Can you replace your Peugeot 205 engine with a 405 engine?

It is possible to replace the engine of a Peugeot 205 with an engine from a Peugeot 405, but it is not a straightforward process and should be undertaken by an experienced mechanic. The following modifications would need to be made:

1) Engine and Transmission:

- Remove the existing 205 engine and transmission.

- The 405 engine and transmission need to be modified to fit the 205 chassis. Engine mounts and transmission bellhousing may require fabrication or modifications.

2) Fuel System:

- The 405's fuel injection system may not be compatible with the 205's fuel system, so modifications or retrofits might be necessary.

3) Electrical System:

- The 205's wiring harness may not be compatible with the 405's engine and its electronics. Custom wiring or modifications may be required.

4) Cooling System:

- Adapt the 405's cooling system to fit the 205's engine bay and radiator configuration.

5) Exhaust System:

- The 405's exhaust system may not fit the 205's chassis, and custom modifications or fabrication might be necessary.

6) Vehicle Inspections and Regulations:

- Depending on your location, engine swaps may need to comply with local regulations and safety inspections.

Due to the complexity of such modifications, it's highly recommended that you consult with a qualified mechanic or a professional automotive workshop to assess the feasibility and safety of the engine swap.