Until recently I had lived with an unsolved mystery all my adult life – at least I think so. Ask any mechanic whether piston ring gaps should be staggered when fitting new rings, and you’ll get one of two answers. Most mechanics, and practically all reference material, will say yes. My own feeling, based on what I think is common sense, and on a number of very convincing websites, is that it doesn’t really matter because rings rotate anyway. At anything over 3 000 r/min the fraction of a second that each stroke takes to complete is simply too small to allow any significant amount of gas to escape.
I recently mentioned this conundrum to an acquaintance and he put me into contact with a professor in mechanical engineering at one of our universities. He solved the mystery by comparing the gas leakage past the rings when the gaps are lined up and when the gaps are suitably staggered. The result was in favour of staggering the gaps and I was forced to change my opinion. What do you think?