Tools, Materials, and Safety Preparations

A BorgWarner air-to-water intercooler upgrade on a Nissan GT-R (R35) is one of the most effective cooling modifications for high-horsepower builds. Unlike the factory integrated air-to-air system, the BorgWarner unit introduces a dedicated water-to-air charge cooler that dramatically reduces intake air temperatures (IATs) and supports sustained boost pressure. This guide provides a comprehensive, step-by-step installation process covering every detail from front bumper removal to final system bleeding.

Before starting, gather the following tools and consumables:

  • Complete BorgWarner air-to-water intercooler kit (including cooler core, water pump, reservoir, heat exchanger, hoses, clamps, and mounting brackets)
  • Metric socket set (10mm, 12mm, 14mm, 17mm, 19mm)
  • Torx bits (T25, T30) for underbody panels and trim
  • Torque wrench (range 10–80 N·m)
  • Pliers for hose clamps
  • Trim removal tools
  • Jack and jack stands or lift
  • Coolant extraction tool (optional but recommended)
  • Fresh engine coolant (Nissan Genuine Long Life or equivalent)
  • Distilled water (if mixing coolant)
  • Shop towels, drain pan, safety glasses, and mechanic’s gloves
  • Drill with step bits if accessory bracket modification is required

Work in a well-ventilated area. The GT-R uses a very full engine bay; careful disassembly and labeling of hoses and fasteners will save time during reassembly.

Disconnecting the Factory Charge Air Cooler System

Step 1: Battery Disconnection and Vehicle Lift

Disconnect the negative battery terminal and secure it away from the post. Raise the front of the vehicle with a jack and support it on jack stands. Remove the front under-engine cover (approximately 12 Torx screws). This exposes the lower charge air cooler piping and the factory intercooler drain plug.

Step 2: Remove the Front Bumper Assembly

The GT-R’s front bumper covers the heat exchanger and intercooler. Remove the upper radiator grille (four clips and two push pins). Then unfasten the bumper cover bolts located at the wheel wells (two per side, 10mm), the upper tie-bar bolts (four 10mm), and the lower bumper bolts (six 10mm). Carefully pull the bumper forward, disconnect the side marker and fog light harnesses, and set the bumper aside on a clean blanket.

Step 3: Drain Coolant and Remove Factory Charge Cooler

Place a drain pan under the engine. Open the lower radiator drain plug (typically 10mm plug on the driver side of the radiator). Next, locate the factory charge cooler drain plug on the lower charge cooler pipe (14mm hex). Drain approximately 2 liters of coolant. Once drained, disconnect the two coolant hoses from the factory charge cooler core. The core sits between the throttle bodies and the upper radiator support. Unbolt the core from its bracket (four 12mm bolts) and remove it. The factory charge cooler system is separate from the engine cooling system; however, the two circuits share the same expansion tank in stock form. The BorgWarner kit typically includes a dedicated water pump and a separate reservoir, so the factory charge cooler components will be removed entirely.

Step 4: Remove the Factory Charge Cooler Pump and Plumbing

On pre-2017 models, the factory charge cooler pump is located near the passenger side fog light area. Unbolt the pump, disconnect its two-pin connector, and loosen the hose clamps to free the hoses. Remove the factory heat exchanger mounted in front of the radiator (frame). For 2017+ models, the heat exchanger is integrated into the condenser stack; the BorgWarner kit will supplement it with a larger aftermarket unit. In either case, remove the factory hoses and any brackets that will interfere with the new system.

Installing the BorgWarner Air-to-Water Intercooler Core

Step 1: Test Fit the Core

The BorgWarner intercooler core is a bar-and-plate design with integrated inlet/outlet ports for the coolant and charge air. Place the core into the stock location, aligning the mounting tabs with the brackets on the radiator support. The core should sit flush. If there is interference with the hood latch or upper radiator hose, adjust the bracket position using the slotted holes provided. BorgWarner kits usually include stainless steel brackets that replace the factory units. Tighten the bolts to 25 N·m (18 ft·lb) per the manufacturer specification.

Step 2: Connect Charge Air Piping

Use the supplied silicone hoses and T-bolt clamps. The inlet hose (from the turbo compressor outlet) connects to the lower passenger-side port of the intercooler core. The outlet hose (to the throttle bodies) connects to the upper driver-side port. Ensure all bends are smooth and not kinked. Tighten clamps to 5–6 N·m (just past snug); overtightening can strip the liner. Apply a small amount of soapy water to the hose ends to ease assembly.

Step 3: Secure the Heat Exchanger

The water-to-air system requires a front-mounted heat exchanger to reject heat from the coolant. Mount the supplied heat exchanger in front of the radiator using the provided brackets. Position it as high as possible to avoid contact with the intercooler drain plug or lower bumper reinforcement. Use foam tape or rubber isolators to prevent metal-on-metal vibration. The heat exchanger should be oriented so that its inlet and outlet ports face toward the driver side for easier hose routing.

Plumbing the Cooling Circuit

Step 1: Install the Water Pump and Reservoir

The BorgWarner kit includes a high-flow electric water pump. Mount the pump near the passenger side frame rail using the supplied bracket. Ensure the pump is below the highest point of the coolant loop (heat exchanger outlet). The separate expansion tank (reservoir) should be mounted on the inner fender well or the firewall, using the provided bracket. Route the power wires to a constant 12V source (e.g., through a relay triggered by the engine start signal). The pump must run continuously when the engine is running; many installs tap into the MAF sensor power or use a dedicated ignition-switched circuit. Refer to the kit’s wiring diagram; a fused 20-amp supply is typical.

Step 2: Route Coolant Hoses

Use the black silicone hoses provided. The circuit flows as follows: Heat exchanger outlet → pump inlet → pump outlet → intercooler core inlet → intercooler core outlet → reservoir → heat exchanger inlet. Keep hose lengths as short as possible to reduce restriction. Use zip ties to secure hoses away from moving parts (fan blades, belts, steering shaft). At the heat exchanger, orient the bleed port (if equipped) to the highest point to facilitate air removal. Clamp all connections with constant-tension wire clamps for reliability.

Step 3: Fill and Bleed the Coolant System

Mix coolant with distilled water at a 50/50 ratio (or follow BorgWarner’s recommendation). Fill the reservoir to the “full” mark. Start the engine and let it idle. Open the bleed valve on the heat exchanger (or the highest point in the line) until a steady stream of coolant without bubbles emerges, then close it. Rev the engine gently to 2,000–2,500 RPM to help purge air pockets. Stop the engine and top off the reservoir. Repeat the process two or three times until no more air is expelled. Check for leaks at every hose joint.

Reassembly and Final Checks

Step 1: Reinstall the Front Bumper

Before refitting the bumper, verify that all hoses and electrical wires are clear of the bumper mounting area. Reconnect the fog light and side marker connectors. Lift the bumper into position and secure it with the bolts and push pins. Reinstall the upper grille.

Step 2: Reconnect Battery and Test Systems

Reconnect the negative battery terminal. Start the engine and listen for the water pump operation (a faint whirring from the passenger side). Using an OBD-II scanner, monitor intake air temperature (IAT) sensor values. At idle, IAT should not rise excessively. After a brief drive (5–10 minutes at moderate load), IAT should be noticeably lower than with the stock system. Stop and inspect for leaks once more.

Step 3: Torque All Fasteners

After a heat cycle (engine fully warm then cool), retorque the intercooler core mounting bolts to 25 N·m and all charge pipe T-bolt clamps. Check the water pump bracket bolts (10–12 N·m). Reinstall the under-engine cover and ensure it does not rub against any new hoses.

Performance Verification and Tuning Considerations

With the BorgWarner air-to-water system in place, you can expect a significant drop in IATs—often 20–30°F (11–17°C) lower than the factory setup under repeated boost runs. This allows for more aggressive timing and less knock retard. However, to fully capitalize on the improved cooling, a professional ECU tune is strongly recommended. The reduced IAT can cause the factory knock sensors to not pull timing as aggressively, but the ECU may need recalibration to adjust fuel trims and boost targets. Contact a reputable GT-R tuner (such as AMP Tuning or COBB Tuning) for a custom calibration.

Monitor the water pump operation periodically. Some BorgWarner kits include a flow indicator window; if not, check the reservoir level every oil change. The system should remain leak-free. For high-horsepower builds (above 700 WHP), consider upgrading to a larger heat exchanger or adding a secondary inline pump. BorgWarner offers a full line of performance cooling components; consult their official documentation for specific flow rate and pressure ratings.

This installation transforms the GT-R’s thermal management, making the car far more consistent on track or during high-speed pulls. A successful install requires patience, clean workmanship, and attention to bleeding. The result is a cooler, more responsive engine that can safely handle increased boost levels.

For additional community insight, the GT-R Life forum has dedicated threads on BorgWarner intercooler installations and troubleshooting. Cross-reference your specific year and modifications before finalizing the tune.