I am suprised that the engine Vendors don't list any flow numbers on the heads they have for sale.
Stage 1 2 3 doesn't tell much ?
CNC PORTED doesn't mean anything either ?
Flow numbers tell it all,especially when compared to stock LS1or LS6 HEADS.

 

Well, unfortunately flow number don't tell the whole story either. There are quite a few ways in which to make a head flow high number but still not make much power. Laying the short turn over or flattening it will jump flow numbers. Not the best way to port, but not the worst either. You can hog the port out HUGE also. This will get flow up there, but the air speed will be low and the head will probably make horrible power until it hits 9000 RPM and above...
There are about 101 tricks to making a head flow better on a flowbench also, but I will just leave those alone....
Now, with that said, here is an example of a set of our stage II heads:
Lift............Flow
.2070"........157.6
.3029"........210.1
.4021"........257.8
.4525"........280.9
.5023"........296.6
.5376"........305.6
.5588"........309.3
.5942"........313.4
.6127:........317.1

There heads have valve sizes of 2.02"/1.570" and were flowed on a stock sized 3.900" bore at 20" of H20. I do have the actual printout from the flowbench along with every set of heads that we have done so far. They are all in the shop for customers to see.

I hope this data helps you.
THanks,

 

Chris,

That is a great informative response. :cheers: