i was being helpful, if you want a full detailed explanation of it google it. not trying to be a jerk, just being me lol

 

found this on a stang forum, so i get what it saying and all but i just dont get the 9.5:1. how it said the 5.0L is a 9.5:1 ratio wich means 10cc of air to 1. idk lol i wasnt good at math lol.

"Compression: Is the amount the air fuel mixture is compressed brfore the spark plug ignites the compressed mixture. Durring the intake stroke a specfic amout of air/fuel is drawn into the cylinder. At the bottom of the stroke the intake valve closes and the piston comrpesses the mixture. The compression makes the mixture more volital and when ignited it will expand more quickly thus giving you power on the downward stroke of the piston. The ratio is the amount of compression that is done. If you take 10ccs of air and compress it to 1cc then your compression ration is 10:1. This is increased but changing the type of piston or closing the combustion chamber size. The typical stock 5.0L engine is about 9 or 9.5:1 meaning 10ccs of air is compressed to 1.9 or 1.95ccs on the compression stroke. The higher the compression typically means the more power you have that is until pre-ignition occures or pinging. This is why you have higher octane in gas to stop pre-ignition. In the old days when 103 octane was use you could run 10:1 or even 11:1 compression. The typical desiel engine runs 15+:1 but this pre-ignition helps that engine burn the fuel it uses."

 

compression ratio is just that, the RATIO between the volume on the cylinder/combustion chamber with with piston at BDC(bottom) and TDC(top)

So if your cyliner is 500cc's with piston all the away down, its only gonna be 52.6cc's with it all the way up, or a 9.5:1 compression ratio

People really are dicks here.....