SoCalDave

706 heads do have a reputation for cracking. 799 heads and 243 heads are known for producing power in stock form and with porting they will do that much better. As far as CoD and other theoritical terms I never factored them into my choice of heads because there is so much useful data from real world use.

Lsbmer

I think the OP is talking about Holdners hot rod article and more recent dyno tests on you tube.

99 Black Bird T/A

iTrader: (4)

Thought this might be of interest.

Speed Talk - Coefficient of Discharge Discussion

Darin Morgan of Reher-Morrison comments in thread. He is one of the true masters when it comes to cylinder heads.

Lsbmer

Yup. Him or Meuax . I always check it even tho it is somewhat theory.
here is a 706. Notice how bad the 100#s are. With bigger cams thats a good thing imho. That's on a 4" bore, oem ls2 head gasket

Che70velle

iTrader: (6)

Wow. I remember following that thread when it was live. Doesn’t seem that long ago to me. Time flies for sure...

Know It All

Yet Curtis Boggs is the one that points out the problem with discharge coefficients and why it's nothing but hot garbage. You can cheat the discharge coefficient number after .25L/D if you blow out throat diameter (>92%), but it will almost always run slower than a port with a correctly sized throat (<92%).