Estimated timing to slow roast a 4lb pork butt?
I'm about the try out David Chang's bo ssam recipe, which suggests a 300 degree, 6 hour roast for a 8-10 lb, bone-in pork butt.
My bone-in pork butt is half that (4 lbs) and I'm wondering how that difference in mass would impact cooking time? I know what kind of internal temp. I should be aiming for but my goal here is to have it done within at least a one hour window or better.
Any educated guesses?
(For example, I've seen the formula as 2 hrs per lb at 225 degrees or 1.5 hrs per lb at 275. That same formula would, mathematically, hold for Chang's ration, which is 1.3 hrs per lb at 300.)
It won't take long for the shoulder to be cooked and edible. But for an effect most similar to Chang's scaled up recipe, following an hour/pound rule is suboptimal. The texture in slow-cooked pork shoulder is determined not only by its final temperature but also by how long it took to get there - a shoulder quickly cooked to, say, 190 f is not going to have quite the same texture as a shoulder slowly cooked to that temp. Also the crust will be different.
Generally speaking, larger hunks of meat fare better with long, dry, moderate heat roasts than smaller hunks of meat do. Since 6 hours at 300 might tend to dry out a smaller shoulder, and 3 hours at 300 probably won't form the desired crust, I suggest you consider cooking for about 20-30 minutes at a higher temp (450ish) and then maybe 3.5 hours at a much lower temp (250ish), otherwise following the chang recipe. If you want, you could flip the process, slow cooking first and then blasting in high heat. That way you get better tenderness and crust with a smaller shoulder.
I have found at bbq temps 1.5 to 2 hrs a pound works no matter the size, I'm guessing because its more about breaking down the connective tissue into collagen (which can make the meat sit at a constant temp for a long time) than the meat itself being done/cooked. However 4lbs is small for a butt so I'm guessing its going to be closer to the low end. That is what i would go with if i was doing it , but I'm no pit master or anything.