Cam Lobe Profile: Solid vs. Hydraulic

[charger_dan]

Okay, you can file this question under "duh, I thought everyone knew that",
but here goes anyway:

Suppose you're comparing two cams: A solid cam and a hydraulic cam.
Both have lobes designed for the .904" Chrysler lifter, and they have
similar overall specifications (duration @ 50, lift, o/lap, etc).

Will both cams produce similar power in the same engine?
If they will differ, in what ways?

Or, stated another way - for a given lifter diameter, why do solid lifter lobes
tend to have a more aggressive profile than hydraulics?

Let's hear from some experts!

[fastmopars .inc]

well, im no expert but i came across this question and might as well answer it as best i can.
i have heard as a general rule of thumb that if you take a hyd cam and a solid cam of the same specifications, the solid cam will make roughly 15% more hp. also the torque should rise a comparable amount and the power should come in sooner and last longer. the reasoning for this is the more accurate valve timing that can be had with a solid lifter.
also, more aggressive 'ramps' can be had with a solid cam because of the lifter's ability to handle more spring tension and much higher rpms, as well as follow the cam lobe that much more accurately.
roller lifters take the aggressiveness one step farther, with the most radical profiles available for a roller. also, take a cam with similar lift and duration specs in roller and solid form, and you will most likely notice much smoother operation from the roller. they tend to keep better idle qualities and such at the same duration.
now i wanna hear what cuda has to say =)

[DartGT66]

I do not believe in that 15%, that's whole lot. Hot ROd magazine made a test years ago with a chevy comparing hydraulic, solid and roller, and the solid had some gain over hydraulic, but it was pretty small. The roller, however was another story. The cams used were in the 280-290 degree range (two of each style). Personally I feel, that the lift used pretty much dictates the style of the cam & lifters used, unless you for a certain reason really want to use a certain type. That is, under 0.5" hydraulic, 0.5-0.6" solid, and above that a roller. Those are rough numbers, but shold give an idea of what I mean.