Seeing as the CA18 is so popular in Aussie... are most of the engines you see the four port or the eight port version?

The four ports seem a lot rarer, I have read they are better flowing in the higher rpm range, I don't think they have the butterflies in the intake to block half the ports at low rpm so by not having them the manifold shoul dflow a wee bit better...
there's not much info about them that I could find on the web, anyone know more?

this is sort of a dead horse topic nowadays with the popularity of the sr

anyway, the 4 port head is rare and is prolly only worth pursuing if you need to have the best n.a. motor in a competetive race class

but 8 port head is fine for turbo, and in high hp situations the butterflies are removed (they're for driveability) and i've even seen the ports siamesed

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wat the f#k how does that work is it like oval or one massive port?

I believe the 4 port heads are the ones found in the northern hemisphere.

It is also possible to remove the butterflies from the second set of ports, and weld up the holes. Its a bit of mucking around, but possible.