[blau911]

By the way, while looking at the engine/model data on page 201 of Wayne's 911 engine rebuild book, I noticed that all of the heads are the same across the board for 2.4 T,E and S engines (46i/40e valves). exept for the port sizes. Better breathing thru large intake/exhaust ports and higher compression pistons appear to be the difference between the 140 hp 911T and 190 hp 911S (putting aside cam profiles and fuel injection set-ups). Is that right? If so, is it possible to mathematically calculate exactly how much additional hp can be specifically attributed to larger intake ports?