The stock engines for a 1989 Ford Tempo were typically:
* 2.3L Inline-4: This is the most common and easiest engine to replace with another similar 2.3L engine (though even then, some specifics of year and model may matter for compatibility with the transmission and other components).
* A less common 1.9L inline-4: This one would also limit your swap options to similarly sized engines.
Swapping engines is a major undertaking. You'll need to consider:
* Engine mounts: You'll likely need custom engine mounts.
* Transmission: The transmission needs to be compatible with the new engine.
* Wiring harness: The electrical system will need to be modified or replaced.
* Exhaust system: A new exhaust system will likely be needed.
* Cooling system: The cooling system may need modifications.
* Fuel system: The fuel system may need adjustments.
* Computer (ECU): Modern engines require sophisticated computers; you'll need to ensure it's compatible or get a standalone system.
* Legality: Modifications may not meet local emissions and safety standards.
In short: Sticking with a similar-sized, naturally aspirated inline-4 (perhaps from another Ford vehicle around the same era) is your best bet for a relatively straightforward (though still challenging) engine swap. Anything larger or significantly different will necessitate an extensive and costly project. Before undertaking such a project, thoroughly research the specifics of any potential donor engine's compatibility with the 1989 Tempo's chassis and ancillary systems.
