I think I have it figured out. My last batch I ended up with 59% efficiency. If I'm understanding things correctly, low mash pH can cause reduced efficiency
According to my city water report (CaCO3 is 35, Ca is 50, and Mg is 49), my residual alkalinity is 15. For a darker beer, my RA needs to be about 200-250. I've just been getting into water chemistry, so I may be way off on this. John Palmers nomograph shows that my untreated is more suited to beers that are under 10 SRM. I guess next batch I will try adding some carbonates before I mess with the grain bill.
I recommend you run fast and and far from that nomograph. John has admitted that it's faulty.
For your next try, here's the "official" recipe...
#264 Bourbon Vanilla Imperial Porter
A ProMash Recipe Report
Recipe Specifics
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Batch Size (Gal): 5.00 Wort Size (Gal): 5.00
Total Grain (Lbs): 17.75
Anticipated OG: 1.086 Plato: 20.58
Anticipated SRM: 45.4
Anticipated IBU: 31.8
Brewhouse Efficiency: 73 %
Wort Boil Time: 70 Minutes
Pre-Boil Amounts
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Evaporation Rate: 1.50 Gallons Per Hour
Pre-Boil Wort Size: 6.75 Gal
Pre-Boil Gravity: 1.063 SG 15.52 Plato
Grain/Extract/Sugar
% Amount Name Origin Potential SRM
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62.0 11.00 lbs. Pale Malt(2-row) America 1.036 2
8.5 1.50 lbs. Brown Malt Great Britain 1.032 70
2.8 0.50 lbs. Crystal 40L America 1.034 40
14.1 2.50 lbs. Munich Malt (Durst) Germany 1.037 10
5.6 1.00 lbs. Crystal 120L America 1.033 120
7.0 1.25 lbs. Chocolate Malt America 1.029 350
Potential represented as SG per pound per gallon.
Hops
Amount Name Form Alpha IBU Boil Time
-----------------------------------------------------------------------------
0.65 oz. Magnum-Domestic Whole 15.00 29.2 60 min.
0.40 oz. Goldings - E.K. Whole 6.00 2.6 10 min.
Extras
Amount Name Type Time
--------------------------------------------------------------------------
0.00 Unit(s)Whirlfloc Fining 15 Min.(boil)
Yeast
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Wy1450, Wy1056, or DCL Yeast US-56 Fermentis American Ale
Mash Schedule
-------------
Mash Name:
Total Grain Lbs: 17.75
Total Water Qts: 23.00 - Before Additional Infusions
Total Water Gal: 5.75 - Before Additional Infusions
Tun Thermal Mass: 0.13
Grain Temp: 65.00 F
Step Rest Start Stop Heat Infuse Infuse Infuse
Step Name Time Time Temp Temp Type Temp Amount Ratio
---------------------------------------------------------------------------------
sacc 0 60 155 155 Infuse 172 23.00 1.30
Total Water Qts: 23.00 - After Additional Infusions
Total Water Gal: 5.75 - After Additional Infusions
Total Mash Volume Gal: 7.17 - After Additional Infusions
All temperature measurements are degrees Fahrenheit.
All infusion amounts are in Quarts.
All infusion ratios are Quarts/Lbs.
When fermentation is complete, split 2 vanilla beans lengthwise. Scrape all the seeds and "gunk" from them and add it to the fermenter. Chop the beans into 2-3 in. long pieces and add them, too. Leave in secondary 10-14 days, then taste. You want the vanilla to be a bit on the strong side since it will fade. If the vanilla flavor is adequate, rack to bottling bucket or keg and add approximately 375 ml. of Jim Beam Black bourbon. You don't need to use an expensive bourbon, and you don't want to add a lot. The beer shouldn't scream "BOURBON!" at you. You should have an integrated flavor of the chocolatey porter, vanilla, and bourbon. This beer does not benefit from extended aging. I prefer it within a few months of brewing. The FG should be in the mid-high 20s, so don't worry about trying to get it lower.
