xtremely High Seat Pressure, 135lb-150lb. 4g63. Not Recommended for Use in Street Cars.
Fits all 4G63 engines including DSM and EVO
•Compatible with all popular cam profiles
•Recommended for applications running 50psi or more boost
•48 piece Kit Includes: Chromoly Steel Retainers, PAC Racing Springs and Treated Steel Seats
•100% Made in the USA
•Seat pressure = 131lbs at 1.530“
•Rate = 310lb/in
•Max recommended lift = 0.500"
•Min recommended spring height at full lift = 1.000“
•Not for use in street cars due to stress and wear induced to other valvetrain components
Kiggly Racing LLC Race Only Beehive Valve Spring Set for high rpm and high boost 4G63 applications requiring extremely high seat pressure. This kit is made in the USA and includes an aggressive PAC Racing beehive spring, FEA-optimized proprietary hardened chrome moly retainers and treated steel seats. This is a drop-in fit with all standard 4g63 components including keepers and seals.
These springs are for serious builds only with a no-shim seat pressure of 131lb and can be shimmed 0.060" to 150lb at 0.470" /12mm lift. This high seat pressure keeps the valves from popping off the seat due to pressure waves up to ~62psi in most applications. By adding 0.060" shims (available here as an option) extends allowable boost in most applications to ~73psi
The limiting factor in the 4G63 valvetrain is typically boost levels, not RPM. To protect against this, we recommend targeting seat pressure at about 1.7x your absolute manifold pressure (boost + 14.7psi). This tends to be the worst case scenario and varies widely with the engine’s parts combo.
