Gapless Rings-Opinions 3

[cycle]

I tried these in a engine I built for racing. Leakdown was excellent,less than 2%.. But, at the time I had no dyno,hence no way to know (other than leakdown) if they were truly beneficial. Was it money wasted or well spent. I normally use a traditional steel alloy/moly top ring , a ferrox coated iron second.Have had very good luck with these also,but always looking for an edge..I am thinking about going with a Total Seal gapless design again,on a mountain motor /nitrous engine. Any experiences out there with these rings?? Street car,race,motorcycle??? Any replies much appreciated........ Craig

 

[sbc]

I've tried gapless rings too, with the same results
as posted here. Great cranking pressure & great on
a leak down test, but more blowby under operation.
I believe this is because air behind the ring needs
to breathe, especialy with tight groove clearances.
I've stoped gaping rings to the minimum, and found
some power there!

 

[evelrod]

sbc---I put the Mini back together with factory spec ring gap. NO extra effort on my part. I, like you, found equal or better perceived performance from the subsequent twincams using a bit wider gaps as supplied by Deves. (That record setting 1984 engine destroyed itself when the block cracked between the core plugs and I spun in the water, got it on video , though.)


Rod

 

[slowkaw]

This stuff really starts to make me think I don't know anything. Cycle and I just tore down my 1075cc Kawasaki, and found the piston-to-cylinder wall at .065" and ring end gap at .019". This engine took me to a 9.61 e.t.@136+mph run while driving through the clutch slightly. This weekend, I bored and honed another cyl. block at .015" and file-fit new rings @.012". The worst leakdown with the old set-up was 4%. After looking at the old rings under a lit magnifing glass, only the edges of the rings were shiny where there was contact with the cylinder wall. I'm hoping for some improvement and will let you all know if you like. After reading some of the previous posts, I am starting to wonder if all the effort is worth it in the long run. Any opinions?

David

 

[MaxRaceSoftware]

i guess i'm sort of from the "old-school" ..that is
i like to see static leakage at below 6 percent on
the engine stand and 2 to 4.5 CFM on the Blowby
..kind of like to have it both ways !!!

since NOS has made a big-impact on racing in last decade
i'm seeing racers coming to dyno with .025" to .027" ring end gaps and still getting 4 to 6 CFM Blowby levels

gaps that are .025" to .027" don't give you great "STATIC" leakdown numbers , but seem to be OK under full load , acceleration dyno testing, enough to get you 4 to
6 CFM blowby if the rest of the parts (Block,Pistons,etc)
are machined/assembled correctly

Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[slowkaw]

I made a big mistake when typing my clearance figures on my last post. I meant to say .0065" piston-to-cyl. clearance.

David

 

[MaxRaceSoftware]

Hey David ,...i knew you meant .0065" , and probably everyone else here too !

my typing isn't so great either ?


Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[cycle]

Something David failed to mention,Typical piston to wall clearance on forged pistons for us is .001 to .0015.. Ring end gap for his diameter piston/application is .008 to max .010.. You see his clearances were way big,yet this engine did not smoke,held leakdown to max of 4%!!Engine performed extremely well for it"s size and condition. His fear is that with a fresh bore in and fresh rings performance will actually diminish?? (I have seen stranger things happen.) A few more weeks of build time will tell.. ... Craig

 

[ShaunT]

I have had all of the ring sealing problems go away once I started final honing with a 280 grit and then brushing it 10 strokes, rather than using the traditional 400 grit and no brush. If you check the finish with a profilometer, you get about 15RAwith a 280 and about 6RA with a 400. The 15RA is what the ring manufacturers want today. You will see instant ring seating and they will last longer.

Shaun Tiede ULTRADYNE Arlington,TX

 

[EngJW]

In reference to the comments on ring unseating, I have heard some opinions (and seen at least one SAE paper) that claim the 2nd ring should have a larger gap than the top ring. The reason is to allow any trapped gas to escape through the 2nd ring gap in order to prevent unseating the top ring. It is a matter of the relationship of the pressure below the top ring to the pressure above it, and this varies throughout the cycle.

John Woodward

 

[evelrod]

This is a very old thread but since your a new member Shaun, I'll post to it again. I like what you have to say about camshaft design, in general but, my work is with DOHC and small I4 SI engines for sport car and vintage racing so some of the Chevy stuff is a little out in left field for me. I had Ron Isky do all my profilling successfully several years back (sometimes I got some wierd comments about what I am running them in). At any rate your welcome here and I hope you will continue to grace us with your expertise in cams.

No matter---to the point of "gapless 2nd rings". As stated last year(posts above)---don't like them. They cause problems with flutter that NEVER existed and lots of blowby at certain rpm. I went back to my old Deves with their wide gaps and all was ok once again. If they work for you, great but, I did not like the results I got.

Rod

 

[ShaunT]

EVELROD: Thanks for the extended invotation. I can design swing and follower cams, but the tooling to manufacture them is totally different from push rod cams. Hence I do not produce any. Is there anything I can do to get you out of left field on this cam lingo stuff?

Shaun Tiede

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[evelrod]

Yeah Shaun. Make me 23 again. That's when I raced an NHRA record class 283 SBC in Amarillo(Jack Moss Automotive).

I'll leave the V8 stuff to y'all and I'll stick to the DOHC and little four bangers. Their fast enough for me.

Rod

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