Time smoking butt

[stonegoat]

I have two 4 pound (biggest I could find  :() Boston butts I'm going to smoke tomorrow for pulled pork.  How long should I expect to smoke them before they're done?  I plan to smoke at about 220 F, and am aiming for an internal temp of ~200.  I know a rule of thumb is 1.5 hours/lb, however, I have read on here that if you do two roasts, add the weight and use that number.  Intuitively I would guess the time to completion should be around 8 hours.  Thoughts???

[Tenpoint5]

Thinking more like 12-14  8 x 1.5 = 12

It also depends on what the ambient temps are, how windy it is, How much you peek. After the smoke period is over empty the water bowl and refill with some boiling water

[stonegoat]

I don't understand why I would use 8 lbs??  I just don't get why it takes as long to heat two four pounders as one eight pounder??  The distance from the edge to the centre of the 8 pounder would be greater than a four pounder.  Why does the number of 4 pounders matter?  Why would it take longer to cook two as compared to one, assuming they are not touching, and the cooking temp is the same??  Just doesnt make sense to me?? What am I missing??

Thanks

[WideGlideMike00]

I don't understand why I would use 8 lbs??  I just don't get why it takes as long to heat two four pounders as one eight pounder??  The distance from the edge to the centre of the 8 pounder would be greater than a four pounder.  Why does the number of 4 pounders matter?  Why would it take longer to cook two as compared to one, assuming they are not touching, and the cooking temp is the same??  Just doesnt make sense to me?? What am I missing??

Thanks

My *guess* is that it is simple mass. 8 lbs. is 8 lbs. There is a finite amount of energy (heat) being produced by the heating element. Both butts will place a demand on the finite amount of energy. Hence, remove one of those butts from the equation, the other butt gets more energy and would theoretically cook quicker.
Theory wise we could get much deeper (variables, thermal zones inside the smoker, relative moisture of each butt, shape, fat content etc.)

I'm sure if we were to introduce some basic thermodynamics principles we might figure it out  8)

I am not an engineer, but I did stay at a Holiday Inn Express once.  ;D

[stonegoat]

I don't understand why I would use 8 lbs??  I just don't get why it takes as long to heat two four pounders as one eight pounder??  The distance from the edge to the centre of the 8 pounder would be greater than a four pounder.  Why does the number of 4 pounders matter?  Why would it take longer to cook two as compared to one, assuming they are not touching, and the cooking temp is the same??  Just doesnt make sense to me?? What am I missing??

Thanks

My *guess* is that it is simple mass. 8 lbs. is 8 lbs. There is a finite amount of energy (heat) being produced by the heating element. Both butts will place a demand on the finite amount of energy. Hence, remove one of those butts from the equation, the other butt gets more energy and would theoretically cook quicker.
Theory wise we could get much deeper (variables, thermal zones inside the smoker, relative moisture of each butt, shape, fat content etc.)

I'm sure if we were to introduce some basic thermodynamics principles we might figure it out  8)

I am not an engineer, but I did stay at a Holiday Inn Express once.  ;D

I understand that, but the way I see it, the energy produced by the heating element is mostly heat energy (with a little light as well), and it is measured by the thermometer.  If the temperature stays a constant 225, why would it matter how many individual roasts are in there??

Anyway, I'm going to give myself 12 hours, and if it's less...I'll just FWC it untill supper.

Thanks!

[WarriorMedic]

You are right on the money Mike, you basically paraphrased the 1st law of thermodynamics and the concept of thermal mass.  Eight pounds is eight pounds, you can't get around physics.  In the end, it will be done when its done.

Stonegoat, 12 hours at 220* is about what I have to use for 7lbs pork shoulders with an IT of 190*.  I FTC for an hour at that point, and the blade slips right out and I just use a couple of gloved hands to mash the meat apart.  At about 160-170* the temp will stall as the collagens are breaking down.  It might take an hour or more to come up by 5 degrees near the end. It is a labor of love, and the time investment is well worth the wait.

Good luck.  It's ADDICTIVE.    ;D ;D