The figures are all being equal, yes the 8v comes on earlier it should be no surprise.
They have a swirl design with twin sparkplugs like the Z18et heads.

Just found out the early 1984/85 s12 ca20e camshaft have the highest lift on the intake/exhast 10mm(0.394) and the longest duration out of all the ca18et ca20e motors ever made.

At pick-a-part the ca18de are dirt cheap and plentiful but never seen a det.