Flowbench Tests - BMC A Series Cylinder Heads

Here are the test results for the following heads:
BMC Works Cast iron Westlake design 8-port x-flow cylinder head tested by David Anton at APT in California
Ken Elder aluMINIum 8-port x-flow
Pierce Manifolds aluMINIum 5-port
Mini Sport modified 12G940 stage II
David Vizard data from 'well ported' 12G940

All these tests were done on Superflow test benches at 25" depression, data corrected for atmospheric conditions. I've highlighted the 0.400" lift line as this is what my Kent cam with 1.5 roller rockers achieves. Beyond that lift it's pretty academic, eh?

The first plot is for intake ports. As you can see, the 8-ports are in a class by themselves, and the 5-ports are difficult to distinguish, within the margin of error for the test method, until 0.030" lift when the Pierce head wheezes out. This could be corrected with a bit of port work, but it works well enough out of the box. I should note that the same Elder head casting was tested in Australia by Graham Russell and by me here. Although the data should match up, Graham showed higher flow at high lift and lower flow at low lift - a difference of 10% crossing 0% at 0.025" lift. Maybe it's the Oz air? No matter, both tests show the head has the potential to make serious power.

It may be a bit unfair to directly compare flows for 5 and 8-port heads. Obviously the port size for the siamese pair will be much larger than the single runner on the 8-port. But, the Elder design is comparable to the old Westlake design and it compares very nicely. Unfortunately I didn't keep an inlet port cast from the Westlake heads when I sold them so I can't compare port sizes. The Westlake has ports coming down from the top of the head at 30 and really doesn't have a short radius at all. The Elder comes in high on the front face and drops to the valve at 17 so the short radius is less important than a siamese head with a 90 turn.

My thinking at the moment is that the 8-port head needs a completely different cam profile to the siamese port head. Since the Elder flows really well at low lift, maybe a profile that doesn't lift so high, but has wider flanks and more duration would maximize the area under the lift-flow curve. I'll consult with Graham Russell about this and see what he says.

Next are the exhausts. Vizard didn't publish any good data in his BIBLE, so no credit to him in this plot. Both the Westlake and Elder heads have excellent exhaust flow with the Pierce and Mini Sport doing a pretty good job as well. The Elder head has very large exhaust ports, especially compared to its intakes. Not much work required on any of these heads.
The last thing I thought I'd throw in is a look at the ratio of exhaust port flow to inlet port flow. Vizard suggests that the exhaust should flow about 70% of the inlet at any given lift. Obviously the Westlake and Elder heads have this covered, but the siamese port heads fall a bit short.
Follow this link to see a cast of the Elder inlet port