That vortec 4200 launched on the trailblazer bravada and gmc envoy in 2002 was the first engine in the atlas family of inline engines which included straight five and inline four engines. The engine features a 3 70 inch bore and a 4 00 inch stroke. The chevy trailblazer comes with several engine options the base model being a 4 2 liter in line six cylinder vortec engine.