?

The stock intercooler on the MR2 (both the SW20 turbo and later revisions) is a tube-and-fin design that often suffers from heat soak, especially during spirited driving or in warm climates. The Greddy Trust intercooler is a bar-and-plate core, which offers superior heat dissipation and lower pressure drop. Key benefits include:

  • Increased Power Output: Cooler, denser intake air allows the engine to run more aggressive ignition timing and boost levels safely. Gains of 15–30 horsepower are common with a supporting tune.
  • Reduced Intake Air Temperatures: Greddy’s core design can lower IATs by 30–50°F compared to the stock unit, reducing the risk of detonation.
  • Better Throttle Response: Less restriction in the intake path means the turbo spools more freely, improving part-throttle drivability.
  • Improved Reliability: Lower charge air temperatures and consistent air density prevent knock, extend engine life, and allow for safer high-boost applications.
  • Direct Fitment: The Greddy Trust kit is engineered specifically for the MR2 chassis, meaning minimal cutting or modification. It bolts directly to the factory mounting points and uses standard 2.5-inch silicone couplers.

For those considering a larger turbo upgrade or higher boost levels, the Greddy Trust intercooler is an essential foundation. Compared to budget universal intercoolers, the Greddy unit offers proven flow characteristics and a reputation for quality that has made it a staple in the JDM performance community.

Tools and Materials Needed

Before beginning, gather all necessary tools and supplies. Proper preparation reduces downtime and prevents mid-job trips to the hardware store.

  • Greddy Trust intercooler kit (includes core, mounting brackets, silicone couplers, T-bolt clamps, hardware)
  • Socket set – 10mm, 12mm, 14mm deep sockets, with extensions and a universal joint
  • Combination wrenches – 10mm, 12mm, 14mm
  • Flathead and Phillips screwdrivers
  • Torque wrench (in-lb range recommended for small fasteners)
  • Trim removal tool or plastic pry bar
  • Coolant – Toyota pink or equivalent (some intercooler kits integrate with the coolant system; check your specific kit)
  • Distilled water (if using water injection or coolant mix)
  • Jack and jack stands or ramps
  • Safety glasses and mechanic’s gloves
  • Shop rags and cleaning solvent
  • Thread locker (medium strength) for mounting bolts
  • Dish soap or leak detection spray for boost leak check
  • Vacuum/boost leak tester (optional but recommended)

Note that the MR2’s intercooler is located behind the passenger side rear wheel well. Access requires removal of the wheel, liner, and, depending on kit configuration, the stock intercooler ducting. Some MR2 owners also remove the rear bumper or lower valance for clearance, but the Greddy Trust kit is designed to fit with only the liner removed.

Step-by-Step Installation Process

Step 1: Preparation – Vehicle Setup and Safety

Park the MR2 on a level surface, engage the parking brake, and chock the front wheels. Disconnect the negative battery terminal to prevent accidental short circuits or ECU resets during the installation. Allow the engine and exhaust components to fully cool down if the vehicle has been driven recently. Remove the passenger side rear wheel using a jack and jack stands. For easier access, place the car on ramps or lift the rear with jack stands under the subframe.

Remove the rear wheel well liner by unscrewing the plastic push pins (use a trim removal tool to avoid breaking them) and any visible 10mm bolts. Set the liner aside. You should now see the stock intercooler positioned just inboard of the rear bumper beam. The core sits vertically, with inlet and outlet hoses running to the turbo and throttle body.

Step 2: Drain Coolant and Disconnect Hoses

If your MR2 has a factory water-to-air intercooler system (rare on late models, but check your year), you must drain the coolant loop. Place a drain pan under the passenger side intercooler coolant lines. Loosen the drain plug on the water pump or remove the lower hose from the intercooler. For standard air-to-air MR2s (all turbo models after 1991 in most markets), no coolant work is needed. However, if your Greddy Trust kit uses a water spray system (some aftermarket kits include one), you’ll need to install related components – but the standard Greddy Trust kit is air-to-air and does not require coolant modification.

Disconnect the rubber hoses from the stock intercooler inlet and outlet. Use a flathead screwdriver to loosen the worm-gear clamps. Expect some residual oil or fuel vapor; have rags ready. Note the orientation of the hoses – the outlet hose (from the throttle body) will have a smaller diameter or a different bend radius depending on your MR2 revision.

Step 3: Remove the Stock Intercooler

The stock intercooler is held in place by two or three 12mm bolts on the bracket that attaches to the chassis. Sometimes there is also a support bracket underneath. Remove these bolts. The intercooler may be connected to a recirculation valve hose or a bypass valve; disconnect that as well. Carefully wiggle the stock intercooler out of its mounting location. It will slide out toward the rear of the car after the hoses are detached. Inspect the stock intercooler for any dirt or debris that may have accumulated; this is a good opportunity to clean your throttle body if you wish.

With the stock intercooler removed, clean the mounting surface of the chassis with a solvent to remove oil and dust. Check the condition of the foam seals around the air guide (if present). The Greddy Trust kit may come with new foam or rubber seals.

Step 4: Test Fit the Greddy Trust Intercooler

Before final installation, test-fit the new intercooler without fully tightening the bolts. Align the mounting brackets that came with the kit onto the intercooler core. The Greddy Trust unit uses slotted brackets to allow fore-aft adjustment for perfect fitment. Place the core into the engine bay, feeding the inlet/outlet ports toward the turbo side (passenger side). Center the core so that there is equal clearance to the bumper beam and the inner fender. The core should sit flush against the opening behind the rear bumper, allowing ambient air to flow directly through it.

Mark the position of the brackets on the chassis if necessary. The kit typically includes hardware that bolts into existing threaded holes. If the bolt holes do not align precisely, do not force them – gently enlarge or ream the bracket slots. Do not modify the chassis. Secure the intercooler loosely with the supplied bolts, then proceed to install the silicone hoses.

Step 5: Install the Silicone Hoses and Clamps

The Greddy Trust kit includes high-quality silicone couplers and T-bolt clamps. Apply a thin film of dish soap or silicone lubricant to the inside of the couplers to ease installation and prevent tearing. Slide the hoses onto the turbo outlet pipe and the throttle body inlet, and onto the corresponding intercooler ports. Position the T-bolt clamps evenly over the end of each coupler – they should be about 6–8 mm from the edge of the coupler. Tighten the clamps to 4–5 Nm (35–45 in-lb) to avoid crushing the silicone or over-tightening onto plastic pipes. Do not tighten fully until all hoses are aligned.

If your MR2 has a blow-off valve or bypass valve that originally attached to the stock intercooler, you will need to relocate it to the charge piping. The Greddy Trust kit usually includes a dedicated port on the charge pipe for this purpose. Use the supplied barb or flange and ensure it is sealed with an O-ring or gasket.

Route the hoses carefully to avoid kinks or contact with sharp edges. Use zip ties to keep the hoses away from hot components like the exhaust manifold or turbo housing. It may be helpful to remove the passenger side rear wheel well liner temporarily to confirm hose routing is free and clear.

Step 6: Securing the Intercooler and Final Bolt Tightening

Once all hoses are connected and aligned, torque the intercooler mounting bolts to the manufacturer’s specification – approximately 12–15 Nm (9–11 ft-lb) for M8 bolts. Do not overtighten, as the aluminum brackets can strip. Apply medium-strength thread locker to the bolts before final torque to prevent loosening from vibration. Double-check that the intercooler is level and that there is no contact with the chassis, bumper beam, or body panels. The outlet pipe should clear the rear structure; if it contacts, adjust the mounting position slightly using the slotted brackets.

Reinstall the wheel well liner, ensuring that the ducting for the intercooler aligns with the airflow openings. Some Greddy Trust kits come with a foam seal that should be placed between the intercooler and the vent opening in the bumper. This directs all incoming air through the core, dramatically increasing cooling effectiveness. Without this seal, a portion of the airflow bypasses the core.

Step 7: Reconnect Battery and Test Fit (No Engine Start)

Reconnect the negative battery terminal. Do not start the engine yet. Perform a visual inspection of all connections – hoses, clamps, electrical connectors that may have been unplugged (like the MAP sensor or boost solenoid). Check for any tools left in the engine bay. Turn the ignition to the “ON” position (without cranking) and listen for the fuel pump prime. Verify that the boost gauge (if aftermarket) reads atmospheric pressure.

Post-Installation Checks and Leak Testing

Step 8: Pressure Test for Boost Leaks

Boost leaks are the most common issue after intercooler installations. A leak will cause poor throttle response, erratic boost, and potential engine damage. Use a boost leak tester (available at most auto parts stores) that connects to the turbo inlet or intercooler outlet. Pressurize the system to 10–15 psi and listen for hissing sounds. Typical leak points include:

  • Clamps not fully tightened
  • Silicone couplers not fully seated over the pipes
  • Blow-off valve gasket misaligned
  • Throttle body gasket (if disturbed during installation)

If any leaks are detected, depressurize, adjust the connection, and re-test. It is better to fix leaks now than after starting the engine.

Step 9: Start Engine and Monitor

Start the engine and let it idle. Listen for any unusual whistling or hissing that may indicate a leak at idle. Check all hose connections with your hand (carefully – components may be hot) to feel for air escaping. Watch the temperature gauge to ensure normal warm-up. If the car has a factory IAT sensor, you can monitor intake air temperature via an OBD2 scanner – a properly functioning intercooler should show IATs dropping after a brief drive compared to pre-installation temperatures.

Take a short test drive, keeping the engine speed below 4,000 rpm for the first few miles. Apply moderate throttle to build boost – observe whether peak boost is reached smoothly. The ECU may need a few drive cycles to adapt if the intercooler changes the charge air density significantly. If you have an aftermarket boost controller or tune, may need recalibration.

Step 10: Final Inspection and Ventilation Check

After the test drive, park the car and visually inspect the intercooler and piping for any signs of rubbing, heat damage, or oil weeping. Re-torque the clamps if necessary (the silicone can settle after heat cycles). Check the intercooler core for any rock damage or debris impact. Ensure that the rear undertray or plastic ducting is properly reinstalled – it directs air over the intercooler and onto the brakes.

Performance Gains and Tuning Considerations

With the Greddy Trust intercooler installed, you can expect measurable performance improvements. On a stock MR2 turbo (2.0L 3S-GTE), the intercooler alone may yield 10–15 horsepower at the wheels due to reduced pressure drop and cooler charge air. When combined with a free-flowing exhaust, intake, and a boost controller (set to 14–16 psi), gains of 30–50 horsepower are realistic. For MR2 owners with upgraded turbochargers (such as a CT20b or precision 5558), the Greddy Trust intercooler is a necessary upgrade to keep IATs in check.

However, the intercooler upgrade alone does not require a tune; the factory ECU will compensate automatically to a degree. To fully exploit the performance potential, a standalone ECU or a piggyback fuel controller (like a Power FC or A’PEXi S-AFC) should be used to adjust fuel and ignition maps. High IAT reduction can also allow for more advanced timing, but always monitor knock via a knock gauge or detonation detection.

Maintenance Tips for Your Greddy Trust Intercooler

To ensure long life and consistent performance:

  • Clean the Core Regularly: Every 6–12 months, clean the front of the intercooler with a soft brush and water to remove accumulated oil, bugs, and debris. Avoid using high-pressure washers directly on the fins, as they can bend and reduce airflow.
  • Inspect Hoses and Clamps: Silicone hoses can harden over time. Check for cracks, especially near the turbo side. Replace T-bolt clamps if they show corrosion.
  • Monitor IATs: If your MR2 is equipped with a data logging system, watch for signs of heat soak after consecutive hard pulls. The Greddy Trust core is highly efficient, but ducting seals must remain intact.
  • Check Mounting Bolts: Vibration can loosen bolts. Torque check annually, especially after track days.

Common Issues and Troubleshooting

  • Boost Creep or Overboost: If the wastegate actuator hose was disconnected during intercooler removal, ensure it is properly routed and not kinked. Sometimes the new intercooler alters flow dynamics, requiring a boost controller adjustment.
  • Engine Stalling or Rough Idle: A post-intercooler leak can cause vacuum/boost leaks. Re-check all connections. Also ensure the MAF sensor (if equipped) is clean and not disturbed.
  • Intercooler Hits Bumper Beam: Some early MR2s have a different bumper support. If clearance is tight, you may need to trim the plastic bumper support slightly (not the beam). The Greddy Trust kit is designed for JDM and USDM MR2s, but aftermarket bumpers can cause interference.
  • Oil Leak from Turbo: If oil is present in the intercooler piping, your turbo seals may be failing. This is unrelated to the intercooler installation but can be discovered during the process. Address it immediately.

External Resources and Further Reading

For detailed specifications and official support, visit the Greddy Performance Products website. The MR2 community is also an invaluable resource: check out the MR2 Owners Club Forum for member installations and tuning advice. If you’re considering a complete turbo upgrade, Garrett Motion provides technical data for matching turbos to intercooler flow capacity. For tuning software, Link ECU offers solutions commonly used in MR2 builds.

Conclusion

Installing a Greddy Trust intercooler on your Toyota MR2 is a straightforward yet highly rewarding upgrade. By following this step-by-step guide, you’ve ensured a proper fitment that maximizes airflow, minimizes intake temperatures, and boosts engine performance. The key to success lies in careful preparation, secure hose connections, and a thorough boost leak test. With the intercooler in place, your MR2 will respond more eagerly to throttle inputs, handle sustained boost without pulling timing, and provide a safer, more powerful driving experience. Whether you’re building for track days or weekend spirited drives, the Greddy Trust intercooler is a proven component that will serve your MR2 well for years to come.