I don't have multiple engineering degrees to be able to address the theoretical reasoning behind the limit to advancing ignition timing beyond a certain point- - - - -you'd need to talk to my brother, who has spent 40+ years doing computer modeling for automotive manufacturers to have that conversation. What I can offer is the results of several decades of hands-on dyno run experience. Just about any engine stops getting a power gain when the centrifugal advance goes beyond about 36-37 crankshaft degrees at maximum torque. Many factors get involved, such as compression ratio, cam timing, combustion chamber shape, the number and arrangement of valves, and computer control of cam timing, fuel/air ratio, and the design of the intake and exhaust systems.
Jerry
