Nothing less than, perhaps.
@ 8.88889 seems to be the max near sea level with some quench. He has none "to my knowledge" so anything under 8.1 would be absolutely safe, basing that on my repeated experience.
My .030 kb hyoer 340 ran 160psi @9.5 compression 69cc heads pistons and around .020 out of the hole. Valve closed iirr 58*
In other words 130-140 PSI is kind of like stock territory... we need to be 150 or better if we're really trying to build any kind of performance or even stock performance motor.
There are engines out there that dont fit the above, but we'll stick to this 340 for now.
