Because the 440 bore size is 4.320-0.070 larger than a standard-bore 426 Hemi-Hemi Conversion motors don't take off-the-shelf Hemi pistons. Arias offers several forged pistons with compression ratios ranging from 7.0 to 14.0:1. Our 9.8:1 slugs feature modest domes, large valve-relief notches, and Lovatt Akadize hard-anodized coating. Each 0.030-oversize piston (4.350 final size) weighs 830 grams with pin. The anodized coating is applied to all nonmachined surfaces for reduced friction.