Factors determining the difficulty:
* Engine Codes: The biggest hurdle is ensuring compatibility between the engine's computer (ECU), wiring harness, and the recipient car's system. If the '91 and '93 cars use the same engine code (and thus the same ECU), the swap will be significantly easier. If the codes differ, you'll likely need to deal with significant electrical rewiring and potentially ECU programming/replacement.
* Turbo System: If the '93 Spirit is *not* a turbo model, you'll need all the turbo-related components (turbocharger, intercooler, plumbing, etc.) from the '91 car. That's not *inherently* major, but it's a substantial amount of extra work compared to a simple engine swap. You'll also need to ensure the '93 Spirit's fuel system and exhaust system are compatible with the turbo setup.
* Transmission: Assuming both cars use the same transmission type (automatic or manual), the swap should be relatively straightforward. However, even if they're the same type, there might be minor differences in mounting points or bellhousing that require adjustments.
* Mounting: Engine mounts are typically pretty close between similar model years, but some minor modifications might still be necessary.
In short:
If both the '91 and '93 Spirits are turbo models with the same engine code, the swap is likely doable with moderate mechanical skill and effort. It would still involve removing and installing the engine, connecting the transmission, plumbing, and electrical connections. Think of it as a very involved engine rebuild.
However, if the '93 Spirit is *not* a turbo model, the swap becomes considerably more complex and time-consuming. You'll need to source and install all the turbocharger and related components, which can be a significant undertaking. This would fall into the "major work" category.
Before attempting this swap, it's vital to thoroughly research the engine codes of both cars and compare the details of their engine bays to determine the extent of the work involved. Consult a repair manual for both years to get a better understanding of the potential challenges.
