How does a hemi work?

The hemi is short for hemispherical and it describes the combustion chamber, which is shaped like a ball cut in two. Chrysler at one time used two overhead rocker arms for each bank of a V8, one for intake and one for exhaust. Overhead cams have replaced that design. They designed the combustion chamber to accomodate that larger design. Over the years car engineers have tried EVERYTHING to beef up an engine. My favorite was Nissan's use of two sets of points in the older distributor, one for low speed and one for high speed. LOL