Alright I'm building a high comp LS and heres the intended setup:
B18a
82mm Bore
JDM B16B pistons(pct) 8.63cc
B20 P8R head 47cc combustion chamber

The problem I'm having is that using zealautowerks compression calculator the first one says that the compression with the above setup will be 11.77 which means I'll have to get the head milled .020" to get the compression to 12.47, whereas the second one says 12.81cr which means I'll have to get a .035" headgasket to bring it down to 12.46.

http://zealautowerks.com/ 11.77cr
http://zealautowerks.com/bseries.html 12.81cr

Does anyone have any experience with this setup and can steer me in the right direction? I need to figure this out asap as I have already ordered the pistons and the block's at the machine shop waiting.

Thanks

 

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/pct-ctr-piston-compression-ratio-717928/

i dont know if there are any posts about an all motor ls build, but you can see, by the compression ratio's of vtec heads, that the compression ratio of your build is going to be on the high side.

 

Ahhh I see what happened, the first calculator doesnt automatically factor in the pct compression height like the second one does. Yea 12.8 is gonna be too high for my daily driver.

One more question what should I be looking at: Static compression or Effective compression?