While basically wanting to kill myself reading some of the total bullshit and garbage(not all of them) over at BansheeHQ, I ran into one guy that consistently knew his sh*t(a engine tech guy...go figure) and went to the extra effort to actually explain things in detail. Some people are more eloquent at putting things into words than myself........this guy is an example.
Might not hurt to sticky it in the "engine info" sticky, although I kind of fear of noobs attacking with thousands of questions. 
http://mullengineering.com/rt/files/2_tech_docs/THE TRUTH ABOUT COMPRESSION TESTING.pdf
http://mullengineering.com/rt/files/2_tech_docs/THE TRUTH ABOUT COMPRESSION TESTING.pdf