Ryan,
Aside from the fact that a sphere has the best surface-area-to-volume ratio, the fact that the valves open inward toward the bore center minimizes valve shrouding, thereby maximizing effectiveness of each valve's curtain area. On the downside, the fact that the valves open toward each other limits ultimate valve size and overlap timing.
Rusty
Aside from the fact that a sphere has the best surface-area-to-volume ratio, the fact that the valves open inward toward the bore center minimizes valve shrouding, thereby maximizing effectiveness of each valve's curtain area. On the downside, the fact that the valves open toward each other limits ultimate valve size and overlap timing.
Rusty