Compression ratio for 91 octane

[olddog]

Originally Posted by donraye

Interesting you mention this as I was actually going to use a thicker .064 head gasket to lower the compression down to around 10.6:1 but now I've been told that a thicker gasket might actually increase the chances of detonation as the engine tolerates detonation best in the .035 to .045 deck range. so the .040 gasket would be the best choice with my 0 decked block.
This is new information to me but the source sounded very knowledgeable and experienced so now I am probably sticking with the .040 gasket as originally planed or perhaps go to the cometic as you mentioned. but I think their gasket are .050 unless ordered custom. I'll check into that.
I was hioping to run one of the self ealing type gaskets that do not require any RTV or other goop, but now I have to re-think the whole deal.
does the Cometic require silicone around the water ports? What did you not like about the copper gaskets?

This is the squish/quench theory. There are quite a few believers out there that if you get the edges of the piston extreamily close to the head, that this squishes the air/fuel charge into the center at high velocities. All this turbulance mixes things up better. It is supposed to eliminate hot spots, as well. Therefore reduces tendency to detonate. They claim the piston to head clearance must be very tight for this to work. I think there is something to all this, but I do not understand it enough to know exactly what is needed or not.