Bourne HPP Inlet & Exhaust Valve Spring Set Honda Civic K20 K24

Bourne HPP K-Series High Performance Dual Valve Spring Set

Complete your cylinder head upgrade with this full set of premium performance valve springs, developed by Bourne HPP. Designed to support the entire valvetrain cycle, this kit includes matched springs for both inlet and exhaust valves, ensuring balanced performance for builds pushing beyond factory power limits.

Engineered for versatility, these springs are rated to handle between 350-700 HP in boosted applications and 200-350 HP in naturally aspirated setups. Despite their enhanced capabilities, they are designed for standard fitment, allowing for a straightforward installation using the original platform shims and retainer setups.

Key Specifications

• Fitment: K20 (Complete Head Set)

• Material: EN 10270-2 SiCr (Silicon Chrome)

• Wire Diameter: 4.10mm

• Outside Diameter: 29.90mm

• Inside Diameter (Min): 21.70mm

• Free Length: 49.61mm

• Solid Length: 25.83mm

Performance Pedigree

These springs are manufactured from high-grade Silicon Chrome alloy (SiCr), selected for its superior fatigue resistance and thermal stability. Whether you are building a high-compression N/A track car or a turbocharged street monster, this complete set provides the necessary seat pressure to prevent valve float and maintain seal integrity on both the intake and exhaust strokes at high RPMs.

Kit Contents

• 8x Bourne HPP Inlet Valve Springs

• 8x Bourne HPP Exhaust Valve Springs

Installation Note: This kit contains 16 springs, providing a complete replacement for a standard K-Series cylinder head. When installing, it is critical to verify installed heights and check for coil bind to ensure proper clearance. We recommend professional installation and measurement.