Here's some ideas for the ENGINE forum...
* Superchargers... i.e. anything to do with superchargers and turbos including roots and centrifugal.
* Exhaust.... anything to do with headers, H or X pipes and so forth.
* Building a Big Block Chevy
* Building a Small Block Chevy
and, if there is enough interest to warrant them, Pontiac, Olds, Ford and Mopar forums.
* Camshaft Tech
* Converter Tech
* Rearend Tech