Recently made this fairly in-depth tutorial for an explosion shader in UE4 - https://vimeo.com/338962167 - pretty straightforward stuff, although I did go into detail on setting up and explaining the motion-vectors blending. Also there’s some nifty UE4 material editor tricks in there too, such as how to convert bits into material functions to keep everything organized.
I hope this is useful, please let me know what you think!
Also, check out my FX pack Explosions for Games: Vol. I - https://vimeo.com/338665938