Yes. It controls compression\squish\flame velocity as well as the ability for the piston to smack the head.
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So tighter is more boom but potentially knocking?
Correct to a point. For example my engine builder played around with different gasket thickness to find that sweet spot. A particular engine liked a bit less compression than pushing the limit of the rules.
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Yeah, closer is more boom but can add pumping losses and/or kill overrev which is essential for some single gear applications…
Like Clayton said, it really depends on the application.
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Ok buying built engines when it comes back around time to do so. Sounds like a good thing to have fully sorted.
It’s all a time = money thing. The more parts you try, the potentially better the performance, and the more money you spend on the dyno. I’m getting my Rotax back from being rebuilt next week, and I’ve got a handful of parts to track test and confirm performance number the dyno gave. That last 5-10% can cost 50-70% more money.
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What material are the brownish base gaskets made of, and are all the gaskets sizes of this same material ora are the thinner ones … 0.1mm , 0.05mm made of a clear color?
The thinnest base gaskets are made from a plastic like material, the thicker ones are made using a normal gasket type paper.
In my experience anyway.
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Anyone has experience and can provide feedback on the thinner clear plastic like gaskets?
Are they throw on & torque down to spec, or anything extra that needs considering?
All gaskets compress when under torque load.
The gasket paper ones will compress more than the plastic ones will.
Plastic ones seem to hold their thickness more consistently than the paper ones, but I feel like they don’t seal as well. That hasn’t stopped me using them to hit the target thickness I am aiming for however.
The thinner plastic ones do seem to be more fragile, and I would not reuse them after being torqued down more than a few times as they get brittle//hard.
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Anyone got some back to bacl testing of a x30 with 0.9mm squish vs 1mm?
At what squish does detonation becomes a real problem?