This is all a little rough.
When opponent folds, you win 1 bb. When opponent calls, you win S*W% and lose S*L% for a net of S*(W%-L%). L%=100%-W% so net=S*(2W%-100%). Your W% is a function of opponents Call%, so as Call% goes up, W% goes up. And when opponents Call% reaches about 5%, W% reaches 50% and EV is always + at that point no matter how big your stack.
When opponent calls about 1/110, W% is about 18% and net = -.64*S and total won is 109-.64*S.
So when opponents call range is KK+, then break even stack size S = 109/.64 = 170 bbs.
If opponent calls twice as often about 1/55 (i.e. adds AK to call range), W% goes up to about 40%, net = -.2*S, and total won is 54 - .2*S. Then break even S = 54/.2 = 270 bbs.
So 170 bbs is the lowest stack size you can shove and still be -EV. Sound about right?