I spoke of the outlet ports on the early 3L uppers Definitely NOT being bigger. The runners are an oval shape and they only split at the exit. Those exits are much smaller. That said, the surface roughness of the oval shaped tube was pretty bad and by my calculations, the Dual honed upper primary and secondary actually has more cross sectional area than the 3L upper that I have.
My disclaimer comes from the fact that I took measurements off the 3L upper that I have here. I would be more than happy to re-do the cross sectional area measurements again if anyone really needs it.
I can only assume that other aluminum 3L upper manifolds are similar. Therefore I see no benefit to switching to the 3L upper.
That does NOT make any claims or comparisons regarding the plastic upper 3L IM.
Regarding this 3L upper stuff, I have to ask the question as to why to use it? If the 3L in stock form using the 3L heads and intake manifolds only makes 200HP, then isn't that what you are going to slap into your car? How can you expect to exceed that power rating by very much if you use all the same components. Custom tuning, exhaust, etc.... Maybe 225-235 at the crank.
My guess is that you would not make more power in the end than a well done hybrid motor. But then, as Lance says: "Prove Me Wrong"
We all benefit when that happens!
Good luck whichever way you go.
warmonger
