I am in the process of rebuilding and want to know the plus's minus's of switching from a WISECO/ 4G63 EVO VIII-IX/ ASYMMETRIC SKIRT/ 9.5:1 to WISECO ASYMMETRIC SKIRT HD2 | 4G63 EVO VIII-IX | 10.5:1 K668M85AP pistons.

I know that the compression is higher. I am running GSC S2 cams so I am just looking to see what the difference in the 2 are and if going high compression is going to be worth the extra $.

 

I would go with the higher compression ratio ones as well as making sure they are the HD pistons with upgraded pins. Stronger and better.

 

Only get the high compression pistons if you're going to be running E85 most of the time. Pump gas won't play well with the high compression..

 

So is high compression and 93 fine with a good, conservative tune? I've been researching pistons and rods and came across this before. I don't want to take his thread but it seems relevant. I run E85 nearly all the time but like the option to run 93.

 

I will be fine as long as your wastegate is capable of pretty low boost.