Rev, there is more sizing a turbine on a turbo than matching C.I. a buick has better intake flow compaired to exhaust, has longer tube type exhaust pipes that loose heat than a six with short iron manifold, a six has better exhaust than intake flow percentage etc.
A/R ratios are only for fine tuning a correct turbine, .63 .83 1.15 will not help if the wheel is wrong !
Also what is a vacuum manifold?
I may be wrong but when I started everyone around here used a smaller turbine until I loaned them my larger one, then everything changed.
Harry
