Extensive modifications under the 350Z's hood are necessary before the Hellcat can fit.
Attempting to shove a 6.2-liter Hellcat V8 into a Nissan 350Z is quite a project. Doing it outside in a Pennsylvania winter makes the undertaking even more impressive to us, and we wish tons of luck to the guy trying this serious engine swap.
The guy tackling this swap is an experienced mechanic at a Chrysler dealer. He got the Hellcat engine for a bargain and already had the 350Z. Naturally, why not try to make them fit together?
Unfortunately, this Nissan might never have the supercharged V8 thumping under its hood. An initial test fit showed that part of the firewall needed to come out in order to install the Hellcat engine. After removing this piece, there still wasn't quite enough room for the larger powerplant to fit.
As it is here, the Hellcat would narrowly work in the 350Z. However, the engine doesn't currently have its header, and there doesn't appear to be enough room to install them without additional cuts The powerplant also needs to come forward in the bay to create room for the bell housing necessary for attaching the transmission, but a frame crossmember is in the way of the oil pan, which requires fabricating a new one or extensively modifying the existing part.
The builder seems very pessimistic at the end of this clip because of the extensive labor necessary to make the Hellcat engine fit. It might be more than a single mechanic working outside can achieve.
With enough time, effort, and money, creating a Hellcat-powered 350Z might be possible. As an example of what's possible, Nick Filippides, co-owner of American Racing Headers, managed to shoehorn a Hellcat into a Toyota Prius, and the builders were able to fit a 4.5-liter supercharger, instead of the standard 2.4-liter blower.
Source: 3F1DDYZEEJAY via YouTube