I know this had been debated several times and I've read the posts. However, here's an interesting little tidbit.
I am using a trial version of the Engine Analyzer Pro (sweet program, BTW), and was doing some research using both my babies, a 350, 10.5:1, and a 406, 9.9:1
Started fooling with different cams and such and it would seem that a hydraulic roller with the same @ .050 duration is only worth a few HP and a few ft-lbs. talking like 10 or so in each case - the average numbers also fell about 6 HP and 8 ft-lbs, telling me that the overall torque and power curves fell slightly. So there is a slight performance advantage, even on paper. And that program does take into account friction. I compared a mild hyd. roller with an aggresive hyd. flat tappet, perhaps not entirely fair, but hey.
So let's see, a roller cam: $275, roller lifters : $450, roller cam buttom, stiff front cover etc, $50 (not to mention different pushrods) Versus a flat tappet voodoo or xtreme NRG from comp with aggresive lobes (which can get closer to a hyd. roller valve actions) for $150-175 with lifters.
Roller: $775, flat tappet $175. $500 for 10 HP hurts baby!
Get nitrous instead.
I feel raped.
Anyone else have a different take on that? Perhaps Engine Analyzer is lying to me????