Is it possible to put a Chevy HHR SS LNF motor into a 2011 HHR? Did they change the engine bay too much or is the engine bay still going to be about the same?

 

Sure, but a lot of work. Engine plus ALL the wiring harness from the SS car must be swapped. ALL the computers have to be swapped. Entire exhaust system has to be changed. Front bumper has to be changed to the SS one. ( Intercooler needs room in the bumper)
Etc, Etc, Etc, Etc.

Been discussed over the years. Just too much work and cost involved. Either buy a SS or look into a supercharger for your present engine.