i have a 2000 civic si block and a b16a head that is milled how much compression will; that be

 

No way to tell by what information you have given. How much was milled off? Best way to tell is CC the combustion chamber and bottom-end with the piston at TDC. Add the volume of the headgasket... Take that total volume, divde it into that volume + your volume from the stroke of the crank and walla... There's your compression ratio.

 

im sorry the head is MILLED 40K

THANKS

 

40 thousandths?

My rough guess is 10.3:1 or 10.4:1.

 

um there is no way if it is milled 40 k that it will only be 10.4 man it will be like 11.3 11.4 i know that i just want an exact number

 

11.3846759637649 I have cc x ray vision

 

allright !!!!! thanks TREVER how did you find that out what mathamatical equasion?

 

There isn't one. Mathematically the largest chamber volume possibly taken away from a 1mm head mill will be 6.5cc, so potentially the compression is as high as ~11.8:1. However 1mm of head mill doesn't equate to that much chamber volume loss, but the only way to know for sure is to cc the head and then do the calculations. If you figured a 5cc loss in volume you'd have 11.4:1.