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How does your "ring" (for a lack of better words) look? Any separation on there?
It's hard to tell from this distance (and with that color) but what is your layer height like? Too high of a layer height could be an issue, but I doubt it with this print.
Printing at too low of a temp could cause the layers to not adhere well. Printing too hot could cause some warping.
I'm also wondering if cooling could be an issue. Do you have your nozzle cooling fan on?
The last thing I can think of is the material you're using. Perhaps that material is prone to shrinkage? To test this, perhaps print a hollow cube? Have you printed other parts of the engine in this color yet? If so, which ones?
I haven't printed these parts myself yet - I hope to probably this weekend.