* Year of the S-10: The body style and frame dimensions varied across the S-10's production run (roughly 1982-2004). Later models generally had slightly more space.
* Modifications: Significant modifications to the engine bay, firewall, and possibly the frame rails are necessary to fit anything substantially larger than the factory options. This includes custom fabrication work.
* Definition of "fit": Does "fit" mean it physically fits with minimal modification, or does it mean it can fit with extensive modifications that might compromise the vehicle's structural integrity or handling?
While some enthusiasts have successfully installed larger V8 engines (like a small-block Chevy or even a big-block with *extensive* modifications), it's a major undertaking requiring significant expertise and fabrication skills. Simply dropping in a larger engine is not feasible. You'll likely need custom engine mounts, headers, radiator relocation, and potentially even body modifications.
Instead of focusing on the "biggest," a more practical approach is to consider engines that are relatively common swap candidates for S-10s and offer a reasonable balance between size, power, and feasibility. These typically involve various small-block Chevrolet V8s.
In short, there's no simple answer. The "biggest" is limited only by the extent of the modifications you're willing to undertake, and even then, there are practical and safety limitations.
