What Am I? Crate Engine

This week’s What Am I? is another puzzle for the automotive nuts in the crowd, but I’m gonna level with you and admit that I don’t know what this is.  It is a photo sent in by friend of DT Pierce who thought it might make a good puzzle.  

The engine in the crate — what is it?  As my linear algebra professor used to say — credit for correct answers will be given only if you show your work.