i have a fully built b16 bored to 85mm with cp pistons and toda spec c cams. i just wanted to know about how much compression 300 psi would be. Thanks

 

There's no conversion formula to give you that measurement. You need to know the bore, stroke and combustion chamber size, headgasket thickness, and the compression height of the piston you're running. FYI you should read the sticky thread at the very top of this forum about CTR pistons and compression ratios. After that you may be able to answer your own question or give us enough info about your setup to answer it for you.