We found the Magnum R/T heads to be an excellent replacement piece box-stock with outstanding possibilities. In milder combinations, simply blending the bowls and bolting them on will provide a dramatic improvement in port flow over any production small-block head with minimal effort. Ported as illustrated here, the R/T heads will support outputs into the mid-500hp range in larger displacement engines. We achieved 270 cfm of intake airflow, which compares favorably with the better CNC-ported aluminum heads offered for competitive makes of engines. Is this the limit? We found all that air with the production Mopar valve job and stock production valves. Valve mods including a back-cut intake and radiused-margin exhaust valves would undoubtedly pick up the numbers at lower lifts, as would a competition valve job. Further flow enhancements could potentially be achieved with chamber mods, including a de-shrouding cut, which would be performed as part of the high-performance seat machining. Given the port layout, we consider the Magnum R/T as kind of a baby W-2, having a terrific port configuration that's just made to support high flow, while retaining the convenience of a bolt-on replacement.
Superflow 600 FlowbenchTested By Steve Dulcich