Intended to be a replacement for stock hydraulic lifters, the Lunati Performance Replacement Hydraulic Lifters provide better performance and durability for mild racing and street applications. Reduced weight allows the check valve disc to close quicker, which results in faster pressure buildup. This pressure increases the stiffness of the lifter and allows the engine to rev higher before valve float occurs. The Performance Replacement Hydraulic Lifters have a longer piston than other competition and stock lifters. This feature provides a larger surface area to distribute the load and increases longevity. Oiling is better controlled through constant contact between the metering valve and pushrod seat, which also prevents the lifters from being over-oiled at high speeds.