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There is more we could talk about on this subject so I am starting new thread to deeper dive on this subject.
I am far from an expert on this, but the stock 12-valve head has a fairly small (modern) combustion chamber in it (and the piston.) My initial guess is that the 4v/cyl would increase the size (at least cross-sectionally where the piston and head meet.)
The main comparison is between old style V8 heads and newer modern ones. (how else is Chevy getting so much hp out of the LS2 (or whatever the latest 2v/cyl engine is.) I don't believe the valve size has changed as hp has shot up. )
4v/cyl have the advantage of more curtain area (more CFM.) However, to truely take advantage of this several other engine parameters would have to be changed (ie. max-rpm, displacement/stroke, cam lift, etc.)
I think there is a lot of potental still in the stock 2-v/cyl heads depending on the goals.
I would love to hear more about 24vshadow's tuning efforts are going.
My understanding is that this is one of the advantages of the more modern pent roof combustion chamber? Smaller, tighter and faster burning combustion chamber allowing more power with less timing and an overall more efficient combustion. This is why I have been looking at mounting the 24V heads to our 3.0 12V block. I believe overall efficiency will improve and allow more boost and timing to be run at a higher compression ratio for better off boost efficiency and performance.
I am far from an expert on this, but the stock 12-valve head has a fairly small (modern) combustion chamber in it (and the piston.) My initial guess is that the 4v/cyl would increase the size (at least cross-sectionally where the piston and head meet.)
The main comparison is between old style V8 heads and newer modern ones. (how else is Chevy getting so much hp out of the LS2 (or whatever the latest 2v/cyl engine is.) I don't believe the valve size has changed as hp has shot up. )
4v/cyl have the advantage of more curtain area (more CFM.) However, to truely take advantage of this several other engine parameters would have to be changed (ie. max-rpm, displacement/stroke, cam lift, etc.)
I think there is a lot of potental still in the stock 2-v/cyl heads depending on the goals.
I would love to hear more about 24vshadow's tuning efforts are going.