【How-to】How much do vortec heads flow

GM’s 706 Vortec heads are the cheapest and most effective heads you can use for your 5.3L, or 4.8L, or even some 6.0L LS engine build. … These cathedral offerings come stock with great flow and, unlike many truck heads, smaller factory combustion chambers (61.15cc) that won’t drop your compression into the basement.