OST-013: Massaging a virgin ;)

[NoHachi]

Couple of questions for people in the know. But first a disclaimer: I'm asking this genuinely as someone who doesn't have the funds to send a head on a round trip to the US and have work done, but could take a risk on junking a 150euro replacement head in a diy effort. Since this thread has become an excellent primer on head work I thought that this would be a logical place for my questions:

@Oldskewltoy: Do you do before and after flow bench tests on your work? The reason I ask is because subtle browsing on the net has shown very unreliable results for modifications sometimes considered a "no brainer". I've seen ports lose flow after a mismatched seat was cleaned up. Enormous differences in flow based on which 3 angles you choose for your seat+valve and their widths.. all within a small band of variation. Etc..
Is there some kind of safe area where you don't pickup much flow, but don't risk on losing much of it either? Maybe there are some before and after results already on the net you could point me to?

@Bean Bandit:
In this pic (thanks for taking the time to show this):


What would be the method of choice to tackle this? Do you machine away that part of the valve seat in an attempt to blend? Wouldn't you risk ending up with a dead pocket in that location and a loss of velocity? Or do you epoxy/weld some material in?

In this pic:

The guides and guide bosses have been chamferred. I know from my old physics book that a circular cross section has an equivalent frontal area that is several times that of a teardrop shape. However it seems that the chamfer has been made in the opposite direction of what my physics book would suggest, with the tail pointing towards the direction of flow. Is there a reason for this? Are there any resources from which I could study this more?

Finally, I've seen ported MX5/miata engines from some great engine builders (Rebello, Sunbelt etc) pick up MASSIVE horsepower simply after porting the head and replacement of only the intake cam shaft. Otherwise some massaged stock manifolds and stock exhaust cam. Jumps from 110whp to 170whp. Does anyone on the boards here have any experience and software tooling to match a cam profile to head flow? In my Formula Student days I did some GTpower engine simulation, but getting a license for this kind of stuff is damned expensive. There are definite gains though and cam grinding is cheap.