Don't confuse fuel delivery (lean / rich) mixture that might cause piston melting with combustion chamber choices that prevents detonation (piston breaking).
A more rich mixture (12:1) keeps the flame temperature down (less chance for detonation) while producing a powerful stroke. A lower compression ratio only prevents detonation.
You have to match the piston to the head gasket, don't mix it... A CF2 piston with a CF3 gasket will cause the pistons to hit the head and break the pistons.
Thanks for the explanation.
A CF2 gasket with a CF3 piston will increase the gap between piston and head, so it will lower the compression ratio. The bad effect is the gap allows the flame to get to the edge of the piston and rings and create hot spots that increases the chance for detonation, so you win and loose at the same time.
//Meanwhile, I resolved my misunderstanding, but I left the text maybe it might help somebody...
I did some tuning on 2T engines. The 2T engines have a different construction than 4t engines. The squish between combuston chamber and the edge of the piston is same all around.
The thing that confuses me on 4T is different height of squish in combustion chamber in cyl head.
I post the picture: (first picture
-Green, small squish (gap)
-Red, big squish (gap)
I just measured the diameter of combustion chamber on cylinder head and it is 81mm (second picture
), and piston is 82.5 on the crown. I thought they were the same.
So, Do you know the dimension of squish for CF3 piston and 0.4mm (CF3) head gasket? I think I read somewhere that is 0.5mm.
The best way to lower CR is to get piston with a deeper dish in the middle with the edges (deck height) of the piston the same - That way you do not alter the squish / quench of the piston and head interaction.
My comment of CF2 system VS CF3 system is that I like the idea that the CF2 fiber gasket is it has less catastrophic failure and cheap to replace that the CF3 metal gasket that is stronger, but it might be too strong that the pistons break rather. That is if something breaks... but it should not break if all is done right
I agree that this is the best way.
My idea for lowering CR is to polish the combustion chamber in cyl. head and remove "bumps" around the spark plugs. Also to do similar job like this on my pistons.
Another solutions are:
-cutting 1mm from conrods
-2x0.4mm metal head gasket
-or CF2 1.9mm head gasket