* Vehicle type: Replacing an engine in a small car is significantly faster than in a large truck or a classic car with limited access.
* Engine type: A simple inline-four is quicker than a complex V8 or a hybrid powertrain.
* Mechanic's skill and experience: A seasoned mechanic will be much faster than someone less experienced.
* Access to tools and equipment: Having the right tools and a lift makes a huge difference.
* Condition of the vehicle: Rust, seized bolts, or other mechanical issues can add significant time.
* Whether the transmission needs to be removed: In some cases, the transmission must be removed to access the engine, adding considerable time.
With all that said, a rough estimate for a relatively straightforward engine replacement in a modern car by a professional mechanic might range from 8 to 24 hours. However, it could easily take much longer (multiple days) depending on the factors listed above. For a complex vehicle or situation, it could take a week or more.
