Big A** firebox

[new smoke]

Ok, I've seen threads that say rule of thumb firebox size 1/3 of cooking chamber. Has anyone used and or broken this rule, and what where the results? I am looking at starting a cooker project this winter using two fuel oil tanks together to equal about 10'x4'x2' of cooking area. Using the 1/3 rule, the firebox is pretty large. I want to get some input on this while still in the planning stage. Thanks.

[Mikey]

On the Bandera & Smoke King Deluxe, the fire box is twice as big as it needs to be, but it still works just fine. In my opinion, I think there can be a bit of variance one way or the other.

[new smoke]

The size I am thinking of making is about 78% of the size it would be if I followed the 1/3 size firebox rule.

[BBQ Engineer]

The firebox on the Iron Maiden is probably twice as big as it needs to be...I won't say that I followed that calculator that much, and I firmly believe that you have a lot of latitude on the firebox. Just my $.02

On Edit...I don't use big fires, however, and I too am interested in responses from others. My fires are typically some charcoal for coals (since I don't use enough wood to generate a good coal base), and then a split or maybe two small splits.

[new smoke]

Thanks guys, for the input. It will be a while before I get this one started. We've got harvest fast approaching, and between that and the hospital and the family, I'll be lucky to find time to breathe. I'm sure I will have many more questions for you seasoned veterans as I get farther into this build. Thanks again.

[curious aardvark]

just purely looking at the thermodynamics, a lot would depend on whether it was a side mounted or bottom mounted box.

Under chamber fire boxes are always going to be more efficient from the point of view of getting heat into the chamber, and if you insulated it as well, I suspect you could get away with a pretty small firebox for a large smoker.
The less heat you waste to external radiation, the more will end up useable in the cooking process.

just a thought :-)

[new smoke]

just purely looking at the thermodynamics, a lot would depend on whether it was a side mounted or bottom mounted box.

Under chamber fire boxes are always going to be more efficient from the point of view of getting heat into the chamber, and if you insulated it as well, I suspect you could get away with a pretty small firebox for a large smoker.
The less heat you waste to external radiation, the more will end up useable in the cooking process.

just a thought :-)

CA- I have been toying with the idea of insulating the firebox. We'll see what the budget comes in at. I suppose for the added expense, it would be worth it.

It's going to be an RF with side firebox cut into the chamber by about 8 inches. Is an 8 inch cut-in for the firebox enough or too much? Anyone have thoughts on this?