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2618 expands more, which generally allows them to take more of a beating, so you have to adjust your clearances accordingly. 4032 has more silicone content which allows you to run tighter clearances since the material expands less than 2618, however, at the expense of being more brittle. I've seen a 4032 piston shatter in a high hp turbo car before. Generally I'd say that 4032 is more suited for all motor applications...2618 is more suited for the abuses of a turbo car. I wonder if anybody runs a 4032 piston for methanol FI setups.

On 94 octane, you could easily run 12.5:1 reliably...just make sure your tuner knows and understands what they're doing.

As for coatings, moly skirts are nice...theoretically...wiseco shelf pistons come with these already. If you're going to coat the piston top, you should coat the chambers as well. Heat will be absorbed through the path of least resistance. Keep it off the piston tops and the head get's to absorb more. Personally, i've never seen any measurable differences. I can see how it could be beneficial, but chances are, if you're at the point where you're counting on coatings to make a difference in the overall picture, you wouldn't be asking.

You can safely go to 88mm on stock sleeves...maybe more...
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