Is this heatsink big enough for Luminus CXM22 COB?

Hello,

I am experimenting with a HortiLum COB from Luminus. I will run one on this heatsink at about 55 watts max.

I have a 6" piece of this from HeatsinkUSA:

https://www.heatsinkusa.com/3-945-wide-extruded-aluminum-heatsink/

Will this be enough for passive cooling? I am probably over thinking this as I normally do. Its a beast of a heatsink, but has fins and not pins, which I have read work better. The C/W/3" rating seems low too compared to a 133mm pin heatsink from CobKits. I have yet to drill the heatsink so wanted to get opinions before I do. I would use thermal paste and a BJB holder.

Thanks!

I dont remember the exact calculations. But check out growmau5 on youtube and look for his early 7 part COB DIY vid series, one of those has the calculations for heat disapation. You need to measure the entire surface area.