RF 4800 XL PIT CALCS

[Irish_lad]

Hi, l was wondering if l could get some answers on my upcoming build. I ordered the RF-4800 plans from Frank Cox, and l'm slowly putting together all if the parts that l need. I got my 24 x 48 tube rolled and am now looking at ordering the sheet steel for the firebox and WC.

When l upload the sizes into the Pit calculator, with the firebox dimensions of 18Hx 19L x 20W, it gives me a firebox area of 94.5% and a throat size of 54.7 sq inches.
If l was to increase the firebox to 20 x 20 x 20, the firebox area changes to 110.52% and the throat increase to 64.0 sq inches.
My first question is how beneficial is changing the firebox dimensions, would l gain much from 94.5% to 110% and would the smoker efficiency be much better?

My second question was just on steel thickness. My tube is rolled from 6mm plate, and l was wondering if l needed to increase my firebox thickness. I didn't want to build an insulated firebox, but l thought l might increase the FB to 10mm or 12mm Max.
Our weather here would be fairly mild, --4 C to -5 C in Winter.
Also, would the increased FB thickness be beneficial to the lifespan of the FB or would 6mm be adequate enough?

Thanks,

Richie

[Big T]

I haven't built from the plans but I usually shoot for 107%-115% max so 110% will be fine. The 6mm(1/4'') is the minimum recommended thickness for a fire box so you could certainly increase it if you wanted. I've used 3/8'' for fire boxes a few times and it works great, anything over that and it's just too heavy for me to work with.

[Irish_lad]

I haven't built from the plans but I usually shoot for 107%-115% max so 110% will be fine. The 6mm(1/4'') is the minimum recommended thickness for a fire box so you could certainly increase it if you wanted. I've used 3/8'' for fire boxes a few times and it works great, anything over that and it's just too heavy for me to work with.

OK, thanks

[Dirtytires]

Agree with big t on the firebox but have to wonder why Frank would “undersize” it. Maybe reach out to him to get his viewpoint??

[Irish_lad]

Agree with big t on the firebox but have to wonder why Frank would “undersize” it. Maybe reach out to him to get his viewpoint??

Yeah, thats a good idea.

Think a PM here on the forum would be ok?
Not sure what the right procedure is

Thanks

[Dirtytires]

You could try a pm but I have not seen Frank on the board in the last year so no idea if he would get it. If your set of plans are like the ones I bought, they had a phone number on them.....I would call. He is a really nice guy and it will require a live conversation anyway.

If you need a contact number, pm me.

[Big T]

A phone call is the way to go.