Open Chamber Heads vs Closed Chamber Heads....
I agree if we're talking power adder motors, but high output NA will have closed chambers. Here is a Chevy RO7 cup car head probably one of the best NA motor head made in the last 20 years. Looks like a tight compact chamber to me.
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The real issue is the definition of what a “closed” and “open” chamber really is. Most chambers are a cross breed of both.
I tried to find a picture of what I consider a true closed chamber BBC head, but I couldn’t.
When you look at the chamber of the RO7 head, you see the spark plug side is laid back and relatively short.
The intake side is very shallow and almost no chamber wall.
On what I consider a true closed chamber, you’d have both sides of the chamber vertical and very close to the valves.
I can tell you the number one flow and power killer is a “hard” “closed” chamber.
It seems we are quibbling over various versions of “soft” “closed” chambers. I haven’t seen what I consider a real closed chamber in 30 years, unless it’s some old thing.
The worst Chrysler chamber I’ve dealt with is the W5 chamber. That is considered a closed chamber and it takes a ton of work to be respectable. Removing the outside quench pad pissed it off. I suggest Chrysler knew this, but the sniveling for a “closed” chamber to get quench (which I have said many times is overrated) and they gave up power for quench.