View Full Version : Port Question

07-14-2003, 09:24 PM
On WinISD, does a 4 inch port mean 4 inch internal or external diameter?? :confused: :banghead:

07-14-2003, 11:08 PM
So a 4" PVC pipe wouldn't work? Cause they are measured externally aren't they?

07-15-2003, 11:43 AM
I think PVC is measured for internal diameter. This allows for calculations of flow rates.

The port doesn't have to be 4". It could be 3.75" or 3.85"
It would just require a different port length for the same tuning freq.

Go to Lowe's and check out the PVC sizes to be sure.

07-15-2003, 04:03 PM
Yea, I double checked on a 1.5" piece of PVC I had lying around. It is internal, but I just wanted to be sure.Thanks