View Full Version : Need help and comformation of a flared port

05-04-2008, 11:14 PM
Guys I know the newb questions get old really fast and most of the time the anwser is just a 'search button' away but I have been searching the last 3 hours all over this board and my eyes are about to bleed.

So I am going to have a 1.2cuft ported box tuned to 35hz useing a 3in flared round port. Now I know (thanks to the search button) that I need 10.76in in length to get the 35hz tuning.

My question is: Is this from the end of flare to the end of flare or just the center part without the flares? The way I see it is it would be from flare to flare.
Heres the 3in port I bought.http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=268-350&ctab=15

My second question is : How do I do the math to find out my port displacement:wow:?

As I sit right this second I have 1.646 cuft with out sub displacement and port displacement. Any help would be great guys, especially the port displacement question so I can make any neccesary tweeks to the box dimensions.

Thanks guys, I appreciate it....

05-04-2008, 11:16 PM
look for a flared port calc and usually you will find a link to here:


05-04-2008, 11:21 PM
I followed that link earlier in my searching and it would not bring up the calculator, dunno why. But according to the calculator since I will be useing the flared port I need a extra inch to get the 35hz.... so 11.76in in length to get the tuning.

The one that I just can not seem to get is the port displacement, and I have been trying to do the equations that I have been finding but I am coming up just flat out lost.

Thanks for the quick reply it is appreciated,



I Think I got the port displacement...someone please confirm the process!

.785 x 3in x 3in x 10.76 = 76.0194 / 1728 = .044 port displacement?


3.14 X 1.5 X 1.5 X10.76 = 76.0194 / 1728 = .044 port displacement?

Is this correct assuming outside diamiter of the port is 3inch's and a length of 10.76? If this is correct how the hell do I do the flared end? Just assume that the extra inch from the flares are just like a straight port?

05-04-2008, 11:49 PM
the direct calc link.



05-04-2008, 11:55 PM
So the calculator gave me 76.088 cu.in., am I still correct at dividing into 1728cu in (= 1cu ft) to get my displacment for the port?

king ranch
05-05-2008, 01:11 AM
yes 0.04 is port displacement and port area is 7.065 i beleive

05-05-2008, 02:41 AM
Thanks for the comformation on the port displacement, I got it down now. Hopefully this topic will help someone else down the line.

05-05-2008, 02:41 AM
Don't forget the pool water.

05-05-2008, 02:48 AM
Don't forget the pool water.
I lol'd!!