Quote:

So its not true to say a hydraulic roller makes more power than a flat tappet?



In general, it goes like this in terms of power:
1. Solid Roller
2. Solid Flat-Tappet
3. Hyd Roller
4. Hyd Flat-tappet.

Your choice shouldn't be made though on a generic "what makes better power" choice...your cam should be selected for your components, goals, budget, etc.

For most people, a HYD flat-tappet cam is all you'll ever want or need. It's less expensive, requires less maintenance, plenty reliable, and can make more than enough power for most street and street/strip applications.

I've got a HYD roller simply because I used a magnum engine to start, and a roller cam is what it had.

Roller cams will generally make more power at a given "size" mostly because will a flat-tappet and HYD roller cam might be the same size in duration @ .050, the quicker ramps allowed by the roller allow the roller to be bigger at .100/.150/.200/.300/.400...particularly at the valve lifts where the heads really begin to flow. Throw on top of that that the aggressive ramps allow for more peak lift too...but really, it's what is "greater area under the curve". Basically the valves actuated by a roller cam can stay open higher for longer while still fitting within the same "@ .050" size.

If you're building a true street engine and budget doesn't matter, go with a HYD roller. But for most cases, it's not critically important, especially when cost is factored in.

1979 Dodge Lil' Red Express - 360 rwhp, 13.2 @ 103mph
1968 Coronet: 318, 2.76, 15.2 @ 92mph! (SOLD)
1976 Valiant: 360, 3.90, 12.90 @ 106 (SOLD)
1989 Shelby CSX #500/500