gapless rings or not?
gapless rings or not? So I've decided to do a little more research on gapless rings and their benefits, or lack thereof. I bought a set for my daily driver stroker build and was advised not to use them by my engine builder. But being one not to just take the advise of only one person (and to satisfy my own curiosity), I'm hoping to get some more insight here.
Who here has experience with the total seal gapless second rings specifically? I've read mixed reviews (and gotten negative feedback from my engine builder), but I'm looking for technical insight into the subject from other engine builders or people running them....also links to tech articles, etc would be awesome. Reports of oil consumption problems, top ring control, or any other problems, if any, would help me a lot
Hopefully I can decide whether or not to use them....and any info is appreciated. Should I use them anyway?
-Josh
Who here has experience with the total seal gapless second rings specifically? I've read mixed reviews (and gotten negative feedback from my engine builder), but I'm looking for technical insight into the subject from other engine builders or people running them....also links to tech articles, etc would be awesome. Reports of oil consumption problems, top ring control, or any other problems, if any, would help me a lot
Hopefully I can decide whether or not to use them....and any info is appreciated. Should I use them anyway?
-Josh
Last edited by beast69camaro; May 5, 2007 at 02:35 AM.
In case it matters, the motor will be 11.6:1 SCR (~8.5:1 DCR w/ the cam I plan on running) on a 383 LT1. Shouldn't see over 6500 rpm, and it will be daily driven.
Rings are the Total Seal TS1 series, 1/16,1/16,3/16 plasma moly gapless second ring set
Rings are the Total Seal TS1 series, 1/16,1/16,3/16 plasma moly gapless second ring set
TECH Junkie
Joined: Dec 2005
Posts: 3,092
Likes: 11
From what I have seen it is a hit or miss proposition. I did not have good luck. My car was an oil burner. I know of another car that also consumed oil. On a third car they worked fine. The builder who did all three cars will not use them again.
On my latest rebuild I went with the standard file fit rings. Everything is great. From what I have seen most engine builders don't like them and there is no benefit from them over the standard rings. However I know of one engine builder who stands by them.
On my latest rebuild I went with the standard file fit rings. Everything is great. From what I have seen most engine builders don't like them and there is no benefit from them over the standard rings. However I know of one engine builder who stands by them.
Last edited by 1989GTA; May 12, 2007 at 05:53 PM.
Yeah. According to my engine builder, the problem with gapless second rings comes from a lack of pressure difference across the top ring. The lack of pressure difference, as I was told, is caused when the pressure on either side of the top ring reaches equilibrium (during the power stroke) because the second rings allow near zero bleed down. Without a pressure difference, the top rings aren't forced against the cylinder walls,don't seal and you lose top ring control in a running motor.
My only argument is that even at idle (~1000 rpm) there is less than .06 seconds for equilibrium to occur (assuming valve events at top and bottom dead center), and even less on a big cammed motor, and less still at higher rpm. I suppose one could argue that residual pressure could be built up between the top and bottom rings over the course of a few crank revolutions so that equilibrium is reached more easily. Even so, even for standard gapped rings, the ring gap on a warm running motor should be close to negligible, and still pose the same problems with hindering a pressure difference across the top ring.
Also, I'm not sure pressure difference across a ring for is necessary for it to seal. It seems more logical to me that so long as the ring is touching the wall (to create a pressure/force bias in the outward radial direction towards the cylinder walls), ANY pressure across the ring whether it be a difference or equilibrium would facilitate ring seal.
Has anyone else thought about this? Looking for other thoughts....or more experiences. Engine builders wanna chime in?
My only argument is that even at idle (~1000 rpm) there is less than .06 seconds for equilibrium to occur (assuming valve events at top and bottom dead center), and even less on a big cammed motor, and less still at higher rpm. I suppose one could argue that residual pressure could be built up between the top and bottom rings over the course of a few crank revolutions so that equilibrium is reached more easily. Even so, even for standard gapped rings, the ring gap on a warm running motor should be close to negligible, and still pose the same problems with hindering a pressure difference across the top ring.
Also, I'm not sure pressure difference across a ring for is necessary for it to seal. It seems more logical to me that so long as the ring is touching the wall (to create a pressure/force bias in the outward radial direction towards the cylinder walls), ANY pressure across the ring whether it be a difference or equilibrium would facilitate ring seal.
Has anyone else thought about this? Looking for other thoughts....or more experiences. Engine builders wanna chime in?
FormerVendor
Joined: Dec 2001
Posts: 2,444
Likes: 2
From: WWW.SPEEDINC.COM
I don't think that a gapless second ring makes much sense, especially since most run the second ring gap larger than the top to insure their is no trapped pressure which will unseat the top ring from it's land.
Even a gapless top ring, which makes much more sense probably isn't worth much, if anything considering a standard top gapped ring will have nearly no gap under running conditions anyway.
Even a gapless top ring, which makes much more sense probably isn't worth much, if anything considering a standard top gapped ring will have nearly no gap under running conditions anyway.
I agree that there are negligible top rings gaps on a hot running motor, but I still don't see how gapless second rings and a corresponding "trapped pressure" between the top and second rings would unseat the top rings, for the reason given in my last post.
Although the marketing of the "gapless" rings sounds good, I have to believe that with the r&d budgets of race teams looking for power, and OEM's looking for economy and reduced emmissions, that if there were any real benefit someone would be using them by now. That being said, I am still curious as to the exact physics of why they aren't any better.
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I bought Total Seal Gapless Top Rings with Napier Second Compression rings and standard tension oil rings for an iron block 408 stroker that I plan to assemble this summer for my truck (daily driver/tow vehicle). I did a good bit of research on this and like you got mixed results. Total Seal tech folks told me that most of the issues that people had experienced were related to not getting a good cylindrical hone (with a plate) and a proper finish on the cylinders. I still plan to use the gapless rings.
Steve
Steve
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TECH Apprentice
Joined: Jan 2002
Posts: 320
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From: Nottingham, Notts, England, UK
I've used gapless second rings on all my cosworth turbo engines. I use file fits and gap them to minimum tolerences and I've never had an issue. I'll always use them. Sometimes they may take a few miles to bed in but that's down to the driver being to gentle. My pistons are always custom and have an accumulator groove between 1st & second ring lands. Recently I heard from another piston supplier that I should fit the gapless ring in the top groove and I'm a bit concerned about this and have no information as to if this is a good or bad thing especially as I'm after 1000 hp. My usual supplier didn't have forgings to clear the reluctor ring hence my having to purchase elsewhere.
Boosted.
Boosted.
Staging Lane
Joined: Aug 2006
Posts: 91
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From: under the hood
I was in a seminar several years ago. I don't remember all the exact numbers, but have them if I ever need them..... according to Federal Mogul, when rings are gappped the old tradition way, where the second ring gap is slightly smaller than the top ring, the gas pressure above the top ring equalizes just beyond 90* ATDC on the power stroke..... I think the real number was 97*, and the top ring seal is lost or "blown". Then, when a gapless second ring is installed and the gasses get trapped between the top two rings, the top seal gets blown off at about 79* ATDC. When the second ring gap is increased to a size slightly bigger than the top gap, the pressures don't equalize until BDC...... 179-181* ATDC. Effectively applying more force for a longer time.
Now, I would typically think this is total hype trying to sell the Sealed Power brand rings, and to discredit Total Seals gapless rings..... but then they discussed a groove between the top and second ring. They claimed that the increase in volume between the rings allowing more time for the gasses to accumulate, allowing further crank rotation before the top ring seal gets blown.
That was nearly 10 years ago, and I can say that nearly all piston manufacturers, even the OEM's are putting in these grooves in now. This tends to make me believe in what F-M was saying.
On a personal note, I've only tried the gapless rings once...... before the seminar.... and that engine did not seem to run any better, nor control oil consumption better than any other engine I've ever built.
Gapless is not for me.
Now, I would typically think this is total hype trying to sell the Sealed Power brand rings, and to discredit Total Seals gapless rings..... but then they discussed a groove between the top and second ring. They claimed that the increase in volume between the rings allowing more time for the gasses to accumulate, allowing further crank rotation before the top ring seal gets blown.
That was nearly 10 years ago, and I can say that nearly all piston manufacturers, even the OEM's are putting in these grooves in now. This tends to make me believe in what F-M was saying.
On a personal note, I've only tried the gapless rings once...... before the seminar.... and that engine did not seem to run any better, nor control oil consumption better than any other engine I've ever built.
Gapless is not for me.
It's kind of hard to believe one ring manf. vs another with each one being biased to selling their own product. Ive been running C&A ZGS rings for the last ten years on almost every performance engine I build, NA, Blown, Turbo and nitrous, gasoline and alcohol. No sealing issues ever except losing ring tension due to overheating with a large dose of nitrous a few years ago. If I saw some independant data that said there was a "decent power gain" going back to conventional rings I would look at it. If there was a 10 horse power gain out of 1000 or more it wouldn't be worth the time for a tear down to put conventional rings in. I would say the opposite would be true too. If I had a good running gapped ring motor I would not tear it down to substitude ZGS's.
Like many I don't have the time to do a back to back comparison of gapless vs gapped other than a leak down test and looking for excessive blowby. The only thing I can say conclusively is the ZGS Leakdown is always lower then traditional gapped rings(assumming proper prep). This is something tangible that can be measured by anyone with a leak down gage. I haven't noticed any increase in blowby but I don't log crank case pressure. Not saying that these rings are an end all for all combinations but I have used them successfully on 500 to 1500 hp motors for 10 years with no percievable issues. Another benefit on alcohol motors is you get less contamination in your oil over time.
The following is a article that was done by Hot Rod on C&A ZGS rings.
http://www.hotrod.com/techarticles/c...ond_ring_test/
Like many I don't have the time to do a back to back comparison of gapless vs gapped other than a leak down test and looking for excessive blowby. The only thing I can say conclusively is the ZGS Leakdown is always lower then traditional gapped rings(assumming proper prep). This is something tangible that can be measured by anyone with a leak down gage. I haven't noticed any increase in blowby but I don't log crank case pressure. Not saying that these rings are an end all for all combinations but I have used them successfully on 500 to 1500 hp motors for 10 years with no percievable issues. Another benefit on alcohol motors is you get less contamination in your oil over time.
The following is a article that was done by Hot Rod on C&A ZGS rings.
http://www.hotrod.com/techarticles/c...ond_ring_test/
so I just found this article:
http://www.stockcarracing.com/techar..._rings_basics/
At first it didn't look like there was any new information, but then I read this:
"If the pressure between these rings equals or exceeds the pressure above the top ring, it can cause the top ring to lift off the bottom of the piston ring groove and lose contact with the sealing surfaces.....To keep inter-ring pressure from becoming a problem, the current trend is to create an easy escape path for the built-up pressure by gapping the second ring larger than the top ring. Another benefit is that because gas pressure is now directed downward toward the sump, any oil that has collected in the ring pack areas will go with it."
I hadn't considered in my first post that the top ring also seals on the bottom surface of the ring land. The above quote still doesn't explain top ring seal problems (I'm still holding to my original theory), but I see now how ring stability and oil control could be a problem. Suddenly gapless second rings seem like a dumb backward idea. I guess that's why total seal introduced gapless tops:
"At least one ring manufacturer--Total Seal--offers gapless rings. Traditionally, these gapless rings went in the second groove along with a conventional top ring, but ring technology refinements and the new thinking on ring sealing has led Total Seal to revise this installation scheme and introduce a new line of gapless top rings...."
I should have gotten gapless tops, lol.
http://www.stockcarracing.com/techar..._rings_basics/
At first it didn't look like there was any new information, but then I read this:
"If the pressure between these rings equals or exceeds the pressure above the top ring, it can cause the top ring to lift off the bottom of the piston ring groove and lose contact with the sealing surfaces.....To keep inter-ring pressure from becoming a problem, the current trend is to create an easy escape path for the built-up pressure by gapping the second ring larger than the top ring. Another benefit is that because gas pressure is now directed downward toward the sump, any oil that has collected in the ring pack areas will go with it."
I hadn't considered in my first post that the top ring also seals on the bottom surface of the ring land. The above quote still doesn't explain top ring seal problems (I'm still holding to my original theory), but I see now how ring stability and oil control could be a problem. Suddenly gapless second rings seem like a dumb backward idea. I guess that's why total seal introduced gapless tops:
"At least one ring manufacturer--Total Seal--offers gapless rings. Traditionally, these gapless rings went in the second groove along with a conventional top ring, but ring technology refinements and the new thinking on ring sealing has led Total Seal to revise this installation scheme and introduce a new line of gapless top rings...."
I should have gotten gapless tops, lol.
Originally Posted by Steve Bryant
I bought Total Seal Gapless Top Rings with Napier Second Compression rings and standard tension oil rings for an iron block 408 stroker that I plan to assemble this summer for my truck (daily driver/tow vehicle). I did a good bit of research on this and like you got mixed results. Total Seal tech folks told me that most of the issues that people had experienced were related to not getting a good cylindrical hone (with a plate) and a proper finish on the cylinders. I still plan to use the gapless rings.
Steve
Steve
Originally Posted by Steve Bryant
Thunder550,
When you have a chance to see how this works out, would you send me a PM.
Thanks,
Steve
When you have a chance to see how this works out, would you send me a PM.
Thanks,
Steve
FYI, my compression and leakdown test numbers looked great, so I don't think it's a ring problem, but you never know....
Looks like our builds are actually pretty similar. I used a Dragonslayer crank, compstar rods, some Diamond Racing 28cc dish pistons, and the TotalSeal gapless stainless top ring, napier second, and std tension oil ring. Currently I have TSP stage 2.5 LS6 heads, but I'm going back to stock 5.3 heads for a couple of reasons. I'll keep you posted.
TECH Junkie
Joined: Dec 2005
Posts: 3,092
Likes: 11
Here is a link to a discussion on total seal rings by some of the top engine builders in the country. You will read both pros and cons.
http://www.speedtalk.com/forum/viewt...tal+seal+rings
http://www.speedtalk.com/forum/viewt...tal+seal+rings
1989GTA, Thanks for the link. Interesting information.
Related to rings and filing them for the proper gap, here's a ring square and electric ring filer that I made https://ls1tech.com/forums/tools-fabrication/689961-homemade-ring-square-electric-filer.html. I like to make tools and I like to employ not shade tree approaches but what I prefer to call Tennessee Technology (in honor of my native state). This is a little off topic, but I thought some of you might find the link interesting.
Steve
Related to rings and filing them for the proper gap, here's a ring square and electric ring filer that I made https://ls1tech.com/forums/tools-fabrication/689961-homemade-ring-square-electric-filer.html. I like to make tools and I like to employ not shade tree approaches but what I prefer to call Tennessee Technology (in honor of my native state). This is a little off topic, but I thought some of you might find the link interesting.
Steve
As stated earlier, Ring Flutter happens quite a bit when getting into the gapless stuff. The info on speedtalk is very good as well. One of the funner boards to read. You can get the extra seal but I personaly have NEVER seen an improvement on the dyno on the numerous motors tested. But then again, we never run Gapless seconds......