As far as I can tell (about ten feet on a clear day), the curved lines show the internal structure of the disc, curved walls slanting backwards with respect to the direction of rotation. Air being flung out by centrifugal force (pace, engineers, I know, no such thing) will be assisted by the "scoop" effect. The straight lines show the grooves on the outer faces of the disc, and with the construction and design Bill describes, they would be facing the direction of rotation, "scooping" air and brake dust inwards.
Mind you, these are drilled disks, so brake dust will clear through the holes and out of the vents. Forward angled grooves will be harsher on the pads, breaking up any glaze and so on. Lousy pad life, I'd expect, but at that level of performance you aren't worried about that, just stopping better than the next guy.
Mind you, these are drilled disks, so brake dust will clear through the holes and out of the vents. Forward angled grooves will be harsher on the pads, breaking up any glaze and so on. Lousy pad life, I'd expect, but at that level of performance you aren't worried about that, just stopping better than the next guy.
