While reading a piece (in a Chevy book) dealing with valve shapes I got to thinking about VW valves. The topic was tulip and flatback valve shapes and how they affect flow. Basicly that tulip valves tend to work well to guide air from a fairly straight port into the cylinder and that flatback valve are used when the valve must make a steep turn (like the VW exhaust port). Seems to me that all the (stock) VW valves I've seen are just the opposite, tulip exhaust and flat intake. Granted, this is with a very tame factory cam. As lift and duration increase, How can we use different shapes to gain flow and power?
