curious.. is it possible to figure compression ration from cyulinder pressure on a 318? when i did the math on mine when i did the heads i came out at 9.8:1 (which prolly means 9.4 with old rings/wore out ****) compression test is 150-160 on all.. saw a old forumula that said 14.5xCyl pressure=CR, but i can't see how a single forumla can work across different engines.. mine would be like 10.3 which is no way..