What is a Chevy sb2 engine?

The "Chevy SB2" isn't a formally designated engine name from Chevrolet. It's likely a shorthand or informal reference to a small-block Chevrolet V8 engine, specifically referring to a generation 2 of the small block.

Chevrolet's small-block V8s have evolved through several generations, with each having subtle and sometimes significant design differences. "SB2" in conversation might indicate someone is talking about a small-block, but not specifying the exact year/model/displacement (e.g., 350, 383, etc.). Context is crucial to understanding what someone means when they use this term.