Thanks Rick. That's interesting. It appears theres a wide range of what plenum volume sizes can be and still be effective.
I've seen V-8 plenum size quoted at 40 to 50 percent around 5k to 6k rpm. 4 cyls's at 50-60 percent and 6's with 2 plenums feeding 3 cyl's each at 65-80 percent, with higher rpms using 10-15 percent smaller volumes.
My tri-power Offy intake plenum for a 218-230ci 6 cyl flathead is about 1 " deep.
I'm way out of my field, so I'm happy to know from the feedback here that I'm in the ball park with the size. I guess it remains to be seen what end of the rpm scale I will be in.
