Thanks Len for the link to the thread I hadn't seen that one. Lots of good info in it.
I still have a question about the cc. If I cut my tank in two I will have a 125gal tank. So do I put 125gal in for the cc size or is my cc the area above the rf plate?
If 125 is my cc then I put 22x22x21 in for my fb and the size diff is 105%. (Of course I will probbaly make my fb 24x24x24 and that is 144% size diff) Will I have any negative effects making my fb that big?
Using the 22x21x22 fb my exhaust should be 4.5" dia and 32" long (which is 508in^3) and I should have an intake of 20.5in^2 (I will make my intake larger) and a throat area of 122in^2 (for the calculator gives 81.3in^2 and 81.3in^2 * 1.5=122in^2) I will make the opening at the end of the rf plate slightly larger than my throat size( around 127in^2)
This is the link to my numbers
http://[url=http://feldoncentral.com/bbqcalculator.html?cc=0,0,125,0,0,0,28875.00,9625.00&fb=22,21,22,0,0,10164.00,9625.00,105.6&ch=4.5,508.20,31.97&fi=3,2.5,0,30.49,4.07&fc=10.18,14.39,81.31]Link to BBQ Pit Calculator[/url]
Here is a link to another good thread. Near the bottom there is a picture with equations on it. I haven't compared the outputs to the ones from feldon's calculator but I think they will be similar. These equations find the area under the rf plate.
What are your ideas on the equations in the picture?