How to change the compression ratio on an engine?

How exactly can u change your engine from say a 9:1 Compression ratio to a 12:1?How to change the compression ratio on an engine?There are a few ways you can do this. Cheapest way to do it is to skim the cylinder head. This'll give u a slight increase. For higher increments, you'll have to opt for high compression pistons. However, do take note that increasing the ratio from 9:1 to 12:1 might result in massive engine pinging (premature detonation). In the long (or short) run, it'll cause engine failure (read kaboom!). You'll also need to increase the fuelling to prevent pinging.How to change the compression ratio on an engine?by using different pistons the top of the pistons are different some are concave some are flat top and some rise up the higher the top of the piston the higher the compression ratio will beHow to change the compression ratio on an engine?you can buy a copression head, or bore it out with larger pistons.How to change the compression ratio on an engine?bigger pistons longer stroke.How to change the compression ratio on an engine?If you want to increase it that much, it would be cheaper to replace the engine.How to change the compression ratio on an engine?this is very expensive depending on the engine you be able to just shave the head but more likely you will need to change your pistons and heads