Cam phasers are specially designed, computer-controlled cam gears that automatically optimize camshaft timing based on engine RPM. They are currently used in 2007 and up GM Gen IV VVT or Variable Valve Timing engines. Engine oil is pressure fed to the phasers through while the engine's computer controls solenoids that adjust oil flow into and out of the phasers control chambers to retard the camshaft.
All TPR camshafts for LT1, LT4, L83, L86 require this limiter
While this technology provides fuel efficiency and the ability to always be in the best position for maximum power regardless of engine RPM, it does present some limitations when it comes to performance cams. With such a wide range of valve timing movement, there is very little piston-to-valve clearance, which limits you to small cam profiles with little overlap.
Comp Cams Cam Phaser Limiter Kits restrict the range of cam timing movement to 22�. This will allow the necessary valve clearance for serious performance cams with tighter lobe separations while still utilizing the benefits of VVT technology.