Which forged pistons to make my ka-e 8.6:1 comp ratio

[Baltezar]

I've been researching for days and I can't wrap my head around it, all the forged pistons are listed for the ka de comp ratio, I've seen people say just subtract one comp point but then I've seen otherwise. I'm thinking a 10.5:1 will get me around 8.6:1, what are your inputs or does somebody have an equation for it? Also is the compression height the same for the e and de.

[Boosted90Hardbody]

IIRC, the de has a 45cc combustion chamber vs the e’s 65cc combustion chamber. There are a lot of variables that will effect your compression ratio: bore, stroke, head volume, head gasket thickness, how far the head and block have been decked, piston dish, etc. I’d recommend google searching “compression ratio calculator” and using the one on Summit’s website to get an exact number for your setup. Long story short, the 9:1 pistons come out to 7-ish:1, depending on deck height, head gasket, and overbore, and the 10.5:1 pistons will be in the neighborhood of 8.5:1.

The wrist pin height is exactly the same between de and e pistons