recently i just finished my vortec heads, but had some disappointing results with them.Car Craft did a test a while back with 355 and a LT4 Hotcam and a stock set of vortecs and made 420hp. then they took the heads and ported them out. I copied them exactly what they did to the vortecs and even added bigger valves on mine. there baseline was 228cfm intake @.500 and 152cfm exhaust@.500 after their porting they got 239cfm intake @.500 and 218cfm exhaust @ .500. then they bolted the heads on and ran another pull and got 460hp.
my baseline with bigger 2.02 vlave with no porting was 194cfm @ .550 and 163cfm exhaust @ .500. with 1.60 valve no porting.
I did my porting exactly to what they did, i blended the bowls in to 85 percent throat diameter.the valve guide bosses were narrowed, and the intake cross sectional area was opened to a .906 wide to a 1.100 wide. with a good gasket match with intake, exhaust ports. I brought my heads to a flow bench and heres my results with vortecs with 2.02 1.60 valves
intake Exhaust
.050 29 28
.100 65 58
.200 129 121
.300 180 169
.400 219 188
.500 224 201
.550 226 203
.600 227 204

these were supposebly flowed at 28 inches of h20. I want to know is the flow bench i used not accurate or is Car craft's numbers a bunch of bull****, has anyone ported a set of vortecs and flowed them in person or a stock set too?