I am going to be running a 3.905 Mahle piston in my LS1 and was wondering what my ring gaps should be. I'm planning on running a 200 shot through my nozzle and a 250 when I pick up a plate.

These are the power pack pistons that come with pins and rings. The ring thickness is 1.5, 1.5, 3.0 if that matters. Not sure if it matters also but I'm switching to a 243 milled to a 59cc chamber and the calculated compression is approx. 10.8 with the pistons.

 

I found a pdf on Mahle ring gaps and from that they say nitrous up to 200hp is 1st .0060 and 2nd .0050 making them .023/.020.
For 200hp and up its .0070 for 1st and 2nd rings. Making my gap .027 for both. Any thoughts? I though generally you want your 2nd ring gap bigger than the first

 

when in doubt, contact the manufacturer.

 

.006" per inch seems a little excessive, but it shouldn't really hurt. Usually I gap them at about .004-.005" per inch for NA and mild power adders. I always make the second ring gap larger than the top.

 

That's what I've read about the top ring gap.


I will probably do that in the next day or so.

 

.022" primary
.028" secondary
you want to bleed off inter ring pressure to minimize flutter...an air pump pays huge on NOS combos
BTW juice dramatically increases pressure............

 

Are you talking about cylinder pressure?

 

Yes. Some cylinder pressure is going to make it past the top ring gap. If the second ring gap is smaller, there's a good chance that pressure will get trapped between the two rings and unseat them, causing poor ring seal, further compounding the problem.

 

Interesting info, I wouldn't have known that.

 

Intyer ring pressure will flutter and unseat the rins which diminishes ring seal.
Even the factory reverse gaps the rings to help with this effect as then the primary ring will press into (seal) against the cylinder wall for a greater number of crankshaft degrees of rotation passed top dead center.....essentially this helps magnify the piston KICK if you will.....less emissions to boot

 

What effect will gapping my ring for a 200-250 shot have on my N/A performance?