Help With Imperial Stout Recipe?

I posted this on the Recipe group but didn't get any responses. Hopefully I'll have better luck in this group.

I have a bunch of leftover pre-crushed specialty grains and partially used hop bags from my last 2 brews and I am trying to formulate a recipe that will use a good amount of them up. I have a lot of dark grains so I decided to try and Imperial Stout, which is one of my favs.

This is my first attempt to formulate a recipe. I looked up a bunch of Imperial Stout recipes and tried to see what are common ingredients and proportions for this style. Again, keep in mind that the recipe is formulated with the primary goal of using up much of what I have on hand, so the quantities may look a little strange.

Some of the questions that I have are: Will this particular the mix of grains complement each other? Do I have the proportions right? What about the hops – are they complementary? I'm doing a mini mash - is the mash temp too high (158)? I used BeerSmith so my gravities and IBUs are pretty much in the style.

Note: this is a 3 gallon batch.

Recipe: Imperial Stout
Style: Imperial Stout
TYPE: Partial Mash
Taste: (35.0)

Recipe Specifications
--------------------------
Batch Size: 3.00 gal
Boil Size: 3.14 gal
Estimated OG: 1.095 SG
Estimated Color: 45.5 SRM
Estimated IBU: 84.6 IBU
Brewhouse Efficiency: 65.00 %
Boil Time: 90 Minutes

Ingredients:
------------
5 lbs LME Pilsen Light (Briess) [Boil for 15 min)
1 lbs LME Pilsen Light (Briess) (2.3 SRM)
1 lbs Pale Malt (2 Row) US (2.0 SRM)
8.0 oz Caramel Malt - 40L (Briess) (40.0 SRM)
6.1 oz Chocolate (Briess) (350.0 SRM)
6.1 oz Roasted Barley (300.0 SRM)
4.0 oz Black (Patent) Malt (500.0 SRM)
4.0 oz Caramel/Crystal Malt -120L (120.0 SRM)
0.35 oz Horizon [12.00 %] (90 min)
0.50 oz Chinook [13.00 %] (90 min)
0.70 oz Williamette [5.50 %] (10 min)
2.00 oz Williamette [5.50 %] (1 min)
0.55 tsp Irish Moss (Boil 10.0 min)
1 Pkgs Safale US-05 (Fermentis)


Mash Schedule: Single Infusion, Full Body, No Mash Out
Total Grain Weight: 2.76 lb
----------------------------
Single Infusion, Full Body, No Mash Out
Step Time Name Description Step Temp
45 min Mash In Add 3.45 qt of water at 170.5 F 158.0 F

The "group" did an 8/8/8 Russian Imperial Stout that won a ton of awards from various brewers. You may want to check that recipe out.

A couple things I noticed... Mashing that high is going to leave you with a lot of unfermentable sugars and could leave you with a sweeter than desired final beer. I'd shoot for 148-152 and let it go a little longer, especially since you only have 1lb of base malt in there. I know it's a mini mash, but the proportions seem a bit off. 1.75lb of specialty/1lb of 2-row might not get good conversion. I'm still pretty new at all grain myself, so take that with a grain of salt.

Less than 1oz of bittering hops seems low, but I'll believe BeerSmith on the IBUs. Also 2.7oz of aroma hops is really high for a stout. Try maybe 1oz - 20min, 1oz - 10min, and .7oz - 1min. That will get you more flavour and a bit less aroma. I love Willamette and have used them in a couple of my stouts. I don't have any experience with Horizon but it looks like a good all purpose bittering hop.

I'm sure others here can give you more advise. Keep us posted.

Terje

Stratotankard, thanks for the comments. I think I'll bump up the 2 row for the mini mash, lower the temp and mash longer. Regarding the bittering hops, I'm doing a late extract add plus 90 min boil so I think that's why the IBUs are coming out that high. Also this is a 3 gallon batch. Good points on the late hops - will adjust.

I'll check out that 8/8/8 recipes also.

Ah! didn't catch the 3 gallon batch size. That would make a little difference. Looks like you're on your way to a tasty brew!

The 8/8/8 recipe is considered by many to be epic.

Terje

Its hardly worth a partial mash with 1# of pale. In addition with the large amount of dark grains your mash ph will very likely be too low. I would steep all/most of the dark grains. If you want to do the partial mash then use a few pounds of pale malt and some of your speciality malts.

Imperial stouts age very well so making a full 5gal batch is highly recommended. That way you have more bottles and may be able to store some away to try for years.

I love the 08-08-08 recipe. Excellent beer and should give you an idea of ratios for your dark malts.

Craig

Do the Black Patent, Chocolate and Roasted Barley need to be mashed or can they just be steeped like the Crystal?