Well I thought I would go back and test the OE 3ltr 12V even-fire head; I had rather thought some one would ask for the comparison... I had done it for the 2.5ltr head casting figures posted, but not bothered with the 3ltr as I had gone straight for finding the delta increases than exact values... Anyway, the results were quite interesting... it's pants! Lol+ c'est pas possssssible mon fallow chicken lickers, mais oui! At about 3/4 OE lift it goes through some interesting turbulent patterns, and flow falls back from the natural progression with valve lift. In fact up to the majority of OE cam lifts approx 8mm, the good old 2.5ltr head out flows the OE 3ltr, now that really is a turn up for the books...
The numbers don't lie, an OE standard 3ltr head on it's own is a backward step, and this also applies to the 610 casting (these results were taken from a 610 casting which is indeed the same as the std 3ltr as far as the ports and chamber are concerned). It only starts gaining from 8mm where the OE 2.5ltr starts to choke.
Food for thought ...
Anyone want to know what the 24V OE head looks like?