Radiator Cap 31-33 psi Hexagon

The Radiator Cap 31-33 psi Hexagon from MOROSO is a high-pressure cooling system component designed for racing and performance vehicles that demand precise thermal management. Built for standard-size radiator necks, this cap regulates coolant pressure at 31–33 psi, allowing you to raise the boiling point of your coolant and prevent cavitation in high-output engines. Whether you're running a naturally aspirated stroker, a turbocharged platform, or a water-cooled race motor, the correct radiator cap rating is critical to engine longevity and consistent performance under sustained load.

This MOROSO radiator cap features a hexagon grip design that provides secure, hand-tight engagement without requiring special tools—a practical feature in the shop or at the track when quick thermal adjustments are needed. The 31–33 psi pressure rating falls into the mid-range of racing caps, making it ideal for moderately boosted or high-RPM naturally aspirated builds that don't require extreme pressurization. By sealing your cooling system at this specification, you reduce the risk of coolant loss, air ingestion, and hot spots that degrade cylinder head integrity and combustion stability.

Mechanics and engine builders rely on MOROSO caps for street performance, bracket racing, and road course applications where thermal cycling is frequent and system pressure consistency is non-negotiable. This cap is a direct replacement for any standard radiator neck and integrates seamlessly into existing cooling plumbing without modification. Always pair your radiator cap with a properly functioning thermostat and matching radiator hose pressure ratings to ensure balanced cooling system performance and prevent catastrophic overheating.