ISR Performance Colder Thermostat: SR & KA

The ISR Performance Colder Thermostat is a lower-temperature replacement thermostat for the Nissan SR20DET and KA24DE engines. Opens at 60 degrees Celsius (140 degrees Fahrenheit) compared to the factory thermostat's 76.5 degrees Celsius (170 degrees Fahrenheit) opening temperature. A simple, low-cost cooling upgrade that gets the radiator into the loop earlier on high-output or hard-driven engines.

What It Does

Once an engine is fully warmed up, the thermostat is the gate that controls when coolant starts flowing through the radiator. A factory thermostat is set conservatively for emissions, fuel economy, and cabin heat performance, which means coolant temperatures climb higher than necessary before the radiator starts pulling heat out. The ISR thermostat opens 16.5 degrees Celsius earlier, which gets coolant flowing through the radiator sooner and helps the engine maintain lower steady-state operating temperatures.

This is a meaningful upgrade on hard-driven SR20DET and KA24DE builds (turbo, drift, track) where the factory thermostat keeps the engine warmer than ideal under sustained load. It's a fully-warmed-up modification, not a way to skip warm-up.

Critical Note

A colder thermostat will not affect cold-start behavior or reduce the warm-up period. It only changes the temperature at which the thermostat opens fully once the engine has reached operating temperature.

Fitment

• Nissan SR20DET (all variants - S13 Redtop, S14, S15)
• Nissan KA24DE (S13 and S14 240SX)

What's in the Box

• 1x ISR Performance colder thermostat (60 degrees Celsius opening)

Product Details

Brand: ISR Performance

Part Number: IS-21200-60

Type: Performance Thermostat (Lower Opening Temp)

Engine Fitment: Nissan SR20DET, KA24DE

ISR Opening Temperature: 60 degrees Celsius (140 degrees Fahrenheit)

Factory Opening Temperature: 76.5 degrees Celsius (170 degrees Fahrenheit)

Temperature Difference: 16.5 degrees Celsius earlier opening

Application: Turbo, drift, track, and other hard-driven SR / KA builds

Sold: Individually

Legality: Off-road and competition use only