Answer:
increase, increase
Step-by-step explanation:
If the bore of an engine is increased without any other changes except for the change to proper-size replacement pistons. the displacement will increase and the compression rate will increase.
Further Explanation:
If the bore is increased, there are several benefits to this. There is more area for the valves this improves flow through the engine. The compression ratio will increase, thereby increasing thermal efficiency. The displacement also increases as the power output increase. Also, higher RPM will further increase power.
However, a decrease in bore will result in corresponding reduction in displacement and power output.