What are the typical VE table changes when better flowing heads and longer duration cams are installed? ie are the values adjusted upward generally? Is there a "bell curve" of adjustment around expected peak torque and/or HP?

 

I haven't seen anybody "roll up" an expected change vs
cam, heads, exhaust based on successful tunes. There
is going to be a lot of fog in that data, if anyone even
tries.

The cam overlap in particular will depress low end VE
and this effect can extend as far up as 2KRPM in my
(limited) experience. The heads & cam will also beef
up the top end as they take away from below. You
can imagine that the entire VE surface is "tilted" to
favor the big end. Torque and HP peaks will be pushed
out to the right.

It would be nice to acquire a data pile from people who
have various engine configurations that are well tuned
up for the combo, speed-density-accuracy-wise. With
some cross referencing to cam and heads and exhaust
a useful rule of thumb could likely be arrived at.

But I think if it existed (outside of some shop secrets)
we would have been talking the hell out of it here.