Compression Ratio. How to measure it?

[GTpuI]

Hi ppl and sifu...I have a question about Compression Ratio. My question are:

1) What compression ratio definitely mean?
2) How to calculate it mathematically?
3) How to measure it. Are they any device to measure it?
4) What the ideal compression ratio for the engine? Is it related to piston size and shape, block size and cylinder size?
5) Is it related directly with engine performance, hp and torque?

I hope ppl, sifu, automotive engineer can give explaination. Thank you...

 

[zan]

Compression ratio - Wikipedia, the free encyclopedia

the answer for you.

 

[GTpuI]

Thanks zan. Very good info. Now I am very clear about this.