I have a ring set by Perfect Circle, Nascar Products. Already know what the end gaps should be. Question I have is, should the end gaps be the same on the top ring and the lower ring? I'm reading mixed information on it.
It's usually better to have the second gap larger to prevent ring flutter caused by gasses that get past the first ring. Many new aftermarket pistons have a groove between the first and second ring that helps alleviate this problem. I also like to set my gaps a little larger than normally called for: .018-.020 top & .022-.024 second.
Well I gotta set it wider since I will be running forced induction. I think they said to put it at 0.024-0.026
The reason your getting so many opinions is because ring gap theory is based on many many factors such as, bore size, ring location on piston, ring material, piston material, the amount of compression or boost you plan on running. Keep in mind you dont have to run wider gap just because your running a supercharger. The intended use and amount of boost intended are going to influence your gap not the fact that its supercharged. Many people put supercharges on stock motors and never have problems. As mentioned running the second ring larger is usually good practice to keep pressure from building up causing ring flutter. On the other side of things, I cant say that I have ever seen ring flutter damage do due ring gap. In many cases its from a piston with wrong ring land clearances or from a builder who didnt check it prior to assembly.
Ring flutter doesn't damage the rings, it causes them to lose seal against the cylinder wall. Ring gaps can get really wide without affecting performance. Years ago one of the major ring producers (Federal Mogul?) did a series of dyno tests where they kept increasing the gaps between tests. They got up to .075" on both the first and second rings and saw no decrease in performance or increase in blowby. The exposed ring gap between the piston and wall is very small and things are happening so fast in a running engine. Bigger concern, especially with power adders, is gaps that are too tight and cause the ring ends to butt.
My post never said ring flutter damages the rings. It damages the piston ring lands gap over time not to be confused with piston ring end gap. Loss of compression is the result of ring flutter not the cause.
