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.