Post #729873 by Wichita Lime Man on Sat, Oct 18, 2014 2:23 PM

Amateur wine makers use Pearson's Square to determine how much booze to add to fortify wines. I think it applies here but I could be wrong. Anyway, it suggests that you would need about 1.8oz 190-proof Everclear to raise 1oz of 80-proof spirits to 151 proof.

  
A   B  
\ /  
X  
/ \  
C   D  
where:  
X = final ABV  
A = ABV of spirit to fortify  
C = ABV of the fortifying spirit  
B = (C - X)  
D = (X - A)  
Let V = the amount of the original spirit to be fortified.  
Solving for the amount of fortifying spirit (N):  
N = V * (1/((B/D))  
N = V * (1 / ((C - X) / (X - A)))  

Plugging in some real numbers,

X = 75.5 (151 proof, the number we're trying to achieve)
A = 40.0 (80 proof, what we're starting with)
C = 95.0 (190 proof everclear)
B = (95.0 - 75.5) = 19.5
D = (75.5 - 40.0) = 35.5
V = 1 (ounce)

N = 1 * (1 / ((95.0 - 75.5) / (75.5 - 40.0)))
N = 1 * (1 / (19.5 / 35.5))
N = 1 * (1 / .55) (rounding here, I'm lazy)
N = 1.8

So, you could round that down to 1.75oz to make the measurement easy, or up to 2oz if you're feeling frisky.