I brewed my first 10 gallon batch a coupe days ago. It was Jamil's Reprobate American Stout, and it was supposed to have an O.G. of 1.073. My plan was to rehydrate a packet of Notty and a packet of Safale 05, and split it into two 5 gallon batches. My mash ton was nearly overflowing, but I managed to shut the lid with no headspace, and mashed at around 150º-154º (i had thermometer issues).
After the boil was done, my O.G. was 1.084! I have no idea why, --I'm guessing super high efficiency-- but i was pretty surprised. I knew by pitching one packet each @ 1.073, i was under-pitching to begin with, but 1.084?! I figured my yeast wouldn't stand a chance, or I'd have all kinds of esters in the end. On the other hand, these 2 yeasts have always proven to be heavyweights when I've used them in the past. The 05 has a 4 inch krausen and is chugging like mad, while the Nottingham, well, I had to pull the airlock off and rig a blow-off.
My question is, what's the highest gravity that you've had with a single packet of either of these yeasts, and how did it turn out?