So I'm putting together a 6.0L LQ9. I'm reusing the factory hypereutectic pistons. I re-honed the cylinders so I bought new rings. I got a Hastings ring set with a plasma moly steel top ring and a ductile iron 2nd ring. I'm trying to gap these and the Hastings gap chart seems way bigger than any other info I can find on the internet. I understand that you need a little more gap with a hyper piston as apposed to a forged or cast, but this seems a little high to me. I'm running a 150 to 200 shot of nitrous on this motor. This is the chart right off there site.



So I have a 4.000 bore. That means they are recommending a 0.034" top ring gap and a 0.026" second ring gap. That seems very large on the top ring, Also I thought the 2nd ring gap was supposed to be larger than the top ring? Anyone have any incite? And yes I know nitrous can be hard on plasma moly rings. But being that this is a Holley controlled progressive shot on a street car the chances of detonation are very low. The tech at Hastings recommended these rings for my application once I told him how the nitrous will be controlled. But he also told me to look at this chart for my ring gap.

 

I hope this helps you (service manual LQ9).

Piston Rings

Piston Ring End Gap - First Compression Ring - Measured in Cylinder Bore - Production
0.31-0.52 mm
0.012-0.02 in

Piston Ring End Gap - First Compression Ring - Measured in Cylinder Bore - Service
0.31-0.59 mm
0.0122-0.023 in

Piston Ring End Gap - Second Compression Ring - Measured in Cylinder Bore - Production
0.51-0.77 mm
0.02-0.03 in

Piston Ring End Gap - Second Compression Ring - Measured in Cylinder Bore - Service
0.51-0.84 mm
0.02-0.033 in

Piston Ring End Gap - Oil Control Ring - Measured in Cylinder Bore - Production
0.31-0.87 mm
0.0122-0.034 in

Piston Ring End Gap - Oil Control Ring - Measured in Cylinder Bore - Service
0.31-0.94 mm
0.0122-0.037 in

Piston Ring to Groove Clearance - First Compression Ring - Production
0.035-0.08 mm
0.0014-0.0031 in

Piston Ring to Groove Clearance - First Compression Ring - Service
0.035-0.08 mm
0.0014-0.0031 in

Piston Ring to Groove Clearance - Second Compression Ring - Production
0.034-0.079 mm
0.0013-0.003 in

Piston Ring to Groove Clearance - Second Compression Ring - Service
0.034-0.079 mm
0.0013-0.003 in

Piston Ring to Groove Clearance - Oil Control Ring - Production
0.012-0.2 mm
0.00047-0.00078 in

Piston Ring to Groove Clearance - Oil Control Ring - Service

 

Thank you! This is a big help. Looking at this if I'm understanding it the upper limit on a stock rebuild for the top ring is 0.023 and the 2nd is 0.030. So I guess me going 0.034 on a top ring and 0.026 on the 2nd ring isn't that big of a deal. I didn't realize that the gaps opened up this much using hyper pistons. This is the first rebuild I have ever done with hyper pistons. Everything before either in a car or ATV was forged. So these gaps just looked strange to me.