Imperial Stout efficiency

[Oneiroi]

So I'm planning to brew the Semi-Skimmed Occultist from Brewdogs DIY dog.

It's a target 1081 OG for 8% abv (73% attenuation) and for a 20l batch the recipe calls for a hefty 11kg of grain total.

Having plugged it into brewers friend I make that a 52% brewhouse efficiency required. I know efficiency goes down as the grist:water ratio increases, but is it really that much??

What kind of efficiency do you guys get when brewing imperials or equivalently big beers?

 

[JonBrew]

I do BIAB, 16L batches (ending kettle volume) and when I brew big beers my efficiency is usually 60-65%, sometimes slightly higher. Usually It's about 75%.

The important question is, what kind of efficiency have you gotten from high OG batches in the past? If you haven't done any, what kind of results have you gotten on standard OG batches?

 

[foxbat]

I took a -5% BH efficiency hit last weekend (82% -> 77%) on my 1.090 RIS but lost nothing at all on my usual mash efficiency. I found this spreadsheet extremely helpful in the planning stage. Download a copy, plug your numbers in and it'll tell you whether it's possible for you to get what you expect. I had to do a bigger sparge which meant a longer boil to hit the number I wanted.

The spreasheet author is user 'doug293cz' from the HBT forum.

 

[Sadfield]

I knock 8% off my efficiency when the target abv goes into double figures. That usually gives me room to move, and add top up water if too high, the worst outcome is more beer.

Another approach is to have some DME on hand to make up the shortfall, and work from your normal efficiency.



Sent from my E5823 using Tapatalk

 

[Oneiroi]

Thanks for the responses! I'll have a play with that spreadsheet foxbat.

I've only ever made one high-OG beer and it was a disaster*

I brew BIAB and usually get 75% efficiency on normal brews.


*I tried to brew a 10l 1.085 beer in a 13l pot and quickly found out it wasn't big enough, ended up splitting the mash into another pot adding 80% more water then boiled it all down to the desired volume. Also broke my hydrometer so didn't find out till a week or so later that the extra water obviously gave a higher efficiency than the recipe I was following... ended up at 1.130 OG and by the time I realised the yeast had passed it's alcohol tolerance and all died. I ended up with a sweet, fusel-y completely flat beer

 

[LarryF]

1081, 1090, 1085. These are big boy beers, not for the faint hearted.