Well, you can always go to
GTS wiki searcher. It's by far the most efficient way to search for game content.
But, that said, the liveries you mentioned are done with multiple decals. The author would make a large number of layers for an engine bay, upload them all and carefully align each layer to make the final effect. This is the only approach because the decal uploader won't upload anything bigger than 15 KB and a sole engine bay SVG with that ammount of detail would surely be waaaay bigger than 15 KB.
If the author didn't make those layers publicly available, you would have to ask for them or doing them yourself.