Replacing piston #1 with piston #2 will not affect which of the following engine parameters?

Replacing piston #1 with piston #2 will not affect engine timing because the timing of an engine primarily depends on the relationship between the crankshaft and camshaft positions relative to the engine cycle. This aspect is dictated by the design of the timing mechanisms and the positioning of the timing components, rather than the specific pistons used in the engine.

When pistons are replaced, certain parameters may be influenced depending on the piston's characteristics, such as the shape of the combustion chamber, stroke length, and overall design. Clearance volume and compression ratio are both impacted by changes in piston shape and design because these factors affect how much space remains in the combustion chamber when the piston is at the top of its stroke. The octane requirement could also be affected by changes in compression ratio if the new piston changes the overall compression characteristics of the engine. Therefore, engine timing remains unaffected by piston replacement, as it operates independently of the specific pistons employed in the engine's operation.