Horse power with VDI ???
 

If a S4 with out VDI and a S5 with VDI were equally ported, how much horse power would they each have?
I did a search on this and I still didn't get the HP of each.
Why does the VDI work better when on a non ported engine, but when on a ported engine it doesn't gain as much HP as a non VDI?
I'm getting ready to rebuild a S5 and I'm tring to figure out if it's worth porting. I want to get as much dependable HP as I can with out spending a ass load of money.
This car is race only and will be run very very hard every time I take it out .
If you have any other HP tricks that will help let me know.

Bruhman.

take a look in the Archive.

on a ported motor a S4 VDI will produce more power

S4's don't have VDI.

On a ported engine, the shorter runners of an S4 engine give higher top-end power. Minimal differences, however.

what if you ported a series 5 motor and left the VDI closed? Wouldn't the closed VDI manifold have even shorter runners?

nevermind, I'm an idiot!