I'm building a turbocharged VVT motor for my '94. I've looked through many posts and it seems like my issue is common amongst builders using Wiseco rings, the top ring pag is tighter then spec (as expected) and the 2nd ring is loose. Minimum ring gap specs per Weisco are 0.017" (top) and 0.019" (2nd) for my bore (bore x Weisco's gap constant).

Issue: my 2nd ring gap out of the package was 0.023" for all four 2nd rings in all 4 cylinders. I've talked with Weisco and they weren't the least bit concerned with the larger gap and kept telling me the calculations are minimum ring gaps.

Question: When is ring gap too large?

I've done a ton of reading, watched the hell out of YouTube, gone up and down forums and people always discuss minimum ring gaps but no one really addresses what maximum ring gap specs are.

 

.050 would be the limit for me, this is with used rings on a cheapo build.
On new stuff probably .030 for 100mm bore and smaller.
Big block American would be more.
Current thinking is to have top ring slightly tighter than bottom.
Ring gaps and piston to wall clearance is commonly sized at minimums.
Piston to bore clearance varies a bunch depending on intended use.
If it gets super hot you want more clearance.
Also if it gets super hot super fast (serious drag racing engine) you want even more...

 

Motor's to be used on a street driven autox/ time trial/ HPDE car. Additionally, engine was bored out to manufacturer's minimum bore clearance.

Assuming 0.030" is the largest ring gap that I'd want and the 2nd ring gap is larger than the top ring. What would be the maximum delta between top and 2nd ring gap? Example, if I run a minimal top ring gap of 0.017, would a 2nd ring gap of 0.025 or greater be an issue?

 

What was the temperature of the block and the rings when you checked end gaps?
IIRC a specific temp is stated for this measurement. I checked mine with the block at 25C (aka, room temp) to make sure.

 

Block and rings were at room temp. Outside temp that day was between 20-25C. Didn't actually measure block or ring temp before fitting but I was conscious that ambient temp would affect results.

 

2nd ring ALWAYS larger than top ring. The 2nd ring is much less important than the top ring. It's also much softer, so a small adjustment can end up with a big change. I believe I asked for .019 top, .021 bottom. I had one at .024 and didn't think twice about continuing assembly. The machine shop gapped the rings and were ~.002" average bigger than I requested. I chocked it up to measurement error and moved on. My point with this is that you may be looking into it a little too hard. Voted accordingly.

 

When I pulled my stock motor apart I think the gaps were like 1/10, a freaking tenth dooood. That thing didn't even smoke, it drank oil and had tons of blow by but still ran high 12's.