ISR Performance Thermostat - Nissan VQ35DE - 68 Degree

The ISR Performance 68°C Thermostat for the Nissan VQ35DE drops the coolant temperature opening point from the factory 78°C to a colder 68°C. Better margin against heat soak on high-performance VQ35DE builds, which is the kind of cheap insurance you want on a hard-driven 350Z or G35. This is the VQ35DE variant with the water port. the VQ35HR and VQ37VHR versions need a different thermostat (IS-21200-31U03, no water port).

What It Does

The factory thermostat opens at 78°C, which is fine for emissions-cycle warm-up but leaves you closer to overheating territory once the engine is making real power. Opening at 68°C means coolant starts flowing through the engine sooner once it warms up, holding lower steady-state temperatures and giving you more margin before the gauge starts climbing. Useful on track days, summer driving, and forced-induction VQ35DE builds.

Fitment

Nissan VQ35DE engines with water port only. Will NOT fit VQ35HR or VQ37VHR engines. those use the IS-21200-31U03 variant without the water port. Confirm your engine code before ordering.

Product Details

Brand: ISR Performance

Part Number: IS-21200-31U13

Type: Cooler-temp thermostat

Engine: Nissan VQ35DE (with water port)

Opening Temperature: 68°C (vs factory 78°C)

Excluded: VQ35HR, VQ37VHR (use IS-21200-31U03)

Application: High-performance VQ35DE builds, track use

Sold: Individually

Legality: Off-road and competition use only