Nissan Skyline GT-R Cooling System Guide: R32, R33, and R34 GT-R (2025 Master Reference)
Nissan Skyline GT-R Cooling System Guide: R32, R33, and R34 GT-R (2025 Master Reference)
Introduction
The cooling system in the Nissan Skyline GT-R (R32, R33, and R34) is often misunderstood and frequently modified incorrectly. Many people see a radiator as a standalone upgrade, but cooling systems are systems — radiator, fan, water pump, thermostat, ducting, oil cooler, intercooler, and tuning — all work together. This guide breaks down every component, from OEM parts to proper upgrades, to keep your GT-R running cool and reliable on street, track, or race.
Cooling System Basics
- Internal combustion engines waste ~65–80% of fuel energy as heat.
- Roughly half of that heat goes to exhaust; the other half into the coolant system.
- The radiator extracts that heat and dumps it into the atmosphere.
- You want the smallest radiator that can maintain safe operating temperatures.
Coolant Temperatures, Boiling Point & Pressure
- Pure water boils at 212°F (100°C) at 1 atm.
- Each 15 psi of system pressure raises boiling point by ~45°F.
- At 1.3 bar (18 psi), coolant boils at ~252°F (122°C).
- Higher pressure increases heat transfer but stresses the system.
OEM Radiators
| Chassis | OEM Radiator Type | Notes |
|---|---|---|
| R32 GT-R | Composite/plastic end tanks | 21460-04U01 |
| R33 GT-R | Composite/plastic end tanks | 21460-22U01 |
| R34 GT-R (early) | All-aluminum | 21460-AA301 |
| R34 GT-R (late 2000+) | Composite/plastic end tanks | 21460-AA301 |
Coolant Capacities
| Engine | Capacity |
|---|---|
| RB20/RB25 | ~9.0 liters |
| RB26DETT | ~9.2 liters |
Bleeding the Cooling System
RB26 has a 10mm bleeder bolt on the balance tube. Use caution when bleeding to avoid coolant spray and dropped hardware.
Coolant Temperature Sensors
| Type | Application | Part Number |
|---|---|---|
| ECU 2-Wire CTS | All RB engines | 22630-44B20 |
| 1-Wire Gauge Sender (R32) | Dash temp gauge | R32: 25080-89903 / |
| 1-Wire Gauge Sender (R33) | Dash temp gauge | R33: 25080-89907 |
| 1-Wire Gauge Sender (R34) | Dash temp gauge | [R34 Part Number] |
Aftermarket Radiators (Trusted Brands)
- Koyo: Excellent fitment, stock fan/shroud compatible.
- CSF: Billet end tanks, 42mm B-tube, highly efficient.
- C&R (PWR Group): Full motorsports spec.
- PWR (Australia): Motorsport proven.
- HPI (Japan): Popular JDM option.
- ARC: Beautiful but expensive.
- Nismo: OEM+ quality.
- Ron Davis: Custom radiators possible.
Radiator Caps
| Brand | Pressure | Notes |
|---|---|---|
| OEM R32 | 0.9 bar (13 psi) | 21430-4B700 |
| OEM Superceded | 88 kPa (12.7 psi) | 21430-7999C |
| OEM 300ZX | 1.2 bar (17.4 psi) | 21430-54P00 |
| Koyo | 1.3 bar (18 psi) | SK-C13 |
| Nismo | 1.3 bar (18 psi) | 21430-RS013 |
Thermostats
| Thermostat | Opening Temp | Part Numbers |
|---|---|---|
| OEM | 76.5°C (170°F) | 21200-42L0A |
| Stant OE Equivalent | 76.5°C | Stant 13947 |
| Stant SuperStat | 76.5°C | Stant 45947 |
Coolant Types
- Water: Best heat transfer, low boiling point.
- 50/50 Glycol: Street safe, higher boiling point.
- Water + Water Wetter: Track safe, best compromise.
- Softened Water: Reduces corrosion risk vs. distilled.
- Distilled Water: Can cause galvanic corrosion long-term.
- Waterless Coolants (Evans): Mixed real-world results.
Radiator Hoses
| Application | Upper Hose | Lower Hose |
|---|---|---|
| R32 GT-R | 21501-05U00 | 21503-72L00 |
| R33 GT-R | 21501-24U10 | 21503-72L00 |
| R34 GT-R | 21501-AA400 | [Lower PN] |
Fans & Fan Clutch
| Application | OEM Blade PN | Fan Clutch PN |
|---|---|---|
| R32 GT-R | 21060-55S01 | 21082-24U00 |
| R33 GT-R | 21060-75T01 | 21082-24U00 |
| R34 GT-R | 21060-5L300 | 21082-24U00 |
- Dayco 115847 clutch available from Australia (~$150 shipped).
- GK Tech fan flows ~40%(suspect) more than OEM (careful on engine movement).
Fan Shroud
Never remove the shroud unless absolutely necessary. It greatly improves low-speed airflow performance and prevents hot-spot recirculation.
Ducting & Airflow
- Airflow must pass through the radiator core, not around it.
- Use radiator panels to seal the airflow path from bumper to radiator face.
- Beta-CAE Ducting Study (Highly Recommended)
Water Pumps
| Pump | Flow Rate | Notes |
|---|---|---|
| OEM | 160 L/min | 21010-21U26 |
| N1 | 192 L/min | 21010-24U27 |
| Reimax | 221 L/min | High-flow race version |
- N1 requires block prep for upper bolt hole clearance.
- Reimax provides true high flow for serious track use.
Oil Cooler Impact
RB26 oil temperature management is critical due to high RPM heat loads. The stock oil-water exchanger helps stabilize oil temps but often needs supplemental external oil cooling for track applications.
Intercooler Impact on Radiator Efficiency
Large or overly thick intercoolers can create airflow blockages that reduce radiator efficiency. Proper ducting between intercooler and radiator is important to prevent overheating.
Tuning Effects
- Retarded ignition timing increases cooling system load.
- Anti-lag, launch control, and aggressive 2-step use rapidly load the cooling system.
- Track wisely and allow proper cool down periods after heavy use.
System Summary Chart
| Subsystem | Key Takeaway |
|---|---|
| Radiator | Don't oversize unless needed |
| Radiator Cap | Raise pressure carefully |
| Thermostat | Opening temp = not running temp |
| Coolant | Water cools best, glycol protects |
| Hoses | OEM fitment highly recommended |
| Fan/Shroud | Stock clutch fan is still best |
| Ducting | Sealed airflow = efficient cooling |
| Water Pump | N1 or Reimax for higher flow |
| Oil Cooler | Highly recommended for track |
| Intercooler | Proper ducting critical |
| Tuning | Timing affects cooling |
