Short Travel Hydraulic Roller Lifters from COMP Cams® are engineered specifically to perform at higher engine speeds. When engines are equipped with a hydraulic lifter, high RPM is often limited by the improper position of the lifter's internal piston as the lifter inevitably "pumps up." This improper location results in open valves and therefore leads to lost power or even engine failure. Both the OE type Short Travel Hydraulic Lifters WITHOUT link bars and retro-fit type lifters WITH link bars limit that internal movement to a minimum, which cuts down on these issues and allows higher engine RPMs.