Contemplating a Russian Imperial Stout

I did this. First batch ever was an extract Milk Stout. Second batch was the same recipe with brown sugar added and only 3.5 gallons instead of the original 5. Pitched onto the cake. The biggest issue other than the required yeast (a cake from smaller stout removes this issue) is fermentation temp control. If you have a way to get the beer temp down to the lower range for the yeast before pitching and keep it that way for 3-5 days, then a way to bump up the temp a few degrees each day then there shouldn't be any problem with pitching on the cake. If you can only get the wort down to 70-75*F post boil then you will have to find a way to get it down to the low 60s. Otherwise you will pitch it on a huge amount of hungry yeast that won't need much of a growth stage in the 70s and get lots of fusels and esters.

 

You could just do the appropriate starter so you don't have a huge yeast cake at the bottom that you have to work around while transferring to secondary. I did a 2L starter and stepped up with another 2L starter for my Imperial Stout. You could us the yeast cake of a beer that just transferred off of it but if you have any off flavors in that yeast from the previous fermentation they'll most likely carry over. So if you're comfortable with your brewing then go ahead but there is just another variable for something to go wrong.

 

If you can get it down to the low 60s you should be fine. If you brew on Saturday morning, get it down to the 70s, transfer to your fermentor, then put it in the fridge and finish the temp drop (should only be a few hours tops). Then rack your beer to bottling bucket. You can either swirl up the cake and pitch it into the wort or re-rack the wort out of the fridge vessel onto the cake.

Yes. You can either use a 6.5 gallon bucket (or bigger), or split it into 2 carboys, or do a blow off and watch it.

Not really, but still a good idea. You would need oxygen for a beer this size for yeast growth, but if you pitch onto a cake you should have enough yeast to ferment w/o much extra growth. Still a good idea to at least splash it around as much as possible when racking in there to get some O2 dissolved though.

Nope

Nope.

 

There is nothing wrong with pitching a Imperial Stout on your yeast cake. There is also no reason to change your fermentation temps. I ferment most ales at 66 degrees. Good luck.

 

I've never done this with a big stout, but I do it with high OG lagers pretty regularly. It's a good technique, saves money, and I've not experienced any downside.

If I'm making something like a 1.082 doppelbock, I'd need to make something like a 4-liter starter, even using two vials of yeast: almost the equivalent of a 5-gal batch of beer. Rather than do that, I'll make a helles or a pils, and when I transfer that beer to a cornie for lagering, I'll drop the doppelbock wort onto the yeast cake. Works great.

I can think of a few potential drawbacks to be aware of: one is that if you're looking for a significant flavor contribution from the yeast, I would think that you're going to get relatively few esters with this method, since you're likely to be overpitching. Also, you want the first beer to be compatible in style to the second beer: ie, if you do a much darker or hoppier beer and then drop a lighter or less hoppy beer on the cake, you might get some unwanted carry over in color or bitterness.