Regarding the bull-nose/knife edge issue, there were a few comments that I didn't agree with. First, last year I had the opportunity to rebuild a 1992 Ferrari Formula 1 engine at the shop I was working in for a customer with more money than God. If you know much about them you will know that Ferrari Formula 1 engines are almost never rebuilt by anyone other than being sent back directly to Ferrari and they will never touch one that hasn't been built by them. I realize that technology has changed somewhat in the last 10 years but typically Formula 1 technology is several years ahead of the rest of us as they have relatively UNLIMITED BUDGETS. I can tell you that in those 5 valve heads the leading edges of the dividers on the intake sides were not knife edged but the exhaust were. I don't mean to say that there was a big fat blunt edge there, only that they weren't knife egde sharp. This thinking has been followed by the crankshaft manufacturers who used to knife edge the leading and trailing edges of their crankshafts and now they have almost all moved to a bull nose leading edge and knife shaped trailing edge. I am not a fluids engineer (though I majored in aerospace engineering for a few years in college and took several classes on aerodynamics) and don't have the desire to spend my day researching formulae on the subject but I know what my flowbench tells me and I know how many top manufacturers and racers have designed their products to compete at the highest levels.