Koyo Hyper Red Radiator Cap (SK-C13)

Koyo 1.3 bar high pressure red radiator cap fits all Koyo aluminum radiators with fill necks and most aftermarket radiators. Fits most Mitsubishi, Subaru and Nissan factory radiators as well.

Vehicle Fitment:
Fits all Koyo Aluminum Radiators with Fill Necks
1992-2015 Evolution I-X
1991-1999 3000GT VR-4
1991-1996 Stealth R/T
1990-1999 Eclipse GST/GSX
1990-1998 Talon TSi
1990-1994 Laser RS
1991-1993 Galant VR4
Subaru WRX & STi (2002-2022+)
Nissan R35 GT-R
Nissan 350Z & 370Z
1988-1991 Honda Civic
1990-1993 Acura Integra
1992-2001 Honda Prelude

More from Koyo:
Extract every ounce of cooling efficiency from Koyorad All Aluminum Performance Radiators with a genuine Koyorad Hyper Cap! This Koyorad Hyper Cap withstands an increased valve pressure rating of 1.3kgf/cm2 (1.3 bar) (18.9 psi) (130 kPa) which increases the boiling point of water and relieves high performance engines of excessive heat. A genuine Koyorad Hyper Cap is recommended for use with every Koyorad All Aluminum Performance Radiator (when applicable). This Koyorad Hyper Cap is manufactured in Japan from high quality components to ensure longevity and performance from your Koyorad Racing radiator.

Why is increased Pressure Better?
It’s simple. When water is pressurized, its natural boiling point is increased. Most modern vehicles are equipped with a 0.9 Bar pressure cap. Koyorad’s Hyper Cap is rated at 1.3 Bar which increases the boiling temperature of your coolant to 267.80 degrees Fahrenheit. That is nearly a 56 degree increase over water's normal boiling point. By increasing the boiling point of water, an engine's cooling system will have the added heat capacity, maximizing performance under ever-changing racing conditions.