stage head flow question

[n20junkie]

for those of you that don't know i am building a SBC twin trubo, for a gn, but i bought a set of pro topline cylinder heads, tehy are made in australia and they have the traditional 23 degree, all the way to 10 degreed valve angle and huge 285 cc intake ports, but bla bla bla, i bought a set that has at 25 inches of vacum and .700 lift flow 318 cfm intake and 205 exhaust, just wondering where these numbers are in comparison to stage heads, ported or not, thanks for the help.
Grant

 

[KendallF]

Chapman quotes 341/247 Int/Exh @ .700 for their S2 CNC program. I have a set of these.

http://www.chapmanracingheads.com/p_Specification.asp?ID=91

The S2 head design remains one of the best GM heads ever; it should be as it was a "fresh sheet" racing-only design, sort of like the SB2 stuff.

Of course, you have two more cylinders and a bunch of extra cubic inches...I don't think you're going to have any problems making power.

 

[n20junkie]

all i can say is wow, them are some nice numbers, the head i have are cnc ported chambers and some hand cleanup behind the valves and the roof of the intakes, the runners are cast amazingly well, but i think that they are going to get a flap wheel to make them a bit better, i am trying to find out, but i think that the heads i have were flowed at 25 inches of vacume, and the stage heads were at 28, but thats not much, them flow numbers are great especilly in the lower lift regions, no mystery where the power comes from in a stage engine, thanks again and any more input would be great.
Grant

 

[turbodave231]

I am using a set of aluminum S2 heads that were ported by Ray Baker (Baker Engineering). The intakes flow 330 cfm .800 lift @28" H2O. 2.02" intake valves and 1.6 exh.

DR