- The piston is 87mm, which is 1mm greater compared to the typical 86mm, and the material is light-weight and strong A4032 solid aluminum alloy. The specified clearance of 0. Also, after you have taken these actions, you can also operate a bigger sump and oil pump to raise oiling. https://rb26motor92592.blogspothub.com/27848999/5-simple-techniques-for-used-rb26-engine