I personally believe the actual coffee flavor gets most of its taste from the roasted barley, but I also like to add a bit of chocolate (min of .25lb. max of 1lb.) to cut some of the acridness of straight roasted barley.
Here's a Guiness Clone I ran into tonight coincidently(not mine and not tried):
9 lbs Brit pale ale
1 lb flaked barley
18 oz roast barley
12 oz carapils
1.5 oz No. Brewer hops (60 min)
1 oz East Kent Goldings hops (60 min)
First, get the "tang" the way Guinness does: Sour about 24 oz (2 bottles) of stout (pref.
Guinness) by leaving it out in a bowl a week or more & then freezing it.
While brewing, thaw the sour stout & heat it to 180-190 F for 20 min.
Mash-in at 155F, hold for 1 hour, boil 1 hour & 15 minutes.
At end boil, add the sour stout.
At 70F, pitch 2 packs of Wyeast #1084.
A month or so of cold lagering (<40F) after bottling or kegging will help.
A certified beer judge could not tell this from bottled Guinness.
