Introduction: Why Upgrade to an Air-to-Water Intercooler?

When you’re chasing higher horsepower or simply want to keep your forced-induction engine running at its peak, the intercooler is a critical component. Stock intercoolers—especially on many turbocharged vehicles—are often designed for average driving conditions and can become a bottleneck under sustained boost. The APS (Advanced Performance Systems) Air to Water Intercooler System offers a significant upgrade by replacing the factory air-to-air setup with a more efficient water-cooled design.

Air-to-water intercoolers use a liquid medium (typically a water/glycol mix) to absorb heat from the compressed intake air, then transfer that heat to a separate radiator. This allows for much shorter intake piping, faster heat dissipation, and more consistent charge air temperatures—especially important for street-driven cars that encounter stop-and-go traffic. In this expanded guide, we’ll walk through every detail of the installation, from gathering the right tools to fine-tuning the system for maximum performance.

How an Air-to-Water Intercooler Works

Before diving into the installation, it helps to understand the physics at play. A traditional air-to-air intercooler relies on ambient airflow passing through its core to cool the hot compressed air from the turbo or supercharger. While effective at highway speeds, it struggles at low speeds or during sustained pulls. An air-to-water system, by contrast, uses a separate water circuit:

  • Hot compressed air flows through a small core inside the intercooler.
  • Coolant (water mixed with antifreeze) circulates through the core, absorbing heat.
  • The heated coolant is pumped to a front-mounted heat exchanger (radiator) where it releases heat into the atmosphere.
  • The cooled liquid returns to the intercooler to start the cycle again.

This closed-loop system offers two major advantages: extremely short intake piping (reducing turbo lag) and the ability to maintain low intake temperatures even when the car is stationary. For a deeper dive into the thermodynamics, Wikipedia’s intercooler article is an excellent resource.

Tools and Materials Needed

Having everything ready before you start will save you hours of frustration. The APS kit typically includes the intercooler core, water reservoir, pump, hoses, clamps, and mounting brackets. Beyond the kit, you’ll need:

  • Full socket set (metric and standard, depending on your vehicle)
  • Combination wrenches (10mm through 19mm)
  • Screwdrivers (flathead and Phillips)
  • Drill with assorted bits (if you need to make mounting holes)
  • Hose cutters or a sharp utility knife
  • Torque wrench (for critical fasteners)
  • Catch pan for old coolant
  • Distilled water and appropriate coolant (e.g., 50/50 mix)
  • Safety goggles and mechanic’s gloves
  • Jack and jack stands (if needed for access)
  • Shop rags and a drip tray

We also recommend having a helper available for lifting and positioning the intercooler system.

Preparation: Getting the Vehicle Ready

Begin by parking your car on a level, well-ventilated surface. If the engine is hot, allow it to cool completely—coolant can be scalding and the turbocharger can cause burns. Disconnecting the battery is a crucial safety step, but we’ll handle that in detail below.

Step 0: Safe Disconnection of the Battery

Use a 10mm wrench to loosen the negative (black) terminal nut. Slide the terminal off the battery post and tuck it away so it cannot accidentally touch the post. This eliminates the risk of short circuits while you work near sensors, fuel lines, or starter wiring.

Removing the Factory Intercooler System

Most vehicles have an air-to-air intercooler mounted at the front of the engine bay or behind the front bumper. The removal process varies, but the following steps cover a typical setup.

Step 1: Drain the Coolant (if applicable)

If the factory intercooler is part of the engine’s cooling system (rare) or if you’re also draining the radiator for other work, place a catch pan under the radiator petcock and open it. For most turbocharged cars, the intercooler is a separate unit with no internal coolant—so skip this unless your vehicle uses a water-cooled charge air cooler system.

Step 2: Remove Bumper and Grille (if necessary)

Many modern cars require removing the front bumper cover to access the intercooler. This usually involves popping push-clips, removing bolts from the wheel wells, and disconnecting any fog light wiring. Set the bumper aside carefully to avoid scratching it.

Step 3: Unbolt and Extract the Stock Intercooler

With the bumper removed, you’ll see the factory intercooler mounted between the condenser and radiator. Using a socket and ratchet, remove the bolts holding the intercooler brackets. Disconnect the two silicone couplers (inlet and outlet) by loosening the worm-gear clamps. Pull the intercooler straight out. Be prepared for some residual oil or debris to drip out—keep rags handy.

If your vehicle has an intercooler under the hood (e.g., some Subaru models), the process is similar but requires removing the intake manifold or other components. Consult your vehicle’s service manual for specifics.

Installing the APS Air-to-Water Intercooler Core

Now the real transformation begins. The APS core is compact and designed to fit in place of the factory unit with minimal modification. However, because an air-to-water core is shorter in length (airflow path) than an air-to-air core, you may need to fabricate new brackets or use provided adapters.

Step 4: Position and Mount the Core

Remove the APS core from its packaging. Compare its dimensions to the factory location. In many cases, the core will bolt directly into the factory intercooler mounts if the kit is vehicle-specific. If not, you’ll need to drill new holes in the core support or use the included bracket set. Use a level to ensure the core is square; misalignment can stress the hoses and cause leaks.

Once positioned, tighten all mounting bolts to the torque spec provided in the APS instructions (typically 8-12 ft-lbs). Double-check that the core does not contact any moving parts, such as the radiator fan or pullies.

Step 5: Install the Water Pump and Reservoir

The APS system includes an electric water pump to circulate coolant through the intercooler core and the front heat exchanger. Choose a location for the pump that is low in the engine bay (below the coolant level in the reservoir) to ensure proper priming. Many installers mount it on the chassis rail or near the radiator. Use rubber isolators to reduce noise transmission.

The reservoir (expansion tank) should be mounted as high as possible—usually against the firewall or on a strut tower—so that air bubbles naturally rise to the top. Secure it with the supplied brackets or zip ties.

Step 6: Run the Coolant Hoses

Now route the silicone hoses from the intercooler core to the pump, from the pump to the front heat exchanger, and from the heat exchanger back to the reservoir. Use the shortest path possible, avoiding sharp bends or rubbing against sharp edges. If a hose passes near exhaust manifolds or turbo housings, use heat sleeve protection.

Cut hoses to length if needed, then secure each connection with two worm-gear clamps per end. Do not overtighten—hand-tight plus a quarter turn is usually sufficient to seal without damaging the hose.

Installing the Front-Mounted Heat Exchanger

The heat exchanger (also called the secondary radiator) is the part that releases heat to the atmosphere. It should be mounted in front of the engine’s main radiator, in the path of incoming air.

Step 7: Mount the Heat Exchanger

Remove the front grille or lower bumper cover if you haven’t already. Position the heat exchanger in the available space—often just behind the bumper. Use the supplied brackets or fabricate mounting tabs. Ensure a minimum of 1/2 inch clearance between the heat exchanger and the main radiator to allow for airflow. Secure it tightly.

Step 8: Connect Coolant Lines to the Heat Exchanger

Attach the two remaining hoses: one from the pump outlet to the heat exchanger inlet, and one from the heat exchanger outlet back to the reservoir. Again, use clamps and check for clearance. If your kit includes a separate bleeder port, install the bleeder valve at the highest point of the heat exchanger to release trapped air later.

Filling and Bleeding the System

With all components installed, it’s time to add coolant and remove air pockets. Air in the system reduces cooling efficiency and can cause the pump to cavitate prematurely.

Step 9: Fill with Coolant

Use a 50/50 mix of distilled water and ethylene-glycol antifreeze (or a specific waterless coolant if preferred). Pour slowly into the reservoir until the level reaches the “full” mark. Do not install the cap yet.

Step 10: Bleed the System

With the reservoir cap off, start the vehicle and turn on the water pump (some APS kits have a manual switch, others are triggered by the ignition). As the pump runs, coolant will circulate and air will bubble up into the reservoir. Top off the reservoir as needed. If your heat exchanger has a bleeder screw, open it until coolant flows steadily, then close it. This process may take 5-10 minutes. Once no more bubbles appear, install the reservoir cap securely.

Final Electrical and Mechanical Checks

Step 11: Reconnect the Battery

Reattach the negative battery terminal and tighten. Check that any other electrical connections (pump wiring, fans) are secure.

Step 12: Inspect for Leaks

With the engine at idle, look at every hose connection, clamp, and the pump itself. Feel for dampness or drips. Slight seepage can be fixed by tightening clamps. If a hose is too loose, replace it with a properly fitting one.

Step 13: Test Drive and Monitor

Take the vehicle for a short drive (10–15 minutes) with varying throttle. Keep an eye on the temperature gauge—if your vehicle has a digital readout for intake air temperature (IAT), you should see a noticeable drop compared to the old air-to-air system. After the drive, park and recheck coolant level and any loose hardware. Listen for unusual pump noise; a quiet hum is normal.

Troubleshooting Common Issues

Even a well-planned installation can hit snags. Here are frequent pitfalls and their fixes:

  • Low coolant flow / no flow: Check that the pump is receiving 12V and is correctly grounded. Air pockets can also block flow—re-bleed the system.
  • Hose rubbing: Use nylon cable ties to secure hoses away from belts and pulleys. Add heat shield wrap if near exhaust.
  • Overheating in traffic: The heat exchanger may need a dedicated electric fan. Consider adding a small Spal or similar fan wired to a temp switch.
  • Whining noise from pump: Usually indicates cavitation due to low coolant level. Top off and bleed again.
  • Intermittent IAT spikes: The reservoir may be too small for sustained WOT runs. Upgrade to a larger auxiliary tank if needed.

For more details on diagnosing cooling system issues, Engine Builder Magazine’s article on air-to-water intercooler tech offers professional insights.

Performance Benefits You Can Expect

After a proper installation, the gains are tangible. Most users report a 15–30°F drop in intake air temperatures compared to factory air-to-air intercoolers, even on hot days. This directly translates to:

  • More consistent power during repeated pulls (less heat soak)
  • Slightly reduced turbo lag due to shorter piping
  • Ability to run higher boost safely (assuming fuel system can support)
  • Lower risk of detonation and pre-ignition

If you’re planning to tune your engine for more power, the APS air-to-water intercooler is an excellent foundation. For further reading on how intercooling affects combustion, check out TuningBlog’s advantages of air-to-water intercooling.

Maintenance Tips for Longevity

An air-to-water system requires periodic attention that a stock air-to-air setup does not:

  • Check coolant level monthly – Especially after the first few heat cycles, as the system settles.
  • Replace coolant every 2 years – Or per the coolant manufacturer’s recommendation. Distilled water mixed with corrosion inhibitor is ideal.
  • Inspect hoses and clamps annually – Look for cracks, swelling, or loose clamps. Silicone hoses can degrade under constant heat.
  • Listen for pump noise changes – A grinding or rattling pump may need replacement.

If you notice performance dropping over time, clean the heat exchanger core with a gentle soap and water to remove dirt and bugs that block airflow.

Conclusion: A Worthwhile Upgrade for Enthusiasts

Installing the APS Air to Water Intercooler System is a hands-on project that delivers meaningful performance improvements. While the initial installation demands patience and attention to detail—especially when bleeding the coolant loop and routing hoses—the result is a cooling system that outperforms factory setups in nearly every driving condition.

Whether you’re building a track-day special or a daily driver that can handle stage 2 tuning, this upgrade ensures your engine breathes cooler, denser air. Follow the steps above, take your time, and don’t hesitate to consult resources like APS Performance’s official site for vehicle-specific notes. Your car—and your right foot—will thank you.