Piston ring help.

Need some help please.

This is a new build 4.187 TFX 7.0 match race motor. It was built with new sleeves, new Venolia pistons and Total seal rings. Stainless top, gap less second. Gaps are .03 top and .033 second. After my initial first couple of runs (3) I did a leakdown and all cylinders were less than 5%. Made another half dozen good runs and did another leak down and it was all over the place. Couple still less than 5, most around 25 and 1 at 40. I pulled the 40 cylinder and everything looked good. Rings were free, walls and piston were good. Installed a new ring set, check leakage and it was back to less than 5%. Made 3 runs and the leakage is back to 30%. The leakage is definatly through the rings. You thoughts please.

Thanks
Steve Timoszyk

 

Could I ask a favor also, I am interested in the issue here, could we keep the discussion on the board as well so I can learn from this. If I come accross this problem I would like to know how other may handle it.

Thanks
Corey

 

Are the ring gaps lined up after you take them apart?

 

Ring Problems

When you took off the set of bad rings, on the worst of the cylinders, did you notice if the rings still had the original wall tension or OD as when they were new in the box? Were they smaller OD than when originally installed? Did you hone the cylinders?
I just had some collapsed/pinched rings that had lost most if not all of the wall tension after about 10 runs. Some pistons had clamped/pinched the rings while some rings were free but lost tension. Laying flat on the table, they had about .050 gap instead of the
.500 they started out with. My rings were Hellfire in a 526 fuel headed hemi on alcohol with 40# boost and 26 timing.
Yes, please do keep the discussion on the board.

 

The gaps where not lined up. They were clocked pretty close to where they were originally set.

The Tension seamed the same as the new rings. I did not hone the cylinder.
26 degrease?

 

If they were, what would you conclude from this ?

 

The top ring seals by the pressure delta not so much spring pressure. Just like a rubber Oring or seal. Put a gapless in the second grove and guess what happens to your compression ring pressure delta? My Ross pistons have an accumulator gruve for just that purpose.

 

my engine builder who builds high end circit race car engines as well as my twin turbo hemis and is based at Based at Silverstone England ( the F1 centre of the world) insists the second ring gap MUST be larger than the top ring as previously said.. more or less

 

fcsteve69,

I run the same Total Seal ring package as you do at 23 psi boost with no problems. I see that your ring gaps are wider than the manufactures specs calls for. This ring package calls for the top ring to be 0.0045 times the bore and the second ring to be 0.0035 times the bore, which calculates to 0.019" and 0.015" respectively. Your gaps are considerably larger at 0.030" and 0.033". However, I would think your leakdown should stay the same if you are not getting the rings to hot to lose their tension.

The problem may be a combination of ring gaps and no cylinder honing?
Joe

 

Out of round cylinder if they are always lined up upon inspection. Other wise they rotate.

Blessings.........Ron

 

Hey Steve....anytime we get "leaky" it was either from detonation, pinching rind lands (but I don't think your abusing it that bad)? or sleeves that go outta round. When Brad quit selling us Dartons and tried pushing some kinda junk Chinese stuff on us...we had HUGE problems! Also we noticed when we switched from 4.375 bore to 4.467 (thinner sleeves) they didn't last near as long! Would go outta round rather quick

 

Yes, if the cylinders are out of round the rings rotate and somehow the ring gaps line up and stay lined up