Same discharge with huge heat sink on one side of cell

Same discharge with huge heat sink on one side of cell
even a monster heat sink cant get the heat out from one side

We saw 100F at the end of the first 62A discharge on the cells with no heatsink. I did the same 62A discharge, but this time instead of insulation, I used a huge finned aluminum heat sink,with a lot of air running over it. the idea is to see how well the heat generated in the discharge was transferred out of the cell with one side kept at 74F.
I was a bit disappointed to see the temp on the back side was only held to 90 degrees instead of the 100. This would lead me to believe that the heat sinks would work much better if they were on both sides of each cell rather than every other one?
Opinions?
Note*
The ambient temperature probe was getting heated by the discharge load. will move it to a better spot in the next test