JZ Upper Water Neck with Swirl Pot

The ultimate cooling upgrade for street, drift, and high-power JZ builds.

Stop fighting trapped air, unstable temps, ugly plumbing, and cramped swap bays.
Our Boost House JZ Upper Water Neck combines CFD-engineered cooling tech with swap-friendly packaging to fix the cooling issues JZ engines are known for.

Key Benefits include

🌀 CFD-Engineered Integrated Swirl Pot 

• High-velocity internal swirl rapidly separates air from coolant.
• Eliminates steam pockets in the back of the head.
• More stable coolant temps under hard driving and long pulls.

❌ Thermostat Bypass Block-Off — Thermostat Delete Recommended

Our design blocks the OEM thermostat bypass port, which forces all coolant through the radiator instead of recirculating directly back into the pump.

➡️ This setup is designed to be used with a thermostat delete.
Using the bypass block-off with a closed thermostat can cause overheating because coolant cannot recirculate during warm-up.

Street Car Options:
We offer two ways to retain controlled bypass flow for street-driven cars:

1. Use the built-in calibrated bleed option:
   The underside of the block-off includes a dimpled pilot hole.
   You can fully drill this through to create a small, controlled bypass orifice.
2. Drill the thermostat itself:
   Use our included drill template to add a precise bleed hole through the thermostat.
   This maintains some warm-up flow while keeping temperatures stable.

💧 +0.35L Extra Coolant Capacity

• Adds ~350 mL to the cooling system.
• More thermal mass = more stability during drift, track, or high-boost pulls.

🔧 Built for Single Turbo Conversions

• Integrated single turbo coolant outlet.
• No more blocking unused twin-turbo ports.
• Cleaner and more reliable coolant routing.

🔻 Low-Profile, Swap-Friendly Design

• Clears tight S-chassis, E36/46, and other transplant bays.
• Perfect for JZ swaps with minimal bonnet clearance.
• No bonnet spacing, cutting, or bracing modifications required.

🧰 Cleaner Bay + Fewer Leak Points

• Integrates the swirl pot, neck, and turbo feed into one compact housing.
• Eliminates tees, adapters, multiple hoses, and messy aftermarket plumbing.
• Reduced leak points and a far more professional look.

🏁 Track-Proven Cooling Stability

• Swirl pot sits at the highest point for effortless bleeding.
• Maintains coolant integrity under high G-forces and rapid temperature swings.
• Ideal for drift, time attack, drag, and high-power street builds.