A W2 is a line of race parts by MoPar Performance. These are race heads made for the small block Chrysler engines. They are still used in NASCAR & drag racing venues.
The “W2” is also applied to the intake manifolds for it as well as any other part designed to fit the W2 head. Depending on the exact model of the W2 head, ether some or none of the stock parts fit
MoPar also has the W5, W7, W8 & the W9 cylinder head. They also have a big block line as well. Stage II, Stage III, StageIV etc....
There are plenty of other pictures and threads about these heads here and around the net.