Hi guys, its been awhile since I've been on this board, but I'd like to share some recent developments. Just flow tested tonight the big port Vortec/Bowtie heads on my SF-1020 bench. These are the 25534371 cast iron heads, dead stock out of the box. I tested with Manley 2.000/1.560 valves with a mild undercut stem (stanard 11500 and 11501's). The intake port was equipped with a radius flow flange, the exhaust with and without a test pipe, all done on a 4.030" bore. As stated this test was performed on a SF-1020 flow bench at 28" H2O.

Lift Intake Exhaust wo/pipe w/pipe
.050 31.6 26.6
.100 61.3 53.0
.150 94.3 80.1
.200 126.4 108.3 112.8
.250 158.5 128.3
.300 187.4 141.2 148.0
.350 208.3 150.7
.400 229.6 158.5
.450 244.4 163.6
.500 255.6 167.3 174.8
.525 258.2 168.7
.550 258.1 169.7
.575 258.3 170.7
.600 260.2 172.0 179.2
.625 261.2 171.8

I also flowed the ports backwards at low lifts and flowed at higher depression, all results looked very good. The intake ports measured 203.8cc, peak velocities were in the 310fps range on the intakes and in the 290's for the exhaust indicating proper port configuration, especially around the guide/bowl area.
Anyway, I thought some of you guys might be interested in these results! Working on intake manifold flow evaluation next (bare in mind these are drilled for both vertical intake bolts and old straight style patterns). I used to do the Vortec conversions for use with TPI intakes, they just didn't work well enough for the street, but these babies should be great! I'll also be evaluating the small port version of the design later.

Race fast and safe - DrHP

 

Thank you DrHP for posting thesw flow values. This will definately help with cam selection for my 383.
Have you run these heads on an engine yet? If so, what combo?