But you see, the problem w/ the 5.4 is that it was designed as a truck engine. Large size due to big block sized stroke (4.165"). The 4.6 makes a better comparison performance wise due to the smaller stroke. Also, because of the stroke, the engine is going to be large but even so, the cylinder heads do make the engine larger, that's the nature and disadvantage of OHC. However, as far as 2V, the only real advantage is torque and size. Multivalve heads always provide more power. This is why in race applications (except for home bread stuff like NHRA, NASCAR, etc.), OHC engines are used since not only do the heads flow more, but the valvetrain is more stable at higher rpms. Except for springs and retainers, the stock valvetrain on a Mod engine can do 9,000+ rpm no problem. Remember, more rpms=more power w/ the right cam. So, OHC engines are more efficient hp/ci or hp/lb but w/ lower rpms, if the OHV engine weights less, then yes, the old OHV set-up is more efficient. However, to get the engine to weight similar, non-stock parts are needed (Aluminum heads).

dbu8554, yes, that's the worst part about the Mod: displacement. However, the engine was designed for FWD applications, hence the tight bore centers and small bores. If Ford didn't plan for this, you would have had an engine family using more typical SB bore sizes yielding larger sizes.

However, fear not, the Boss engine is coming that can go up to 7.0L. Also, 72BlackonBlack, the engine is going to be OHC and wedge heads (except for 4V which is penthouse). Rousch has a 777 version that is detailed in Car Craft (7,000 rpm, 7.0L, 700+ hp).