I experiment with this a lot. Every engine is different; with SBC race engines my current thinking is 0.050” piston to head at assembly is ideal. I learn something every day so this is subject to change.
Reducing the squish clearance enhances turbulence intensity; this reduces detonation tendencies to a point. The down side of ultra tight squish clearance is increased crevice space; these shadowed areas can lead to detonation. As with everything it’s a trade off. Get the squish clearance tight enough to enhance turbulence but not so tight that it creates areas of unburned mixture.
And of course we haven’t mentioned squish to bore ratio!
Reducing the squish clearance enhances turbulence intensity; this reduces detonation tendencies to a point. The down side of ultra tight squish clearance is increased crevice space; these shadowed areas can lead to detonation. As with everything it’s a trade off. Get the squish clearance tight enough to enhance turbulence but not so tight that it creates areas of unburned mixture.
And of course we haven’t mentioned squish to bore ratio!