Maderensto, those VT6 do look decent. they are rated at 30amps discharge with a 3120 capacity. The Sanyo cells I use are rated at 3500 at only 10 amps discharge. The Sanyo cells really only have about 3400 MAH. The VT6 do have a lot of capacity at 3120.
If you use them at 8-9C you are with 14 of them in parallel having a burst wattage of around 30,000 watts. WOW.
What controller will you be using because if you are using a Max-E you are limited to 14,000 watts.
I would say that for me my pack has way too much capacity and I would have considered those VT6 cells to get the full wattage from my Max-e of 14,000. However, I currently only use 8KW max on my max-e, and don't even max out my wattage potential with the Sanyo cells.
When you build your pack you will first have to place all 280 cells in the frame. Then you will have to take paper or cardboard and wedge it around the edges of the pack to really keep the pack extremely tight. This makes gluing it difficult and messy, you will have to glue through the little holes and squirt glue down between the cells when the pack is squeezed together. The glue will only go about half way so you will have to glue both sides.
If you take a look at how I did my pack in the picture, you will see that I wedged paper all around the pack to squeeze all the cells together tightly. Then I glued them when they were all tight like that.
In this picture you can see the mess I made getting the glue on the cell contacts because I had to wipe away the excess glue, this was extremely time consuming to remove and took me hours. You need to place Kapton tape over the contacts to avoid this, or even scotch tape will work but will leave residue behind that will need to be removed without getting alcohol on the glue that is between the cells as that will weaken the glue bond holding the cells together. SO you have to use a Qtip and be very careful. Just put tape to cover the contacts before gluing.
Actually, the reason for the glue mess was because after I glued the cells together there was glue sticking up that would have gotten in the way of the nikel strip, I had to use a hot clothes Iron to melt the glue flat as there was no way to easily cut it down. When I used the hot clothes iron it melted the glue over the contacts as you can see in the pictures.
A tip to glue the pack is I used a small metal round rod to push the glue down through the hole. What I did was squirt glue into the hole, then used a metal rod to push it down about half way, then squirt more glue, then pushed it down again. This is because the glue will not fill the whole easily unless you push it down.
Even with the pack being built squeezed tightly, I still had to very slightly file down certain areas of the frame so that the cells would fit in without rubbing the edges of the frame opening when inserting the pack. This is only when inserting the pack as once it gets through the frame opening there is plenty of room. I also reinforced the edges with 3M paint protection film and painted them so they are not so easily seen, but if you zoom into the picture you can see where I circled in red, where I filed with a rounded file the edges of the opening where certain cells were rubbing when inserting the pack.
What will happen is if you rub the edges of the cells when inserting the pack into the frame it is possible that you may short different areas of the pack if you cut into the outside of the cell. Imagine shorting two separate parallel groups through the frame while inserting it??? The 18650 cell shrink wrap can easily be cut into if you are forcing a pack through the frame opening and rubbing against the edges.