The Stock Fan System: A Bottleneck for the VQ35DE

The Nissan 350Z, powered by the VQ35DE engine, is a formidable sports car that earned its reputation for balanced performance and a thrilling powerband. However, like any highly engineered machine, it has specific weak points that become apparent under sustained high-performance driving or in hot climates. The factory engine cooling system, specifically the mechanical engine-driven fan, is one of those bottlenecks that leaves performance on the table.

The stock setup uses a viscous clutch fan. While this design is simple and generally reliable, it introduces significant parasitic drag on the engine. The heavy clutch assembly and plastic fan blades spin constantly, robbing the crankshaft of power that could otherwise go to the wheels. This drag is most noticeable during acceleration and high-rpm driving. Beyond the power loss, the mechanical fan struggles to move sufficient air at idle or low speeds, especially when the air conditioning is running. This leads to elevated coolant temperatures in stop-and-go traffic, a common complaint among 350Z owners. The weight of the entire assembly, located directly on the water pump, also places unnecessary stress on the water pump bearings.

Heat soak is another critical issue amplified by the stock fan. When the engine is shut off after a hard run, the mechanical fan stops immediately. Without active airflow, the engine bay acts like an oven, soaking components in residual heat. This can make hot restart performance sluggish and increase under-hood temperatures to levels that degrade hoses and electrical connectors prematurely. For these reasons, switching to an efficient, purpose-designed electric fan system is one of the most impactful upgrades a 350Z owner can make.

Why Griffin? A Purpose-Built Solution

When it comes to aftermarket cooling solutions, Griffin Thermal Products has a long-standing reputation for quality and performance, with roots deep in motorsports. Their electric fan conversion kits for the Nissan 350Z are not one-size-fits-all universal fans. Instead, they are engineered to fit the specific contours and dimensions of the 350Z’s radiator core, maximizing surface area coverage and airflow efficiency.

A standard universal fan typically lacks a proper sealed shroud. Without a shroud, the fan is inefficient because it can only pull air through the section of the radiator it directly covers, leaving the rest of the core unused. Griffin kits come with a fully ducted shroud that seals against the radiator, forcing air to be pulled evenly across the entire cooling surface. This design is critical for achieving consistent cooling at low speeds and during idle.

Griffin offers both single and dual fan configurations for the 350Z. The dual fan setup is the more popular choice for performance applications, as it provides a higher total airflow volume (measured in CFM) and offers redundancy—if one fan fails, the other can provide enough cooling to prevent an immediate overheat. The motors used in Griffin fans are high-torque, sealed units designed to withstand the harsh under-hood environment. For any 350Z owner looking for a “set it and forget it” cooling solution, a Griffin kit represents a substantial upgrade over both the stock clutch fan and generic aftermarket alternatives.

Cost of the Conversion: DIY vs. Professional Installation

The total financial outlay for a Griffin electric fan conversion can vary significantly based on the specific kit chosen, the quality of supporting components, and whether you perform the labor yourself. It is essential to budget not just for the fan kit, but for the electrical components required to wire it correctly.

Component Cost Breakdown

  • Griffin Electric Fan Kit (Dual 12-inch setup): $400 – $600. This includes the fans, high-quality shroud, and basic mounting hardware.
  • Fan Controller or Thermostatic Switch Kit: $50 – $200. Options range from simple adjustable thermostatic switches that splice into the upper radiator hose to fully programmable electronic control modules (ECMs) that manage fan speed based on coolant temperature.
  • Wiring Harness, Relays, and Fuse Holder: $40 – $100. Do not use the cheap, pre-wired universal harnesses from auto parts stores. Invest in a proper 40-amp relay for each fan, a weatherproof fuse holder, and quality automotive-grade wire (10-12 AWG).
  • Miscellaneous Hardware and Connectors: $20 – $40. This includes heat shrink tubing, solderless connectors, wire loom, zip ties, and mounting brackets for the relays.
  • Coolant and Coolant Additives: $20 – $40. You will need to drain and refill the cooling system. Use Nissan OEM (blue) coolant or an equivalent high-quality ethylene glycol coolant.
  • Labor (Optional): $300 – $600. Many reputable performance shops will charge 4-6 hours of labor for this installation, which involves draining the coolant, removing the front bumper or radiator support for access, fabricating wiring, and testing the system.

Total Estimated Investment

For a DIY installation using a quality controller, you can expect to spend between $500 and $850. If you opt for professional installation, the total cost can range from $800 to $1,400. While this may seem significant compared to a $50 universal fan, the Griffin system provides reliability and performance that far exceeds budget alternatives. The improved throttle response and engine protection quickly justify the cost for a 350Z that sees regular spirited driving or track time.

Installation Deep Dive

Installing a Griffin electric fan conversion is a weekend project for a competent DIY mechanic. The stock fan system must be completely removed, and the new electrical system must be integrated cleanly and safely. A sloppy wiring job can lead to electrical fires or fan failure at the worst possible moment.

Tools and Materials Required

  • Socket and ratchet set (metric, 10mm-14mm)
  • Flathead and Phillips screwdrivers
  • Pliers (standard and needle-nose)
  • Wire cutters/strippers
  • Soldering iron and solder (or high-quality crimp connectors)
  • Heat gun (for heat shrink tubing)
  • Multimeter (essential for testing circuits)
  • Jack and jack stands (or ramps)
  • Drain pan for coolant

Step 1: Disconnect Battery and Drain Coolant

Safety first. Disconnect the negative terminal of the battery. With the engine cold, remove the radiator cap and open the radiator drain plug located on the lower passenger side. Drain the coolant into a suitable container for proper disposal or recycling.

Step 2: Remove the Stock Mechanical Fan and Shroud

Remove the factory fan shroud by unscrewing the retaining bolts. The clutch fan assembly is often held on by a large nut. Using a wrench, loosen this nut while holding the water pump pulley stationary. Lift the entire assembly out of the engine bay. This alone clears up significant space and removes approximately 5-7 pounds of rotating weight from the front of the engine.

Step 3: Install the Griffin Fan Shroud

Position the Griffin fan shroud against the back of the radiator. The kit is designed to fit between the radiator and the engine using the factory mounting points or provided brackets. Ensure the shroud sits flush against the radiator core to prevent air bypass. Secure the shroud using the included hardware. Ensure the fan blades have adequate clearance from the water pump pulley and engine accessories.

Step 4: Wiring the Electrical System (The Critical Phase)

This is where the quality of your installation will be determined. Each Griffin fan should be controlled by a dedicated 40-amp relay. The heavy power wire (10 AWG) should run from the battery positive terminal through a circuit breaker or fuse (50-60 amp total) to the relay common contacts. The fan motors connect to the normally open contacts of the relays.

The relays are triggered by a low-current signal from the fan controller or thermostatic switch. This switch should be installed in the upper radiator hose using a hose splice adapter or in a welded bung on the thermostat housing. Set the controller to turn the fans on at approximately 195-200°F and off at 180-185°F.

Wiring Best Practices:

  • Use a standard automotive relay wiring diagram to ensure correct pin placement.
  • Mount the relays and fuse block in a dry location, such as the passenger side strut tower area or the factory fuse box area.
  • Use heat shrink tubing on all connections to prevent corrosion.
  • Wrap the entire harness in high-temperature split loom tubing to protect it from engine bay heat.
  • Install a manual override switch inside the cabin. This allows you to turn the fans on manually, which is helpful for cooling down the engine before shutoff or in heavy traffic.

Step 5: Refill and Bleed the Cooling System

Reconnect the negative battery terminal. Refill the system with a 50/50 mix of Nissan blue coolant and distilled water. Bleed the air from the system by running the engine with the radiator cap off and the heater set to full hot. Squeeze the upper radiator hose to help burp air pockets. Top off the coolant as needed.

Step 6: Test the System

Start the engine and allow it to reach operating temperature. Watch the temperature gauge. The thermostatic switch should engage the fans when the engine reaches the specified temperature. Check for proper airflow direction (pulling air through the radiator toward the engine). Cycle the air conditioning to ensure the fans engage correctly when the AC compressor is running.

Choosing the Right Fan Controller

The controller is the brain of your electric fan system. The simplest option is a probe-style thermostatic switch that inserts into the radiator fins. While effective, these can be inaccurate because they measure fin temperature rather than coolant temperature directly.

A superior option is an inline hose adapter with a threaded bung for a temperature sender. This provides a direct coolant temperature reading. Adjustable controllers allow you to set the exact on/off temperatures. For the 350Z, setting the fans to activate at lower temperatures (190°F) helps maintain consistent power output and prevents the heat soak that plagues the stock system.

For the ultimate in control, consider a Dakota Digital or equivalent PWM fan controller. These units vary the fan speed based on coolant temperature, which reduces electrical load and noise while providing precise thermal management. They also include a built-in AC trigger and a manual override wire.

Verifiable Results: Before and After

Data logging and driver feedback confirm the effectiveness of this conversion. Under identical conditions (80°F ambient, stop-and-go traffic), a stock 350Z may see coolant temperatures climb to 220-230°F, with the mechanical fan struggling to bring it down. With a properly ducted Griffin dual fan setup, temperatures typically stabilize between 190-200°F, even with the AC running.

On a road course, the benefits are even more pronounced. The electric fans provide immediate airflow when exiting a corner, whereas the mechanical fan’s clutch sometimes remains disengaged, delaying cooling. This immediate response keeps cylinder head temperatures in a safer range, reducing the risk of detonation and allowing the ECU to maintain optimal ignition timing.

The reduction in rotating mass is noticeable. Removing the heavy clutch fan assembly allows the engine to rev more freely. This is not a dyno queen upgrade, but a real-world driver experience improvement that makes the car feel livelier. Throttle response sharpens, and the engine note becomes cleaner without the constant roar of the mechanical fan.

Maintaining Your Electric Fan Setup

An electric fan system requires minimal maintenance compared to a mechanical clutch fan, but it is not a “fit and forget” installation. Checking the system monthly can prevent a roadside failure.

  • Visual Inspection: Look for frayed wires, loose connections, or debris lodged in the fan blades. Clean the radiator and condenser fins annually to ensure maximum airflow.
  • Functional Test: Turn on the AC and visually confirm both fans engage. Use the manual override switch to test the relays and wiring.
  • Relay Maintenance: Relays are a common failure point. Keep a spare 40-amp relay in your glove box. If a fan stops working, swapping the relay is the simplest diagnostic step.
  • Thermostatic Switch: If you notice the fans are running constantly or not at all, check the coolant temperature reading at the switch. The sender may become coated in deposits over time and require cleaning or replacement.

The Final Verdict

The Griffin electric fan conversion is one of the smartest reliability and performance modifications available for the Nissan 350Z. It directly addresses the parasitic power loss and heat soak issues inherent to the factory mechanical fan. The result is a cooler-running engine that makes consistent power, a more responsive throttle, and a car that can handle traffic and track days with equal composure.

While the cost is higher than generic alternatives, the quality of the Griffin hardware and the importance of a proper electrical installation make this a worthwhile investment. If you are looking to maximize your VQ35DE’s potential and protect your engine from the stresses of heat, this conversion delivers proven, repeatable results. For more specific tuning advice and owner experiences, the My350Z.com community is an excellent resource for troubleshooting and build inspiration.