fast lift cam question

[flyinlow]

I keep hearing about fast opening camshaft rates (hydraulic flat tappit). Lunati ,comp and others state some of their cams open faster for better power. Mopars have larger diameter lifters . Is this the reason they can get away with this? Better metalurgy today? Better oil?

[Ghoste]

It's the larger diameter lifter.  (sure isn't better oil!)  Basically, the larger diameter of the Mopar lifters mean that the lifter bottom surface is meeting the ramp of cam lobe at a lower angle of attack which allows the cam maker to put a steepr ramp on there which in turn is going to get the lifter to the highest point of the cam lobe more quickly.