Considering the low cylinder pressure, what thickness would you accept as safe?
Given the lower cylinder pressure, I can only make a comparison and comment on what I feel a safe range of chamber thickness may be. Having said that, we used .125"(1/8") of thickness to be the minimum thickness for a cylinder wall on the major thrust side in our V8 race engines. A cylinder has both thrust loading and some compressive pressures on them, while a chamber would only have compression pushing against it. So I would feel that .150" thick for the chamber would be a safe starting point and maybe work your way down to less if you think you need to. However, the chamber is a source of high heat, and machining the chamber thinner may make it create more heat. So I would be interested to see what thickness the stock chamber is to begin with and see how far from my guess of .150" it is from that. But throw a turbo on there where higher chamber temps can be expected and you may want to have the chamber thicker.
