* 2.5L I4: A four-cylinder engine, generally considered the base model engine. Horsepower and torque varied slightly depending on specifics, but it was around 100 hp.
* 4.3L V6: A more powerful V6, this was a popular option. Horsepower was typically around 160 hp.
To know the exact engine specs for *a specific* 1991 S10 Blazer, you need to check the vehicle's documentation (owner's manual, vehicle identification number (VIN) decode) or look at the engine itself for the displacement information.
