Compression ratio

Based on the second graph in this video, is it actually possible for two of the same model of engine with different compression ratios to have the same peak compression? Secondly, would the engine with the higher compression ratio be left with a greater volume in each cylinder at BDC than the engine with the lower compression ratio or is it more likely to simply have less volume at TDC? Finally, is a stroker kit an example of how someone might increase their engine's compression ratio? Thank you in advance,

-Nick

Hi Nick,

If you're talking about identical engines and as static compression ratio and not dynamic then the answer is no. Running an engine at 10:1 will have more peak compression than running an identical engine at 5:1. The graph in the video is more aimed to simplify the example on the expansion ratio.

Once again working on the same engines, the ways to change compression ratio would be piston design/volume, combustion chamber volume etc. The engine with the higher compression ratio will have a smaller volume when the piston is TDC (smaller combustion chamber volume) although because cylinder size and stroke has not changed the volume at BDC is the same (cylinder volume).

Usually the main goal with changing stroke is to change engine volume. To change compression ratio you're looking at things like changing piston design with a dish or dome and also changing combustion chamber volume.