Koyo radiator cap high-pressure 1.3 bar for performance aluminium radiators — OE-grade, Japan-made

The Koyo SKC-13 is a high-pressure 1.3 bar radiator cap engineered to improve cooling system reliability and hold consistent pressure on performance and racing aluminum radiators.

Built from OE-grade materials and assembled in Japan, the Koyo SKC-13 (also called the Hyper Cap) is designed for tuners and enthusiasts who run upgraded all-aluminum radiators and want dependable pressure retention under repeated heat cycles. It replaces standard caps to maintain a higher system pressure, which raises coolant boiling point and supports stable cooling performance in demanding driving conditions.

How does the Koyo SKC-13 affect cooling system pressure and performance?

By sealing the cooling system at a higher specified pressure (1.3 bar), the SKC-13 increases the coolant’s boiling threshold and helps the system operate without premature vapor formation. This gives a more stable thermal environment for engines under load without changing coolant type or core components.

• Rated pressure: 1.3 bar (approx. 1.3 kgf/cm²)
• Improves boiling point compared to lower-rated caps
• Consistent seal under repeated heat cycles

What materials and build quality can I expect from this radiator cap?

Koyo uses OE-grade metals and engineered plastics in their cooling components; the SKC-13 follows that standard. The cap is manufactured to resist corrosion and thermal fatigue so it maintains fit and function through long-term under-hood exposure.

• Constructed from high-grade alloys and durable plastics
• Designed for repeated thermal cycling and road use
• Produced to Koyo’s quality standards in Japan

Will the SKC-13 work with my radiator and how do I install it?

The SKC-13 is intended for use with compatible Koyo all-aluminum radiators and most standard filler necks designed for aftermarket caps. Installation is a simple swap: remove the old cap when the engine is cool, align and press the SKC-13 into the filler neck until it seats and locks.

• Recommended for Koyo All-Aluminum Racing Radiators
• Direct replacement for standard-style radiator filler necks
• Install only when the engine is cool; ensure proper seating and secure closure

Are there precautions or maintenance steps I should follow?

Inspect the cap and the filler neck periodically for signs of wear, leaks, or degraded seals, and replace the cap if the spring tension or rubber seal shows deterioration. Use the cap’s higher pressure rating only with components and hoses rated for that pressure to avoid over-stressing the cooling system.

• Check seals and spring tension during routine service
• Do not open when the engine is hot or under pressure
• Use with radiator hoses and components rated for 1.3 bar system pressure

Who is this for: The Koyo SKC-13 Hyper Radiator Cap is aimed at performance car owners, track-day enthusiasts and tuners who pair aftermarket all-aluminum radiators with higher-pressure components. It suits anyone seeking a reliable, higher-rated cap manufactured to OE-grade standards in Japan — especially when consistent pressure control and thermal stability are priorities during spirited driving or racing conditions.