[7T2]

if ya wanna know why, look at where the extra "meat" for the new hemi castings resides...

i see your point, old one; for a perfectly mixed mixture you are right. but an incoming air/fuel charge is an amalgamation of righ and lean spots. the burning of such results in fast(lean) and slow(rich) flame propagation. this will distort the flame front and hurt combustion efficiency.
if a hemi chamber really was that efficient, wouldnt all the automakers be incorporating some derivitave thereof in modern engines?
jim