Chevy Vortec Cylinder Heads - King Vortec

After testing the untouched OE Vortec versions we wanted to see how lightly hand-ported pieces would do in comparison. The heads were the same part number as the previous ones, but touched-up using a Standard Abrasives porting and polishing kit. The actual amount of material removed was very minimal because no carbide cutters were employed. We rounded sharp edges to help create a smooth, flowing port. On the Superflow flow bench, our hand-ported parts delivered roughly 5-15 cfm more flow than the stock version and made us curious as to what the dyno would have to say.

We fastened our ported Vortec castings to the Hye-Tech motor using the same Fel-Pro MLS head gaskets and ARP head bolts. Then we hooked the fuel line up to the 750-cfm Speed Demon carburetor and set the timing at 36 degrees. Our first pull delivered a slight gain in low-speed torque, posting 369 lb-ft at 2,000 rpm and a peak of 434 lb-ft at 4,000 rpm. So our home-porting job had moved the powerband up 100 rpm and delivered a peak horsepower number of 394 hp at 5,500 rpm. Though not much of a gain, we felt it was still worth noting for grind-happy enthusiasts. In all, the average power numbers showed a gain of 3 lb-ft of torque and a loss of 1 hp.