Roller cam/lifter problem
The initial opening of the valves with a FT is usually quicker but the overall opening rate with a roller can be a bit higher, at least that's my understanding. I think where
@moper is going is that the potential overall quicker ramp rates of a roller cam are negated by the increased weight and hydraulic lifter plunger collapsing at higher RPMs with a hydraulic setup; to really get the benefits of a roller cam design you need to run solid lifters... I think? lol
Correct! The best bennifit to the Hyd. roller cams is the overall curve. The way I see the Hyd. roller cams best use is in mild to moderate street engines because of there limitations in high rpm ranges and lifter issues in high rpm ranges. This is not to say they can not perform really well and make good power.
But it does make sense to switch to a solid roller at some point for higher rpm capability, reliability and stability. This would also be the same for Hyd. Flat tappet cams.
So I am confused. What was said is that Flat Tappet makes more power? Then what was said is that more aggressive ramps are the reason.
FT cams can, if, the cam lobes are designed to do so.
But I thought even solid FT lifters could only go so fast on ramps without the edge digging into the cam.
Correct. And at that point, your looking at a wickedly aggressive camshaft.
That rollers, solid or Hyd, could have more aggressive ramps than FT. So I am wrong?
Only to a degree. It depends on what the cam is ground for. You can grind in many different profiles from a gas sipping mileage master to a full blown take no chit race cam.
and a solid FT cam can be more aggressive ramps than a Roller?
Well, yes and no. Again, it depends on what the cam is ground for. What your mentioning here is a dividing point in aggressive cam lobe action.
The initial opening rate of a racing solid cam can be super aggressive. More so than a roller. However, the roller can be created to have more overall curve than a solid. To find and approach these levels, you must be in the most aggressive race engine territory. Not a mundane and 400 hp engine. You can create 400 hp with a very mild cam!
To break it down for a mental visual...
To cars at the starting line for a 1/4 mike drag race. In the left lane a small block, (solid lifter cam) in the right lane, a big block, (solid roller cam) both full blown race engines.
The small block takes off faster than the big block. It jumps out for a sizable leed in the first 400-500 feet. But what you notice is that big block is rolling up on the small block really quick and it’s getting faster and faster until it just not over takes the small block but buried it deep by the finish line.
Did that help? LOL!