2G Wiseco HD/4G64 Question

[CrackedDSM]

Alright, so I've been doing a little research on my current piston setup and need some answers. From someone either knowledgable about this subject, or with personal experience using these pistons.


I asked my machinist for 9:1 pistons on my built long-rod 2.4, and the pistons he provided me with he said were 9:1. But I searched the part number (K627M87AP) and it comes up as Evo pistons. They said 9:1 on an Evo, but Evo's use 43cc combustion chambers. Everything I've found said these should be 8.5:1 on a DSM.


However I was sifting through ExtremePSI and found this. http://www.extremepsi.com/store/product.php?productid=21528&cat=1586&page=1

I used the information listed there in a compression ratio calculator here http://www.gtsparkplugs.com/CompRatioCalc.html and it gave me 8.82 to 1 compression. I used .011 Piston-to-deck height in my calculations though and I'm unsure if that's proper or not.


Any thoughts/experience/advice would be awesome. Will these be 8.5:1 or 8.8:1 like my math shows?



Edit: Did a little more digging. I'll check back in later with my actual deck height clearance and compression once I do the measuring.

 

[CrackedDSM]

Whoops. Forgot about this thread. Update is, actual compression is based on piston to deck height which is set by the machinist or the installer. Mine happens to be .004" which results in 8.92:1, basically 9:1 for sake of argument with a 47cc combustion chamber, and stock HG thickness, 87mm bore, 100mm stroke, etc. Hope this helps!