It is possible to put a 1990 Toyota Celica GT 2.0 liter engine into a 1992 Toyota Celica ST, but it will require some modifications to the engine mounts and wiring harness. The 1990 Celica GT engine uses a different engine management system than the 1992 Celica ST, so the wiring harness will need to be modified to match the new engine. Additionally, the engine mounts for the 1990 Celica GT engine are different from the 1992 Celica ST, so the engine mounts will also need to be modified to fit the new engine.
Overall, it is a complex and time-consuming process, and it is not recommended for those who are not experienced with engine swaps. It is also important to note that such modifications may affect the safety and reliability of the vehicle, and it may also affect its emissions compliance.
