In pf range I mentioned, but no longer in his range as we enter the turn: no pair, no draw (not even a bd draw), and only a single dirty over; so I figured he'd let them go on the flop.
edit: did the same with 98s/87s, fwiw; figured I already had enough weak hands included in his flop peel range.

ahh, makes sense - thx

More homework.....

First, a nit about my prior work (negligible, but just to be thorough): I forgot to include A2-A5 of 's in his range to call a turn bet; bringing the total # of combos in his range going into the turn to 125 (instead of 121). It actually marginally improves our equity against his call range, but also reduces the % of time that he folds.
Without showing all of the work, it brings the net EV of the 1 (or 2) bets we put in on the turn with a b/call line from +0.22624 down to +0.22608 BB.

Anyway, to compare to a c/c line we need to also know our equity share of the existing (5.5 BB) pot going into the turn.

Against his full 125 combo range, that is:

Board: Qc 5h 2d Jd
Dead:

equity win tie pots won pots tied
Hand 0: 56.509% 54.60% 01.91% 3003 105.00 { AdKd }
Hand 1: 43.491% 41.58% 01.91% 2287 105.00 { JJ-44, AJs-ATs, Ac9c, Ah9h, Ac8c, Ah8h, Ac7c, Ah7h, Ac6c, Ah6h, A5s-A2s, KJs-K9s, QTs-Q9s, JcTc, JhTh, Jc9c, Jh9h, Tc9c, Td9d, Th9h, AKo, AJo-ATo, KJo-KTo }

So....
0.56509 x 5.5 = 3.108 BB is our share of the existing pot*

Now to figure the EV +/- of the 1 BB potentially going in if we c/c the turn.....
I assumed he's not going to pure bluff this board, but did throw in a hefty dose of semi-bluff drawing hands, and any pair >/= 6 and better made hands, and one of his combos of A5s. It comes to 81 of his 125 combos (64.8%) are betting, and here's our equity against:

Board: Qc 5h 2d Jd
Dead:

equity win tie pots won pots tied
Hand 0: 46.212% 46.21% 00.00% 1647 0.00 { AdKd }
Hand 1: 53.788% 53.79% 00.00% 1917 0.00 { JJ-55, AJs-ATs, As5s, KJs-KTs, QTs-Q9s, JcTc, JhTh, Jc9c, Jh9h, Td9d, AJo, KJo-KTo }

So the EV of that bet we may put in:

(0.46212 x 0.648) – (0.53788 x 0.648) = 0.2995 – 0.3485 = -0.049 BB

So overall equity of b/c line on turn:

3.108 + 0.22608 = +3.33408 BB*

Overall equity of c/c line:

3.108 - 0.049 = +3.059 BB

*Full equity requires always seeing SD, except in the event he raises me on turn and I'm UI on river. I already said I'd fold the river UI in that instance, though in the evaluation I've done that's not sacrificing any equity, as he's always ahead of my UI AK when he raises turn.
I can't guarantee I'd call every single river UI if he calls me on turn and then bet river. But I would call a lot of them, and the difference again is perhaps compensated for by implieds against his raising range when we hit big on river.
We'll improve 39.1% of the time (18 outs), and most of them are pretty solid outs: 10 of our 18 outs are to the absolute nuts; another 2 are to what will likely be the best hand (nut flush, but on a paired board). The last 6 being to a tptk hand, which is a touch more shaky.

So anyway, based on my evaluation I still like the turn bet. I think he'd need way more tp hands in his flop flatting range for the turn bet to be a bad idea. Conceivable, surely; I'm open to running the numbers again with more Qx in his flop calling range if anyone wants.

I would have thought it would go
(.46 equity vs vill's bet range * 64.8%) * 6.5 bets after he bets +
(.66 equity vs vill checking back range * 35.2% ) * 5.5
= 3.2256

Your method works, too. But you included how much of that extra turn bet we get to claim when we win (our 46.212% of 6.5 BB the 64.8% of the time he bets), but not the loss of that 1 BB when we lose (53.788% of the 64.8% of the time he bets ). And I have our equity much higher against his check back range:

Board: Qc 5h 2d Jd
Dead:

equity win tie pots won pots tied
Hand 0: 75.465% 70.04% 05.42% 1356 105.00 { AdKd }
Hand 1: 24.535% 19.11% 05.42% 370 105.00 { 44, Ac9c, Ah9h, Ac8c, Ah8h, Ac7c, Ah7h, Ac6c, Ah6h, Ac5c, Ac4c, Ah4h, As4s, Ac3c, Ah3h, As3s, Ac2c, Ah2h, As2s, K9s, Tc9c, Th9h, AKo, ATo }

By your method:
[(.46212 x .648)* 6.5] + [(0.75465 x 0.352)* 5.5] - (0.53788 x 0.648)= 3.05895 BB (same as with my method above)

again, you rock - thanks
I'm slowly getting a little better at these things - a year ago I wouldn't have even been able to follow what you were doing...