Here's a breakdown of the factors:
* Engine Bay Space: The Nova's engine bay is relatively compact. While you *could* fit a very large engine, it would require significant fabrication and modification. Things like firewall clearance, steering column interference, and exhaust routing become major hurdles.
* Subframe and Suspension: The stock subframe and suspension aren't designed for the weight and stress of extremely large, powerful engines. Reinforcement or a complete custom subframe might be necessary.
* Transmission: The transmission must be able to handle the torque of a large engine. A heavy-duty unit, likely a custom setup, would be needed for anything significantly larger than what the car was originally designed for.
* Driveshaft: Similar to the transmission, the driveshaft will need to be strengthened or replaced.
* Cooling System: Larger engines generate more heat and will require a more robust cooling system. A larger radiator, upgraded water pump, and possibly an electric fan are almost guaranteed.
* Cost: The cost of engine swaps, especially those involving significant fabrication, can quickly become prohibitive.
While some people have successfully installed big-block Chevy engines (e.g., 454 cubic inch) into Novas, they often involved significant modification. Engines larger than that (like some of the largest big-blocks or even some smaller diesel engines) are very unlikely to fit without major, custom work. Even a successful 454 swap is not a simple bolt-in affair.
In short: You could potentially fit a very large engine, but it wouldn't be a straightforward or inexpensive project. A well-executed 454 swap is at the upper end of what's reasonably achievable without becoming a full-blown custom build.
