I haven’t made a beer in a few months and I am long overdue. With 2 large bags of freshly picked Centennial hops from my backyard hop bines, I’d like to put together some sort of an “Imperial” IPA using a couple of beer kits that I have in storage.
What I have are 2 Coopers Beer Kits (Draught with an expiration of December 2013), 
1 kg Coopers Brew Enhancer 1 (Dextrose will work just fine) and the Centennial hops that I picked. I want to use an American ale yeast strain with this, most likely Safale US-05. I plan on making only 18 liters in order to achieve the higher level of bitterness and alcohol content typical for an “Imperial” IPA.
From brewwiki.com I pulled the specifications of an Imperial IPA.
- Color Range: 8.0-15.0 SRM
- Original Gravity Range: 1.075-1.095 SG
- Final Gravity Range: 1.012-1.020 SG
- Bitterness Range: 60.0-110.0 IBU
- Alcohol by Volume Range: 7.5-10.0 %
- Carbonation Range: 2.2-2.7 vols
- BJCP Style Number: 14 C
My calculation for the bitterness level of this brew using the 2 Coopers Draught Kits is as follows:
420 x 3.4 / 18 = 79 IBU (International Bitterness Units). With a potential reduction of 10% to 30% or a final range of 55.5 IBU to 71.4 IBU.
My calculation for the estimated color of the brew is as follows (darkening of the wort will occur in the can depending on age and storage temperature):
130 x 3.4 / 18 = 24.56 EBC. SRM = EBC x .508. = 12.47 SRM. With a potential reduction of 10% to 30% or a final range of 8.74 SRM to 11.22 SRM.
For more on how I calculated these, you can view this video here.
I calculated that the ABV for this beer made to 18 liters will be 8.75%
I just kegged this beer and also had a taste. So far it is great. I can’t wait to taste it carbonated. I used both bags of the Centennial hops (I harvested another bag last week that I plan to use on my next brew).