According to Feldon's BBQ calculator my firebox-to-cooking chamber ratio is about right. My firebox to cook chamber opening is about 50% of what it should be, and my two-inch diameter firebox air intake is about 1/5 of what is recommended by the calculator. The center of my two-inch diameter intake is positioned about three inches off the floor of my firebox, and the bottom of my wood grate (made of 1/2" steel rod) is four inches off the floor. So the bottom half of the firebox intake is directed beneath the grate and the top half just kinda is directed directly at the grate itself.
I'm really not sure what they base the firebox intake size on. Once the fire is going good, I either leave the two-inch opening open or I throttle it down some. Only when the fire I first lit or I really want to build up some temperature quickly do I need to leave the firebox door open a little bit. So why would I need FIVE two-inch diameter intakes for the firebox?
A related, but different question is positioning any additional intakes. Should I be considering one or more air intakes directing air to the upper portions of the firebox - i.e. towards the flame area? I've heard some talk that such an intake can help improve combustion. What say anyone on that? If I were to install one or more intakes for the upper portion of the firebox it would be easy to add adjustable openings on the firebox door.
Thanks. A couple of pictures are below along with a link to Feldon's calculator with my data entered.
near Tampa Bay, Florida
[url=http://feldoncentral.com/bbqcalculator.html?cc=0,0,0,24,18,33.5,14472.00,4824.00&fb=22,12.5,21.5,0,0,5912.50,4824.00,122.6&ch=4,295.63,23.54&fi=0,0,2,17.74,5.65&fc=7.76,10.97,47.30]Link to BBQ Pit Calculator[/url]