The Street Performance Hydraulic Lifters are made from a cold formed body with a clipped axle and have 6500 RPM capability. These lifters have .120 plunger travel and have an 80% fill rate with the test oil. Recommended Spring Pressures are 100-180 lbs Seat Pressure and 280-380 lbs Open Pressure
The Standard Mechanical Lifters are made from a billet body with a clipped axle and have 7500 RPM capability.
The Street Performance Mechanical Lifters are made from a cold formed body with a clipped axle and have 7000 RPM capability.
The HLT roller lifters, also known as Limited Travel lifters, have a clipped axle and are intended for use in Stock Racing Classes where some plunger travel is required. These lifters have between .015-.030 plunger travel before going solid. Due to the short plunger travel on these lifters there is some Valve Train Noise that can be associated with them.