Creating this effect

If you have a PNG, then there is no parallax shift, so any 2D layer with moving noise, feathered edges, a bit of a glow, and a blend mode of Screen or Add would closely mimic the engines.

Video Copilot has a free plug-in called Saber that is free. It will mimic the rocket engines on a single layer. 

A gradient, Fractal Noise/ Roughen Edges/ Turbulent Displace with animated evolution and offset and overlaid over the gradient with blending modes like add, some masking to create the spiky shape. Then this pre-comp is simply parented to the layer in the top comp as a 3D layer.

Mylenium